WO2024192754A1 - 一种二次电池和电子装置 - Google Patents

一种二次电池和电子装置 Download PDF

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Publication number
WO2024192754A1
WO2024192754A1 PCT/CN2023/083311 CN2023083311W WO2024192754A1 WO 2024192754 A1 WO2024192754 A1 WO 2024192754A1 CN 2023083311 W CN2023083311 W CN 2023083311W WO 2024192754 A1 WO2024192754 A1 WO 2024192754A1
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WIPO (PCT)
Prior art keywords
secondary battery
electrolyte
battery according
positive electrode
present application
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PCT/CN2023/083311
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English (en)
French (fr)
Inventor
郑烨珍
周邵云
林孟衍
兰弟胜
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宁德新能源科技有限公司
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Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to PCT/CN2023/083311 priority Critical patent/WO2024192754A1/zh
Priority to CN202380012191.0A priority patent/CN117480657A/zh
Publication of WO2024192754A1 publication Critical patent/WO2024192754A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical technology, and in particular to a secondary battery and an electronic device.
  • secondary batteries have been widely used in electric vehicles, consumer electronics, energy storage devices and other fields, and have gradually become the mainstream batteries in the above fields due to their advantages such as high energy density and no memory effect.
  • the electric vehicle, power and energy storage industries have entered a stage of rapid development, providing broad application prospects for the use of secondary batteries.
  • the secondary batteries they form Due to the characteristics of lithium iron phosphate cathode materials, the secondary batteries they form have the characteristics of high safety performance, long service life, good high temperature performance, low cost, and green environmental protection, which have great advantages and good application prospects compared to other types of secondary batteries. Despite the above advantages, as the performance requirements for secondary batteries in fields such as power and energy storage are getting higher and higher, how to further improve the cycle performance, storage performance, and kinetic performance of lithium-ion batteries is still of great value.
  • the purpose of this application is to provide a secondary battery and an electronic device, so that the secondary battery has good cycle performance and storage performance, and also has excellent dynamic performance.
  • the specific technical solution is as follows:
  • the first aspect of the present application provides a secondary battery, which includes a positive electrode plate, a negative electrode plate and an electrolyte, wherein the electrolyte includes vinyl carbonate, and the mass percentage a of the vinyl carbonate is 0.1% to 3% based on the total mass of the electrolyte; the positive electrode plate includes a positive electrode active material, and the positive electrode active material includes a carbon element, and the mass percentage b of the carbon element is 0.5% to 6% based on the total mass of the positive electrode active material.
  • the electrolyte and positive electrode plate in the secondary battery provided by the present application meet the above characteristics, and can simultaneously improve the ion and electron conductivity of the secondary battery, and reduce the consumption rate of the electrolyte, so that the secondary battery has good cycle performance and storage performance, and also has excellent kinetic performance.
  • a is 0.1% to 2.5%, preferably 0.5% to 2.5%, more preferably 0.8% to 2.5%, and/or b is 0.5% to 5%, preferably 0.5% to 4.5%.
  • the ratio of a to b is 0.22 to 6.
  • the electrolyte further comprises a nitrogen-containing heterocyclic compound
  • the mass percentage c of the nitrogen-containing heterocyclic compound is 0.01% to 1% based on the total mass of the electrolyte.
  • the ratio of a to c is 2 to 60.
  • the cycle performance and storage performance of the secondary battery can be further improved.
  • the nitrogen-containing heterocyclic compound includes the following compound (Formula I) or (Formula II):
  • R1 , R2 and R3 are each independently selected from any one of substituted or unsubstituted C1 - C5 alkylene, substituted or unsubstituted C2 - C5 alkenylene, substituted or unsubstituted C2- C5 alkynylene, substituted or unsubstituted C3 - C5 alkenylene, and when substituted, the substituent is a halogen atom.
  • the electrolyte further comprises an isocyanate compound
  • the mass percentage d of the isocyanate compound is 0.01% to 2% based on the total mass of the electrolyte.
  • the ratio of a to d is 2 to 60.
  • the cycle performance and storage performance of the secondary battery can be further improved.
  • the isocyanate compound includes the following compound (Formula III) or (Formula IV):
  • the isocyanate compound includes at least one -NCO group, and R3 and R4 are each independently selected from a C1 to C7 hydrocarbon group or a C1 to C7 aromatic hydrocarbon group.
  • the electrolyte further comprises an anhydride compound
  • the mass percentage e of the anhydride compound is 0.01% to 2% based on the total mass of the electrolyte.
  • the ratio of a to e is 2 to 60. By regulating the ratio of a to e within the above range, the cycle performance and storage performance of the secondary battery can be further improved.
  • the anhydride compound includes at least one of maleic anhydride, dimethyl maleic anhydride, citraconic anhydride, glutaric anhydride, succinic anhydride, succinic anhydride, maleic anhydride, biphenyl anhydride, pyridine dianhydride, pyrazine dianhydride, 2,3-pyridine dianhydride, pyridine-3,4-dicarboxylic anhydride or 2,3-pyrazine dicarboxylic anhydride.
  • the electrolyte further comprises a silane compound, and based on the total mass of the electrolyte, the mass percentage content f of the silane compound is 0.01% to 2%.
  • the mass percentage content f of the silane compound is 0.01% to 2%.
  • the ratio of a to f is 2 to 60.
  • the silane compound includes at least one of tetramethyl divinyl disiloxane, maleic acid bis (trimethylsilyl) ester, diphenyl difluorosilane, heptamethyl disilazane, tetramethyl divinyl disiloxane, tetraethoxysilane, 2-cyanoethyl triethoxysilane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane or vinyl triethoxysilane.
  • the electrolyte further comprises a nitrogen-containing heterocyclic boron trifluoride complex
  • the mass percentage g of the nitrogen-containing heterocyclic boron trifluoride complex is 0.01% to 1% based on the total mass of the electrolyte.
  • the ratio of a to g is 2 to 60.
  • the cycle performance and storage performance of the secondary battery can be further improved.
  • the nitrogen-containing heterocyclic boron trifluoride complex includes at least one of boron trifluoride pyridine, boron trifluoride pyrazine, boron trifluoride pyridazine, 2-fluoropyridine boron trifluoride complex, boron trifluoride pyrimidine, boron trifluoride pyrrole, boron trifluoride pyrazole or boron trifluoride imidazole.
  • the positive electrode active material includes at least one of lithium iron phosphate or lithium manganese iron phosphate.
  • the second aspect of the present application provides an electronic device, which includes the secondary battery in any of the above embodiments. Therefore, the electronic device provided by the present application has good performance.
  • the present application provides a secondary battery and an electronic device, wherein the secondary battery comprises a positive electrode plate, a negative electrode plate and an electrolyte, wherein the electrolyte comprises vinyl carbonate, and the mass percentage a of vinyl carbonate is 0.1% to 3% based on the total mass of the electrolyte; the positive electrode plate comprises a positive electrode active material, and the positive electrode active material comprises a carbon element, and the mass percentage b of the carbon element is 0.5% to 6% based on the total mass of the positive electrode active material.
  • the secondary battery provided by the present application satisfies the above characteristics, can simultaneously improve the ion and electron conduction capabilities of the secondary battery, and reduce the consumption rate of the electrolyte, so that the secondary battery has good cycle performance and storage performance, and also has excellent kinetic performance.
  • lithium-ion batteries are used as an example of secondary batteries to explain the present application, but the secondary batteries of the present application are not limited to lithium-ion batteries.
  • the specific technical solution is as follows:
  • the first aspect of the present application provides a secondary battery, which includes a positive electrode plate, a negative electrode plate and an electrolyte, the electrolyte includes vinyl carbonate, and the mass percentage a of vinyl carbonate is 0.1% to 3% based on the total mass of the electrolyte; the positive electrode plate includes a positive electrode active material, the positive electrode active material includes carbon element, and the mass percentage b of the carbon element is 0.5% to 6% based on the total mass of the positive electrode active material.
  • carbon coating will increase the active reaction area of the positive electrode active material and the electrolyte, which will increase the side reactions.
  • Vinylene carbonate has a low oxidation potential and can form a film on the surface of the positive electrode active material at a faster rate, inhibiting the occurrence of side reactions of the positive electrode material and the electrolyte.
  • the secondary battery By adding a specific amount of vinylene carbonate to the secondary battery and the positive electrode active material containing a specific amount of carbon, the ion and electron conductivity of the secondary battery can be improved at the same time, and the consumption rate of the electrolyte can be reduced, so that the secondary battery has good cycle performance and storage performance, as well as excellent kinetic performance.
  • the mass percentage a of vinylene carbonate can be 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8%, 3% or a range consisting of any two of the above values.
  • a is 0.1% to 2.5%. More preferably, a is 0.5% to 2.5%. More preferably, a is 0.8% to 2.5%.
  • the mass percentage b of carbon element can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%. 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% or a range consisting of any two of the above values.
  • b is 0.5% to 5%. More preferably, b is 0.5% to 4.5%.
  • the mass percentage of vinylene carbonate is too low (for example, less than 0.1%), the protective film formed on the surface of the positive and negative electrodes is insufficient, and the interface side reactions and transition metal dissolution cannot be suppressed, and the secondary battery cycle performance and high-temperature storage performance are not significantly improved; when the mass percentage of vinylene carbonate is too high (for example, higher than 3%), the film formation impedance at the interface of the positive and negative electrodes is too large, which will lead to poor charge and discharge performance, especially poor charge and discharge performance at low temperatures.
  • a film can be polymerized on the positive electrode surface, and a stable solid electrolyte interface film can also be formed on the negative electrode interface, so that the secondary battery has good cycle performance and storage performance while also having excellent kinetic performance.
  • the secondary battery provided by the present application, wherein the electrolyte includes vinyl carbonate, and the positive electrode active material includes carbon element.
  • the vinyl carbonate has a high film-forming efficiency and can generate a high-quality electrolyte interface film on the surface of the positive electrode after carbon coating, thereby effectively protecting the interface; and the carbon coating can improve the ion conductivity of the positive electrode active material, thereby preventing the interface impedance from deteriorating.
  • the two work together to enable the secondary battery to have good cycle performance and storage performance while also having excellent kinetic performance.
  • the ratio of a to b represents the content of vinylene carbonate corresponding to the unit carbon content, and further represents the generation of the solid electrolyte interface film on the carbon coated on the positive electrode surface.
  • the ratio of a to b is 0.22 to 6.
  • the ratio of a to b can be 0.22, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6 or a range consisting of any two of the above values.
  • the positive electrode surface By regulating the ratio of a to b within the above range, not only can the positive electrode surface have a high-quality electrolyte interface film and reduce the electrolyte consumption rate, but also the interface impedance can be further taken into account without deterioration, so that the secondary battery has better cycle performance, storage performance and kinetic performance.
  • the electrolyte further comprises a nitrogen-containing heterocyclic compound
  • the mass percentage c of the nitrogen-containing heterocyclic compound is 0.01% to 1% based on the total mass of the electrolyte.
  • c can be 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1% or a range consisting of any two of the above values.
  • a stable solid electrolyte interface film can be formed on the negative electrode surface during the formation process, inhibiting the reduction and decomposition of other components in the electrolyte on the negative electrode surface, thereby improving the cycle performance of the secondary battery, while inhibiting gas production during storage and circulation.
  • a good positive electrode electrolyte interface film can also be formed at the positive electrode interface, inhibiting the decomposition and consumption of the electrolyte at the positive electrode, and the nitrogen-containing heterocyclic compound in the electrolyte can react with trace water or HF to remove trace water and HF in the electrolyte, reduce interface side reactions, and reduce the dissolution of positive electrode transition metals, thereby inhibiting gas production and improving cycle performance and safety performance.
  • the mass percentage c of the nitrogen-containing heterocyclic compound within the above range, a suitable negative electrode interface impedance and good charge and discharge performance can be obtained, and the electrolyte interface film on the positive and negative electrode surfaces can also be strengthened to improve the cycle performance of the secondary battery.
  • the ratio of a to c is 2 to 60.
  • the cycle performance and storage performance of the secondary battery can be further improved.
  • the nitrogen-containing heterocyclic compound includes the following compound (Formula I) or (Formula II):
  • R 1 , R 2 and R 3 are each independently selected from any one of substituted or unsubstituted C 1 -C 5 alkylene, substituted or unsubstituted C 2 -C 5 alkenylene, substituted or unsubstituted C 2 -C 5 alkynylene, substituted or unsubstituted C 3 -C 5 alkenylene, and when substituted, the substituent is a halogen atom.
  • the cycle performance and storage performance of the secondary battery can be further improved.
  • the electrolyte further includes an isocyanate compound
  • the mass percentage d of the isocyanate compound is 0.01% to 2% based on the total mass of the electrolyte.
  • d can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2% or a range consisting of any two of the above values. Since the isocyanate compound is active in nature and easily reacts with water, acid, etc., it can have a certain effect of removing water and acid.
  • the generation of HF in the electrolyte can be effectively reduced, and the dissolution of the positive transition metal can be reduced, thereby inhibiting gas production and improving cycle performance and safety performance.
  • the mass percentage d of the isocyanate compound within the above range, suitable negative electrode interface impedance and better charge and discharge performance can be obtained, and the electrolyte interface film on the positive and negative electrode surfaces can be strengthened to improve the cycle performance of the secondary battery.
  • the ratio of a to d is 2 to 60.
  • the cycle performance and storage performance of the secondary battery can be further improved.
  • the isocyanate compound includes the following compound (Formula III) or (Formula IV):
  • the isocyanate compound includes at least one -NCO group, and R3 and R4 are each independently selected from a C1 to C7 hydrocarbon group or a C1 to C7 aromatic hydrocarbon group.
  • the cycle performance and storage performance of the secondary battery can be further improved.
  • the electrolyte further includes an anhydride compound
  • the mass percentage e of the anhydride compound is 0.01% to 2% based on the total mass of the electrolyte.
  • e can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2% or a range consisting of any two of the above values.
  • the anhydride compound can neutralize the residual base groups on the surface of the positive electrode material and reduce the decomposition effect of the base on the carbonate solvent; in addition, the anhydride can also react with trace water in the secondary battery to generate organic acid substances, reduce the formation of strong acid and thus reduce its damage to the material. Therefore, the anhydride compound has the effect of improving high temperature performance and reducing battery gas production.
  • the cycle performance of the secondary battery can be improved, while suppressing gas generation during storage and circulation.
  • the ratio of a to e is 2 to 60. By regulating the ratio of a to e within the above range, the cycle performance and storage performance of the secondary battery can be further improved.
  • the anhydride compound includes at least one of maleic anhydride, dimethyl maleic anhydride, citraconic anhydride, glutaric anhydride, succinic anhydride, succinic anhydride, maleic anhydride, biphenyl anhydride, pyridine dianhydride, pyrazine dianhydride, 2,3-pyridine dianhydride, pyridine-3,4-dicarboxylic anhydride or 2,3-pyrazine dicarboxylic anhydride.
  • the electrolyte further comprises a silane compound
  • the mass percentage f of the silane compound is 0.01% to 2% based on the total mass of the electrolyte.
  • f can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2% or a range consisting of any two of the above values.
  • the silane compound can react with H2O or HF, and thus has good water removal and acid removal functions, blocking the continuous occurrence of subsequent side reactions, and this type of additive can also form a stable and low-impedance interface film at the interface, thereby improving the electrochemical performance of the secondary battery.
  • This type of additive can also form a stable and low-impedance interface film at the interface, thereby improving the electrochemical performance of the secondary battery.
  • the ratio of a to f is 2 to 60.
  • the silane compound includes at least one of tetramethyl divinyl disiloxane, maleic acid bis (trimethylsilyl) ester, diphenyl difluorosilane, heptamethyl disilazane, tetramethyl divinyl disiloxane, tetraethoxysilane, 2-cyanoethyl triethoxysilane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane or vinyl triethoxysilane.
  • the electrolyte further comprises a nitrogen-containing heterocyclic boron trifluoride complex
  • the mass percentage g of the nitrogen-containing heterocyclic boron trifluoride complex is 0.01% to 1% based on the total mass of the electrolyte.
  • g can be 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1% or a range consisting of any two of the above values.
  • the nitrogen-containing heterocyclic boron trifluoride complex contains two active functional groups, namely, Lewis acid -BF 3 and nitrogen-containing heterocyclic organic base.
  • the nitrogen-containing heterocyclic organic base part can not only neutralize the acidic substances in the electrolyte, but also coordinate with the transition metal ions in the electrolyte to inhibit the side reactions on the negative electrode surface; while -BF 3 is a boron-containing Lewis acid, which can act as an anion receptor, increase the dissociation degree of lithium salts and the migration of lithium ions, and reduce impedance.
  • the interfacial side reactions can be reduced, and the influence of transition metals on the negative electrode can be reduced, thereby improving the cycle and storage performance of the secondary battery.
  • a suitable negative electrode interface impedance and good charge and discharge performance can be obtained, and the electrolyte interface film on the positive and negative electrode surfaces can be strengthened to improve the cycle performance of the secondary battery.
  • the ratio of a to g is 2 to 60.
  • the cycle performance and storage performance of the secondary battery can be further improved.
  • the nitrogen-containing heterocyclic boron trifluoride complex includes at least one of boron trifluoride pyridine, boron trifluoride pyrazine, boron trifluoride pyridazine, 2-fluoropyridine boron trifluoride complex, boron trifluoride pyrimidine, boron trifluoride pyrrole, boron trifluoride pyrazole or boron trifluoride imidazole.
  • the electrolyte of the secondary battery of the present application also includes lithium salt and non-aqueous solvent.
  • the lithium salt may include various commonly used A lithium salt, such as at least one of LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , Li 2 SiF 6 , lithium bis(oxalatoborate) (LiBOB) or lithium difluoroborate.
  • the present application has no particular limitation on the concentration of the lithium salt in the electrolyte, as long as the purpose of the present application can be achieved.
  • the concentration of the lithium salt in the electrolyte is 0.4mol/L to 2mol/L, preferably, the concentration of the lithium salt in the electrolyte is 0.5mol/L to 1.2mol/L, and illustratively, the concentration of the lithium salt in the electrolyte can be 0.4mol/L, 0.6mol/L, 0.8mol/L, 1mol/L, 1.2mol/L, 1.4mol/L, 1.6mol/L, 1.8mol/L, 2mol/L or a range consisting of any two of the above values.
  • the present application has no particular restrictions on the non-aqueous solvent, as long as the purpose of the present application can be achieved, for example, it may include but is not limited to at least one of a carbonate compound, a carboxylate compound, an ether compound or other organic solvents.
  • the above-mentioned carbonate compound may include but is not limited to at least one of a linear carbonate compound, a cyclic carbonate compound or a fluorinated carbonate compound.
  • the above-mentioned linear carbonate compound may include but is not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC) or methyl ethyl carbonate (MEC).
  • the above-mentioned cyclic carbonate may include but is not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) or vinyl ethylene carbonate (VEC).
  • Fluorinated carbonate compounds may include but are not limited to at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate.
  • FEC fluoroethylene carbonate
  • the above-mentioned carboxylate compound may include but is not limited to at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decanolactone, valerolactone or caprolactone.
  • the above-mentioned ether compound may include but is not limited to at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include but are not limited to at least one of dimethyl sulfoxide, 1,2-dioxolane, cyclopentane, methyl cyclopentane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate or trioctyl phosphate.
  • the mass percentage of the non-aqueous solvent in the electrolyte may be 70% to 95%, for example, 70%, 75%, 80%, 85%, 90%, 95% or a range consisting of any two of the above values.
  • the secondary battery also includes a positive electrode plate, which includes a positive electrode collector and a positive electrode material layer disposed on at least one surface of the positive electrode collector.
  • a positive electrode plate which includes a positive electrode collector and a positive electrode material layer disposed on at least one surface of the positive electrode collector.
  • the above-mentioned "positive electrode material layer disposed on at least one surface of the positive electrode collector” means that the positive electrode material layer can be disposed on one surface of the positive electrode collector along the thickness direction of itself, or on two surfaces of the positive electrode collector along the thickness direction of itself.
  • the "surface” here can be the entire area of the positive electrode collector or a partial area of the positive electrode collector.
  • This application has no special restrictions, as long as the purpose of this application can be achieved.
  • This application has no special restrictions on the positive electrode collector, as long as the purpose of this application can be achieved.
  • it can include aluminum foil, aluminum alloy foil or a composite current collector (such as an aluminum-carbon composite current collector).
  • the positive electrode material layer includes a positive electrode active material, and the positive electrode active material of the present application may include at least one of lithium iron phosphate or lithium iron manganese phosphate.
  • the positive electrode active material of the present application may have a coating on the surface, or may be mixed with another compound having a coating.
  • the present application has no particular restrictions on the other compound, as long as the purpose of the present application can be achieved.
  • the other compound may be lithium nickel cobalt manganese oxide (such as common NCM811, NCM622, NCM523, NCM111), lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO 2 ), lithium manganate, lithium iron manganese phosphate or lithium titanate.
  • the above-mentioned coating may include an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element.
  • the coating element may include one or more of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As or Zr.
  • the present application has no particular restrictions on the method of applying the coating, as long as the purpose of the present application can be achieved, such as spraying, dipping.
  • the positive electrode material layer also includes a conductive agent and a binder.
  • the present application does not particularly limit the types of conductive agents and binders, as long as the purpose of the present application can be achieved.
  • the binder may include but is not limited to polyvinyl alcohol, hydroxypropyl cellulose, polyvinylidene fluoride, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin or nylon;
  • the conductive agent may include but is not limited to at least one of carbon-based materials, metal-based materials, conductive polymers or mixtures of the above substances.
  • carbon-based materials may include natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber or any combination thereof; metal-based materials may include metal powder, metal fiber, copper, nickel, aluminum, silver; conductive polymers may include polyphenylene derivatives.
  • the present application has no particular restrictions on the mass ratio of the positive electrode active material, the conductive agent, and the binder in the positive electrode material layer. Those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved.
  • the present application has no particular restrictions on the thickness of the positive electrode current collector and the positive electrode material layer, as long as the purpose of the present application can be achieved.
  • the thickness of the positive electrode current collector is 6 ⁇ m to 12 ⁇ m, and the thickness of the positive electrode material layer is 30 ⁇ m to 120 ⁇ m.
  • the present application has no particular restrictions on the thickness of the positive electrode plate, as long as the purpose of the present application can be achieved, for example, the thickness of the positive electrode plate is 50 ⁇ m to 150 ⁇ m.
  • the positive electrode plate may also include a conductive layer, which is located between the positive electrode current collector and the positive electrode material layer.
  • the composition of the conductive layer is not particularly limited, and it may be a conductive layer commonly used in the art.
  • the conductive layer includes a conductive agent and a binder.
  • the present application has no particular restrictions on the preparation process of the positive electrode active material, as long as the purpose of the present application can be achieved.
  • the positive electrode active material is prepared by the following method: Li 2 C 2 O 4 , FeC 2 O 4 ⁇ 2H 2 O, and NH 4 H 2 PO 4 are mixed according to the stoichiometric ratio of LiFePO 4 , and then dry-milled for 40 to 50 hours to obtain a precursor. A carbon source of different mass percentages is added to the obtained precursor, and wet-milled for 5 to 6 hours. The obtained solid-liquid mixture is dried on a spray dryer, and the dried powder is pre-sintered at 500° C. to 600° C.
  • the carbon source may include, but is not limited to, at least one of glucose, sucrose, graphite, or starch.
  • the present application has no particular restrictions on the method for regulating the carbon content in the positive electrode active material, as long as the purpose of the present application can be achieved.
  • the carbon content in the positive electrode active material generally increases with the increase in the content of different carbon sources added, such as glucose, etc., and the carbon content in the positive electrode active material can be adjusted by adjusting the content of the carbon source during the preparation process.
  • the secondary battery also includes a negative electrode plate, which includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.
  • the present application has no special restrictions on the negative electrode current collector, as long as the purpose of the present application can be achieved.
  • it can include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper or composite current collector, etc.
  • the negative electrode active material layer in the present application includes a negative electrode active material, a conductive agent and a binder.
  • the negative electrode active material of the present application may include natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, SiOx (0.5 ⁇ x ⁇ 1.6,), Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , spinel structure lithium titanate Li 4 Ti 5 O 12 , Li-Al alloy and metallic lithium, etc.
  • MCMB mesophase microcarbon beads
  • the present application has no particular restrictions on binders and There is no particular restriction on the type of conductive agent, as long as the purpose of the present application can be achieved.
  • the binder and the conductive agent may include but are not limited to at least one of the above substances.
  • the thickness of the negative electrode current collector and the negative electrode active material layer there is no particular restriction on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of the present application can be achieved.
  • the thickness of the negative electrode current collector is 6 ⁇ m to 10 ⁇ m, and the thickness of the negative electrode active material layer is 30 ⁇ m to 120 ⁇ m.
  • the thickness of the negative electrode sheet there is no particular restriction on the thickness of the negative electrode sheet, as long as the purpose of the present application can be achieved.
  • the thickness of the negative electrode sheet is 50 ⁇ m to 150 ⁇ m.
  • the negative electrode sheet may also include a conductive layer, which is located between the negative electrode current collector and the negative electrode active material layer.
  • the composition of the conductive layer is not particularly limited, and it may be a conductive layer commonly used in the art.
  • the conductive layer includes a conductive agent and a binder.
  • the secondary battery also includes a separator to separate the positive electrode plate and the negative electrode plate, prevent the internal short circuit of the secondary battery, allow the electrolyte ions to pass freely, and do not affect the electrochemical charge and discharge process.
  • the present application has no special restrictions on the separator, as long as the purpose of the present application can be achieved.
  • the material of the separator may include but is not limited to polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyesters (for example, polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex or aramid;
  • the type of separator may include at least one of a woven membrane, a non-woven membrane, a microporous membrane, a composite membrane, a rolled membrane or a spun membrane.
  • the isolation membrane may include a substrate layer and a surface treatment layer.
  • the substrate layer may be a non-woven fabric, a film or a composite film having a porous structure, and the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric or a polypropylene-polyethylene-polypropylene porous composite film may be used.
  • a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by a mixed polymer and an inorganic substance.
  • the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, for example, they may include at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the binder is not particularly limited, for example, it may be at least one of the above-mentioned binders.
  • the polymer layer contains polymers, and the polymer material includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly(vinylidene fluoride-hexafluoropropylene).
  • the secondary battery of the present application also includes a packaging bag for containing a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte, as well as other components known in the field of secondary batteries, and the present application does not limit the above-mentioned other components.
  • the present application does not specifically limit the packaging bag, and it can be a packaging bag known in the art, as long as it can achieve the purpose of the present application.
  • the secondary battery of the present application is not particularly limited, and may include any device that undergoes an electrochemical reaction.
  • the secondary battery may include, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
  • the preparation process of the secondary battery of the present application is well known to those skilled in the art, and there is no special limitation in the present application.
  • it may include but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and other operations as needed to obtain an electrode assembly of a winding structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain a secondary battery; or stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and then fixing the four corners of the entire stacked structure with tape to obtain an electrode assembly of a stacked structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain a secondary battery.
  • overcurrent protection elements, guide plates, etc. may also be placed in the packaging bag as needed to prevent the pressure inside the secondary battery from rising and overcharging and discharging.
  • the second aspect of the present application provides an electronic device, which includes the secondary battery in any of the above embodiments. Therefore, the electronic device provided by the present application has good performance.
  • the electronic device of the present application is not particularly limited, and it can be used for any electronic device known in the prior art.
  • the electronic device can include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.
  • the carbon content of the powder is directly tested using a carbon-sulfur analyzer.
  • the sheets in the coated area were cut into sheets, ultrasonically vibrated in a 100°C NMP bath for 48 hours, the current collector was removed, the remaining material was ground for 1 hour, washed and filtered 3 times to remove the colloid, and the remaining solid material was dried at 100°C for 8 hours, and the obtained powder was taken to test the carbon content using a carbon-sulfur analyzer.
  • the cycle performance of the lithium-ion battery at 60°C was tested.
  • the lithium-ion battery was placed in a 60°C constant temperature box and left to stand for 30 minutes to allow the lithium-ion battery to reach a constant temperature of 60°C.
  • the charge and discharge cycle steps were the same as the above-mentioned 45°C charge and discharge cycle steps.
  • the lithium-ion battery was transferred to a 25°C constant temperature box, left to stand for 60 minutes, discharged to 2.5V at a constant current of 1C, and the discharge capacity was recorded as the residual capacity C 1 ; then charged to 3.65V at a constant current of 1C, charged to 0.05C at a constant voltage, and then discharged to 2.5V at a constant current of 1C, and the discharge capacity was recorded as the recovery capacity C 2 .
  • the thickness of the lithium-ion battery tested was T 1 , the open circuit voltage, and the impedance.
  • the residual capacity retention rate and the recovery capacity retention rate of the lithium-ion battery were calculated according to the following formula as indicators for evaluating the 100% SOC high temperature storage performance of the lithium-ion battery.
  • the thickness of the lithium-ion battery tested is T 3 , open circuit voltage and impedance.
  • Severe lithium deposition is defined as obvious lithium deposition on the entire surface of the main body or the capacity retention rate after 10 cycles is less than 90%; moderate lithium deposition is defined as lithium deposition in local areas of the main body, corners, etc. or the capacity retention rate after 10 cycles is between 90% and 98%; slight lithium deposition is defined as lithium deposition only in the corners or the head and tail of the lithium-ion battery or the capacity retention rate after 10 cycles is between 98% and 99.5%; all positions are golden yellow, which is defined as no lithium deposition.
  • Li 2 C 2 O 4 , FeC 2 O 4 ⁇ 2H 2 O, and NH 4 H 2 PO 4 were prepared according to the stoichiometric ratio of LiFePO 4 , and then dry-milled for 40 hours to obtain a precursor. A certain amount of glucose was added to the obtained precursor, and wet-milled for 5 hours. The obtained solid-liquid mixture was dried on a spray dryer. The dried powder was pre-sintered at 500°C for 5 hours in a tube furnace under a N 2 protective atmosphere, and then continued to heat up to 600°C and sintered for 10 hours to obtain a LiFePO 4 sample containing 1.5% carbon. Among them, there will be a certain degree of carbon content loss during the sintering process in the N 2 atmosphere, which is about 50%.
  • the mass percentage of LiPF 6 was 12.5%
  • the mass percentage of vinylene carbonate was 0.1%
  • the mass percentage of the base solvent was 87.4%.
  • a porous polyethylene film with a thickness of 7 ⁇ m (provided by Celgard Company) was used.
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then wound to obtain an electrode assembly; the electrode assembly is placed in an outer packaging foil, and the moisture is removed at 80°C, and the prepared electrolyte is injected, and after vacuum packaging, standing, formation (0.02C constant current charging to 3.3V, and then 0.1C constant current charging to 3.6V), shaping, capacity testing and other processes, a soft-pack lithium-ion battery (thickness 3.3mm, width 39mm, length 96mm) is obtained.
  • the mass percentage of LiPF 6 was 12.5%
  • the mass percentage of vinylene carbonate was 2%
  • the mass percentage of pyridine was 0.01%
  • the mass percentage of the basic solvent was 85.49%.
  • Example 2-1 Except for adjusting the relevant preparation parameters in ⁇ Preparation of electrolyte> according to Table 3, the rest is the same as Example 2-1.
  • the mass percentage of LiPF 6 was 12.5%
  • the mass percentage of vinylene carbonate was 2%
  • the mass percentage of hexamethylene diisocyanate was 0.01%
  • the mass percentage of the base solvent was 85.49%.
  • Example 3-1 Except for adjusting the relevant preparation parameters in ⁇ Preparation of electrolyte> according to Table 5, the rest is the same as Example 3-1.
  • the mass percentage of LiPF 6 was 12.5%
  • the mass percentage of vinylene carbonate was 2%
  • the mass percentage of maleic anhydride was 0.01%
  • the mass percentage of the base solvent was 85.49%.
  • Example 4-1 Except for adjusting the relevant preparation parameters in ⁇ Preparation of electrolyte> according to Table 7, the rest is the same as Example 4-1.
  • the mass percentage of LiPF 6 was 12.5%
  • the mass percentage of vinylene carbonate was 2%
  • the mass percentage of tetramethyl divinyl disiloxane was 0.1%
  • the mass percentage of the base solvent was 85.4%.
  • Example 5-1 Except for adjusting the relevant preparation parameters in ⁇ Preparation of electrolyte> according to Table 9, the rest is the same as Example 5-1.
  • the mass percentage of LiPF 6 is The mass percentage of the raw material is 12.5%, the mass percentage of vinylene carbonate is 2%, the mass percentage of boron trifluoride pyridine is 0.01%, and the mass percentage of the basic solvent is 85.49%.
  • Example 6-1 Except for adjusting the relevant preparation parameters according to Table 11 in ⁇ Preparation of electrolyte>, the rest is the same as Example 6-1.
  • Example 1-1 Except for preparing the electrolyte according to the following method, the rest is the same as Example 1-1.
  • the mass percentage of LiPF 6 was 12.5%
  • the mass percentage of the basic solvent was 87.5%.
  • Table 1 Note: In Table 1, “/” indicates no relevant preparation parameters.
  • the lithium-ion battery in the examples of the present application has a longer 45°C cycle number and a 60°C cycle number, a lower 100% SOC high temperature storage thickness expansion rate and a 0% SOC high temperature storage thickness expansion rate, a higher 100% SOC high temperature storage residual capacity retention rate and a recovery capacity retention rate, and a lower DCR and lithium precipitation degree, which shows that the lithium-ion battery in the present application has a longer 45°C cycle number and a 60°C cycle number, a lower 100% SOC high temperature storage thickness expansion rate and a higher 100% SOC high temperature storage residual capacity retention rate and a recovery capacity retention rate, and a lower DCR and lithium precipitation degree.
  • the lithium-ion battery made of the supplied electrolyte and positive electrode active material has good cycle performance and storage performance as well as excellent
  • the obtained lithium-ion battery has a longer 45°C cycle number and 60°C cycle number, a lower 100% SOC high-temperature storage thickness expansion rate and 0% SOC high-temperature storage thickness expansion rate, and a higher 100% SOC high-temperature storage residual capacity retention rate and recovery capacity retention rate, which indicates that the lithium-ion battery prepared using the electrolyte provided in the present application can further improve the cycle performance and storage performance.
  • the obtained lithium-ion battery has a longer 45°C cycle number and 60°C cycle number, a lower 100% SOC high-temperature storage thickness expansion rate and 0% SOC high-temperature storage thickness expansion rate, and a higher 100% SOC high-temperature storage residual capacity retention rate and recovery capacity retention rate, which indicates that the lithium-ion battery prepared using the electrolyte provided in the present application can further improve the cycle performance and storage performance.
  • the obtained lithium-ion battery has a longer 45°C cycle number and 60°C cycle number, a lower 100% SOC high-temperature storage thickness expansion rate and 0% SOC high-temperature storage thickness expansion rate, and a higher 100% SOC high-temperature storage residual capacity retention rate and recovery capacity retention rate, which indicates that the lithium-ion battery prepared using the electrolyte provided in the present application can further improve the cycle performance and storage performance.
  • the obtained lithium-ion battery has a longer 45°C cycle number and 60°C cycle number, a lower 100% SOC high-temperature storage thickness expansion rate and 0% SOC high-temperature storage thickness expansion rate, a higher 100% SOC high-temperature storage residual capacity retention rate and recovery capacity retention rate, and a lower degree of lithium precipitation, which means that the lithium-ion battery prepared using the electrolyte provided by the present application has good cycle performance and storage performance while also having excellent kinetic performance.
  • the obtained lithium-ion battery has a longer 45°C cycle number and 60°C cycle number, a lower 100% SOC high-temperature storage thickness expansion rate and 0% SOC high-temperature storage thickness expansion rate, and a higher 100% SOC high-temperature storage residual capacity retention rate and recovery capacity retention rate, which indicates that the lithium-ion battery prepared using the electrolyte provided in the present application can further improve the cycle performance and storage performance.

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Abstract

本申请提供了一种二次电池和电子装置，二次电池包括正极极片、负极极片和电解液，电解液包括碳酸亚乙烯酯，基于电解液的总质量，碳酸亚乙烯酯的质量百分含量a为0.1％至3％；正极极片包括正极活性材料，正极活性材料包括碳元素，基于正极活性材料的总质量，碳元素的质量百分含量b为0.5％至6％。本申请提供的二次电池满足上述特征，使二次电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。

Description

一种二次电池和电子装置 技术领域
本申请涉及电化学技术领域，特别是涉及一种二次电池和电子装置。
背景技术
目前，二次电池已广泛应用于电动汽车、消费电子产品、储能装置等领域，并凭借其高能量密度、无记忆效应等优势逐渐成为上述领域的主流电池。尤其是电动汽车、动力和储能行业进入到了快速发展的阶段，为二次电池的运用提供了广阔的应用前景。
由于磷酸铁锂正极材料本身的特质，其构成的二次电池具有安全性能高、使用寿命长、高温性能好、成本低、绿色环保的特点，相对其他类型的二次电池具有较大的优势和良好的应用前景。尽管其具有上述优点，但随着动力和储能等领域对二次电池的性能要求越来越高，如何进一步提升锂离子电池的循环性能、存储性能和动力学性能依然具有重要的价值。
发明内容
本申请目的在于提供一种二次电池和电子装置，使二次电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。具体技术方案如下：
本申请的第一方面提供了一种二次电池，其包括正极极片、负极极片和电解液，所述电解液包括碳酸亚乙烯酯，基于所述电解液的总质量，所述碳酸亚乙烯酯的质量百分含量a为0.1％至3％；所述正极极片包括正极活性材料，所述正极活性材料包括碳元素，基于所述正极活性材料的总质量，所述碳元素的质量百分含量b为0.5％至6％。本申请提供的二次电池中的电解液和正极极片满足上述特征，可以同时提升二次电池的导离子和导电子能力，并降低电解液的消耗速率，使得二次电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。
在本申请的一些实施方案中，所述a为0.1％至2.5％，优选为0.5％至2.5％，更优选为0.8％至2.5％，和/或所述b为0.5％至5％，优选为0.5％至4.5％。通过调控a与b的值在上述范围内，能够进一步提高二次电池的循环性能、存储性能和动力学性能。
在本申请的一些实施方案中，所述a与b的比值为0.22至6。通过调控a与b的比值在上述范围内，不仅能够使得正极表面具有高质量的电解质界面膜，还能进一步兼顾界面阻抗不恶化，进一步提高二次电池的循环性能、存储性能和动力学性能。
在本申请的一些实施方案中，所述电解液还包括含氮杂环化合物，基于所述电解液的总质量，所述含氮杂环化合物的质量百分含量c为0.01％至1％。通过调控含氮杂环化合物的质量百分含量c在上述范围内，能够改善二次电池的循环性能。
在本申请的一些实施方案中，所述a与所述c的比值为2至60。通过调控a与c的比值在上述范围内，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述含氮杂环化合物包括以下化合物(式Ⅰ)或(式Ⅱ)：
其中，R1、R2和R3各自独立地选自经取代或未经取代的C1-C5亚烷基、经取代或未经取代的C2-C5亚烯基、经取代或未经取代的C2-C5亚炔基、经取代或未经取代的C3-C5亚连烯基中的任意一种，并且，当经取代时，取代基为卤素原子。通过选择上述范围内的含氮杂环化合物，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述电解液还包括异氰酸酯化合物，基于所述电解液的总质量，所述异氰酸酯化合物的质量百分含量d为0.01％至2％。通过调控异氰酸酯化合物的质量百分含量d在上述范围内，能够改善二次电池的循环性能。
在本申请的一些实施方案中，所述a与所述d的比值为2至60。通过调控a与d的比值在上述范围内，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述异氰酸酯化合物包括以下化合物(式Ⅲ)或(式Ⅳ)：
其中，所述异氰酸酯化合物包括至少一个-NCO基团，R3和R4各自独立地选自C1至C7的烃基或C1至C7的芳香烃基。通过选择上述范围内的异氰酸酯化合物，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述电解液还包括酸酐化合物，基于所述电解液的总质量，所述酸酐化合物的质量百分含量e为0.01％至2％。通过调控酸酐化合物的质量百分含量e在上述范围内，能够改善二次电池的循环性能。
在本申请的一些实施方案中，所述a与所述e的比值为2至60。通过调控a与e的比值在上述范围内，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述酸酐化合物包括马来酸酐、二甲基马来酸酐、柠康酐、戊二酸酐、丁二酸酐、片烯二酸酐、顺丁烯二酸酐、联苯酸酐、吡啶二酸酐、吡嗪二酸酐、2,3-吡啶二酸酐、吡啶-3,4-二羧酸酐或2,3-吡嗪二羧酸酐中的至少一种。通过选择上述范围内的酸酐化合物，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述电解液还包括硅烷化合物，基于所述电解液的总质量，所述硅烷化合物的质量百分含量f为0.01％至2％。通过调控硅烷化合物的质量百分含量f在上述范围内，能够改善二次电池的循环性能。
在本申请的一些实施方案中，所述a与所述f的比值为2至60。通过调控a与f的比值在上述范围内，能够进一步改善二次电池的循环性能、存储性能和动力学性能。
在本申请的一些实施方案中，所述硅烷化合物包括四甲基二乙烯基二硅氧烷、马来酸双(三甲硅烷)酯、二苯基二氟硅烷、七甲基二硅氮烷、四甲基二乙烯基二硅氧烷、四乙氧基硅烷、2-氰基乙基三乙氧基硅烷、1,3,5,7-四乙烯基-1,3,5,7-四甲基环四硅氧烷、2,4,6-三乙烯基-2,4,6-三甲基环三硅氧烷或乙烯基三乙氧基硅烷中的至少一种。通过选择上述范围内的硅烷化合物，能够进一步改善二次电池的循环性能、存储性能和动力学性能。
在本申请的一些实施方案中，所述电解液还包括含氮杂环三氟化硼络合物，基于所述电解液的总质量，所述含氮杂环三氟化硼络合物的质量百分含量g为0.01％至1％。通过调控含氮杂环三氟化硼络合物的质量百分含量g在上述范围内，能够改善二次电池的循环性能。
在本申请的一些实施方案中，所述a与所述g的比值为2至60。通过调控a与g的比值在上述范围内，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述含氮杂环三氟化硼络合物包括三氟化硼吡啶、三氟化硼吡嗪、三氟化硼哒嗪、2-氟吡啶三氟化硼配合物、三氟化硼嘧啶、三氟化硼吡咯、三氟化硼吡唑或三氟化硼咪唑中的至少一种。通过选择上述范围内的含氮杂环三氟化硼络合物，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述正极活性材料包括磷酸铁锂或磷酸锰铁锂中的至少一种。
本申请的第二方面提供了一种电子装置，其包括前述任一实施方案中的二次电池。因此，本申请提供的电子装置具有良好的使用性能。
本申请有益效果：
本申请提供了一种二次电池和电子装置，二次电池包括正极极片、负极极片和电解液，电解液包括碳酸亚乙烯酯，基于电解液的总质量，碳酸亚乙烯酯的质量百分含量a为0.1％至3％；正极极片包括正极活性材料，正极活性材料包括碳元素，基于正极活性材料的总质量，碳元素的质量百分含量b为0.5％至6％。本申请提供的二次电池满足上述特征，可以同时提升二次电池的导离子和导电子能力，并降低电解液的消耗速率，使二次电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，在以下内容中，以锂离子电池作为二次电池的例子来解释本申请，但是本申请的二次电池并不仅限于锂离子电池。具体技术方案如下：
本申请的第一方面提供了一种二次电池，其包括正极极片、负极极片和电解液，电解液包括碳酸亚乙烯酯，基于电解液的总质量，碳酸亚乙烯酯的质量百分含量a为0.1％至3％；正极极片包括正极活性材料，正极活性材料包括碳元素，基于正极活性材料的总质量，碳元素的质量百分含量b为0.5％至6％。
发明人研究发现，人们通常通过碳包覆来提升正极活性材料的导电子和导离子能力，然而碳包覆会导致正极活性材料和电解液的活性反应面积增加，使得副反应增加；而碳酸亚乙烯酯氧化电位低，能以较快的速率在正极活性材料表面成膜，抑制正极材料和电解液副反应的发生。通过在二次电池中添加特定含量的碳酸亚乙烯酯同时正极活性材料含有特定含量的碳元素，可以同时提升二次电池的导离子和导电子能力，并降低电解液的消耗速率，从而使二次电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。
具体地，碳酸亚乙烯酯的质量百分含量a可以为0.1％、0.2％、0.4％、0.5％、0.6％、0.8％、1％、1.2％、1.4％、1.6％、1.8％、2％、2.2％、2.4％、2.5％、2.6％、2.8％、3％或为上述任意两个数值组成的范围。优选地，a为0.1％至2.5％。更优选地，a为0.5％至2.5％。更优选地，a为0.8％至2.5％。碳元素的质量百分含量b可以为0.5％、1％、1.5％、2％、2.5％、 3％、3.5％、4％、4.5％、5％、5.5％、6％或为上述任意两个数值组成的范围。优选地，b为0.5％至5％。更优选地，b为0.5％至4.5％。当碳酸亚乙烯酯的质量百分含量过低时(例如低于0.1％)，正负极表面形成的保护膜不充分，无法抑制界面副反应及过渡金属溶出，二次电池循环性能和高温存储性能改善不明显；当碳酸亚乙烯酯的质量百分含量过高时(例如高于3％)，在正负极界面成膜阻抗过大，会导致充放电性能较差，尤其是低温下的充放电性能较差。当碳元素的质量百分含量过低时(例如低于0.5％)，会导致动力学性能较差；当碳元素的质量百分含量过高时(例如高于6％)，会导致循环性能和存储性能较差。通过调控电解液中碳酸亚乙烯酯和正极活性材料中碳元素的质量百分含量在本申请范围内，能够在正极表面聚合成膜，同时也在负极界面形成稳定的固体电解质界面膜，使二次电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。
本申请提供的二次电池，其中电解液包括碳酸亚乙烯酯，正极活性材料包括碳元素，通过调控碳酸亚乙烯酯和碳元素的质量百分含量在本申请范围内，碳酸亚乙烯酯成膜效率高，能够在包碳后的正极表面生成高质量的电解质界面膜，有效保护界面；且碳包覆能够提高正极活性材料的导离子能力，从而使界面阻抗不恶化，二者相互协同，使二次电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。
在本申请中，a与b的比值表示单位碳含量所对应的碳酸亚乙烯酯的含量，进一步表示正极表面包覆的碳上固体电解质界面膜的生成情况。在本申请的一些实施方案中，a与b的比值为0.22至6。具体地，a与b的比值可以为0.22、0.4、0.6、0.8、1、1.2、1.4、1.6、1.8、2、2.2、2.4、2.6、2.8、3、3.2、3.4、3.6、3.8、4、4.2、4.4、4.6、4.8、5、5.2、5.4、5.6、5.8、6或为上述任意两个数值组成的范围。通过调控a与b的比值在上述范围内，不仅能够使得正极表面具有高质量的电解质界面膜，降低电解液消耗速率，还能进一步兼顾界面阻抗不恶化，从而使二次电池具有较好的循环性能、存储性能和动力学性能。
在本申请的一些实施方案中，电解液还包括含氮杂环化合物，基于电解液的总质量，含氮杂环化合物的质量百分含量c为0.01％至1％。具体地，c可以为0.01％、0.05％、0.1％、0.15％、0.2％、0.25％、0.3％、0.35％、0.4％、0.45％、0.5％、0.55％、0.6％、0.65％、0.7％、0.75％、0.8％、0.85％、0.9％、0.95％、1％或为上述任意两个数值组成的范围。通过在电解液中加入含氮杂环化合物，能够在化成过程中在负极表面形成稳定的固体电解质界面膜，抑制电解液中其他组份在负极表面还原分解，从而提高二次电池的循环性能，同时抑制存储和循环过程中的产气。此外，也可以在正极界面形成良好的正极电解质界面膜，抑制电解液在正极的分解消耗，且电解液中的含氮杂环化合物能与痕量水或HF反应，清除电解液中的痕量水和HF，减少界面副反应，降低正极过渡金属的溶出，从而抑制产气、改善循环性能和安全性能。通过调控含氮杂环化合物的质量百分含量c在上述范围内，能够得到合适的负极界面阻抗和较好的充放电性能，还能够强化正负极表面的电解质界面膜，改善二次电池的循环性能。
在本申请的一些实施方案中，a与c的比值为2至60。通过调控a与c的比值在上述范围内，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，含氮杂环化合物包括以下化合物(式Ⅰ)或(式Ⅱ)：
其中，R1、R2和R3各自独立地选自经取代或未经取代的C1-C5亚烷基、经取代或未经取代的C2-C5亚烯基、经取代或未经取代的C2-C5亚炔基、经取代或未经取代的C3-C5亚连烯基中的任意一种，并且，当经取代时，取代基为卤素原子。
通过选择上述范围内的含氮杂环化合物，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，电解液还包括异氰酸酯化合物，基于电解液的总质量，异氰酸酯化合物的质量百分含量d为0.01％至2％。具体地，d可以为0.01％、0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1％、1.1％、1.2％、1.3％、1.4％、1.5％、1.6％、1.7％、1.8％、1.9％、2％或为上述任意两个数值组成的范围。由于异氰酸酯化合物性质活泼，容易与水、酸等反应，因此可以起到一定的除水除酸效果。通过在电解液中加入异氰酸酯化合物，可以有效减少电解液中HF的产生，降低正极过渡金属的溶出，从而抑制产气、改善循环性能和安全性能。通过调控异氰酸酯化合物的质量百分含量d在上述范围内，能够得到合适的负极界面阻抗和较好的充放电性能，还能够强化正负极表面的电解质界面膜，改善二次电池的循环性能。
在本申请的一些实施方案中，a与d的比值为2至60。通过调控a与d的比值在上述范围内，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，异氰酸酯化合物包括以下化合物(式Ⅲ)或(式Ⅳ)：
其中，异氰酸酯化合物包括至少一个-NCO基团，R3和R4各自独立地选自C1至C7的烃基或C1至C7的芳香烃基。
通过选择上述范围内的异氰酸酯化合物，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，电解液还包括酸酐化合物，基于所述电解液的总质量，所述酸酐化合物的质量百分含量e为0.01％至2％。具体地，e可以为0.01％、0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1％、1.1％、1.2％、1.3％、1.4％、1.5％、1.6％、1.7％、1.8％、1.9％、2％或为上述任意两个数值组成的范围。其中，酸酐化合物能够中和正极材料表面的残碱基团，减少碱对碳酸酯溶剂的分解作用；除此之外，酸酐还可以与二次电池中的痕量水反应，生成有机酸类物质，降低强酸的形成进而降低其对材料的破坏。因此酸酐类化合物具有提升高温性能、减少电池产气的效果。通过在电解液中加入酸酐化合物，能够提高二次电池的循环性能，同时抑制存储和循环过程中的产气。通过调控酸酐化合物的质量百分含量e在上述范围内，能够得到合适的负极界面阻抗和较好的充放电性能，还能够强化正负极表面的电解质界面膜，改善二次电池的循环性能。
在本申请的一些实施方案中，a与e的比值为2至60。通过调控a与e的比值在上述范围内，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，酸酐化合物包括马来酸酐、二甲基马来酸酐、柠康酐、戊二酸酐、丁二酸酐、片烯二酸酐、顺丁烯二酸酐、联苯酸酐、吡啶二酸酐、吡嗪二酸酐、2,3-吡啶二酸酐、吡啶-3,4-二羧酸酐或2,3-吡嗪二羧酸酐中的至少一种。通过选择上述范围内的酸酐化合物，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，电解液还包括硅烷化合物，基于电解液的总质量，硅烷化合物的质量百分含量f为0.01％至2％。具体地，f可以为0.01％、0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1％、1.1％、1.2％、1.3％、1.4％、1.5％、1.6％、1.7％、1.8％、1.9％、2％或为上述任意两个数值组成的范围。硅烷化合物可以与H2O或HF发生反应，因而具有较好的除水、除酸功能，阻断后续副反应的持续发生，并且该类添加剂也能在界面形成稳定且低阻抗的界面膜，从而改善二次电池的电化学性能。通过调控硅烷化合物的质量百分含量f在上述范围内，有利于碳酸亚乙烯酯成膜，提高成膜致密性，强化正负极表面的电解质界面膜，除水除酸效果较好，改善二次电池的循环性能。
在本申请的一些实施方案中，a与f的比值为2至60。通过调控a与f的比值在上述范围内，能够进一步改善二次电池的循环性能、存储性能和动力学性能。
在本申请的一些实施方案中，硅烷化合物包括四甲基二乙烯基二硅氧烷、马来酸双(三甲硅烷)酯、二苯基二氟硅烷、七甲基二硅氮烷、四甲基二乙烯基二硅氧烷、四乙氧基硅烷、2-氰基乙基三乙氧基硅烷、1,3,5,7-四乙烯基-1,3,5,7-四甲基环四硅氧烷、2,4,6-三乙烯基-2,4,6-三甲基环三硅氧烷或乙烯基三乙氧基硅烷中的至少一种。通过选择上述范围内的硅烷化合物，能够进一步改善二次电池的循环性能、存储性能和动力学性能。
在本申请的一些实施方案中，电解液还包括含氮杂环三氟化硼络合物，基于电解液的总质量，含氮杂环三氟化硼络合物的质量百分含量g为0.01％至1％。具体地，g可以为0.01％、0.05％、0.1％、0.15％、0.2％、0.25％、0.3％、0.35％、0.4％、0.45％、0.5％、0.55％、0.6％、0.65％、0.7％、0.75％、0.8％、0.85％、0.9％、0.95％、1％或为上述任意两个数值组成的范围。含氮杂环三氟化硼络合物中包含了路易斯酸-BF3和含氮杂环有机碱两种活性官能团，其中，含氮杂环有机碱部分不仅可以中和电解液中的酸性物质，还能与电解液中的过渡金属离子配位，抑制其在负极表面发生副反应；而-BF3则是含硼路易斯酸，可作为阴离子受体，可以提高锂盐的解离度及锂离子的迁移，降低阻抗。通过在电解液中加入含氮杂环三氟化硼络合物能够减少界面副反应，降低过渡金属对负极的影响，从而提高二次电池的循环及存储性能。通过调控含氮杂环三氟化硼络合物的质量百分含量g在上述范围内，能够得到合适的负极界面阻抗和较好的充放电性能，还能够强化正负极表面的电解质界面膜，改善二次电池的循环性能。
在本申请的一些实施方案中，a与g的比值为2至60。通过调控a与g的比值在上述范围内，能够进一步改善二次电池的循环性能和存储性能。
在本申请的一些实施方案中，所述含氮杂环三氟化硼络合物包括三氟化硼吡啶、三氟化硼吡嗪、三氟化硼哒嗪、2-氟吡啶三氟化硼配合物、三氟化硼嘧啶、三氟化硼吡咯、三氟化硼吡唑或三氟化硼咪唑中的至少一种。通过选择上述范围内的含氮杂环三氟化硼络合物，能够进一步改善二次电池的循环性能和存储性能。
本申请的二次电池的电解液中还包括锂盐和非水溶剂。锂盐可以包括本领域常用的各 种锂盐，例如LiPF6、LiBF4、LiAsF6、LiClO4、LiB(C6H5)4、LiCH3SO3、LiCF3SO3、LiN(SO2CF3)2、LiC(SO2CF3)3、Li2SiF6、双草酸硼酸锂(LiBOB)或二氟硼酸锂中的至少一种。本申请对锂盐在电解液中的浓度没有特别限制，只要能实现本申请的目的即可。例如，锂盐在电解液中的浓度为0.4mol/L至2mol/L，优选地，锂盐在电解液中的浓度为0.5mol/L至1.2mol/L，示例性地，锂盐在电解液中的浓度可以为0.4mol/L、0.6mol/L、0.8mol/L、1mol/L、1.2mol/L、1.4mol/L、1.6mol/L、1.8mol/L、2mol/L或为上述任意两个数值组成的范围。本申请对非水溶剂没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。上述环状碳酸酯可以包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、1-乙氧基-1-甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯或磷酸三辛酯中的至少一种。电解液中上述非水溶剂的质量百分含量可以为70％至95％，例如可以为70％、75％、80％、85％、90％、95％或为上述任意两个数值组成的范围。
在本申请中，二次电池还包括正极极片，正极极片包括正极集流体以及设置于正极集流体至少一个表面上的正极材料层。上述“设置于正极集流体至少一个表面上的正极材料层”是指，正极材料层可以设置于正极集流体沿自身厚度方向上的一个表面上，也可以设置于正极集流体沿自身厚度方向上的两个表面上。需要说明，这里的“表面”可以是正极集流体的全部区域，也可以是正极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。本申请对正极集流体没有特别限制，只要能够实现本申请目的即可，例如，可以包含铝箔、铝合金箔或复合集流体(例如铝碳复合集流体)等。
正极材料层包括正极活性材料，本申请的正极活性材料可以包含磷酸铁锂或磷酸锰铁锂中的至少一种。本申请的正极活性材料可以在表面上具有涂层，也可以与具有涂层的另一化合物混合。本申请对另一化合物没有特别限制，只要能够实现本申请目的即可，例如，另一化合物可以为镍钴锰酸锂(例如常见的NCM811、NCM622、NCM523、NCM111)、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂(LiCoO2)、锰酸锂、磷酸锰铁锂或钛酸锂中的至少一种。上述涂层可以包括涂覆元素的氧化物、涂覆元素的氢氧化物、涂覆元素的羟基氧化物、涂覆元素的碳酸氧盐(oxycarbonate)或涂覆元素的羟基碳酸盐 (hydroxycarbonate)中的至少一种。上述化合物可以是非晶的或结晶的。上述涂覆元素可以包括Mg、Al、Co、K、Na、Ca、Si、Ti、V、Sn、Ge、Ga、B、As或Zr中的一种或多种。本申请对施加涂层的方法没有特别限制，只要能够实现本申请目的即可，例如喷涂、浸渍。
正极材料层还包括导电剂和粘结剂，本申请对导电剂和粘结剂的种类没有特别限制，只要能够实现本申请目的即可，例如，粘结剂可以包括但不限于聚乙烯醇、羟丙基纤维素、聚偏二氟乙烯、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙中的至少一种；导电剂可以包括但不限于基于碳的材料、基于金属的材料、导电聚合物或上述物质的混合物中的至少一种。示例性地，基于碳的材料可以包括天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合；基于金属的材料可以包括金属粉、金属纤维、铜、镍、铝、银；导电聚合物可以包括聚亚苯基衍生物。本申请对正极材料层中正极活性材料、导电剂、粘结剂的质量比没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。本申请对正极集流体和正极材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极集流体的厚度为6μm至12μm，正极材料层的厚度为30μm至120μm。本申请对正极极片的厚度没有特别限制，只要能够实现本申请目的即可，例如，正极极片的厚度为50μm至150μm。任选地，所述正极极片还可以包含导电层，所述导电层位于正极集流体和正极材料层之间。所述导电层的组成没有特别限制，可以是本领域常用的导电层。所述导电层包括导电剂和粘结剂。
本申请对正极活性材料的制备过程没有特别限制，只要能实现本申请目的即可。在一种示例中，正极活性材料通过如下方法制备：将Li2C2O4、FeC2O4·2H2O、NH4H2PO4按LiFePO4的化学计量比配料，然后干磨40h至50h得到前驱体。在获得的前驱体中加入不同质量百分含量的碳源，湿磨5h至6h，得到的固-液混合物在喷雾干燥机上干燥，干燥后的粉末在N2保护气氛下于管式炉中500℃至600℃下预烧结5h至7h，然后继续升温，在600℃至700℃下烧结10h至12h，得到含碳的LiFePO4样品。碳源可以包括但不限于葡糖糖、蔗糖、石墨或淀粉中的至少一种。
本申请对调控正极活性材料中碳元素含量的方法没有特别限制，只要能实现本申请目的即可。例如，正极活性材料中碳元素含量通常随加入的不同碳源的含量如葡萄糖等的含量的增加而增加，可以通过在制备过程中调整碳源的含量，从而调整正极活性材料中碳元素含量。
在本申请中，二次电池还包括负极极片，负极极片包含负极集流体及设置于负极集流体的至少一个表面上的负极活性材料层。本申请对负极集流体没有特别限制，只要能够实现本申请目的即可，例如，可以包含铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体等。本申请中的负极活性材料层包括负极活性材料、导电剂和粘结剂。本申请的负极活性材料可以包括天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳、软碳、硅、硅-碳复合物、SiOx(0.5<x<1.6，)、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO2、尖晶石结构的钛酸锂Li4Ti5O12、Li-Al合金及金属锂等中的至少一种。本申请对粘结剂和 导电剂的种类没有特别限制，只要能够实现本申请目的即可，例如，粘结剂和导电剂可以包括但不限于上述物质中的至少一种。在本申请中，对负极集流体和负极活性材料层的厚度没有特别限制，只要能够实现本申请目的即可，例如，负极集流体的厚度为6μm至10μm，负极活性材料层的厚度为30μm至120μm。在本申请中，对负极极片的厚度没有特别限制，只要能够实现本申请目的即可，例如，负极极片的厚度为50μm至150μm。任选地，所述负极极片还可以包含导电层，所述导电层位于负极集流体和负极活性材料层之间。所述导电层的组成没有特别限制，可以是本领域常用的导电层。所述导电层包括导电剂和粘结剂。
本申请中，二次电池还包括隔离膜，用以分隔正极极片和负极极片，防止二次电池内部短路，允许电解质离子自由通过，且不影响电化学充放电过程的进行。本申请对隔离膜没有特别限制，只要能够实现本申请目的即可。例如，隔离膜的材料可以包括但不限于聚乙烯(PE)、聚丙烯(PP)为主的聚烯烃(PO)类、聚酯(例如，聚对苯二甲酸二乙酯(PET)膜)、纤维素、聚酰亚胺(PI)、聚酰胺(PA)、氨纶或芳纶中的至少一种；隔离膜的类型可以包括织造膜、非织造膜、微孔膜、复合膜、碾压膜或纺丝膜中的至少一种。
例如，隔离膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。例如，无机物层包括无机颗粒和粘结剂，所述无机颗粒没有特别限制，例如可以包括氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。所述粘结剂没有特别限制，例如可以是上述粘结剂中的至少一种。聚合物层中包含聚合物，聚合物的材料包括聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚或聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。
本申请的二次电池还包括包装袋，用于容纳正极极片、隔离膜、负极极片和电解液，以及二次电池领域中已知的其它部件，本申请对上述其它部件不做限定。本申请对包装袋没有特别限制，可以为本领域公知的包装袋，只要能够实现本申请目的即可。
本申请的二次电池没有特别限定，其可以包括发生电化学反应的任何装置。在一些实施例中，二次电池可以包括但不限于锂金属二次电池、锂离子二次电池(锂离子电池)、锂聚合物二次电池或锂离子聚合物二次电池等。
本申请的二次电池的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，可以包括但不限于以下步骤：将正极极片、隔离膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装袋内，将电解液注入包装袋并封口，得到二次电池；或者，将正极极片、隔离膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入包装袋内，将电解液注入包装袋并封口，得到二次电池。此外，也可以根据需要将防过电流元件、导板等置于包装袋中，从而防止二次电池内部的压力上升、过充放电。
本申请的第二方面提供了一种电子装置，其包括前述任一实施方案中的二次电池。因此，本申请提供的电子装置具有良好的使用性能。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
碳元素含量测试：
对于正极活性材料粉末，直接采用碳硫分析仪测试粉末的碳元素含量。
对于制备好的正极极片或从锂离子电池中拆下的正极极片，将涂布区域的极片剪成片状，在100℃NMP浴中超声振动48h后，取走集流体，将其余物质研磨1h，洗涤过滤3次，去除胶状物，将其余的固体物质在100℃下烘干8h后，取所得粉末采用碳硫分析仪测试碳元素含量。
循环性能测试：
将锂离子电池置于45℃恒温箱中，静置30min，使锂离子电池达到恒温45℃。将锂离子电池以1C恒流充电至3.65V，然后以3.65V恒压充电至0.05C，接着以1C恒流放电至2.5V，此为一个充放电循环。以首次放电的容量为100％，反复进行充放电循环，至放电容量衰减至70％时，停止测试，记录循环圈数，作为评价锂离子电池循环性能的指标。
同时测试锂离子电池在60℃的循环性能，将锂离子电池置于60℃恒温箱中，静置30min，使锂离子电池达到恒温60℃，充放电循环工步同上述45℃的充放电循环工步。
100％荷电状态(SOC)高温存储测试：
将锂离子电池置于25℃恒温箱中，静置30min，使锂离子电池达到恒温25℃。以1C恒流充电至3.65V，恒压充电至0.05C，然后以1C恒流放电至2.5V，记录放电容量为初始容量C0。之后以0.5C恒流充电至3.65V，恒压充电至0.05C，用千分尺测试并记录电池的厚度T0。将锂离子电池转至60℃恒温箱中存储90天，期间每隔30天测试并记录一次电池厚度，然后将锂离子电池转移至25℃恒温箱中，静置60min，以1C恒流放电至2.5V，记录放电容量为剩余容量C1；再以1C恒流充电至3.65V，恒压充电至0.05C，然后以1C恒流放电至2.5V，记录放电容量为恢复容量C2，测试锂离子电池的厚度为T1、开路电压和阻抗。按照下式计算锂离子电池的剩余容量保持率和恢复容量保持率，作为评价锂离子电池100％SOC高温存储性能的指标。
100％SOC高温存储厚度膨胀率＝(T1-T0)/T0×100％；
100％SOC高温存储剩余容量保持率＝C1/C0×100％；
100％SOC高温存储恢复容量保持率＝C2/C0×100％。
0％SOC高温存储测试：
将锂离子电池置于25℃恒温箱中，静置30min，使锂离子电池达到恒温25℃。以1C恒流充电至3.65V，恒压充电至0.05C，然后以1C恒流放电至2.5V，记录放电容量为初始容量C3。用千分尺测试并记录电池的厚度T2。将锂离子电池转至60℃恒温箱中存储90天，期间每隔30天测试并记录一次电池厚度，然后将锂离子电池转移至25℃恒温箱中，静置60min，以1C恒流充电至3.65V，恒压充电至0.05C，然后以1C恒流放电至2.5V，记录放电容量为恢复容量C4，测试锂离子电池的厚度为T3、开路电压和阻抗。按照下式计算锂离子电池的厚度膨胀率，并作为评价锂离子电池0％SOC高温存储性能的指标。
0％SOC高温存储厚度膨胀率＝(T3-T2)/T2×100％。
直流阻抗(DCR)测试：
将锂离子电池在0℃高低温箱中静置4h；以0.1C恒流充电至3.65V，恒压充电至0.05C，静置10min；再以0.1C恒流放电至2.5V，静置10min；再以0.1C恒流充电至3.65V，恒压充电至0.05C；静置10min；再以0.1C恒流放电3h；然后以1C恒流放电1s；计算锂离子电池70％SOC状态对应的直流阻抗。
充电性能测试：
在25℃条件下按照下述步骤进行充放电：1)静置5min；2)以0.5C恒流放电至2.5V；3)静置15min；4)以1.5C恒流充电至3.65V，恒压充电至0.05C；5)静置60min；6)重复第3步到第5步10次。
取测试完成后的满充电池进行拆解，并观察负极极片界面析锂程度。主体整面有明显析锂或10圈后容量保持率小于90％定义为严重析锂；主体局部区域、拐角等有析锂或10圈后容量保持率在90％至98％之间定义为中度析锂；仅拐角或锂离子电池头尾部有析锂或10圈后容量保持率在98％至99.5％之间定义为轻微析锂；所有位置均为金黄色定义为不析锂。
实施例1-1
<正极活性材料的制备>
将Li2C2O4、FeC2O4·2H2O、NH4H2PO4按LiFePO4的化学计量比配料，然后干磨40h得到前驱体。在获得的前驱体中加入一定含量的葡萄糖，湿磨5h，得到的固-液混合物在喷雾干燥机上干燥，干燥后的粉末在N2保护气氛下于管式炉中500℃预烧结5h，然后继续升温至600℃烧结10h，得到含碳1.5％的LiFePO4样品。其中，在N2气氛中烧结过程中会有一定程度的碳含量损失，大约为50％。
<正极极片的制备>
将LFP、Super P、PVDF按照重量比96.3∶1.5∶2.2进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为72wt％的浆料，真空搅拌均匀后得到正极浆料。将正极浆料均匀涂覆在厚度为10μm的正极集流体铝箔上的一个表面上，85℃条件下烘干，得到涂层厚度为100μm的单面涂布正极材料层的正极极片。然后在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极材料的正极极片。经冷压、裁片、焊接极耳后，在85℃下真空干燥4h，得到规格为74mm×867mm的正极极片待用。
<负极极片的制备>
将人造石墨、Super P、羧甲基纤维素钠(CMC)、丁苯橡胶(SBR)按照重量比96.4∶1.5∶0.5∶1.6进行混合，加入去离子水作为溶剂，调配成为固含量为54wt％的浆料，真空搅拌机搅拌均匀后得到负极浆料。将负极浆料均匀涂覆于厚度为10μm的负极集流体铜箔的一个表面上，85℃条件下烘干，得到涂层厚度为100μm的单面涂布负极材料层的负极极片。然后在铜箔的另一个表面上重复以上步骤，即得到双面涂布负极材料层的负极极片。经冷压、裁片、焊接极耳后，在120℃下真空干燥12h，得到规格为78mm×875mm的负极极片待用。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)按照质量比EC∶EMC＝35∶65进行混合得到基础溶剂，接着加入碳酸亚乙烯酯，溶解并充分搅拌后加入锂盐LiPF6，混合均匀后获得电解液。其中，LiPF6的质量百分含量为12.5％，碳酸亚乙烯酯的质量百分含量为0.1％，基础溶剂的质量百分含量为87.4％。
<隔离膜的制备>
采用厚度为7μm的多孔聚乙烯薄膜(Celgard公司提供)。
<锂离子电池的制备>
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片之间起到隔离的作用，然后卷绕得到电极组件；将电极组件置于外包装箔中，并在80℃下脱去水分，注入上述制备好的电解液，经过真空封装、静置、化成(0.02C恒流充电到3.3V，再以0.1C恒流充电到3.6V)、整形、容量测试等工序，获得软包锂离子电池(厚度3.3mm、宽度39mm、长度96mm)。
实施例1-2至实施例1-19
除了在<正极活性材料的制备>中，通过调控葡萄糖的质量百分含量从而调控正极活性材料中的碳元素含量，以及在<电解液的制备>中按照表1调整相关制备参数以外，其余与实施例1-1相同。
实施例2-1
除了按照下述方法制备电解液并按照表3调整相关制备参数以外，其余与实施例1-5相同。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)按照质量比EC∶EMC＝35∶65进行混合得到基础溶剂，接着加入碳酸亚乙烯酯和吡啶，溶解并充分搅拌后加入锂盐LiPF6，混合均匀后获得电解液。其中，LiPF6的质量百分含量为12.5％，碳酸亚乙烯酯的质量百分含量为2％，吡啶的质量百分含量为0.01％，基础溶剂的质量百分含量为85.49％。
实施例2-2至实施例2-11
除了在<电解液的制备>中按照表3调整相关制备参数以外，其余与实施例2-1相同。
实施例3-1
除了按照下述方法制备电解液并按照表5调整相关制备参数以外，其余与实施例1-5 相同。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)按照质量比EC∶EMC＝35∶65进行混合得到基础溶剂，接着加入碳酸亚乙烯酯和六亚甲基二异氰酸酯，溶解并充分搅拌后加入锂盐LiPF6，混合均匀后获得电解液。其中，LiPF6的质量百分含量为12.5％，碳酸亚乙烯酯的质量百分含量为2％，六亚甲基二异氰酸酯的质量百分含量为0.01％，基础溶剂的质量百分含量为85.49％。
实施例3-2至实施例3-11
除了在<电解液的制备>中按照表5调整相关制备参数以外，其余与实施例3-1相同。
实施例4-1
除了按照下述方法制备电解液并按照表7调整相关制备参数以外，其余与实施例1-5相同。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)按照质量比EC∶EMC＝35∶65进行混合得到基础溶剂，接着加入碳酸亚乙烯酯和马来酸酐，溶解并充分搅拌后加入锂盐LiPF6，混合均匀后获得电解液。其中，LiPF6的质量百分含量为12.5％，碳酸亚乙烯酯的质量百分含量为2％，马来酸酐的质量百分含量为0.01％，基础溶剂的质量百分含量为85.49％。
实施例4-2至实施例4-11
除了在<电解液的制备>中按照表7调整相关制备参数以外，其余与实施例4-1相同。
实施例5-1
除了按照下述方法制备电解液并按照表9调整相关制备参数以外，其余与实施例1-5相同。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)按照质量比EC∶EMC＝35∶65进行混合得到基础溶剂，接着加入碳酸亚乙烯酯和四甲基二乙烯基二硅氧烷，溶解并充分搅拌后加入锂盐LiPF6，混合均匀后获得电解液。其中，LiPF6的质量百分含量为12.5％，碳酸亚乙烯酯的质量百分含量为2％，四甲基二乙烯基二硅氧烷的质量百分含量为0.1％，基础溶剂的质量百分含量为85.4％。
实施例5-2至实施例5-9
除了在<电解液的制备>中按照表9调整相关制备参数以外，其余与实施例5-1相同。
实施例6-1
除了按照下述方法制备电解液并按照表11调整相关制备参数以外，其余与实施例1-5相同。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)按照质量比EC∶EMC＝35∶65进行混合得到基础溶剂，接着加入碳酸亚乙烯酯和三氟化硼吡啶，溶解并充分搅拌后加入锂盐LiPF6，混合均匀后获得电解液。其中，LiPF6的质量百分含量为 12.5％，碳酸亚乙烯酯的质量百分含量为2％，三氟化硼吡啶的质量百分含量为0.01％，基础溶剂的质量百分含量为85.49％。
实施例6-2至实施例6-10
除了在<电解液的制备>中按照表11调整相关制备参数以外，其余与实施例6-1相同。
对比例1
除了按照下述方法制备电解液，其余与实施例1-1相同。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)按照质量比EC∶EMC＝35∶65进行混合得到基础溶剂，溶解充分后加入锂盐LiPF6，混合均匀后获得电解液。其中，LiPF6的质量百分含量为12.5％，基础溶剂的质量百分含量为87.5％。
对比例2至对比例4
除了在<正极活性材料的制备>中，通过调控葡萄糖的质量百分含量从而调控正极活性材料中的碳元素含量，以及在<电解液的制备>中按照表1调整相关制备参数以外，其余与实施例1-1相同。
各实施例和对比例的制备参数及性能测试如表1至表12所示。
表1


注：表1中，“/”表示无相关制备参数。
表2
从实施例1-1至实施例1-19、对比例1至对比例4可以看出，实施例中碳酸亚乙烯酯和碳元素的质量百分含量均在本申请范围内，而对比例1至对比例4并未同时满足上述特征。本申请实施例中的锂离子电池具有较长的45℃循环圈数和60℃循环圈数、较低的100％SOC高温存储厚度膨胀率和0％SOC高温存储厚度膨胀率、较高的100％SOC高温存储剩余容量保持率和恢复容量保持率、较低的DCR和析锂程度，从而说明采用本申请提 供的电解液和正极活性材料制得的锂离子电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。
表3

注：表3中，“/”表示无相关制备参数。
表4
从实施例2-1至实施例2-11可以看出，当加入的含氮杂环化合物种类及含量在本申请的范围内，得到的锂离子电池具有较长的45℃循环圈数和60℃循环圈数、较低的100％SOC高温存储厚度膨胀率和0％SOC高温存储厚度膨胀率、较高的100％SOC高温存储剩余容量保持率和恢复容量保持率，从而说明采用本申请提供的电解液制得的锂离子电池能够进一步改善循环性能和存储性能。
表5

注：表5中，“/”表示无相关制备参数。
表6

从实施例3-1至实施例3-11可以看出，当加入的异氰酸酯化合物种类及含量在本申请的范围内，得到的锂离子电池具有较长的45℃循环圈数和60℃循环圈数、较低的100％SOC高温存储厚度膨胀率和0％SOC高温存储厚度膨胀率、较高的100％SOC高温存储剩余容量保持率和恢复容量保持率，从而说明采用本申请提供的电解液制得的锂离子电池能够进一步改善循环性能和存储性能。
表7

注：表7中，“/”表示无相关制备参数。
表8

从实施例4-1至实施例4-11可以看出，当加入的酸酐化合物种类及含量在本申请的范围内，得到的锂离子电池具有较长的45℃循环圈数和60℃循环圈数、较低的100％SOC高温存储厚度膨胀率和0％SOC高温存储厚度膨胀率、较高的100％SOC高温存储剩余容量保持率和恢复容量保持率，从而说明采用本申请提供的电解液制得的锂离子电池能够进一步改善循环性能和存储性能。
表9

注：表9中，“/”表示无相关制备参数。
表10

从实施例5-1至实施例5-9可以看出，当加入的硅烷化合物种类及含量在本申请的范围内，得到的锂离子电池具有较长的45℃循环圈数和60℃循环圈数、较低的100％SOC高温存储厚度膨胀率和0％SOC高温存储厚度膨胀率、较高的100％SOC高温存储剩余容量保持率和恢复容量保持率、较低的析锂程度，从而说明采用本申请提供的电解液制得的锂离子电池在具有较好的循环性能和存储性能的同时，还具有优良的动力学性能。
表11

注：表11中，“/”表示无相关制备参数。
表12
从实施例6-1至实施例6-10可以看出，当加入的含氮杂环三氟化硼络合物种类及含量在本申请的范围内，得到的锂离子电池具有较长的45℃循环圈数和60℃循环圈数、较低的100％SOC高温存储厚度膨胀率和0％SOC高温存储厚度膨胀率、较高的100％SOC高温存储剩余容量保持率和恢复容量保持率，从而说明采用本申请提供的电解液制得的锂离子电池能够进一步改善循环性能和存储性能。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (22)

  1. 一种二次电池，其包括正极极片、负极极片和电解液，所述电解液包括碳酸亚乙烯酯，基于所述电解液的总质量，所述碳酸亚乙烯酯的质量百分含量a为0.1％至3％；
    所述正极极片包括正极活性材料，所述正极活性材料包括碳元素，基于所述正极活性材料的总质量，所述碳元素的质量百分含量b为0.5％至6％。
  2. 根据权利要求1所述的二次电池，其中，所述a为0.1％至2.5％，和/或所述b为0.5％至5％。
  3. 根据权利要求1所述的二次电池，其中，所述a为0.5％至2.5％，和/或所述b为0.5％至4.5％。
  4. 根据权利要求1所述的二次电池，其中，所述a为0.8％至2.5％，和/或所述b为0.5％至4.5％。
  5. 根据权利要求1所述的二次电池，其中，所述a与所述b的比值为0.22至6。
  6. 根据权利要求1所述的二次电池，其中，所述电解液还包括含氮杂环化合物，基于所述电解液的总质量，所述含氮杂环化合物的质量百分含量c为0.01％至1％。
  7. 根据权利要求6所述的二次电池，其中，所述a与所述c的比值为2至60。
  8. 根据权利要求6所述的二次电池，其中，所述含氮杂环化合物包括以下化合物(式Ⅰ)或(式Ⅱ)：
    其中，R1、R2和R3各自独立地选自经取代或未经取代的C1-C5亚烷基、经取代或未经取代的C2-C5亚烯基、经取代或未经取代的C2-C5亚炔基、经取代或未经取代的C3-C5亚连烯基中的任意一种，并且，当经取代时，取代基为卤素原子。
  9. 根据权利要求1所述的二次电池，其中，所述电解液还包括异氰酸酯化合物，基于所述电解液的总质量，所述异氰酸酯化合物的质量百分含量d为0.01％至2％。
  10. 根据权利要求9所述的二次电池，其中，所述a与所述d的比值为2至60。
  11. 根据权利要求9所述的二次电池，其中，所述异氰酸酯化合物包括以下化合物(式Ⅲ)或(式Ⅳ)：
    其中，所述异氰酸酯化合物包括至少一个-NCO基团，R3和R4各自独立地选自C1至C7的烃基或C1至C7的芳香烃基。
  12. 根据权利要求1所述的二次电池，其中，所述电解液还包括酸酐化合物，基于所述电解液的总质量，所述酸酐化合物的质量百分含量e为0.01％至2％。
  13. 根据权利要求12所述的二次电池，其中，所述a与所述e的比值为2至60。
  14. 根据权利要求12所述的二次电池，其中，所述酸酐化合物包括马来酸酐、二甲基 马来酸酐、柠康酐、戊二酸酐、丁二酸酐、片烯二酸酐、顺丁烯二酸酐、联苯酸酐、吡啶二酸酐、吡嗪二酸酐、2,3-吡啶二酸酐、吡啶-3,4-二羧酸酐或2,3-吡嗪二羧酸酐中的至少一种。
  15. 根据权利要求1所述的二次电池，其中，所述电解液还包括硅烷化合物，基于所述电解液的总质量，所述硅烷化合物的质量百分含量f为0.01％至2％。
  16. 根据权利要求15所述的二次电池，其中，所述a与所述f的比值为2至60。
  17. 根据权利要求15所述的二次电池，其中，所述硅烷化合物包括四甲基二乙烯基二硅氧烷、马来酸双(三甲硅烷)酯、二苯基二氟硅烷、七甲基二硅氮烷、四甲基二乙烯基二硅氧烷、四乙氧基硅烷、2-氰基乙基三乙氧基硅烷、1,3,5,7-四乙烯基-1,3,5,7-四甲基环四硅氧烷、2,4,6-三乙烯基-2,4,6-三甲基环三硅氧烷或乙烯基三乙氧基硅烷中的至少一种。
  18. 根据权利要求1所述的二次电池，其中，所述电解液还包括含氮杂环三氟化硼络合物，基于所述电解液的总质量，所述含氮杂环三氟化硼络合物的质量百分含量g为0.01％至1％。
  19. 根据权利要求18所述的二次电池，其中，所述a与所述g的比值为2至60。
  20. 根据权利要求18所述的二次电池，其中，所述含氮杂环三氟化硼络合物包括三氟化硼吡啶、三氟化硼吡嗪、三氟化硼哒嗪、2-氟吡啶三氟化硼配合物、三氟化硼嘧啶、三氟化硼吡咯、三氟化硼吡唑或三氟化硼咪唑中的至少一种。
  21. 根据权利要求1所述的二次电池，其中，所述正极活性材料包括磷酸铁锂或磷酸锰铁锂中的至少一种。
  22. 一种电子装置，其包括权利要求1至21中任一项所述的二次电池。
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