JP2006019070A - Nonaqueous electrolyte, nonaqueous electrolyte secondary battery and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery having an excellent cycle life and excellent safety, using a carbon material for a negative electrode and using an ionic liquid for the nonaqueous electrolyte. <P>SOLUTION: This nonaqueous electrolyte comprises the ionic liquid comprising onium cations and non-aluminate-based anions, and a lithium salt. The nonaqueous electrolyte is characterized by dissolving at least one kind of Lewis acids represented by chemical formula or the like in the nonaqueous electrolyte as an additive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a non-aqueous electrolyte and an electrochemical device using the non-aqueous electrolyte, in particular, a battery, and an improvement of the manufacturing method thereof.

The electrolyte used for the non-aqueous electrolyte battery uses a solute dissolved in a non-aqueous solvent. For the non-aqueous solvent, a cyclic carbonate, a chain carbonate, a cyclic carboxylate, or the like is used. It is done. Here, examples of the cyclic carbonate include propylene carbonate (PC) and ethylene carbonate (EC). Examples of the chain carbonate include diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). Etc. Examples of the cyclic carboxylic acid ester include γ-butyrolactone (GBL) and γ-valerolactone (GVL). Furthermore, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium bistrifluoromethanesulfonate imide (LiN (CF ₃ SO ₂ ) ₂ ) and the like are used as solutes. .

Nonaqueous electrolytes composed of these nonaqueous solvents and solutes have been actively developed so far for nonaqueous electrolyte secondary batteries having a high energy density such as so-called lithium ion batteries. Here, in a lithium ion battery, as a positive electrode active material, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ , LiMnO ₂ ), lithium ferrate (LiFeO ₂ ) Transition metal oxides such as amorphous carbon, artificial graphite fired at a temperature of 2000 ° C. or higher, natural graphite, and other hosts that occlude and release lithium ions and sodium ions. Material is used.

  Non-aqueous electrolytes based on organic solvents such as those described above have traditionally been concerned about battery safety due to their flammability, and to prevent overcharge and overdischarge to ensure safety. The protection circuit has been used together.

On the other hand, in order to avoid the flammability problem of the non-aqueous electrolyte as described above, an ionic liquid that is liquid at room temperature but hardly burns due to extremely low vapor pressure has been proposed. As this ionic liquid, a mixture of 1-ethyl-3-methylimidazolium chloride and AlCl ₃ is conventionally known, but in recent years, a non-aluminate anion was used instead of the AlCl ₄ anion. Ionic liquids have been studied.

Among them, LiN (CF ₃ SO ₂ ) ₂ is dissolved in an ionic liquid composed of trimethylhexylammonium ion (+) which is a kind of onium cation and an anion of N (CF ₃ SO ₂ ) ₂ (−). It has been proposed that lithium metal can be deposited and dissolved by using an electrolyte. (For example, see Patent Document 1)
JP-A-11-297355

  However, even if the electrolyte composed of an ionic liquid in which a lithium salt is dissolved as described above is applied to a nonaqueous electrolyte battery having a negative electrode using lithium as an active material, the battery capacity is reduced or the battery is charged. The challenge of a short discharge cycle life remained significant.

For example, in a secondary battery using lithium metal as a negative electrode, during charging (lithium deposition), ammonium cations are simultaneously reduced and decomposed, so that the charging efficiency does not reach 100%, and the deposited lithium is in a dendritic form. Furthermore, the efficiency decreased.

  In addition, in lithium ion batteries that use a carbon material that can occlude and release lithium ions such as graphite as the negative electrode, reductive decomposition of ammonium cations occurs during charging, as well as lithium metal, and carbon powder is more than the electrode due to significant electrode expansion. There was a problem that the cycle life would be shortened.

  An object of the present invention is to provide a nonaqueous electrolyte battery excellent in cycle life and safety, using a carbon material as a negative electrode and further using an ionic liquid as a nonaqueous electrolyte. .

  In order to solve the above problems, the nonaqueous electrolyte of the present invention is a nonaqueous electrolyte composed of an ionic liquid composed of an onium cation and a nonaluminate anion and a lithium salt, and the nonaqueous electrolyte comprises ( It is characterized in that at least one of the Lewis acids represented by chemical formula 1) or chemical formula 2 is dissolved as an additive.

Here, the onium cation is a cation formed by a Lewis base using a non-bonded electron pair to form a coordinate bond, and examples thereof include NR ₄ ⁺ , PR ₄ ⁺ and SR ₃ ^+. .

  When this nonaqueous electrolyte is applied to a nonaqueous electrolyte battery, a battery having excellent cycle characteristics can be provided.

Further, from the viewpoint of cost, it is preferable that the Lewis acid of (Chemical Formula 1) is BF ₃ and the Lewis acid of (Chemical Formula 2) is PF ₅ .

  This addition amount shows the effect of the present invention even in a small amount, but it is preferably 4 mmol or more per 1 mol of the onium cation. Even if the upper limit is added until saturation, there is no particular adverse effect, and only the cost is increased.

  Further, in the above configuration, the non-aqueous electrolyte contains at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, and γ-butyrolactone in addition to the ionic liquid. Furthermore, it is preferable for improving.

The Lewis acid having the above structure may be directly dissolved in an ionic liquid composed of an onium cation and a non-aluminate anion, but by dissolving a lithium salt such as LiBF ₄ or LiPF ₆ and heating the entire solution. Lewis acids such as BF ₃ or PF ₅ can also be generated in the ionic liquid. At this time, a lithium salt such as LiF produced after the generation of Lewis acid precipitates or contributes as an ion conductive salt depending on its structure.

  In addition, the reaction proceeds when the heating temperature is normal temperature or higher, but it is preferable that the heating temperature is equal to or higher than the decomposition temperature of each lithium salt because a remarkable effect can be obtained. Further, when the heating temperature exceeds 300 ° C., the onium cation starts to decompose, and therefore 300 ° C. or less is preferable.

  The nonaqueous electrolyte battery of the present invention uses the nonaqueous electrolyte prepared as described above for a battery including a negative electrode made of a carbon material.

Furthermore, even if the Lewis acid is not dissolved, an electrolyte salt such as LiPF ₆ can be dissolved, and the entire battery can be heated after the battery is assembled to generate a Lewis acid such as PF _{5 in} the battery. .

  In this case, the lithium salt such as LiF generated after the generation of the Lewis acid functions as a protective film for the positive electrode and the negative electrode if it is insoluble in the electrolyte, and acts as an ion conductive salt if it is soluble.

According to the present invention, a non-aqueous electrolyte battery having excellent cycle characteristics can be obtained by dissolving a Lewis acid in a non-aqueous electrolyte made of an ionic liquid. In addition, a Lewis acid having such an effect can be easily generated by thermal decomposition of LiBF ₄ or LiPF ₆ , and a battery having excellent reliability can be provided at a low cost.

A special technical feature of the present invention is represented by (chemical formula 3) or (chemical formula 4) in an ionic liquid composed of an onium cation such as NR ₄ ⁺ , PR ₄ ⁺ , SR ₃ ⁺ and a non-aluminate anion. It dissolves Lewis acid.

The reason why the performance of the negative electrode using an alkali metal such as lithium as an active material can be improved by dissolving Lewis acid in a non-aqueous electrolyte composed of an ionic liquid is presumed as follows. That is, before the onium cation is reduced, the Lewis acid is reduced and decomposed to form a film on the negative electrode. Although this film suppresses the reductive decomposition of the onium cation, since it has lithium ion conductivity, good charge / discharge is possible. In addition to such a film effect, when a carbon material that occludes / releases lithium ions is used, even if the onium cation is reduced to form a Lewis base such as NR ₃ , it is coordinated with the Lewis acid. Since the bulk increases due to the coordinate bond, the Lewis base cannot penetrate between the layers of the carbon material. Accordingly, it is possible to suppress a decrease in capacity and load characteristics of the carbon material negative electrode.

The Lewis acid represented by indicating such action and effect (Formula 3) or (Formula 4), tributoxyethyl Chevrolet preparative (R1 = R2 = R3 = C 4 H 9 O), triphenoxide Chevrolet preparative (R1 = R2 = R3 = PhO), tribenzylidene Loki Chevrolet preparative (R1 = R2 = R3 = PhCH 2 O), tris (trifluoroacetyl) borate (R1 = R2 = R3 = CF 3 C (= O) O), tris (pentafluorophenyl acetyl) borate (R1 = R2 = R3 = CF 3 CF 2 CO), tris (trifluoromethyl) borate (R1 = R2 = R3 = CF 3), trifluoromethyl difluoromethyl borate (R1 = R2 = F, R3 = CF 3) , bis (trifluoromethyl) tetrafluoroborate (R1 = F, R2 = R3 = CF 3), tris (pentafluoroethyl) borate (R1 = R2 = R3 = ₂ F _5), tris (pentafluorophenyl methyl) difluoro phosphate (R4 = R5 = F, R6 = R7 = R8 = CF 3), tris (pentafluoroethyl) difluoro phosphate (R4 = R5 = F, R6 = R7 = R8 = C ₂ F ₅ ) or phosphoryl fluoride (R4 = R5 = R6 = F, R7 = O, no R8), but BF ₃ or PF ₅ is preferable in terms of cost. Here, phosphoryl fluoride is a compound contained in (Chemical Formula 4), and since the functional group of R7 is O, R8 is absent.

  Examples of the present invention are shown below. For the negative electrode of the nonaqueous electrolyte secondary battery of the example, a carbon material capable of occluding and releasing lithium was used. However, a single metal, alloy, or composite oxide that forms an alloy with other lithium may be used. The same effect can be obtained by using an alkali metal such as lithium or sodium.

Example 1
(I) Preparation of non-aqueous electrolyte TMPA · TFSI (trimethylpropylammonium bis [trifluoromethanesulfonyl] imide) was used as the ionic liquid. LiTFSI (lithium bis [trifluoromethanesulfonyl] imide) was used as the lithium salt.

TMPA · TFSI and LiTFSI were weighed so as to have a molar ratio of 1 / 0.1 and mixed to obtain a uniform electrolyte. PF ₅ gas was bubbled into this electrolytic solution, and 50 mmol was dissolved in 1 mol of TMPA ions.
(Ii) Production of positive electrode sheet 85 parts by weight of LiCoO ₂ (lithium cobaltate) powder, 10 parts by weight of acetylene black as a conductive agent, and 5 parts by weight of polyvinylidene fluoride resin as a binder were mixed and dehydrated. A slurry-like positive electrode mixture was prepared by dispersing in N-methyl-2-pyrrolidone. This positive electrode mixture was applied onto a positive electrode current collector made of an aluminum foil, dried and rolled to obtain a positive electrode sheet.
(Iii) Production of negative electrode sheet 75 parts by weight of artificial graphite powder, 20 parts by weight of acetylene black as a conductive agent, and 5 parts by weight of polyvinylidene fluoride resin as a binder were mixed, and these were dehydrated N-methyl-2 -A slurry-like negative electrode mixture was prepared by dispersing in pyrrolidone. This negative electrode mixture was applied onto a negative electrode current collector made of copper foil, dried and then rolled to obtain a negative electrode sheet.
(Iv) Battery assembly The positive electrode sheet and the negative electrode sheet were cut into a size of 35 mm × 35 mm and ultrasonically welded to an aluminum plate with a lead and a copper plate, respectively. The aluminum plate and the copper plate were taped and integrated so that each electrode sheet was opposed to the polypropylene separator. Next, this integrated product was placed in a cylindrical aluminum laminated bag having both ends open, and one opening of the bag was welded at the lead portion. And the electrolyte solution prepared from the other opening part was dripped.

The battery thus assembled was charged with a current of 0.35 mA for 20 hours, then degassed at -750 mmHg for 10 seconds, and the injected opening was sealed by welding.
<< Comparative Example 1 >>
The assembly was performed in the same manner as in Example 1 except that PF ₅ was not dissolved in the electrolytic solution in Example 1.

Using the batteries of Example 1 and Comparative Example 1 assembled as described above, charging and discharging were performed with a constant current of 0.35 mA and an upper limit voltage of 4.2 V and a lower limit voltage of 3.0 V. FIG. 1 is a plot of the discharge capacity in each cycle of the batteries of Example 1 and Comparative Example 1. Here, a line connecting 1 circles is a plot of the discharge capacity of the battery of Example 1, and a line connecting 2 triangles is a plot of the discharge capacity of the battery of Comparative Example 1. . The discharge capacity is expressed in terms of the weight of the positive electrode active material.

In the battery of Comparative Example 1, the discharge capacity is small from the beginning of the cycle. This is because PF ₅ is not dissolved, so that a stable film formation does not occur on the negative electrode, and the capacity is reduced by the reaction between the ionic liquid and the negative electrode (lithium in it). In addition, it is presumed that the cycle deterioration is large in the battery of Comparative Example 1 because there are few stable films, and the capacity decreases as the negative electrode and the ionic liquid continue to react even during the cycle.

Example 2
(I) Preparation of non-aqueous electrolyte TMPA · TFSI (trimethylpropylammonium bis [trifluoromethanesulfonyl] imide) was used as the ionic liquid. Further, LiTFSI (lithium bis [trifluoromethanesulfonyl] imide) and LiPF6 were used as lithium salts.

TMPA · TFSI, LiTFSI, and LiPF ₆ were weighed and mixed at a molar ratio of 1 / 0.1 / 0.01 to obtain a uniform electrolyte. The solution was heated at 110 ° C. for 24 hours. Centrifugation was performed after the heating, and LiF settled, so it was confirmed that PF ₅ was dissolved in the electrolyte.

The assembly was performed in the same manner as in Example 1 except that the electrolytic solution was prepared as described above.
<< Comparative Example 2 >>
A battery was assembled in the same manner as in Example 2 except that the electrolytic solution was not heated.

Using the batteries of Example 2 and Comparative Example 2 assembled as described above, charging and discharging were performed at a constant current of 0.35 mA and an upper limit voltage of 4.2 V and a lower limit voltage of 3.0 V. Based on (Equation 1), the cycle deterioration rate of each battery was calculated.

  The cycle deterioration rate of Example 2 was 1.7% / cycle, and the cycle deterioration rate of Comparative Example 2 was 2.8% / cycle. The cycle deterioration rate of the battery of Example 1 is 1.0% / cycle, and the cycle deterioration rate of Comparative Example 1 is 3.0% / cycle.

In Example 2, the electrolyte was heated at 110 ° C., which is higher than the decomposition temperature of LiPF ₆ , but it is effective even when heated at a temperature lower than the decomposition temperature (about 100 ° C.), but is remarkable. No effect was observed.

Example 3
(I) Preparation of nonaqueous electrolyte As an ionic liquid, TMPA · TFSI (trimethylpropylammonium bis [
Trifluoromethanesulfonyl] imide). Further, LiTFSI (lithium bis [trifluoromethanesulfonyl] imide) and LiPF ₆ were used as lithium salts.

As shown in (Table 1), 19 mg (50 mmol) of TMPA · TFSI, 1.4 g (5 mmol) of LiTFSI, and 1.5 mg (0.01 mmol) to 0.76 g (5 mmol) of LiPF ₆ were weighed. Mix and dissolve lithium salt. These solutions were then heated at 110 ° C. for 24 hours. Here, the amount of PF5 generated in the solution was calculated by quantifying the amount of LiF precipitated after heating. When the amount of LiPF ₆ exceeded 5 mmol, the solution solidified at room temperature and could not be evaluated.

The assembly was performed in the same manner as in Example 1 except that the electrolytic solution was prepared as described above.
<< Comparative Example 3 >>
A battery was assembled in the same manner as in Example 3 except that the electrolytic solution was not heated to 110 ° C.

  Using the batteries of Example 3 and Comparative Example 3 assembled as described above, charging and discharging were performed at a constant current of 0.35 mA and an upper limit voltage of 4.2 V and a lower limit voltage of 3.0 V. Then, the cycle deterioration rate of each battery was calculated and summarized in (Table 1). Table 1 shows the cycle deterioration rates of the batteries of Example 3 and Comparative Example 3.

From Table 1, it can be seen that the cycle deterioration rate is reduced in the electrolytic solution heated at 110 ° C., and that the reduction in the cycle deterioration rate is more effective as the amount of LiPF ₆ is increased. This is considered to be because as the amount of LiPF ₆ increases, the amount of LiPF ₆ not dissociated in the electrolytic solution increases and is easily decomposed into LiF and PF ₅ .

Example 4
(I) Preparation of non-aqueous electrolyte TMPA · TFSI (trimethylpropylammonium bis [trifluoromethanesulfonyl] imide) was used as the ionic liquid. Further, LiTFSI (lithium bis [trifluoromethanesulfonyl] imide) and LiBF ₄ were used as lithium salts.

As shown in (Table 2), 19 g (50 mmol) of TMPA · TFSI, 1.4 g (5 mmol) of LiTFSI, and LiBF ₄ were weighed from 0.94 mg (0.01 mmol) to 0.47 g (5 mmol). Mix and dissolve lithium salt. Here, when LiBF ₄ exceeded 5 mmol, not all lithium salts could be dissolved, and the mixture solidified at room temperature. These uniformly dissolved electrolytes were heated at 230 ° C. for 24 hours. Then, to quantify the amount of precipitated after heating LiF, and calculate the amount of BF ₃ generated in the electrolytic solution.

The assembly was performed in the same manner as in Example 1 except that the electrolytic solution was prepared as described above.
<< Comparative Example 4 >>
A battery was assembled in the same manner as in Example 4 except that the electrolytic solution was not heated to 230 ° C.

  Using the batteries of Example 4 and Comparative Example 4 assembled as described above, charging and discharging were performed with a constant current of 0.35 mA and an upper limit voltage of 4.2 V and a lower limit voltage of 3.0 V. Then, the cycle deterioration rate of each battery was calculated and summarized in (Table 2). Table 2 shows the cycle deterioration rates of the batteries of Example 4 and Comparative Example 4.

From Table 2, it can be seen that the cycle deterioration rate is reduced in the electrolyte heated at 230 ° C., and that the reduction in the cycle deterioration rate is more effective as the amount of LiBF ₄ is increased. This is because as LiBF ₄ amount is large, LiBF ₄ undissociated in the electrolytic solution is increased, presumably because easily decomposed into LiF and BF _3.

In Example 4, the electrolytic solution was heated at 230 ° C., which is higher than the decomposition temperature of LiBF ₄ , but even when heated at a temperature lower than the decomposition temperature (about 200 ° C.), there is an effect, but remarkable. No effect was observed.

Example 5
(I) Preparation of non-aqueous electrolyte TMPA · TFSI (trimethylpropylammonium bis [trifluoromethanesulfonyl] imide) was used as the ionic liquid. Further, LiTFSI (lithium bis [trifluoromethanesulfonyl] imide) and LiPF ₆ were used as lithium salts.

TMPA · TFSI (19 g, 50 mmol), LiTFSI (1.4 g, 5 mmol), and LiPF ₆ (0.38 g, 2.5 mmol) were weighed and mixed to dissolve the lithium salt.
(Iv) Battery assembly As in Example 1, the positive electrode sheet and the negative electrode sheet were cut out and ultrasonically welded to an aluminum plate and a copper plate with leads, respectively, and each electrode sheet was placed between polypropylene separators. The aluminum plate and the copper plate were taped and integrated so as to face each other. Next, this integrated product was placed in a cylindrical aluminum laminated bag having both ends open, and one opening of the bag was welded at the lead portion. And the electrolyte solution prepared from the other opening part was dripped.

  The battery thus assembled was heated at 85 ° C. for 10 hours. Then, after charging with a current of 0.35 mA for 20 hours, degassing was performed at −750 mmHg for 10 seconds, and the injected opening was further sealed by welding.

A battery was fabricated in the same manner as in Example 1 except for assembling as described above.
<< Comparative Example 5 >>
A battery was assembled in the same manner as in Example 5 except that the battery was not heated to 85 ° C. during assembly.

  Using the batteries of Example 5 and Comparative Example 5 assembled as described above, charging and discharging were performed with a constant current of 0.35 mA and an upper limit voltage of 4.2 V and a lower limit voltage of 3.0 V. And the cycle deterioration rate of each battery was calculated. As a result, the cycle deterioration rate in the battery of Example 5 was 0.6% / cycle, and in Comparative Example 5, it was 2.4% / cycle.

  Here, although the electrolytic solution is not heated at a temperature higher than the decomposition temperature of the lithium salt as in Example 2 or 4, the cycle deterioration rate is reduced. It is presumed that the moisture contained therein reacts with the lithium salt to easily generate a Lewis acid.

Example 6
(I) Preparation of non-aqueous electrolyte TMPA · TFSI (trimethylpropylammonium bis [trifluoromethanesulfonyl] imide) was used as the ionic liquid. LiTFSI (lithium bis [trifluoromethanesulfonyl] imide) was used as the lithium salt.

  TMPA · TFSI (19 g, 50 mmol) and LiTFSI (1.4 g, 5 mmol) were weighed and mixed to dissolve the lithium salt. To this electrolyte solution, 2.5 mmol of Lewis acid as shown in (Table 3) was added. Table 3 shows the cycle deterioration rate of the battery using the electrolytic solution to which Lewis acid was added in Example 6.

As described above, a battery was fabricated in the same manner as in Example 1 except that the Lewis acid shown in (Table 3) was added instead of PF ₅ . Then, charging and discharging were performed while the upper limit voltage was 4.2 V and the lower limit voltage was 3.0 V at a constant current of 0.35 mA, and the cycle deterioration rate of each battery was calculated. The results are shown in Table 3.

  (Table 3) shows that the cycle deterioration rate is reduced in the battery to which the Lewis acid is added. From Table 3, it can be seen that the larger the functional group bonded to B or P and the greater the electron withdrawing property, the lower the cycle deterioration rate.

Example 7
(I) Preparation of non-aqueous electrolyte TMPA · TFSI (trimethylpropylammonium bis [trifluoromethanesulfonyl] imide) was used as the ionic liquid. Moreover, the compound shown in Table 4 was used as an organic solvent. Further, LiTFSI (lithium bis [trifluoromethanesulfonyl] imide) and LiPF ₆ were used as lithium salts.

12 g of TMPA · TFSI, 7 g of each organic solvent, 1.4 g (5 mmol) of LiTFSI, and 76 mg (0.5 mmol) of LiPF ₆ were weighed and mixed to dissolve the lithium salt. This electrolyte was heated at 110 ° C. for 24 hours. The assembly was performed in the same manner as in Example 1 except that the electrolytic solution was prepared as described above. Table 4 shows the cycle deterioration rate of the battery mixed with the organic solvent in Example 7.

  From Table 4, the cycle deterioration rate is reduced by mixing an organic solvent as shown in Table 4 rather than using only an ionic liquid as a medium for dissolving the electrolyte salt. The cause of this is not clear, but it is thought that the presence of the Lewis acid facilitated the formation of a good film on the negative electrode due to the ring opening of the organic solvent.

Example 8
(I) Preparation of non-aqueous electrolyte As the ionic liquid, an ionic liquid as shown in Table 5 was used. Further, LiTFSI (lithium bis [trifluoromethanesulfonyl] imide) and LiPF ₆ were used as lithium salts.

12 g of each ionic liquid, 7 g of ethylene carbonate, 1.4 g (5 mmol) of LiTFSI, and 76 mg (0.5 mmol) of LiPF ₆ were weighed and mixed to dissolve the lithium salt. And this electrolyte solution was heated at 110 degreeC for 24 hours.

A battery was assembled in the same manner as in Example 2 except that the electrolytic solution was prepared as described above. << Comparative Example 8 >>
A battery was assembled in the same manner as in Example 8 except that the electrolytic solution was not heated.
Table 5 shows the cycle deterioration rate of the battery using the ionic liquid in Example 8.

  Using the batteries of Example 8 and Comparative Example 8 assembled as described above, charging and discharging were performed with a constant current of 0.35 mA and an upper limit voltage of 4.2 V and a lower limit voltage of 3.0 V. And the cycle deterioration rate of each battery was calculated.

  (Table 5) shows that the cycle deterioration rate is reduced by dissolving the Lewis acid in the electrolyte using various ionic liquids.

In Example 8, TFSI was used as the anion of the ionic liquid, but the ionic liquid composed of other anionic species such as BF ₄ ⁻ , PF ₆ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ^−. The same effect was obtained even when using.

  A nonaqueous electrolyte battery using the nonaqueous electrolyte of the present invention is useful as a power source for portable equipment such as a mobile phone because it has high safety and good cycle characteristics.

The figure which shows the cycling characteristics of the battery of the nonaqueous electrolyte battery which is an Example of this invention, and a comparative example

Explanation of symbols

1 Discharge capacity of the battery of Example 1 2 Discharge capacity of the battery of Comparative Example 1

Claims (6)

An ionic liquid comprising an onium cation and a non-aluminate anion and a non-aqueous electrolyte comprising a lithium salt, wherein the non-aqueous electrolyte contains at least one of Lewis acids represented by (Chemical Formula 1) or (Chemical Formula 2) Is dissolved as an additive, a non-aqueous electrolyte.

The non-aqueous electrolyte according to claim 1, wherein the Lewis acid of (Chemical formula 1) is BF ₃ and the Lewis acid of (Chemical formula 2) is PF ₅ . 2. The non-aqueous electrolyte according to claim 1, wherein the non-aqueous electrolyte further includes at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, and γ-butyrolactone, in addition to the ionic liquid. Electrolytes. LiBF ₄ or LiPF ₆ as a lithium salt is dissolved in an ionic liquid composed of an onium cation and a non-aluminate anion to prepare a non-aqueous electrolyte, and the whole non-aqueous electrolyte is heated to enter the non-aqueous electrolyte. A method for producing a non-aqueous electrolyte, characterized by generating BF ₃ or PF ₅ . The nonaqueous electrolyte battery which comprised the positive electrode, the negative electrode which consists of carbon materials, and the nonaqueous electrolyte in any one of the said Claims 1-3. A nonaqueous electrolyte battery comprising a positive electrode, a negative electrode made of a carbon material, and the nonaqueous electrolyte according to any one of claims 1 to 3, wherein the nonaqueous electrolyte battery is heated by heating the entire battery after the battery is assembled. A method for producing a non-aqueous electrolyte battery, characterized by generating a Lewis acid in an electrolyte battery.

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