JP2000133274A - Polymer lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery with excellent high rate discharge characteristics and long charge/discharge cycle life by installing a positive electrode containing a current collector; a thermosetting resin layer placed on the current collector and giving high conductivity; and a positive electrode layer placed on the thermosetting resin layer. SOLUTION: A positive electrode 1 is formed by sticking a thermosetting resin layer 5 having conductivity and a positive electrode layer 6 to a positive current collector 4 in order. A negative electrode 2 is formed by sticking a thermosetting resin layer 8 having conductivity and a negative electrode layer 9 to a negative current collector 7. A belt-shaped positive terminal 10 is formed by extending the positive current collector 4 of the positive electrode 1, and a belt-shaped negative terminal is formed by extending the negative current collector 7 of the negative electrode 2. For example, a positive lead 12 made of a belt-shaped aluminum plate is connected to two positive terminals 10, and a negative lead 2 made of a belt-shaped copper plate is connected to the negative terminal 11. A power generating element is sealed in an outer jacket material 13 having a barrier function against moisture and air, and the positive lead 12 and the negative lead are taken out of the outer jacket material 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polymer lithium secondary battery.

[0002]

2. Description of the Related Art In recent years, with the development of electronic equipment, there has been a demand for the development of a non-aqueous electrolyte secondary battery that is small, lightweight, has a high energy density, and can be repeatedly charged and discharged. Such a secondary battery includes a negative electrode using lithium or a lithium alloy as an active material, a positive electrode containing an oxide, sulfide, or selenide such as molybdenum, vanadium, titanium, or niobium as an active material, and a nonaqueous electrolyte. There is known a lithium secondary battery including:

In recent years, a negative electrode containing a carbonaceous material that absorbs and releases lithium ions, such as coke, graphite, carbon fiber, a resin fired body, and pyrolytic gas phase carbon, has been used as a negative electrode. The development and commercialization of lithium ion secondary batteries using lithium and lithium manganese oxide-containing batteries are being actively pursued.

Meanwhile, in order to further reduce the weight and size of the secondary battery, for example, US Pat.
As disclosed in US Patent No. 6,318, a polymer lithium secondary battery has been developed. A polymer lithium secondary battery includes a positive electrode having a structure in which a positive electrode layer containing an active material, a non-aqueous electrolyte, and a polymer holding the electrolyte is supported on a current collector, an active material, a non-aqueous electrolyte, and the electrolyte. A negative electrode having a structure in which a negative electrode layer containing a polymer holding
It has a structure in which a power generation element mainly composed of a non-aqueous electrolyte and an electrolyte layer containing a polymer that holds the electrolyte is adhered between the positive electrode and the negative electrode, and is housed in a film-made exterior material. The exterior material, for example, a heat-fusible resin film such as an acid-modified polyolefin film is disposed on the inner surface, and a metal foil such as an aluminum foil is interposed in the intermediate layer to prevent intrusion of moisture and the like from the outside. It is formed from a laminate film.

[0005]

However, since the polymer lithium secondary battery has low adhesion between the positive and negative electrode layers and the current collector, it has a high internal resistance and a low discharge capacity when discharged at a high rate. There is a problem. Further, in the secondary battery, when the expansion and contraction of the power generation element are repeated with the progress of the charge and discharge cycle, the positive and negative electrode layers are separated from the current collector, the internal resistance is increased, and the discharge capacity is reduced. Create problems.

Japanese Unexamined Patent Application Publication No. 9-199133 discloses an electrode in which an electrode constituting material layer comprising at least an electrode active material and a binder is formed on the surface of a current collector. a) an acrylic copolymer comprising a monomer having a carboxylic acid group or a carboxylic anhydride group and (b) at least one monomer selected from an acrylate ester and a methacrylate ester, wherein the carboxylic acid group or An electrode treated with an acrylic copolymer in which the proportion of a monomer having a carboxylic anhydride group is 0.5 to 20% by weight of the copolymer is described.

An object of the present invention is to provide a polymer lithium secondary battery having excellent discharge characteristics even at a high rate and having improved charge / discharge cycle life.

[0008]

According to the present invention, there is provided a polymer lithium secondary battery comprising: a current collector;
A positive electrode including a thermosetting resin layer provided with conductivity and a positive electrode layer laminated on the thermosetting resin layer is provided.

The polymer lithium secondary battery according to the present invention is characterized in that a current collector is coated with a thermosetting resin having conductivity, and a positive electrode not impregnated with a non-aqueous electrolyte is coated on the thermosetting resin. After arranging a sheet and thermosetting the thermosetting resin by subjecting the obtained laminate to thermocompression bonding, a positive electrode impregnated with a non-aqueous electrolyte is provided. .

[0010] Another polymer lithium secondary battery according to the present invention comprises a current collector, a thermosetting resin layer laminated on the current collector and provided with conductivity, and a thermosetting resin layer. And a negative electrode including a stacked negative electrode layer.

In another polymer lithium secondary battery according to the present invention, a current collector is coated with a thermosetting resin having conductivity, and a non-aqueous electrolyte solution is not impregnated on the thermosetting resin. After the thermosetting resin is thermoset by subjecting the obtained laminate to thermocompression bonding, a negative electrode impregnated with a non-aqueous electrolyte is provided. It is.

[0012] Still another polymer lithium secondary battery according to the present invention is a current collector, a thermosetting resin layer laminated on the current collector and provided with conductivity, and a thermosetting resin layer. A positive electrode including a positive electrode layer laminated on a current collector, a thermosetting resin layer laminated on the current collector and provided with conductivity, and a negative electrode laminated on the thermosetting resin layer And a negative electrode including the layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of a polymer lithium secondary battery according to the present invention will be described with reference to FIG.

That is, a polymer lithium secondary battery is:
A power generation element is mainly provided by integrating a positive electrode 1, a negative electrode 2, and an electrolyte layer 3 disposed between the positive electrode 1 and the negative electrode 2. The positive electrode 1 includes a porous current collector 4
And a thermosetting resin layer 5 adhered to both surfaces of the current collector 4 and imparted with conductivity, and a positive electrode layer 6 bonded to each of the thermosetting resin layers 5. On the other hand, the negative electrode 2
A porous current collector 7, a thermosetting resin layer 8 bonded to both sides of the current collector 7 and having conductivity, and a negative electrode layer 9 bonded to each of the thermosetting resin layers 8. Consists of The strip-shaped positive electrode terminal 10 is obtained by extending the current collector 4 of each of the positive electrodes 1 in a strip shape. On the other hand, the strip-shaped negative electrode terminal 11 is obtained by extending the current collector 7 of the negative electrode 2 in a strip shape. For example, a positive electrode lead 12 made of a strip-shaped aluminum plate is connected to the two positive electrode terminals 10. For example, a negative electrode lead (not shown) made of a strip-shaped copper plate is connected to the negative electrode terminal 11. The power generating element having such a configuration is hermetically sealed in a state in which the positive electrode lead 12 and the negative electrode lead extend from the exterior material 13 in an exterior material 13 having a barrier function against moisture, air, and the like.

As the positive electrode, the negative electrode and the electrolyte layer of the polymer lithium secondary battery, for example, those described below can be used.

(Positive Electrode 1) This positive electrode 1 is made of a porous current collector 4
A thermosetting resin layer 5 that is laminated on both sides of the current collector 4 and is provided with conductivity; and a thermosetting resin layer 5 that is laminated on each of the thermosetting resin layers 5, a positive electrode active material, a non-aqueous electrolyte solution, And a positive electrode layer 6 containing a binder for holding the electrolyte.

Examples of the positive electrode active material include various oxides (eg, lithium manganese composite oxide such as LiMn ₂ O ₄ , manganese dioxide, lithium-containing nickel oxide such as LiNiO _2, and lithium-containing cobalt oxide such as LiCoO _2). Oxide, lithium-containing nickel-cobalt oxide, lithium-containing amorphous vanadium pentoxide and the like, and chalcogen compounds (for example, titanium disulfide and molybdenum disulfide). Among them, it is preferable to use a lithium manganese composite oxide, a lithium-containing cobalt oxide, and a lithium-containing nickel oxide.

The non-aqueous electrolyte is prepared by dissolving an electrolyte in a non-aqueous solvent.

Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and dimethyl carbonate (D
MC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (γ-
BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. The non-aqueous solvents may be used alone or as a mixture of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ) and lithium hexafluorophosphate (L
iPF _6), boric tetrafluoride lithium (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium salts such as lithium trifluoromethane sulfonate (LiCF ₃ SO ₃₎ may be mentioned.

The amount of the electrolyte dissolved in the non-aqueous solvent is preferably 0.2 mol / l to 2 mol / l.

The binder has a function of holding a non-aqueous electrolyte. Examples of such a binder include a polyethylene oxide derivative, a polypropylene oxide derivative, a polymer containing the derivative, polytetrafluoropropylene, a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), and polyvinylidene fluoride ( PVdF) or the like can be used. Among them, a VdF-HFP copolymer is preferred.

The positive electrode may include a conductive material from the viewpoint of improving conductivity. Examples of the conductive material include artificial graphite, carbon black (eg, acetylene black), nickel powder, and the like.

As the porous current collector, for example, a mesh made of aluminum or an aluminum alloy, an expanded metal, a punched metal, or the like can be used.

The thermosetting resin used in the thermosetting resin layer 5 provided with the conductivity is preferably a non-aqueous electrolyte-resistant resin. Examples of such a thermosetting resin include an epoxy thermosetting resin, a modified urethane thermosetting resin, and an acrylic thermosetting resin. Above all, those in which the state before the thermosetting is liquid (solvent-free) are preferable.

It is desirable that the thermosetting resin has a viscosity at 25 ° C. within a range of 100 cp to 200,000 cp. This is due to the following reasons. If the viscosity is less than 100 cp, there is a possibility that a problem such as the sedimentation of the conductive powder dispersed in the resin layer may occur.
On the other hand, if the viscosity exceeds 200,000 cp, the viscosity of the resin may be too high and it may be difficult to provide a uniform resin layer on the surface. A more preferred range of the viscosity is 1000
cp to 100,000 cp.

It is preferable that the thermosetting resin has a temperature at which a curing reaction is caused to be 100 to 200 ° C. This is due to the following reasons. If the curing temperature is lower than 100 ° C., it takes a long time to cure the resin layer, which may cause a problem such as insufficient curing. On the other hand, when the curing temperature is 200
If the temperature exceeds ℃, the current collector may be oxidized by the heat of the thermosetting reaction, and the conductivity of the current collector may be reduced. A more preferable range of the temperature is 130 to 170 ° C.

The application of conductivity to the thermosetting resin can be performed, for example, by dispersing a conductive powder in the thermosetting resin. As such conductive powder,
For example, aluminum powder, nickel powder, carbon powder and the like can be mentioned. Among them, carbon powder is preferable.
Further, two or more of these powders may be used in combination. Note that the shape of the conductive powder can be, for example, fibrous or granular.

The amount of the conductive powder in the thermosetting resin layer is preferably in the range of 1% by weight to 50% by weight. This is due to the following reasons. If the amount of the conductive powder is too small, conduction between the positive electrode layer and the current collector deteriorates, so that a high discharge capacity at a high rate may not be obtained. On the other hand, if the amount of the conductive powder is too large, the adhesiveness between the positive electrode layer and the current collector may be reduced. Therefore, it is necessary to sufficiently improve both the discharge characteristics at a high rate and the charge / discharge cycle life. May not be possible. In particular, when the thermosetting resin is an epoxy-based thermosetting resin, the amount of the conductive powder is from 1% by weight to 50% by weight.
(More preferably, 1% by weight to 35% by weight). When the thermosetting resin is a modified urethane-based thermosetting resin, the amount of the conductive powder is from 1% by weight to 40% by weight (more preferably, 1% by weight).
-20% by weight). Further, when the thermosetting resin is an acrylic thermosetting resin, the amount of the conductive powder is in the range of 1% by weight to 50% by weight (more preferably, 2% by weight to 30% by weight). Is preferred.

The amount of the thermosetting resin layer provided with the conductivity is 0.5 to 1.5 g / m 2 per one surface of the current collector.
It is preferred to be in the range of ² . This is due to the following reasons. If the amount of adhesion is less than 0.5 g / m ² , the adhesion between the positive electrode layer and the current collector may be reduced, so that both the high-rate discharge characteristics and the charge / discharge cycle life are sufficiently improved. May be unable to do so. On the other hand, when the adhesion amount exceeds 1.5 g / m ² ,
Since the internal resistance of the positive electrode increases, a high discharge capacity at a high rate may not be obtained. A more preferable range of the adhesion amount is 0.75 to 1.25 g / m ² .

When a negative electrode having a structure in which a negative electrode layer is laminated on a current collector via a conductive thermosetting resin layer is used as the negative electrode, the current collector has a structure in which the positive electrode layer is supported on the current collector. Can be used.

(Negative electrode 2) This negative electrode 2 is made of a porous current collector 7
A thermosetting resin layer 8 that is laminated on both surfaces of the current collector 7 and is provided with conductivity; and a laminate that is laminated on each of the thermosetting resin layers 8, a negative electrode active material, a non-aqueous electrolyte, And a negative electrode layer 9 containing a binder for holding the electrolyte.

Examples of the negative electrode active material include carbonaceous materials that occlude and release lithium ions. Such carbonaceous materials include, for example, those obtained by firing organic polymer compounds (eg, phenolic resin, polyacrylonitrile, cellulose, etc.), those obtained by firing coke and mesophase pitch, and those made by artificial graphite. And carbonaceous materials represented by natural graphite and the like. Among them, it is preferable to use a carbonaceous material obtained by firing the mesophase pitch at a temperature of 500 ° C. to 3000 ° C. in an inert gas atmosphere such as an argon gas or a nitrogen gas under normal pressure or reduced pressure.

As the non-aqueous electrolyte, those similar to those described above for the positive electrode are used.

The binder has a function of holding a non-aqueous electrolyte. As such a binder, a polymer of the same type as that described in the above-described positive electrode can be used, and among them, a VdF-HFP copolymer is preferable.

As the porous current collector, for example, a mesh made of copper or a copper alloy, an expanded metal, a punched metal, or the like can be used.

As the thermosetting resin used in the thermosetting resin layer 8 provided with the conductivity, a resin having non-aqueous electrolyte resistance is desirable. Examples of such thermosetting resins include the same ones as described for the positive electrode described above. Above all, those in which the state before the thermosetting is liquid (solvent-free) are preferable.

The thermosetting resin has a viscosity of 10 at 25 ° C. for the same reason as described above for the positive electrode.
It is desirable to be within the range of 0 cp to 200,000 cp. A more preferable range of the viscosity is 1000 cp to 100,000 c.
p.

The thermosetting resin has a temperature at which a curing reaction occurs, for one reason, for the same reason as described for the positive electrode.
It is preferably from 00 to 200 ° C. A more preferable range of the temperature is 130 to 170 ° C.

The application of conductivity to the thermosetting resin can be performed, for example, by dispersing a conductive powder in the thermosetting resin. As such conductive powder,
Examples similar to those described for the positive electrode described above can be given. Among them, carbon powder is preferable. Further, two or more of these powders may be used in combination. Note that the shape of the conductive powder can be, for example, fibrous or granular.

The amount of the conductive powder in the thermosetting resin layer is preferably in the range of 1% by weight to 50% by weight. This is due to the following reasons. If the amount of the conductive powder is too small, conduction between the negative electrode layer and the current collector is deteriorated, so that a high discharge capacity at a high rate may not be obtained. On the other hand, if the amount of the conductive powder is too large, the adhesiveness between the negative electrode layer and the current collector may be reduced. Therefore, it is necessary to sufficiently improve both the discharge characteristics at a high rate and the charge / discharge cycle life. May not be possible. In particular, when the thermosetting resin is an epoxy-based thermosetting resin, the amount of the conductive powder is from 1% by weight to 50% by weight.
(More preferably, 1% by weight to 35% by weight). When the thermosetting resin is a modified urethane-based thermosetting resin, the amount of the conductive powder is from 1% by weight to 40% by weight (more preferably, 1% by weight).
-20% by weight). Further, when the thermosetting resin is an acrylic thermosetting resin, the amount of the conductive powder is in the range of 1% by weight to 50% by weight (more preferably, 2% by weight to 30% by weight). Is preferred.

The amount of the thermosetting resin layer provided with the conductivity is 0.5 to 1.5 g / m 2 per one surface of the current collector.
It is preferred to be in the range of ² . This is due to the following reasons. When the adhesion amount is less than 0.5 g / m ² , there is a possibility that the adhesion between the negative electrode layer and the current collector may be reduced, so that both the discharge characteristics at a high rate and the charge / discharge cycle life are sufficiently improved. May be unable to do so. On the other hand, when the adhesion amount exceeds 1.5 g / m ² ,
Since the internal resistance of the negative electrode increases, a high discharge capacity at a high rate may not be obtained. A more preferable range of the adhesion amount is 0.75 to 1.25 g / m ² .

When a positive electrode having a structure in which a positive electrode layer is laminated on a current collector via a conductive thermosetting resin layer is used as the positive electrode, the negative electrode has a structure in which the current collector has the negative electrode layer carried thereon. Can be used.

(Electrolyte Layer) This electrolyte layer contains a non-aqueous electrolyte and a binder for holding the electrolyte.

As the non-aqueous electrolyte, those similar to those described above for the positive electrode are used.

The binder has a function of holding a non-aqueous electrolyte. As the binder, a polymer of the same type as that described for the positive electrode described above can be used, and among them, a VdF-HFP copolymer is preferable.

From the viewpoint of further improving the strength, the electrolyte layer may contain organic particles or inorganic particles such as silicon oxide powder.

The polymer lithium secondary battery is manufactured, for example, by the method described below. Including a plasticizer,
A positive electrode not impregnated with the nonaqueous electrolyte, a negative electrode containing the plasticizer and not impregnated with the nonaqueous electrolyte, and an electrolyte layer containing the plasticizer and not impregnated with the nonaqueous electrolyte are prepared. The positive electrode and the negative electrode are laminated with the electrolyte layer interposed therebetween, and integrated by thermocompression bonding. The plasticizer is removed from the obtained laminate by, for example, solvent extraction, impregnated with a non-aqueous electrolyte, and then sealed with an exterior material to obtain the secondary battery.

The plasticizer has excellent compatibility with the binder and can impart flexibility to the positive electrode, the negative electrode or the electrolyte layer, and can melt the positive electrode, the negative electrode or the electrolyte layer during thermocompression bonding. It is preferable that the material has the four properties that it can be easily removed. Examples of the plasticizer include dibutyl phthalate (DBP), dimethyl phthalate (DMP), and ethyl phthalyl ethyl glycolate (EPEG).

The solvent used for the solvent extraction is preferably a solvent having high volatility and in which a polymer having a function of holding a nonaqueous electrolyte is not dissolved. Examples thereof include alcohols such as methanol and ethanol, hydrocarbons such as hexane and cyclohexane, and ethers.

In the solvent extraction, it is preferable to heat the solvent or to apply ultrasonic waves to the solvent.

The positive and negative electrodes and the electrolyte layer, which contain a plasticizer and are not impregnated with a non-aqueous electrolyte, are produced, for example, by the method described below.

<Preparation of Positive Electrode Containing Plasticizer and Not Impregnated with Nonaqueous Electrolyte> The positive electrode is prepared, for example, by the method described below.

An active material, a polymer having a function of holding a non-aqueous electrolyte, a conductive material, and a plasticizer are mixed in an organic solvent such as acetone to prepare a paste, and the paste is formed into a film. A liquid-impregnated positive electrode sheet is prepared. On the other hand, by dispersing the conductive powder and the thermosetting resin in an appropriate solvent, or by dispersing the conductive powder in a liquid thermosetting resin, a thermosetting resin solution in which the conductive powder is dispersed is prepared. . The resulting solution is applied to both sides of the current collector. The positive electrode sheet is disposed on both sides of the current collector, and the thermosetting resin is thermally cured by applying heat and pressure to the positive electrode sheet, and the positive electrode sheet is provided on one surface of the thermosetting resin layer provided with conductivity. And a current collector is bonded to the other surface to obtain the positive electrode.

<Preparation of Negative Electrode Containing a Plasticizer and Not Impregnated with Nonaqueous Electrolyte> The negative electrode is prepared, for example, by a method described below.

A negative electrode sheet not impregnated with a non-aqueous electrolyte is prepared by mixing an active material, a polymer having a function of holding the non-aqueous electrolyte, and a plasticizer in an organic solvent such as acetone to prepare a paste and forming a film. Is prepared. On the other hand, by dispersing the conductive powder and the thermosetting resin in an appropriate solvent, or by dispersing the conductive powder in a liquid thermosetting resin, a thermosetting resin solution in which the conductive powder is dispersed is prepared. . The resulting solution is applied to both sides of the current collector. The negative electrode sheet is disposed on both surfaces of the current collector, and the thermosetting resin is thermally cured by applying heat and pressure to the negative electrode sheet, and the negative electrode sheet is provided on one surface of the thermosetting resin layer provided with conductivity. And a current collector is bonded to the other surface to obtain the negative electrode.

<Preparation of Electrolyte Layer Containing Plasticizer and Not Impregnated with Nonaqueous Electrolyte> The electrolyte layer may be prepared, for example, by adding a polymer having a function of holding the nonaqueous electrolyte and a plasticizer to an organic solvent such as acetone. To prepare a paste, and the paste is formed into a film.

In FIG. 1 described above, an example in which a current collector having a porous structure is used as the negative electrode current collector has been described, but a metal foil such as a copper foil may be used.

In FIG. 1 described above, an example is described in which a power generating element having a five-layer structure in which a positive electrode, an electrolyte layer, a negative electrode, an electrolyte layer, and a positive electrode are stacked in this order has been described. Alternatively, a power generating element having a three-layer structure including a positive electrode, an electrolyte layer, and a negative electrode may be used. The power generating element having a three-layer structure includes a positive electrode having a structure in which a positive electrode layer is supported on both surfaces of a porous current collector, a negative electrode having a structure in which a negative electrode layer is supported on both surfaces of the porous current collector, and a positive electrode and a negative electrode. A positive electrode having a structure consisting of an electrolyte layer bonded between them, or a structure in which a positive electrode layer is supported on one side of a metal foil such as an aluminum foil, and a negative electrode layer on one side of a metal foil such as a copper foil The structure may include a negative electrode having a supported structure and an electrolyte layer adhered between the positive and negative electrode layers. When a metal foil is used as a current collector for the positive and negative electrodes of such a three-layer power generation element, a thermosetting resin layer having conductivity is formed on a surface on which the positive and negative electrode layers are supported. I just want to.

As described in detail above, the polymer lithium secondary battery according to the present invention comprises: a current collector; a thermosetting resin layer laminated on the current collector and provided with conductivity; And a positive electrode layer laminated on the conductive resin layer. Since the thermosetting resin layer has excellent adhesion to both the positive electrode layer and the current collector, the contact resistance between the positive electrode layer and the current collector can be reduced. Therefore, the polymer lithium secondary battery including the positive electrode can obtain a high capacity even when discharged with a large current, and can enhance the stability of the discharge characteristics. Further, in the secondary battery, since the positive electrode layer can be prevented from peeling off as the charge / discharge cycle progresses, the charge / discharge cycle life can be improved.

Further, the polymer lithium secondary battery according to the present invention is characterized in that a current-setting thermosetting resin is applied to a current collector, and the thermosetting resin is impregnated with a non-aqueous electrolyte solution. A positive electrode sheet is provided, and the obtained laminate is subjected to thermocompression bonding to thermoset the thermosetting resin, followed by impregnation with a nonaqueous electrolyte. Such a positive electrode can firmly adhere both a positive electrode sheet impregnated with a non-aqueous electrolyte and a current collector to a thermosetting resin layer provided with conductivity formed by thermosetting. Therefore, the polymer lithium secondary battery including the positive electrode can obtain a high capacity even when discharged with a large current, and can enhance the stability of the discharge characteristics. Further, in the secondary battery, the positive electrode sheet can be prevented from peeling off as the charge / discharge cycle progresses, so that the charge / discharge cycle life can be improved.

Another polymer lithium secondary battery according to the present invention includes a current collector, a thermosetting resin layer laminated on the current collector and having conductivity, and a thermosetting resin layer. And a negative electrode including a stacked negative electrode layer. Since the thermosetting resin layer has excellent adhesiveness to both the negative electrode layer and the current collector, the contact resistance between the negative electrode layer and the current collector can be reduced. Therefore, the polymer lithium secondary battery including the negative electrode can obtain a high capacity even when discharged with a large current, and can enhance the stability of the discharge characteristics. Further, in the secondary battery, the negative electrode layer can be prevented from peeling off as the charge / discharge cycle progresses, so that the charge / discharge cycle life can be improved.

In another polymer lithium secondary battery according to the present invention, a thermosetting resin having conductivity is applied to a current collector, and a non-aqueous electrolyte solution is applied on the thermosetting resin. An impregnated negative electrode sheet is provided, and the obtained laminate is subjected to thermocompression bonding to thermoset the thermosetting resin, followed by impregnation with a nonaqueous electrolyte. In such a negative electrode, both a negative electrode sheet impregnated with a non-aqueous electrolyte and a current collector can be firmly bonded to a thermosetting resin layer provided with conductivity formed by thermosetting. Therefore,
The polymer lithium secondary battery provided with the negative electrode can obtain a high capacity even when discharged with a large current, and can enhance the stability of discharge characteristics. In the secondary battery, the negative electrode sheet can be prevented from peeling off as the charge / discharge cycle progresses, so that the charge / discharge cycle life can be improved.

[0064] Still another polymer lithium secondary battery according to the present invention is a current collector, a thermosetting resin layer laminated on the current collector and provided with conductivity, and a thermosetting resin layer. A positive electrode including a positive electrode layer laminated on a current collector, a thermosetting resin layer laminated on the current collector and provided with conductivity, and a negative electrode laminated on the thermosetting resin layer And a negative electrode including the layer. Such a secondary battery can further improve the discharge capacity and the charge / discharge cycle life when discharged with a large current.

[0065]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below in detail with reference to the drawings.

Example 1 <Preparation of Positive Electrode Not Impregnated with Nonaqueous Electrolyte> 56% by weight of a lithium manganese composite oxide represented by a composition formula of LiMn ₂ O ₄ as an active material and 5% by weight of carbon black And 17% by weight of a vinylidene fluoride-hexafluoropropylene (VdF-HFP) copolymer powder as a binder.
And 22% by weight of dibutyl phthalate (DBP) were mixed in acetone to prepare a paste. The obtained paste was applied on a PET film to prepare a positive electrode sheet not impregnated with a non-aqueous electrolyte.

On the other hand, under the curing conditions of 150 ° C. for 3 minutes, 3% by weight of acetylene black powder was dispersed in a liquid epoxy-based thermosetting resin. Such a thermosetting resin was applied to both surfaces of a collector made of expanded metal made of aluminum using a spray gun so that the amount of adhesion on each surface was 1 g / m ² .

The non-aqueous electrolyte solution is obtained by sandwiching the positive electrode current collector between the two positive electrode sheets, passing the current collector between heater blocks heated to 140 to 150 ° C., and further pressing the same with a hot roll at 70 ° C. An unimpregnated positive electrode was prepared.

<Preparation of Negative Electrode Impregnated with Nonaqueous Electrolyte> 58% by weight of mesophase pitch carbon fiber as active material, 17% by weight of VdF-HFP copolymer powder as binder, dibutyl phthalate (DBP) 25% by weight was mixed in acetone to prepare a paste. The obtained paste was applied on a PET film to produce a non-aqueous electrolyte-unimpregnated negative electrode sheet. The obtained negative electrode sheet was heat-pressed with heat rolls on both surfaces of a current collector made of a copper expanded metal to produce a non-aqueous electrolyte-unimpregnated negative electrode.

<Preparation of Electrolyte Layer Not Impregnated with Nonaqueous Electrolyte> 33.3 parts by weight of silicon oxide powder and VdF as a binder
22.2 parts by weight of -HFP copolymer powder and 44.5 parts by weight of dibutyl phthalate (DBP) were mixed in acetone to form a paste. The obtained paste was applied on a PET film, formed into a sheet, and cut to form an electrolyte layer not impregnated with a non-aqueous electrolyte.

<Preparation of Nonaqueous Electrolyte> LiPF ₆ as an electrolyte was mixed with a nonaqueous solvent in which ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed at a volume ratio of 2: 1 at a concentration of 1 mol / mol. 1 to prepare a non-aqueous electrolyte.

<Battery Assembly> A positive electrode not impregnated with a non-aqueous electrolyte was
Sheets, one non-aqueous electrolyte impregnated negative electrode and two non-aqueous electrolyte non-impregnated electrolyte layers were prepared, and these were laminated so that the electrolyte layer was interposed between the positive electrode and the negative electrode. A non-aqueous electrolyte-unimpregnated power generating element was prepared by heat-pressing with a heated rigid roll.

Such a power generating element was immersed in methanol, and allowed to stand in a reduced pressure atmosphere while applying ultrasonic waves.
This operation was repeated until the concentration of DBP in methanol by gas chromatography became 20 ppm or less, whereby the plasticizer in the power generating element was removed. After drying the laminate, the power generating element is impregnated with the non-aqueous electrolyte having the composition described above, and a laminate in which a polyethylene terephthalate (PET) film, an aluminum foil, and a heat-fusible resin film are laminated in this order from the outermost layer A polymer lithium secondary battery having a theoretical capacity of 110 mAh and having the structure shown in FIG. 1 described above was manufactured by sealing with a film packaging material.

(Example 2) <Preparation of positive electrode not impregnated with non-aqueous electrolytic solution>
3% by weight of acetylene black powder was dispersed in a liquid modified urethane-based thermosetting resin at 10 ° C. for 10 minutes. Such a thermosetting resin was applied to both surfaces of a collector made of expanded metal made of aluminum using a spray gun so that the amount of adhesion on each surface was 1 g / m ² .

Two positive electrode sheets not impregnated with a non-aqueous electrolyte similar to those described in Example 1 were prepared, and the positive electrode current collector was sandwiched between these positive electrode sheets and heated to 140 to 150 ° C. Pass between heater blocks, then 70 ° C
The non-aqueous electrolyte-unimpregnated positive electrode was prepared by heat-pressing with a hot roll.

A polymer lithium secondary battery was manufactured in the same manner as in Example 1 except that such a positive electrode not impregnated with a nonaqueous electrolyte was used.

(Example 3) <Preparation of positive electrode not impregnated with non-aqueous electrolytic solution>
At 5 ° C. for 5 minutes, 3% by weight of acetylene black powder was dispersed in a liquid acrylic thermosetting resin. Spray such a thermosetting resin on both sides of a current collector made of expanded metal made of aluminum with an amount of 1 g on each side using a spray gun.
/ M ² .

Two positive electrode sheets not impregnated with a non-aqueous electrolyte similar to those described in Example 1 were prepared, and the positive electrode current collector was sandwiched between these positive electrode sheets and heated to 140 to 150 ° C. Pass between heater blocks, then 70 ° C
The non-aqueous electrolyte-unimpregnated positive electrode was prepared by heat-pressing with a hot roll.

A polymer lithium secondary battery was manufactured in the same manner as in Example 1 except that such a positive electrode not impregnated with a nonaqueous electrolyte was used.

(Example 4) <Preparation of a positive electrode not impregnated with a non-aqueous electrolyte>
In 3 minutes at ℃, liquid epoxy-based thermosetting resin
Minium powder was dispersed at 3% by weight. Such thermosetting
Made of expanded metal made of conductive resin
Spray gun on both sides of the conductor with 1g / m ^Two
It applied so that it might become.

Two positive electrode sheets not impregnated with a non-aqueous electrolyte solution similar to those described in Example 1 were prepared, and the positive electrode current collector was sandwiched between these positive electrode sheets and heated to 140 to 150 ° C. Pass between heater blocks, then 70 ° C
The non-aqueous electrolyte-unimpregnated positive electrode was prepared by heat-pressing with a hot roll.

A polymer lithium secondary battery was manufactured in the same manner as in Example 1, except that such a positive electrode not impregnated with a nonaqueous electrolyte was used.

(Example 5) <Preparation of positive electrode not impregnated with non-aqueous electrolyte> A paste having the same composition as in Example 1 described above was applied on a PET film to prepare a positive electrode sheet not impregnated with a non-aqueous electrolyte. did. A current collector made of expanded metal made of aluminum is sandwiched between the two positive electrode sheets, passed through a heater block heated to 140 to 150 ° C., and further heated and pressed by a hot roll, so that the non-aqueous electrolyte is not impregnated. Was produced.

<Preparation of Negative Electrode Not Impregnated with Nonaqueous Electrolyte> 3% by weight of acetylene black powder was dispersed in a liquid epoxy-based thermosetting resin at 150 ° C. for 3 minutes.
Such a thermosetting resin is applied with a spray gun to both sides of a collector made of expanded metal made of copper, and the amount of adhesion on one side is 1 g.
/ M ² .

Two negative electrode sheets not impregnated with a non-aqueous electrolyte solution similar to those described in Example 1 were prepared, the current collector was sandwiched between the negative electrode sheets, and a heater heated to 140 to 150 ° C. The mixture was passed between the blocks and heated and pressed with a hot roll at 70 ° C. to produce a non-aqueous electrolyte-unimpregnated negative electrode.

Two positive electrodes not impregnated with the non-aqueous electrolyte, one negative electrode not impregnated with the non-aqueous electrolyte, and two electrolyte layers not impregnated with the non-aqueous electrolyte as in Example 1 were prepared. Then, these were laminated so that the electrolyte layer was interposed between the positive electrode and the negative electrode, and heated and pressed by a heated rigid roll to produce a non-aqueous electrolyte-unimpregnated power generating element.

The power generating element was immersed in methanol and left in a reduced pressure atmosphere while applying ultrasonic waves.
This operation was repeated until the concentration of DBP in methanol by gas chromatography became 20 ppm or less, whereby the plasticizer in the power generating element was removed. After drying the laminate, the power generating element is impregnated with a non-aqueous electrolyte having the same composition as described in Example 1, and a laminate film of the same type as described in Example 1 is used. By sealing with an exterior film that becomes
The theoretical capacity having the structure shown in FIG. 1 described above is 110 mA.
h. A polymer lithium secondary battery was manufactured.

(Example 6) <Preparation of a negative electrode not impregnated with a non-aqueous electrolyte solution>
3% by weight of acetylene black powder was dispersed in a liquid modified urethane-based thermosetting resin at 10 ° C. for 10 minutes. Such a thermosetting resin is coated with a spray gun on both surfaces of a collector made of expanded metal made of copper to have an adhesion amount of 1 g / m2 on one surface.
² was applied.

Two negative electrode sheets not impregnated with a non-aqueous electrolyte similar to those described in Example 1 were prepared, and the negative electrode current collector was sandwiched between these negative electrode sheets and heated to 140 to 150 ° C. Pass between heater blocks, then 70 ° C
The non-aqueous electrolyte-unimpregnated negative electrode was prepared by heat-pressing with a hot roll.

A polymer lithium secondary battery was manufactured in the same manner as in Example 5, except that such a negative electrode not impregnated with a nonaqueous electrolyte was used.

(Example 7) <Preparation of negative electrode not impregnated with non-aqueous electrolyte>
At 5 ° C. for 5 minutes, 3% by weight of acetylene black powder was dispersed in a liquid acrylic thermosetting resin. Such a thermosetting resin was applied to both surfaces of a current collector made of a copper expanded metal by a spray gun so that the adhesion amount on one surface was 1 g / m ² .

Two negative electrode sheets not impregnated with a non-aqueous electrolyte similar to those described in Example 1 were prepared, and the negative electrode current collector was sandwiched between the negative electrode sheets and heated to 140 to 150 ° C. Pass between heater blocks, then 70 ° C
The non-aqueous electrolyte-unimpregnated negative electrode was prepared by heat-pressing with a hot roll.

A polymer lithium secondary battery was manufactured in the same manner as in Example 5, except that such a negative electrode not impregnated with a non-aqueous electrolyte was used.

Example 8 <Preparation of Negative Electrode Impregnated with Non-Aqueous Electrolyte>
At 3 ° C., 10% by weight of aluminum powder was dispersed in a liquid epoxy-based thermosetting resin. Such a thermosetting resin was applied to both surfaces of a current collector made of a copper expanded metal by a spray gun so that the adhesion amount on one surface was 1 g / m ² .

Two negative electrode sheets not impregnated with a non-aqueous electrolyte solution similar to those described in Example 1 were prepared, and the negative electrode current collector was sandwiched between these negative electrode sheets and heated to 140 to 150 ° C. Pass between heater blocks, then 70 ° C
The non-aqueous electrolyte-unimpregnated negative electrode was prepared by heat-pressing with a hot roll.

A polymer lithium secondary battery was manufactured in the same manner as in Example 5, except that the negative electrode not impregnated with the nonaqueous electrolyte was used.

(Comparative Example) Two positive electrodes not impregnated with a non-aqueous electrolyte similar to that of Example 5 described above, and one negative electrode impregnated with a non-aqueous electrolyte similar to that of Example 1 described above, and Two non-aqueous electrolyte solution-impregnated electrolyte layers similar to those in Example 1 were prepared, and these were laminated so that the electrolyte layer was interposed between the positive electrode and the negative electrode, and were thermocompression-bonded with a heated rigid roll. Thus, a polymer lithium secondary battery was manufactured in the same manner as in Example 1 except that a power generating element not impregnated with the non-aqueous electrolyte was prepared.

Table 1 shows the types and characteristics of the thermosetting resin layers used in the secondary batteries of Examples 1 to 8.

The obtained secondary batteries of Examples 1 to 8 and Comparative Example were charged at a constant current of 1 C (110 mAh) at a constant current of 1 C.
(110 mAh) constant current discharge / discharge cycle was performed. Table 2 below shows the capacity at the third cycle and the capacity at the 200th cycle at this time.

[0100]

[Table 1]

[0101]

[Table 2]

As is clear from Tables 1 and 2, the secondary batteries of Examples 1 to 4 provided with a positive electrode in which a thermosetting resin layer provided with conductivity was provided between a positive electrode layer and a current collector. The secondary batteries of Examples 5 to 8 provided with a negative electrode in which a thermosetting resin layer provided with conductivity is provided between the negative electrode layer and the current collector have no such thermosetting resin layer. As compared with the secondary battery of the comparative example having the positive and negative electrodes formed, the discharge capacity when discharging with a large current of 1 C is high, and the discharge capacity when performing 200 charge / discharge cycles with such a large current It can be seen that the decrease in the value can be suppressed.

(Example 9) Two positive electrodes not impregnated with a non-aqueous electrolyte similar to that of Example 1 described above, and one negative electrode impregnated with a non-aqueous electrolyte similar to that of Example 5 described above, and Example 1
By preparing two electrolyte layers not impregnated with the same nonaqueous electrolyte as described above, laminating these so that the electrolyte layer is interposed between the positive electrode and the negative electrode, and heat-pressing with a heated rigid roll A polymer lithium secondary battery was manufactured in the same manner as in Example 1 except that a power generating element not impregnated with a non-aqueous electrolyte was prepared.

Example 10 Two positive electrodes not impregnated with a non-aqueous electrolyte similar to that of Example 4 described above, and one negative electrode impregnated with a non-aqueous electrolyte similar to that of Example 8 described above, and Two non-aqueous electrolyte-unimpregnated electrolyte layers similar to those in Example 1 were prepared,
These are laminated so that the electrolyte layer is interposed between the positive electrode and the negative electrode, and heated and pressed by a heated rigid roll, thereby producing a non-aqueous electrolyte-unimpregnated power generating element. A polymer lithium secondary battery was manufactured in the same manner as in Example 1.

The obtained secondary batteries of Examples 9 to 10 were charged at a constant current of 1 C (110 mAh) at a constant current of 1 C (110 mAh).
(mAh) of constant current discharge. When the capacity at the third cycle and the capacity at the 200th cycle at this time were measured, the secondary battery of Example 9 had a discharge capacity at the third cycle of 106 mAh and a discharge capacity at the 200th cycle of 98 mAh. The secondary battery of Example 10 is 3
The discharge capacity at the cycle was 107 mAh, and the discharge capacity at the 200th cycle was 100 mAh.

[0106]

As described above in detail, according to the present invention, a polymer capable of achieving high capacity and long life even when discharged with a large current, and having stable discharge capacity and charge / discharge cycle characteristics. A lithium secondary battery can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a polymer lithium secondary battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 2 ... Negative electrode, 3 ... Electrolyte layer, 4 ... Positive electrode collector, 5 ... Thermosetting resin layer provided with conductivity, 6 ... Positive electrode layer, 7 ... Negative electrode current collector, 8 ... Conduction Thermosetting resin layer provided with properties, 9: negative electrode layer, 13: exterior material.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) DJ08 EJ00 EJ12

Claims (5)

[Claims] 1. A positive electrode comprising a current collector, a thermosetting resin layer laminated on the current collector and provided with conductivity, and a positive electrode layer laminated on the thermosetting resin layer. A polymer lithium secondary battery characterized in that: 2. A current collector is coated with a thermosetting resin having conductivity, and a positive electrode sheet not impregnated with a non-aqueous electrolyte is disposed on the thermosetting resin. A polymer lithium secondary battery comprising a positive electrode obtained by thermosetting the thermosetting resin by performing thermocompression bonding and then impregnating with a nonaqueous electrolyte. 3. A negative electrode comprising a current collector, a thermosetting resin layer laminated on the current collector and provided with conductivity, and a negative electrode layer laminated on the thermosetting resin layer. A polymer lithium secondary battery characterized in that: 4. A thermosetting resin having conductivity is applied to a current collector, and a non-aqueous electrolyte-unimpregnated negative electrode sheet is disposed on the thermosetting resin. A polymer lithium secondary battery comprising a negative electrode obtained by thermosetting the thermosetting resin by performing thermocompression bonding and then impregnating with a nonaqueous electrolyte. 5. A positive electrode comprising: a current collector; a thermosetting resin layer laminated to the current collector and provided with conductivity; and a positive electrode layer laminated to the thermosetting resin layer. A current collector, a negative electrode including a thermosetting resin layer laminated on the current collector and provided with conductivity, and a negative electrode layer laminated on the thermosetting resin layer. Polymer lithium secondary battery.