JP5192658B2 - Lithium ion polymer battery - Google Patents

Description

  The present invention relates to a lithium ion polymer battery, and more particularly to a lithium ion polymer battery in which an electrode active material layer is surface-treated.

  In recent years, various portable devices have been reduced in size, and accordingly, a battery serving as a power source is required to have a higher capacity, a higher output, and a variety of shapes. In addition, high safety is also required for portable devices. Currently, many portable devices use lithium ion batteries. However, many lithium ion batteries are enclosed in an aluminum can case, which has a drawback of low design freedom.

  Lithium ion polymer batteries use a gel electrolyte instead of an electrolyte, and the leakage resistance is improved. Therefore, it is possible to make a laminate exterior using a laminate exterior body with a simple productivity as the exterior body, and there is a degree of freedom in shape selection. It has the feature of being high. Further, when the internal pressure of the battery rises due to some trouble, the laminate exterior is destroyed at a pressure lower than that of the can case, so the influence on the periphery is small. In addition, by using a gel electrolyte that does not leak, there is an advantage that a flammable liquid does not leak to the outside even if the exterior body is broken, and development is progressing as a battery with high safety.

  There are roughly two methods for producing a lithium ion polymer battery.

  First, as described in Patent Document 1 and Patent Document 2, a solution (pregel solution) capable of forming a gel electrolyte is applied to the positive electrode, the negative electrode, or the separator, and the gel electrolyte is applied by actinic rays such as ultraviolet rays, electron beams, or heat. There is a method (coating-curing type) in which after forming a layer or a polymer layer, a battery is formed by laminating or winding electrodes (positive electrode and negative electrode) and coating is applied. In this case, since it has the process of apply | coating a pregel solution on an electrode or a separator, and the process of hardening it, a manufacturing process becomes complicated. In addition, since the pregel solution is exposed to the air in the coating process, it is necessary that the electrolyte solution does not volatilize under the coating and curing conditions. In other words, in order to prevent the electrolyte from volatilizing, low-boiling solvents such as highly volatile diethyl carbonate (DEC) and methyl ethyl carbonate (MEC) cannot be used, and ethylene carbonate (EC), propylene carbonate (PC), etc. The use of a high boiling point solvent is forced. Therefore, there is a problem that the viscosity of the pregel solution is increased and it is difficult to impregnate the electrode and the separator.

  Next, as described in Patent Document 3, a positive electrode and a negative electrode are opposed to each other through a separator, sealed in an outer package, and then injected with a solution capable of forming a gel electrolyte (pregel solution), sealed, and heated by gel There is a technique for forming an electrolyte (post-injection type). In this case, the manufacturing process requires only the process of gelling the pregel solution injected into the battery with heat. Since the pregel solution is not exposed to the atmosphere, the selectivity of the solvent is widened and a low boiling point solvent can be used. However, since the polymer component is added, the viscosity of the pregel solution tends to be larger than that of a normal electrolytic solution. Therefore, since the impregnation property is lowered, the capacity and rate characteristics tend to be lower than that of a lithium ion battery using an electrolytic solution.

  In addition, as a method for improving the wettability between the positive electrode and the electrolytic solution at a low temperature, Patent Document 4 describes that a positive electrode slurry to which a silane coupling agent having an epoxy group or an amino group as an organic reactive group is added is applied. is there.

JP 2000-67866 A Japanese Patent Laid-Open No. 10-74526 Japanese Patent Laid-Open No. 11-283673

  In the lithium ion polymer battery, a step of impregnating the electrode with the pregel solution is required. At that time, the impregnation property of the pregel solution to the electrode is very important. For example, when the electrode and the pregel solution are easily compatible or when the viscosity is low, the pregel solution is impregnated into the electrode by vacuum impregnation. However, even when the viscosity of the pregel solution is low, it is not easy to impregnate the electrode filled with high density. When the impregnation property is poor, a portion where the electrode active material and the gel electrolyte cannot contact with each other is generated in the electrode pores, and when the capacity is reduced or the contact is not sufficient, the high-rate characteristic is deteriorated because the ion conduction path is narrow. In particular, in a lithium ion polymer battery designed for high capacity, the electrode density of the negative electrode is increased, so that the impregnation property of the electrolytic solution in the negative electrode is very problematic.

  Furthermore, the viscosity can be lowered by lowering the polymer concentration of the pregel solution, but in that case, the pregel solution may not gel in the electrode, and if the acrylic monomer remains in the battery, the battery characteristics may be deteriorated. There is.

  In addition, the coating-curing type in which the pregel solution is applied to the electrode is formed by laminating or winding the electrode and the separator after the gel electrolyte layer is formed. In the post-injection type in which the pregel solution is injected and cured, it is difficult to make the adhesion at the flat portion and the bent portion of the wound electrode winding body (hereinafter referred to as J / R) uniform. Therefore, the charge may be biased with the charge / discharge cycle, and the electrode may swell.

  When applying a positive electrode slurry to which a silane coupling agent is added, the impregnation property at low temperature is improved by the action of the positive electrode treated with the silane coupling agent and the electrolytic solution. Only by forming the layer, the layer becomes a resistance component, and the low temperature characteristic or the rate characteristic cannot be improved. Further, the impregnation is important for the negative electrode. When a gel electrolyte is used, sufficient impregnation cannot be obtained even if the positive electrode is subjected to a surface treatment.

  The present invention ensures high impregnation of a pregel solution having a sufficient polymer concentration into a high-density filled electrode, and further improves the adhesion between the electrode and the gel electrolyte, thereby providing excellent rate characteristics and The present invention provides a lithium polymer battery in which an increase in resistance and an increase in cell thickness are suppressed.

  More specifically, the present invention uses a positive electrode and a negative electrode modified with a surface treatment agent, or an electrode active material of a negative electrode, and more specifically, (1) an electrode coated and dried on a current collector is adjusted to a predetermined pH concentration. An electrode that has been surface-treated by immersing and impregnating in a surface-treating agent solution made of the adjusted coupling agent and then subjecting the electrode substrate to a coupling agent at a predetermined temperature, or (2) current collection After applying a coupling agent solution adjusted to a predetermined pH concentration to the electrode applied and dried on the body, surface treatment was performed by causing a condensation reaction between the electrode substrate and the coupling agent at a predetermined temperature. After the electrode or (3) powdered electrode active material is immersed in or sprayed into a surface treatment agent solution comprising a coupling agent adjusted to a predetermined pH concentration, the electrode active material and the coupling agent are heated at a predetermined temperature. An electrode made of an electrode active material that has been surface-treated by a combined reaction, or (4) an electrode slurry to which a coupling agent solution has been added is applied on a current collector, dried, and then an electrode substrate at a predetermined temperature. Using a surface-treated electrode by performing a condensation reaction between the acrylate-based pregel solution and (A) coating-curing type, or (B) post-injection type, It has been found that the above-mentioned problems can be solved by obtaining.

That is, the lithium ion polymer battery of the present invention is a lithium ion polymer battery having a positive electrode, a negative electrode, a separator, and a gel electrolyte, and at least the negative electrode active material layer of the positive electrode and the negative electrode has an organic functional group. The surface treatment agent includes at least one selected from a silane coupling agent, an aluminum coupling agent, and a titanium coupling agent, and serves as the surface treatment agent. The organic functional group of the agent includes at least one selected from an acryl group, a methacryl group, an epoxy group, and a vinyl group, and the gel electrolyte includes at least a polymer of an acrylate monomer or a methacrylate monomer, and the electrode active material of the negative electrode In the gel electrolyte via the surface treatment agent on the surface of Wherein the binding of Rimmer is formed.

The front Symbol electrode active material, the may be treated by impregnation of the surface treatment agent, it may be treated by coating, formed by mixing the surface treating agent in the slurry of the electrode active material May be . The positive electrode active material, absorbs lithium ions, oxides capable of releasing, for _{example, LiCoO 2, LiNi 1-x} Co x O 2, LiMn 2 O 4, LiNi x Mn 2-x O 4 ( where 0 < Metal oxide positive electrode materials such as x ≦ 1) can be used. As the negative electrode active material, graphite, amorphous carbon, diamond-like carbon, carbon nanotube, carbon nanohorn, or the like containing lithium, or a composite thereof or metallic lithium can be used.

  According to the present invention, the electrode active material is modified by the surface treatment agent, the pregel solution is impregnated into the electrode active material, and the adhesion between the electrode and the gel electrolyte is improved, thereby increasing the resistance of the battery accompanying the charge / discharge cycle. Further, rate characteristics can be improved while suppressing an increase in cell thickness. In other words, surface treatment with a coupling agent on the active material surface in the electrode pores improves the impregnation property of the gel electrolyte into the electrode pores, and the ion conduction path is sufficiently formed, resulting in high rate characteristics. Will improve. In addition, as shown in the schematic diagram of the state of bonding between the electrode active material surface and the gel electrolyte via the coupling agent of the present invention in FIG. 2, the gel via the coupling agent 23 on the surface of the electrode active material 24. Since a bond with the polymer 22 in the electrolyte is formed, the adhesion between the electrode active material 24 and the polymer 22 in the gel electrolyte is increased, and an increase in cell thickness associated with the cycle can be suppressed.

  In the present invention, the coupling agent of the surface treatment agent, in a solution adjusted to a predetermined pH concentration, a methoxy group becomes a hydroxyl group, hydrogen bonds with a hydroxyl group present on the substrate, and causes a condensation reaction by heating, A coupling agent binds on the substrate. Furthermore, when the gel electrolyte of the present invention is an acrylate type, when the organic functional group of the coupling agent bonded to the base material is a polymerization group, it reacts with the acrylate in the pregel solution, and the gel electrolyte and the base material are combined. . In addition, since the coupling agent is present in the pores of the electrode active material layer as the base material, the compatibility with the pregel solution is improved, and the impregnation property of the pregel solution is improved. Therefore, a pregel solution having a sufficient polymer concentration can be used, the gelation of the gel electrolyte proceeds sufficiently, and the acrylic monomer does not remain.

  According to the present invention, the pregel solution is impregnated by coupling a coupling agent to a hydroxyl group present on the surface of a carbon material such as graphite or amorphous carbon used as a negative electrode or a surface functional group such as a carbonyl group by a condensation reaction. And the contact between the electrode active material and the gel electrolyte can be sufficiently achieved, so that the capacity reduction is prevented and the high-rate characteristics are improved. In addition, since the electrode active material and the gel electrolyte are directly bonded, the adhesion is improved and the gel electrolyte can follow the swelling and shrinkage associated with the charge / discharge cycle, thereby preventing the electrode active material and the gel electrolyte interface from peeling off and increasing the resistance. Can be suppressed. Moreover, since the swelling of an electrode can be suppressed by the gel electrolyte couple | bonded with the electrode active material, the increase in the cell thickness accompanying a charging / discharging cycle can be suppressed.

  A coupling agent can be bonded to the surface of a metal oxide such as lithium cobaltate or lithium manganate used as the positive electrode by a condensation reaction. Therefore, the impregnation property of the pregel solution is improved, and the electrode active material and the gel electrolyte can be sufficiently contacted, so that the capacity is prevented from decreasing and the high rate characteristics are improved. In addition, since the electrode active material and the gel electrolyte are directly bonded, the adhesion is improved and the gel electrolyte can follow the swelling and shrinkage associated with the charge / discharge cycle, thereby preventing the electrode active material and the gel electrolyte interface from peeling off and increasing the resistance. Can be suppressed. Moreover, since the swelling of an electrode can be suppressed by the gel electrolyte couple | bonded with the electrode active material, the increase in the cell thickness accompanying a charging / discharging cycle can be suppressed.

  In the present invention, lithium ion having a step of injecting a pregel solution by post-injection (post-injection type) also into a lithium ion polymer battery having a step of applying a pregel solution to an electrode (application-curing type). It can also be applied to polymer batteries.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing a structure of an electrode of a lithium ion polymer battery of the present invention. As shown in FIG. 1, a positive electrode containing an oxide positive electrode active material capable of inserting and extracting lithium ions formed on both surfaces of a positive electrode current collector 14 made of an aluminum foil or the like from which a positive electrode tab 17 made of aluminum or the like is drawn. 11 and a carbon material or oxide that occludes and releases lithium ions formed on both surfaces of a negative electrode current collector 15 made of a copper foil or the like from which a negative electrode tab 18 made of nickel or the like is drawn, a metal that forms an alloy with lithium, A negative electrode 12 containing a negative electrode active material made of either lithium metal itself or a mixture thereof is laminated and wound through a gel electrolyte 16 and a separator 13 containing the same, and the positive electrode and negative electrode, or The electrode active material layer of the negative electrode is surface-treated with a surface treatment agent composed of a coupling agent.

  The surface treatment method is as follows: (1) The electrode coated and dried on the current collector is immersed and impregnated in a coupling agent solution adjusted to a predetermined pH concentration, and then the electrode substrate and the coupling agent are condensed at a predetermined temperature. By applying a reaction, the surface-treated electrode, or (2) a coating agent solution adjusted to a predetermined pH concentration is applied to the electrode applied and dried on the current collector, and then the electrode is applied at a predetermined temperature. Immersion in a surface-treating agent solution consisting of an electrode that has been surface-treated by causing a condensation reaction between the base material and the coupling agent, or (3) a coupling agent in which a powdered electrode active material is adjusted to a predetermined pH concentration After impregnation or spraying, an electrode composed of an electrode active material that has been surface-treated by a condensation reaction between the electrode active material and a coupling agent at a predetermined temperature, or (4) an electrode to which a coupling agent solution has been added After applying the slurry onto the current collector and drying, a condensation reaction between the electrode base material and the coupling agent is performed at a predetermined temperature, and the surface-treated electrode is used to prepare an acrylate-based pregel solution (A Although a lithium ion polymer battery can be obtained by a coating-curing type or a (B) post-injection type, (B) is preferred because (A) makes the manufacturing process complicated.

  In the present invention, examples of the coupling agent include a silane coupling agent, an aluminum coupling agent, and a titanium coupling agent. In addition, examples of the organic functional group of these coupling agents include an acrylic group, a methacryl group, an epoxy group, a vinyl group, and the like, and have an organic reactive group capable of polymerizing with an acrylate.

  The coupling agent solution used in the present invention may be one containing 0.1 to 5% by mass of the above coupling agent in an acetic acid aqueous solution adjusted to pH 4 to 7, in order to reduce the viscosity. Further, methyl alcohol or ethyl alcohol may be added.

  In the present invention, the separator is not particularly limited as long as it is generally used in lithium polymer batteries, such as a nonwoven fabric and a polyolefin microporous membrane. The material is not particularly limited as long as it is porous, such as polyethylene, polypropylene, polystyrene, and polytetrafluoroethylene. Preferably, the film is a polyethylene microporous film having a thickness of 5 to 25 μm, more preferably 7 to 16 μm.

  In the present invention, examples of the gelling component contained in the gel electrolyte include a monomer, oligomer, copolymer oligomer and the like having two or more polymerized groups per molecule.

  Examples of the gelling component include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, propylene diacrylate, dipropylene diacrylate, tripropylene diacrylate, and 1,3-butanediol diacrylate. , 1,4-butanediol diacrylate, bifunctional acrylate such as 1,6-hexanediol diacrylate, trifunctional acrylate such as trimethylolpropane triacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, And tetrafunctional acrylates such as pentaerythritol tetraacrylate and the above methacrylate monomers. But it is not limited thereto.

  In addition to the gel component, monomers such as urethane acrylate and urethane methacrylate, copolymer oligomers thereof, and copolymer oligomers with acrylonitrile are exemplified, but the invention is not limited thereto.

  The gel component is not limited to the described monomer, oligomer, or polymer, and any gel component that can be gelled can be used. Further, the gelation is not limited to one type of monomer, oligomer or polymer, and a plurality of types of gelation components can be mixed as required.

  In the present invention, as a plasticizer contained in the gel electrolyte, generally lithium ions such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propionate, γ-butyrolactone, 1,2-dimethoxyethane, etc. Although the organic solvent used for a battery can be used 1 type or in mixture of 2 or more types, it is not limited to these.

In the present invention, the electrolyte contained in the gel electrolyte may be an electrolyte generally used for lithium ion batteries such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , It is not limited to these.

  In the present invention, benzoins, peroxides, and the like can be used as thermal polymerization initiators as necessary, but are not limited thereto.

  In the present invention, an additive having an electrode film-forming ability, for example, a compound having a sulfonyl group or a vinylene carbonate compound can be added as necessary, but is not limited thereto.

In the present invention, as the positive electrode active material, absorbs lithium ions, oxides capable of releasing, for _{example, LiCoO 2, LiNi 1-x} CoxO 2, LiMn 2 O 4, LiNi x Mn 2-x O 4 ( where 0 < Metal oxide positive electrode materials such as x ≦ 1) can be used, but are not limited thereto.

  In the present invention, examples of the negative electrode active material include graphite that absorbs lithium, amorphous carbon, diamond-like carbon, carbon nanotube, carbon nanohorn, and the like, and composites and metallic lithium, but are not limited thereto. It is not something. In addition, the former is desirable for safety because of the laminate exterior.

Example 1 will be described with reference to FIG. The positive electrode 11 was produced as follows. A mixture of 85% by mass of LiMn ₂ O ₄ , 7% by mass of acetylene black as a conductive auxiliary and 8% by mass of polyvinylidene fluoride as a binder is added to N-methylpyrrolidone and further mixed to prepare a positive electrode slurry. did. This was applied to both surfaces of the positive electrode current collector 14 made of an Al foil having a thickness of 20 μm so that the thickness after the roll press treatment was 160 μm. The positive electrode had a length of 185 mm and a width of 42 mm. Further, an uncoated portion connected to the coated portion was formed, and a positive electrode tab 17 made of aluminum was attached by ultrasonic welding.

  The negative electrode 12 was prepared by mixing 90% by mass of graphite and 10% by mass of polyvinylidene fluoride as a binder, adding N-methylpyrrolidone, and further mixing to prepare a negative electrode slurry. This was applied to both surfaces of the negative electrode current collector 15 made of a Cu foil having a thickness of 10 μm so that the thickness after the calendar treatment was 120 μm. The negative electrode had a length of 187 mm and a width of 44 mm. Further, an uncoated portion connected to the coated portion was formed, and a negative electrode tab 18 made of nickel was attached by ultrasonic welding.

  Coupling agent solution added 0.3 mass% KBM503 (3-methacryloxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. to a solution of 50 mass% water and 50 mass% methanol adjusted to pH 4 with acetic acid. Used as a silane coupling solution.

  The surface treatment of the coupling agent is performed by immersing the positive electrode and the negative electrode in a silane coupling agent solution and vacuum impregnating for 2 minutes, and then removing the excess silane coupling solution and heating at 125 ° C. for 2 hours. It was.

  As the separator 13, a polyethylene microporous film having a film thickness of 12 μm and a porosity of 35% was used.

  The J / R shown in FIG. 1 was produced with the positive electrode 11 sandwiched between separators 13 and the negative electrode 12 facing each other.

The pregel solution is composed of 30% by mass of ethylene carbonate (EC), 58% by mass of diethyl carbonate (DEC) and 12% by mass of LiPF ₆ as a lithium salt, and triethylene glycol diacrylate and triethylene as a gelling material. After adding 3.4% by mass and 0.6% by mass of methylolpropane triacrylate respectively and mixing well, it was prepared by mixing 0.5% by mass of t-butyl peroxypivalate as a polymerization initiator.

  Subsequently, J / R was housed in an embossed laminate, one side of the embossed laminate outer body was folded back, and heat fusion was performed leaving a portion for injecting the pregel solution.

  Next, the pregel solution is injected from the injected portion and vacuum impregnated, and then the remaining portion is heat-sealed under reduced pressure, and the laminated and sealed battery is gelled by placing it at 80 ° C. for 2 hours, The lithium ion polymer battery of Example 1 was obtained.

  The surface treatment of the electrode coupling agent in Example 2 was the same as in Example 1 except that after the electrode application, the coupling agent solution was sprayed on each of the positive electrode and the negative electrode, followed by heat treatment at 125 ° C. for 2 hours. A lithium ion polymer battery was prepared.

  In Example 3, a lithium ion polymer battery was produced in the same manner as in Example 1 except that only the negative electrode 12 was subjected to the coupling agent surface treatment.

  In this Example 4, a coupling agent solution prepared in the same manner as in Example 1 was mixed with 1 kg of graphite powder as a negative electrode active material at a ratio of 500 g, and then dried at 125 ° C. overnight to perform negative electrode active. The material was surface treated. A negative electrode and a positive electrode were produced in the same manner as in Example 1 except that the positive electrode and the negative electrode were not immersed in the silane coupling agent solution, and a J / R was produced to obtain a lithium ion polymer battery.

  The negative electrode 12 in Example 5 was produced as follows. 90% by mass of graphite and 10% by mass of polyvinylidene fluoride as a binder are mixed, N-methylpyrrolidone is added and further mixed to prepare a negative electrode slurry, and a coupling agent solution prepared in the same manner as in Example 1 is prepared. 10% by mass was added to the slurry. This was applied to both surfaces of a negative electrode current collector 15 made of Cu foil having a thickness of 10 μm so that the thickness after calendering was 120 μm, dried at 125 ° C., and surface-treated. The electrode had a length of 187 mm and a width of 44 mm. Further, an uncoated portion connected to the coated portion was formed, and a negative electrode tab 18 made of nickel was attached by ultrasonic welding. Otherwise, a lithium ion polymer battery was produced in the same manner as in Example 1.

  In Example 6, a lithium ion polymer battery was produced in the same manner as in Example 1 except that KBM403 (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. having an epoxy group was used as a coupling agent. did.

(Comparative Example 1)
In Comparative Example 1, a polymer battery was produced in the same manner as in Example 1 except that a positive electrode and a negative electrode that were not subjected to surface treatment with a coupling agent were used.

  Table 1 shows the 0.2 C discharge capacity at 20 ° C., the 1 C discharge capacity retention rate (rate characteristic) with respect to the 0.2 C discharge capacity, and the 200 at 1 C at 20 ° C. for Examples 1 to 6 and Comparative Example 1. The discharge capacity maintenance rate and the cell thickness change rate after cycling are shown. Here, the discharge capacity retention rate is the ratio to the discharge capacity at the first cycle, and the cell thickness change rate is the ratio of the cell thickness after 200 cycles to the cell thickness before the cycle.

  FIG. 3 shows the cycle characteristics of the 1C discharge capacity retention rate for Examples 1 to 6 and Comparative Example 1.

  Example 1 had a large capacity of 312 mAh and excellent rate characteristics of 97%. Further, the capacity retention rate after 200 cycles was 92.1%, and the increase in cell thickness was also suppressed. This is because the coupling agent penetrated into the electrode pores, and a bond with the gel electrolyte via the coupling agent (see FIG. 2) was formed on the surface of the electrode active material. In other words, the contact area with the gel electrolyte is increased, the ion conduction path for the high rate is sufficiently formed, the rate characteristics are improved, the adhesion between the electrode active material and the gel electrolyte is increased, and the expansion of the electrode accompanying the cycle is suppressed. did it.

  In Example 2, since the treatment was performed by spraying, the capacity was slightly reduced because of less penetration of the coupling agent compared to Example 1. In Examples 3, 4, and 5, the negative electrode was treated with the coupling agent, but a great effect was obtained when only the negative electrode was treated. In Example 6, since the bonding force between the polymer component of the gel electrolyte and the coupling agent is lower than that in Example 1, the expansion of the electrode accompanying the cycle is not sufficiently suppressed, and the capacity is decreased and the cell thickness is increased compared to Example 1. Was big. In any case, good results were obtained with respect to Comparative Example 1.

The perspective view which shows the structure of the electrode of the lithium ion polymer battery of this invention. The schematic diagram of the coupling | bonding of the electrode active material surface and gel electrolyte through the coupling agent (silane coupling agent) of this invention. The figure which shows the cycling characteristics of 1C discharge capacity maintenance factor of Examples 1-6 of this invention, and the comparative example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Positive electrode 12 Negative electrode 13 Separator 14 Positive electrode collector 15 Negative electrode collector 16 Gel electrolyte 17 Positive electrode tab 18 Negative electrode tab 21 Electrolytic solution 22 (in gel electrolyte) Polymer 23 (in gel electrolyte) Electrode active material and gel electrolyte Coupling agent bonded to polymer 24 Electrode active material

Claims (7)

In the lithium ion polymer battery having a positive electrode, a negative electrode, a separator, and a gel electrolyte, at least the electrode active material layer of the negative electrode among the positive electrode and the negative electrode is modified with a surface treatment agent having an organic functional group ,
The surface treatment agent comprises at least one selected from a silane coupling agent, an aluminum coupling agent, and a titanium coupling agent,
The organic functional group of the coupling agent serving as the surface treatment agent includes at least one selected from an acrylic group, a methacrylic group, an epoxy group, and a vinyl group,
The gel electrolyte includes at least a polymer of an acrylate monomer or a methacrylate monomer,
A lithium ion polymer battery, wherein a bond with the polymer in the gel electrolyte is formed on the surface of the negative electrode active material via the surface treatment agent. 2. The lithium ion polymer battery according to claim 1, wherein the electrode active material of the positive electrode contains an oxide capable of inserting and extracting lithium ions. The positive electrode active material includes at least one selected from LiCoO ₂ , LiNi _1-x Co _x O ₂ , LiMn ₂ O ₄ , and LiNi _x Mn _2−x O ₄ (where 0 <x ≦ 1). The lithium ion polymer battery according to claim 1 or 2 . The negative electrode active material, according to claim 1 to 3, characterized in that it comprises at least one selected graphite of occluding lithium, amorphous carbon, diamond-like carbon, carbon nanotube, carbon nanohorn, or from metallic lithium, The lithium ion polymer battery according to any one of the above. The electrode active material, at least one selected from the positive electrode or the negative electrode, a lithium ion polymer battery according to any one of claims 1 to 4, characterized in that it has been treated by impregnation of the surface treatment agent. The electrode active material, wherein said at least one selected from the positive electrode or the negative electrode, a lithium ion polymer battery according to any one of claims 1 to 4, characterized in that it has been treated by coating of the surface treatment agent. The lithium ion polymer battery according to any one of claims 1 to 6 , wherein the electrode active material is formed by mixing a surface treatment agent in a slurry of the electrode active material.

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