JPH06338330A - High molecular solid electrolytic battery and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a high molecular solid electrolytic battery capable of enlarging a reaction area of the battery by increasing ionic conductivity in an electrolyte without decreasing strength of an electrolytic layer, and further by infiltrating a high molecular solid electrolyte sufficiently into an active material layer. CONSTITUTION:A mixture of positive pole active material powder with a binder is compressed to form a porous positive pole active material layer 2, and after applying a mixed solution containing a negative pole active material or a compound containing this negative pole active material, high molecular solid electrolyte, electrolytic fluid and a solvent to the positive pole active material layer 2, the solvent is volatilized to form a high molecular solid electrolytic layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer solid electrolyte battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art A polymer solid electrolyte battery in which a positive electrode active material layer and a negative electrode active material layer are laminated via a polymer solid electrolyte layer has been proposed as a battery capable of preventing leakage of an electrolytic solution and achieving a thinner battery. ing. The polymer solid electrolyte layer of this type of battery is formed of a polymer solid electrolyte having a relatively high molecular weight so that the positive electrode active material layer and the negative electrode active material layer can be reliably insulated. However, since the polymer solid electrolyte has a significantly lower ionic conductivity than the liquid electrolyte, the polymer solid electrolyte battery has a problem that it has a low capacity and is difficult to discharge at a high rate. Therefore, a polymer solid electrolyte battery has been proposed in which a polymer compound holds a polymer solid electrolyte having a relatively high ionic conductivity and a low molecular weight to form an electrolyte layer. Further, in the polymer solid electrolyte battery, since both the electrolyte and the active material are solid, there is a problem that the contact state between the two is poor and the reaction area of the battery becomes small. Therefore, it has been proposed to apply a solution in which a solid polymer electrolyte is dissolved and dispersed in an appropriate solvent to the active material layer, and then volatilize and remove the solvent to impregnate the active material layer with the solid polymer electrolyte.

[0003]

However, the process for producing an electrolyte layer in which a low molecular weight polymer solid electrolyte is held in a polymer compound is complicated. Further, in this electrolyte layer, since the ionic conductivity is sufficiently increased, there arises a problem that the strength of the electrolyte layer is lowered when the amount of the low molecular weight solid polymer electrolyte is increased.

In order to increase the reaction area of the battery,
Even when a solution in which a solid polymer electrolyte is dissolved and dispersed in an appropriate solvent is applied to the active material layer, this solution has a high viscosity and does not sufficiently penetrate into the active material layer, increasing the reaction area of the battery. The object of the present invention, which has a limit, is to increase the ion conductivity in the electrolyte without lowering the strength of the electrolyte layer, and to increase the reaction area between the polymer solid electrolyte layer and the active material layer. A polymer solid electrolyte battery and a method for manufacturing the same are provided.

[0005]

According to a first aspect of the present invention, there is provided a high polymer solid electrolyte battery comprising a positive electrode active material layer and a negative electrode active material layer, which are laminated via a solid polymer electrolyte layer. An electrolyte solution is included in the molecular solid electrolyte layer, and an electrolyte solution and a polymer solid electrolyte are included in at least one of the positive electrode active material layer and the negative electrode active material layer.

The invention of claim 2 is directed to a method for producing a polymer solid electrolyte battery by laminating a positive electrode active material layer and a negative electrode active material layer via a polymer solid electrolyte layer. In the production method of the present invention, the positive electrode active material layer is formed into a porous layer, and a mixed solution containing at least a polymer solid electrolyte material, an electrolytic solution, and a solvent is applied to the positive electrode active material layer, and then the solvent is volatilized to form a polymer. A solid electrolyte layer is formed.

The invention of claim 3 is directed to a method for producing a polymer solid electrolyte battery by laminating a positive electrode active material layer and a negative electrode active material layer with a polymer solid electrolyte layer interposed therebetween. In the production method of the present invention, a dispersion solution in which the positive electrode active material powder is dispersed in a solution containing at least an electrolytic solution, a solid polymer electrolyte material, and a solvent is applied to a current collector, and then the solvent is volatilized from the dispersion solution. The positive electrode active material layer is formed by applying the solution containing at least the solid polymer electrolyte material, the electrolytic solution, and the solvent to the positive electrode active material layer, and then the solvent is volatilized to form the solid polymer electrolyte layer.

[0008]

According to the invention of claim 1, an electrolyte having a high ionic conductivity is impregnated into the solid polymer electrolyte layer and the active material layer, and at least one of the positive electrode active material layer and the negative electrode active material layer has a high concentration. When the molecular solid electrolyte is included, the ionic conductivity in the polymer solid electrolyte layer and the active material layer is increased, and the contact area between the active material layer and the polymer solid electrolyte can be increased. Therefore, according to the present invention, the ions of the negative electrode active material can be efficiently transmitted to the positive electrode active material side. Moreover, the ion conductivity is greatly improved by simply impregnating a high molecular weight solid polymer electrolyte layer with a small amount of electrolytic solution, thus increasing the capacity of the battery without lowering the strength of the solid polymer electrolyte layer as in the past. be able to.

A solution obtained by dissolving a polymer solid electrolyte in a solvent together with an electrolytic solution has a lower viscosity than a solution obtained by dissolving and dispersing only a polymer solid electrolyte in a solvent. Therefore, when the mixed solution containing the polymer solid electrolyte and the electrolytic solution is applied to the porous positive electrode active material layer as in the invention of claim 2, the mixed solution sufficiently penetrates into the voids in the positive electrode active material layer. Then, the solid polymer electrolyte can be easily impregnated into the positive electrode active material layer.

According to the third aspect of the invention, since the electrolytic solution and the solid polymer electrolyte are mixed when the positive electrode active material layer is formed,
A required amount of solid polymer electrolyte can be included in the positive electrode active material layer.

[0011]

【Example】

(Example 1) FIG. 1 is a schematic sectional view of a battery of Example 1 in which the present invention is applied to a flat type polymer solid electrolyte lithium battery. In FIG. 1, 1 is a positive electrode current collector, 2 is a positive electrode active material layer, 3 is a solid polymer electrolyte layer, 4 is a negative electrode active material layer, 5 is a negative electrode current collector, and 6 is a hot melt.

The positive electrode current collector 1 is formed of a nickel foil having a thickness of about 20 μm. The positive electrode active material layer 2 is made of a mixture of vanadium pentoxide xerogel (V ₂ O ₅ .nH ₂ O) powder, carbon black powder, and a binder made of tetrafluoroethylene resin, and is porous. Inside, an electrolyte solution consisting of propylene carbonate and methoxy oligoethyleneoxy polyphosphazene (MEP
It is impregnated with the solid polymer electrolyte material of 7). The polymer solid electrolyte layer 3 is made of lithium perchlorate (LiC
lO ₄₎ and are formed by the electrolytic solution (propylene carbonate) and high molecular weight containing a methoxy oligoethyleneoxy polyphosphazene (MEP7). The negative electrode active material layer 4 is formed of lithium foil. Negative electrode current collector 5
Is formed of a stainless foil having the same dimensions as the positive electrode current collector 1. Each of the positive electrode current collector 1 and the negative electrode current collector 5 constitutes a part of the outer case of the battery and also functions as a terminal. The hot melt 6 is a frame member that melts from the surface side when heated and exhibits adhesiveness. The hot melt 6 is a ring having a rectangular contour corresponding to the outer peripheral end faces 1b and 5b of the current collectors 1 and 5, and is specifically made of a polyolefin resin. The outer peripheral end faces 1b and 5b of the current collectors 1 and 5 are connected to the hot melt 6 to assemble the battery.

The battery of this example was manufactured as follows. First, vanadium pentoxide xerogel (V ₂ O ₅ · nH
₂ O) powder, carbon black powder, and a binder made of tetrafluoroethylene resin were mixed at a weight ratio of 80: 15: 5 to form a sheet-like positive electrode active material having a thickness of 100 μm by roll molding. Then, this positive electrode active material was placed on the central portion of one surface 1a of the positive electrode current collector 1 made of nickel foil having a thickness of 20 μm to form the positive electrode active material layer 2. Next, methoxyoligoethyleneoxypolyphosphazene (MEP), which is a kind of polyphosphazene derivative,
7) Polymer solid electrolyte material (average molecular weight 150
~ 2 million) and 8% by weight of LiC based on the MEP7
and lO _4, 10 wt% of the electrolyte solution relative to the MEP7 solution for solid polymer electrolyte dissolved in a proportion of 20% by weight in a solvent consisting of (propylene carbonate) and 1,2-dimethoxyethane (DME) This solution was applied to the positive electrode active material layer 2 so as to entirely cover the positive electrode active material layer 2. The preferable ratio of the electrolytic solution (propylene carbonate) to MEP7 is 1 to 15% by weight. When the proportion of the electrolytic solution exceeds 15% by weight, the electrolyte changes from a solid electrolyte to a fluid electrolyte. Then, it is dried to a thickness of 100 by casting to volatilize DME.
A μm solid electrolyte layer 3 was prepared. The boiling point of DME (8
Since (5 degrees) is lower than the boiling point of propylene carbonate (242 degrees), propylene carbonate remains in the solid electrolyte layer 3 even if DME is volatilized. Further, the solid electrolyte layer 3 can be formed by applying a solution for a polymer solid electrolyte onto the positive electrode active material layer 2 and then applying pressure, depressurization or depressurization using an autoclave or the like if necessary. Next, the negative electrode active material layer 4 made of Li foil having a thickness of 40 μm was placed on the solid electrolyte layer 3, and the hot melt 6 was placed on the outer peripheral end 1b of the positive electrode current collector 1. Then, the negative electrode current collector 5 made of stainless steel foil having the same size as the positive electrode current collector 1 was placed so as to cover the negative electrode active material layer 4 and the hot melt 6. Next, the hot melt 6 was completely connected to the outer peripheral end portions 1b and 5b of the current collectors 1 and 5 by heating to complete the polymer solid electrolyte lithium battery.

Example 2 The battery of this example has the same structure as the battery of Example 1 except for the positive electrode active material layer. The positive electrode active material layer of the battery of this example was formed as follows.

First, vanadium pentoxide xerogel (V ₂ O
₅ · nH ₂ O) powder and a conductive auxiliary agent composed of graphite powder were mixed at a weight ratio of 2: 1 to prepare a mixture. Next, a solid polymer electrolyte material composed of methoxyoligoethyleneoxypolyphosphazene (MEP7) and the ME
8% by weight of LiClO ₄ with respect to P7 and 10% by weight of electrolyte solution (propylene carbonate) with respect to the MEP7
And 2 are dissolved in a solvent consisting of 1,2-dimethoxyethane (DME) at a ratio of 20% by weight to form a solution, and the above mixture is added to this solution, and vanadium pentoxide xerogel powder and graphite powder are added to the solution. Dispersed to make a dispersion solution. The weight ratio of vanadium pentoxide xerogel, graphite and MEP7 in the dispersion solution was 2: 1: 1.
Has become. Next, this dispersion solution was further stirred and dispersed by a homogenizer, and then the dispersion solution was applied to the central portion of one surface 1a of the positive electrode current collector 1 with a dropper or the like. Then, only DME was volatilized and removed from the dispersion solution to form a positive electrode active material layer made of MEP7 containing propylene carbonate between vanadium pentoxide xerogel and graphite.

Next, a conventional battery manufactured by the same method as the battery of Example 1 except that propylene carbonate (electrolyte) was not added to MEP7 and the batteries of Examples 1 and 2 had a final voltage of 2. The discharge characteristics of each battery were examined by discharging to 0 V at a current density of 50 μA / cm ² (25 ° C.). FIG. 2 shows the measurement result. As shown in FIG. 2, the batteries of Examples 1 and 2 have a discharge operating voltage of about 10 as compared with the conventional batteries.
It can be seen that it is as high as 0 mv and that the discharge duration to the final voltage (2.0 V) is long. The high discharge operating voltage of the batteries of Examples 1 and 2 is considered to be because the ion conductivity in the electrolyte layer was improved by impregnating the polymer solid electrolyte layer with the electrolytic solution (propylene carbonate). . Further, the discharge duration is long because the MEP7 / DME solution containing propylene carbonate has a low viscosity, so that the impregnation property into the porous positive electrode active material layer is improved, and even if the DME is volatilized and removed, it is high. It is considered that this is because the effective reaction area of the battery increased due to the molecular solid electrolyte remaining in the positive electrode active material layer.

In each of the above examples, the positive electrode active material layer was impregnated with the electrolytic solution and the polymer solid electrolyte, but the negative electrode active material layer may be impregnated with the electrolytic solution and the polymer solid electrolyte. Of course. For example, a negative electrode active material layer obtained by compression-molding lithium powder using an appropriate binder, or a negative electrode active material layer obtained by doping a negative electrode active material support made of a powdery or fibrous carbon material with lithium ions is used as an electrolyte solution. Also, it was confirmed that the discharge characteristics were improved as in the case of the present example even when the polymer solid electrolyte was impregnated.

Although each of the above embodiments is an example in which the present invention is applied to a polymer solid electrolyte lithium battery, the present invention is not limited to this, and the present invention is applied to other polymer solid electrolyte batteries and Of course, it can be applied to the manufacturing method.

[0019]

According to the invention of claim 1, an electrolytic solution having high ion conductivity is impregnated into the solid polymer electrolyte layer and the active material layer, and at least one of the negative electrode active material layer and the positive electrode active material layer is provided. Since the solid polymer electrolyte is included in, the ions of the negative electrode active material can be efficiently transmitted to the positive electrode active material side. Moreover, the ion conductivity is greatly improved by simply impregnating a high molecular weight solid polymer electrolyte layer with a small amount of electrolytic solution, thus increasing the capacity of the battery without lowering the strength of the solid polymer electrolyte layer as in the past. be able to.

According to the second aspect of the present invention, since the mixed solution containing the solid polymer electrolyte and the electrolytic solution is applied to the porous positive electrode active material layer, the mixed solution is sufficiently filled in the voids in the positive electrode active material layer. The solid polymer electrolyte can be easily impregnated into the positive electrode active material layer. Therefore, according to the present invention, a high capacity battery can be obtained relatively easily. In the invention of claim 3, since the electrolytic solution and the solid polymer electrolyte are mixed when the positive electrode active material layer is formed, a required amount of the solid polymer electrolyte can be contained in the positive electrode active material layer.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a battery of an example of the present invention.

FIG. 2 is a diagram showing discharge characteristics of a battery used in a test.

[Explanation of symbols]

 2 Positive electrode active material layer 3 Solid electrolyte layer 4 Negative electrode active material layer

Front page continuation (72) Inventor Hayakawa et al. KUKUMI 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Inside Shin-Kindo Electric Co., Ltd. (72) Inventor Akio Komaki 2-chome, Nishishinjuku, Shinjuku-ku, Tokyo No. 1 In Shinjin To Denki Co., Ltd. (72) Inventor Weibun Nakabun, 463 Kagasuno, Kawauchi Town, Tokushima City, Tokushima Prefecture Otsuka Chemical Co., Ltd., Tokushima Laboratory (72) Inventor Masatoshi Taniguchi Chuo-ku, Osaka City, Osaka Prefecture Otetsu 3-chome 2-27 Otsuka Chemical Co., Ltd.

Claims (3)

[Claims] 1. A polymer solid electrolyte battery comprising a positive electrode active material layer and a negative electrode active material layer laminated via a polymer solid electrolyte layer, wherein the polymer solid electrolyte layer contains an electrolytic solution, A polymer solid electrolyte battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer contains an electrolytic solution and a polymer solid electrolyte. 2. A method for producing a polymer solid electrolyte battery by laminating a positive electrode active material layer and a negative electrode active material layer via a polymer solid electrolyte layer, wherein the positive electrode active material layer is formed porous. A solid polymer electrolyte characterized by forming the solid polymer electrolyte layer by applying a mixed solution containing at least a solid polymer electrolyte material, an electrolytic solution and a solvent to the positive electrode active material layer, and then volatilizing the solvent. Battery manufacturing method. 3. A method for producing a polymer solid electrolyte battery by stacking a positive electrode active material layer and a negative electrode active material layer with a polymer solid electrolyte layer interposed between at least an electrolytic solution, a polymer solid electrolyte material, and a solvent. The positive electrode active material powder is dispersed in a solution containing the above, and the positive electrode active material layer is formed by applying the dispersion solution to the current collector and then volatilizing the solvent from the dispersion solution. A method for producing a polymer solid electrolyte battery, comprising applying a solution containing a liquid and a solvent to the positive electrode active material layer, and then volatilizing the solvent to form the polymer solid electrolyte layer.