JP5373355B2 - Positive electrode for all solid-state polymer battery, manufacturing method thereof, and all solid-state polymer battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in an all-solid polymer battery that, when a porous positive electrode active material with a large pore volume is used, dry polymer electrolyte does not permeate easily in the pores, and contact between the positive electrode active material and the dry polymer electrolyte tends to be insufficient, wherefore, a reaction area of the dry polymer electrolyte and the positive electrode active material gets smaller, and a battery capacity obtained tends to be lower than a theoretical capacity of the positive electrode. <P>SOLUTION: The positive electrode 1 for an all-solid polymer battery contains a positive electrode collector 10 and a positive electrode active material layer 11, which latter 11 contains a porous positive electrode active material, a conductive material and dry polymer electrolyte. The porous positive electrode active material has pores inside it, and, contains high-boiling-point organic matter with a boiling point of 150&deg;C or higher in the pores. Thus, an all-solid polymer battery with a large capacity is obtained, even with the use of the porous positive electrode active material. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a positive electrode for an all solid-state polymer battery, a method for producing the same, and an all solid-state polymer battery. More specifically, the present invention mainly relates to an improvement in the positive electrode in an all solid-state polymer battery.

  Nonaqueous electrolyte batteries are roughly classified into an electrolyte type battery in which an electrolyte is interposed between a positive electrode and a negative electrode, and an all solid state battery in which a solid electrolyte is interposed between a positive electrode and a negative electrode. All solid-state batteries have the advantages of high reliability and safety as batteries, and easy thinning and stacking because there is no risk of liquid leakage.

  As a solid electrolyte used for an all solid state battery, an inorganic material or an organic material is used. A solid electrolyte made of an inorganic material has high ionic conductivity, but is highly brittle, so that it is difficult to process into a flexible film. On the other hand, among organic materials, a dry polymer electrolyte made of an organic polymer compound containing a supporting salt is more flexible than a solid electrolyte made of an inorganic material and can be easily formed into a thin film. For this reason, development of an all-solid-state polymer battery having a thin and high energy density using a dry polymer electrolyte is expected.

As a dry polymer electrolyte, a dry polymer electrolyte in which polyethylene oxide and a supporting salt such as a lithium salt or a sodium salt are combined is generally known. However, this dry polymer electrolyte has a low ion conductivity of 10 ⁻⁴ to 10 ⁻⁷ S / cm at room temperature. For this reason, the all-solid-state polymer battery containing this dry polymer electrolyte has a problem of low battery capacity when charged and discharged with a large current.

In view of such a problem, for example, a dry polymer electrolyte in which the molecular arrangement is made amorphous by substituting a short ethylene oxide chain with a side chain has been proposed (for example, see Non-Patent Document 1). Non-Patent Document 1 describes that this dry polymer electrolyte exhibits a conductivity of 10 ⁻⁴ S / cm or more at room temperature.

On the other hand, in a conventional all solid-state polymer battery, for example, LiCoO ₂ having high crystallinity, a low porosity, and a small pore volume is used as a positive electrode active material (see, for example, Patent Document 1). When a positive electrode active material having a low porosity and the dry polymer electrolyte of Non-Patent Document 1 are used in combination, an all solid-state polymer battery having a battery capacity close to the theoretical capacity of the positive electrode when charged and discharged at a small current near room temperature. Is obtained. In this case, it is more effective to reduce the porosity of the positive electrode active material layer to 0.045 to 0.40 ml / g.

  On the other hand, in order to increase the output of the all solid-state polymer battery, the positive electrode active material or the positive electrode active material layer is being made porous. For example, the porosity means increasing the porosity of the positive electrode active material or the positive electrode active material layer to increase the porosity. Specifically, for example, a positive electrode that includes a positive electrode current collector and a positive electrode active material layer, and the porosity of the positive electrode active material layer is 30% or more has been proposed (see, for example, Patent Document 2). However, in an all solid-state polymer battery, when a positive electrode with a high porosity as in Patent Document 2 and a conventional dry polymer electrolyte typified by the dry polymer electrolyte of Non-Patent Document 1 are used in combination, the following problems occur. Arise.

  Since the dry polymer electrolyte is a solid, it has poor fluidity compared to a liquid electrolyte or a polymer electrolyte impregnated with a liquid. For this reason, the contact area between the dry polymer electrolyte and the positive electrode active material or the positive electrode active material layer tends to be small. Therefore, even when a positive electrode active material or a positive electrode including a positive electrode active material layer having a large pore volume and a high porosity is used, the dry polymer electrolyte does not easily penetrate into the pores. The area or reaction area does not increase. As a result, the obtained battery capacity is significantly lower than the theoretical capacity of the positive electrode. For this reason, in a conventional all solid-state polymer battery, a positive electrode including a positive electrode active material or a positive electrode active material layer having a small pore volume and a low porosity is often used.

The latest polymer battery technology II, supervised by Seiji Kanamura, page 113, published in September 2003, published by CMC Publishing Co., Ltd. JP-A-10-270081 JP 2007-109636 A

  The object of the present invention includes a positive electrode with a high porosity containing a positive electrode active material with a large pore volume, and the positive electrode, has a battery capacity close to the theoretical capacity of the positive electrode, and has a high output, An object of the present invention is to provide an all-solid-state polymer battery excellent in reliability and safety.

  In the research process for solving the above-mentioned problems, the inventors have made an organic solvent exist in the pores of the porous cathode active material, and the porous cathode active material layer and the dry polymer electrolyte are passed through the organic solvent. The idea is to increase the contact area, ie the reaction area. The inventors have further studied based on this idea. As a result, by using a high boiling point organic solvent, the high boiling point organic solvent was successfully present in the pores of the porous positive electrode active material.

  Then, the present inventors have found that when a porous positive electrode active material in which a high boiling point organic solvent is present in the pores is used, an all solid-state polymer battery having a high capacity and a high output can be obtained. Further, the present inventors have found that there is no risk of liquid leakage despite the presence of a high-boiling organic solvent in the pores of the porous positive electrode active material, and the reliability that is a feature of all solid-state polymer batteries. And it was found that high safety was maintained. Based on these findings, the inventors have completed the present invention.

  In the present invention, the reason why the above excellent effect is obtained is not sufficiently clear, but is presumed as follows. That is, it is considered that the presence of the high-boiling organic solvent facilitates the penetration of the dry polymer electrolyte into the pores of the porous positive electrode active material, thereby increasing the contact area between the porous positive electrode active material and the dry polymer electrolyte. As a result, it is considered that transfer of ions between the porous positive electrode active material and the dry polymer electrolyte proceeds easily, and a battery capacity close to the theoretical capacity of the porous positive electrode active material can be obtained.

That is, the present invention includes a positive electrode current collector and a positive electrode active material layer formed on the surface of the positive electrode current collector, wherein the positive electrode active material layer has pores, a porous positive electrode active material, a conductive material, and a dry polymer electrolyte The porous positive electrode active material is manganese dioxide, the porous positive electrode active material has an average pore diameter of 10 to 20 nm, a pore volume of 0.03 to 0.15 cm ³ / g, and is porous positive electrode active material, contains a high-boiling organic solvents higher than the boiling point 0.99 ° C. in the pores, Ru engaged in a positive electrode for an all solid-state polymer battery.

The high boiling point organic solvent is preferably at least one selected from N-methyl-2-pyrrolidone and glymes.
Porous positive electrode active material, in its pores, it is not preferable to contain a high-boiling organic solvent of 0.01 to 3% by volume of the pore volume.

The present invention also provides a porous positive electrode active material obtained by pulverizing manganese dioxide to have pores, an average pore diameter of 10 to 20 nm, and a pore volume of 0.03 to 0.15 cm ³ / g. A paste preparation step for preparing a paste by mixing a porous positive electrode active material obtained in the pulverization step, a conductive material, a dry polymer electrolyte and a high boiling point organic solvent having a boiling point of 150 ° C. or higher, and a paste preparation step And an active material layer forming step of applying the paste obtained in step 1 to the surface of the positive electrode current collector and drying the paste, and a method for producing a positive electrode for a porous all solid-state polymer battery.

In the pulverization step, the positive electrode active material is preferably wet pulverized in a solvent.
The solvent used in the pulverization step is preferably a protic solvent.
The protic solvent is preferably at least one selected from a secondary alcohol and a tertiary alcohol.
Furthermore, the present invention relates to an all solid state polymer battery including the positive electrode, the negative electrode, and the solid electrolyte membrane for the all solid state polymer battery of the present invention.

  According to the present invention, although a porous positive electrode active material having a relatively large pore volume is used, the battery capacity close to the theoretical capacity of the positive electrode including the porous positive electrode active material and a large output are obtained. A solid type polymer is provided. In addition, the all solid-state polymer battery of the present invention has no risk of liquid leakage and is excellent in reliability and safety, as in the conventional all solid-state polymer battery.

[All-solid polymer battery positive electrode]
The positive electrode for an all solid-state polymer battery of the present invention uses a porous positive electrode active material having pores inside, and the porous positive electrode active material contains a high boiling point organic solvent having a boiling point of 150 ° C. or higher in the pores. It is characterized by containing, and the configuration other than that can be the same as the conventional configuration.
FIG. 1 is a longitudinal cross-sectional view showing a simplified configuration of a positive electrode 1 for an all solid-state polymer battery (hereinafter simply referred to as “the positive electrode 1 of the present invention”), which is one embodiment of the present invention. The positive electrode 1 of the present invention includes a positive electrode current collector 10 and a positive electrode active material layer 11.

  As the positive electrode current collector 10, those commonly used in the field of all solid-state polymer batteries can be used. For example, a metal sheet-like material can be used. Examples of the metal sheet-like material include a metal film, a metal foil, and a non-woven sheet of metal fibers. Examples of the metal include silver, nickel, palladium, gold, platinum, aluminum, and stainless steel. A metal can be used individually by 1 type or in combination of 2 or more types. The thickness of the positive electrode current collector 10 is not particularly limited, and is, for example, 1 to 30 μm.

The positive electrode active material layer 11 is formed on one or both surfaces of the positive electrode current collector 10 in the thickness direction, and contains a porous positive electrode active material, a conductive material, and a dry polymer electrolyte.
The porous positive electrode active material has pores therein, and contains a high-boiling organic solvent having a boiling point of 150 ° C. or higher (hereinafter simply referred to as “high-boiling organic solvent”) in the pores. When an organic solvent having a boiling point of less than 150 ° C. is used, it becomes difficult to contain a desired amount of the organic solvent inside the pores of the porous positive electrode active material.

  By using a high-boiling organic solvent, a porous positive electrode active material containing a desired amount of organic solvent in the pores can be obtained as shown in the method for producing the positive electrode 1 of the present invention described later. In addition, since the porous positive electrode active material contains a high-boiling organic solvent in the pores, the dry polymer electrolyte easily penetrates into the pores, and the porous positive electrode active material and the dry polymer electrolyte are in the pores. It is estimated that the contact area increases.

  Further, when the all solid-state polymer battery is stored at a high temperature, the high boiling point organic solvent suppresses the reaction between the porous positive electrode active material layer and the dry polymer electrolyte to the minimum, so that the self-discharge amount can be reduced. Furthermore, since the high boiling point organic solvent does not easily volatilize in the use environment of the all-solid-state polymer battery, the effect is maintained for a long time. As described above, since the porous positive electrode active material contains a high boiling point organic solvent in its pores, even if a porous positive electrode active material having a large pore volume is used, the battery capacity and output are high, and the storage characteristics are high. All-solid-state polymer battery excellent in the above can be obtained.

The porous positive electrode active material has pores having a pore diameter in the range of 0.1 to 1000 nm. The average pore diameter is preferably 10 to 20 nm. The pore volume is preferably 0.03 to 0.15 cm ³ / g. The average pore diameter and pore volume can be calculated by, for example, pore distribution measurement. When the average pore diameter of the porous positive electrode active material is less than 10 nm, the permeability of the high boiling point organic solvent into the pores may be insufficient. On the other hand, if the average pore diameter exceeds 20 nm, the permeation amount of the high-boiling organic solvent into the pores becomes too large, and the advantage of the all-solid-state polymer battery that liquid leakage does not occur may be impaired.

Further, when the pore volume of the porous cathode active material is less than 0.03 m ³ / g, the contact area between the surface of the porous cathode active material and the dry polymer electrolyte is reduced in the pores of the porous cathode active material layer. The capacity of the all solid-state polymer battery may be reduced. When the pore volume exceeds 0.15 m ³ / g, the same problem as when the average pore diameter exceeds 20 nm occurs.

If the average pore diameter of the porous positive electrode active material is in the above range, it is considered that the high boiling point organic solvent easily penetrates into the pores. Further, when the pore volume of the porous positive electrode active material is in the above range, it is considered that the contact property between the pore surface of the porous positive electrode active material and the dry polymer electrolyte is sufficiently improved. High-boiling organic solvents have a relatively small molecular diameter and molecular volume. Taking N-methyl-2-pyrrolidone (hereinafter referred to as “NMP”) as an example, the molecular diameter of NMP is about 0.5 to 1 nm and the molecular volume is about 2 × 10 ⁻²⁸ cm ³ . Therefore, it is clear that the permeability of NMP into the pores is good.

  The content of the high boiling point organic solvent in the pores of the porous positive electrode active material is preferably 0.01% by volume to 3% by volume of the pore volume, more preferably 0.01% by volume to 0.00% of the pore volume. 5% by volume. Accordingly, the dry polymer electrolyte easily penetrates into the pores of the porous positive electrode active material, and the contact area between the porous positive electrode active material and the dry polymer electrolyte increases. As a result, the battery capacity can be increased while maintaining the high reliability and safety that are the characteristics of the all solid-state polymer battery.

  If the content of the high-boiling organic solvent is less than 0.01% by volume of the pore volume, the effect of allowing the dry polymer electrolyte to permeate into the pores becomes insufficient, and a high-capacity all-solid polymer battery may not be obtained. There is. In addition, when the content of the high boiling point organic solvent exceeds 3% by volume of the pore volume, the high boiling point organic solvent does not settle in the pores of the porous positive electrode active material and exists as a free liquid, resulting in liquid leakage. This may cause As a result, the reliability and safety of the all solid-state polymer battery may be impaired. Furthermore, the high boiling point organic solvent and the negative electrode active material may react at the interface between the negative electrode active material and the dry polymer electrolyte, and an insulating coating that adversely affects battery performance may be generated.

  The content of the high-boiling organic solvent in the pores of the porous positive electrode active material can be adjusted, for example, by controlling the drying temperature, the drying time, the degree of vacuum, etc. in the drying step when the positive electrode 1 is produced. Further, the content of the high-boiling organic solvent can be measured by, for example, a heat extraction GC / MS analysis method.

  The high-boiling organic solvent is not particularly limited as long as the boiling point is 150 ° C. or higher, but at least one selected from NMP and glymes is preferable in consideration of the molecular diameter and molecular volume. NMP is N-methyl-2-pyrrolidone as indicated above. Since NMP and glymes have a small molecular volume, they easily penetrate into the pores.

Glymes are organic solvents having an ethylene oxide chain: (CH ₂ CH ₂ O) _n . Among the glymes, those having a value of n indicating the number of ethylene oxide chain repeats of 2 to 5 are preferred. Specific examples of glymes having an n value of 2 to 5 include, for example, methyl diglyme, methyl triglyme, methyl tetraglyme, methyl pentag lime, ethyl diglyme, ethyl triglyme, ethyl tetraglyme, and the like. It is done.

  The porous positive electrode active material is not particularly limited in terms of composition as long as it has pores therein, and those commonly used in this field can be used. This field is the field of all solid-state polymer batteries using lithium ions as ion conductors. Specific examples of the composition of the porous positive electrode active material include manganese dioxide, carbon fluorides, sulfide, lithium-containing composite oxide, vanadium oxide and its lithium compound, niobium oxide and its lithium compound, organic Examples thereof include a conjugated polymer containing a conductive substance, a chevrel phase compound, and an olivine compound. Among these, manganese dioxide, carbon fluorides, sulfides, lithium composite oxides, and the like are preferable.

Examples of the carbon fluorides include (CF _w ) _m (wherein 0 <w ≦ 1, m represents an integer of 1 or more). Examples of the sulfide include TiS ₂ , MoS ₂ , FeS _{2 and the} like. Examples of the lithium-containing composite oxide include Li _xa CoO ₂ , Li _xa NiO ₂ , Li _xa MnO ₂ , Li _xa Co _y Ni _1-y O ₂ , Li _xa Co _y M _1-y O _z , Li _xa Ni _{1-y M y O z,} Li xb Mn 2 O 4, Li xb Mn 2-y M y O 4 ( in each of the formulas above, M is Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu And at least one element selected from the group consisting of Zn, Al, Cr, Pb, Sb and B. xa = 0 to 1.2, xb = 0 to 2.0, y = 0 to 0.9, z = 2.0 to 2.3). In addition, the xa value and the xb value in each of the above composition formulas are values before the start of charge / discharge, and increase / decrease by charge / discharge.

  Among the preferable porous positive electrode active materials described above, those having manganese dioxide as a main component are preferable. The reaction potential of manganese dioxide is in a region where the dry polymer electrolyte is electrochemically stable. Further, when it is assumed that the reaction of manganese dioxide in the battery is a one-electron reaction, the theoretical capacity per mass is as high as 308 mAh / g. Further, manganese dioxide is available at a low cost. Among manganese dioxides, electrolytic manganese dioxide is preferable.

  Porous positive electrode active materials mainly composed of manganese dioxide include porous positive electrode active materials made of manganese dioxide, porous positive electrode active materials containing manganese dioxide and inevitable impurities in the manufacturing process, manganese dioxide and others There are one or more of the positive electrode active materials, and a porous positive electrode active material having the highest manganese dioxide content. In this invention, the porous positive electrode active material which has the said composition can be used individually by 1 type or in combination of 2 or more types.

  The volume average particle diameter of the porous positive electrode active material is not particularly limited, but is preferably 0.1 to 20 μm. Thereby, when the positive electrode mixture paste containing the porous positive electrode active material is applied to the positive electrode current collector to produce a thin positive electrode having a thickness of 50 μm or less, it is possible to suppress the occurrence of uneven coating such as streaks. By suppressing the occurrence of uneven coating, it is possible to reduce variations in electrode capacity per unit area.

  As the conductive material, those commonly used in all solid-state polymer batteries using lithium ions as ion conductors can be used. Specific examples of the conductive material include, for example, graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, carbon fiber, metal fiber, and the like. Conductive fibers, metal powders such as aluminum powder, conductive whiskers such as zinc oxide whisker and potassium titanate whisker, conductive metal oxides such as titanium oxide, and organic conductive materials such as phenylene derivatives It is done. A conductive material can be used individually by 1 type or in combination of 2 or more types.

  The dry polymer electrolyte is used as a binder in the positive electrode active material layer 11. Thereby, ions can easily move from the surface of the positive electrode active material layer 11 to the interface between the positive electrode current collector 10 and the positive electrode active material layer 11. In this case, the dry polymer electrolyte can be used alone, or the dry polymer electrolyte and another binder can be used in combination.

The dry polymer electrolyte contains a matrix polymer and a lithium salt.
The matrix polymer has a polymer chain containing an electron donating element. The electron donating element can generate a strong interaction with lithium ions. This interaction is as strong as that of lithium ions and anions. Therefore, the electron donating element can dissociate the lithium salt. The dissociated lithium ions are coordinated to the electron donating element and further move in the polymer or on the polymer chain. Lithium ions are thought to be able to move through the matrix polymer mainly by segmental movement of the polymer chain. Thereby, the matrix polymer has good ionic conductivity.

  As the matrix polymer, for example, a polymer in which one or both of the main chain and the side chain of the polymer contains an electron donating element can be used. Although it does not restrict | limit especially as an electron-donating element, For example, electron-donating oxygen, such as ether oxygen and ester oxygen, is preferable. Specific examples of the matrix polymer include, for example, polyethylene oxide, polypropylene oxide, a copolymer of ethylene oxide and propylene oxide, a polymer having an ethylene oxide unit, a polymer having a propylene oxide unit, and a polycarbonate. A matrix polymer can be used individually by 1 type or in combination of 2 or more types.

The lithium salt is at least partially dissociated into lithium ions and anions and exists in the matrix polymer in a dissolved state. As described above, dissociation of the lithium salt occurs when the matrix polymer contains an electron donating element. As the lithium salt, those commonly used in this field can be used. For example, LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAlCl ₄ , LiSbF ₆ , LiSCN, LiCF ₃ SO ₃ , LiAsF ₆ , lower aliphatic lithium carboxylate, Examples include LiCl, LiBr, LiI, chloroborane lithium, lithium tetraphenylborate, LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) _{2 and the} like. Lithium salts can be used alone or in combination of two or more. This field refers to the field of all solid-state polymer batteries using lithium ions as ion conductors.

  As the binder other than the dry polymer electrolyte, those commonly used in the battery field can be used. Specific examples thereof include, for example, polyvinylidene fluoride (PVdF), polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyacrylic acid Ethyl, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene butadiene rubber, carboxy Examples include methyl cellulose. Binders other than the dry polymer electrolyte can be used alone or in combination of two or more.

  The positive electrode active material layer 11 can be formed, for example, by applying a positive electrode mixture slurry to the surface of the positive electrode current collector 10, drying, and rolling as necessary, whereby the positive electrode 1 can be produced. The positive electrode mixture slurry can be prepared by mixing a porous positive electrode active material that does not contain a high boiling point organic solvent in the pores, a conductive material, a dry polymer electrolyte, and a high boiling point organic solvent. The thickness of the positive electrode active material layer 11 is not particularly limited, and is, for example, 1 to 30 μm. The manufacturing method of the positive electrode 1 will be described in detail below.

[Method for producing positive electrode for all solid-state polymer battery]
The production method of the present invention includes a pulverization step, a paste preparation step, and an active material layer formation step.
In the pulverization step, the positive electrode active material is pulverized. By the pulverization, pores are formed in the positive electrode active material, and a porous positive electrode active material is obtained. The average pore diameter and pore volume can be adjusted, for example, by appropriately selecting the grinding time. Further, many positive electrode active materials have a relatively large volume average particle size and large variations in particle size. Therefore, when the positive electrode active material layer 11 is formed without subjecting the positive electrode active material to pulverization, the structure of the positive electrode active material layer 11 becomes non-uniform, and the resulting positive electrode 1 may have insufficient performance. Therefore, it is important to improve the performance of the positive electrode 1 after pulverizing the positive electrode active material and adjusting the particle diameter.

  Moreover, it is preferable to grind | pulverize also about the positive electrode active material which has a pore in the state which does not grind | pulverize only for the purpose of adjustment of a pore volume average diameter and a pore volume, and uniformization of a particle diameter. Examples of such a positive electrode active material include electrolytic manganese dioxide. Electrolytic manganese dioxide generally has a volume average particle diameter of about 40 μm and a large variation in particle diameter, so that the effect of the pulverization treatment is remarkable.

  Both the dry pulverization method and the wet pulverization method can be used for pulverizing the positive electrode active material. Dry pulverization is a method of pulverizing the positive electrode active material in powder form. The wet pulverization is a method of pulverizing the positive electrode active material in a solvent. In the wet pulverization, the positive electrode active material is dispersed in a solvent together with a medium such as a ball to prepare a slurry, and this slurry is pulverized. Wet pulverization makes it difficult for the pulverized particles to adhere to the media and the inner wall of the pulverizer, and because the particles are dispersed in a solvent. is there. Therefore, the positive electrode active material is preferably pulverized by wet pulverization.

  Examples of the solvent used for wet pulverization include aprotic solvents and protic solvents. As the aprotic solvent, for example, hexane, acetone, n-butyl acetate and the like can be used. Examples of the protic solvent include water, methyl alcohol, ethyl alcohol, 1-propyl alcohol, primary alcohol such as 1-butyl alcohol, secondary alcohol such as 2-propyl alcohol (isopropyl alcohol), cyclohexyl alcohol, 2-butyl alcohol (tert-butyl alcohol), 2-methyl-2-propanol and the like can be used. An aprotic solvent and a protic solvent can be used individually by 1 type or in combination of 2 or more types.

  Of the aprotic solvent and the protic solvent, a protic solvent is preferable. In many cases, a hydroxyl group which is a hydrophilic group is present on the surface of the positive electrode active material. When a protic solvent is used as a solvent for dispersing the positive electrode active material, the dispersibility of the positive electrode active material in the protic solvent is improved by the interaction between the hydroxyl group of the positive electrode active material and the protic solvent. As a result, the particle diameter of the porous positive electrode active material obtained after pulverization becomes uniform.

  Furthermore, among the protic solvents, secondary alcohols and tertiary alcohols are more preferable. When water or primary alcohol is used, the solvent and the positive electrode active material may react during pulverization, and the reduction reaction of the positive electrode active material may proceed. Due to the reduction reaction, impurities that cannot contribute to the electrochemical reaction are generated in the positive electrode active material, which may reduce the capacity of the all-solid-state polymer battery. Since the secondary alcohol and the tertiary alcohol are excellent in oxidation resistance, the reduction reaction of the positive electrode active material is difficult to proceed, and as a result, capacity reduction of the all solid-state polymer battery can be suppressed.

  In addition, it is preferable that the porous positive electrode active material obtained by a grinding | pulverization process exists in the range whose volume average particle diameter is 0.1-20 micrometers. Moreover, the high boiling point organic solvent is not contained inside the pores of the porous positive electrode active material obtained in the pulverization step.

  In the paste preparation step, the positive electrode mixture paste is prepared by mixing the porous positive electrode active material, conductive material, dry polymer electrolyte and high boiling point organic solvent obtained in the pulverization step. At this time, the high boiling point organic solvent penetrates into the pores of the porous positive electrode active material. A general mixer can be used for mixing these components.

In the active material layer forming step, the positive electrode mixture paste obtained in the paste preparation step is applied to the surface of the positive electrode current collector 10, dried, and rolled as necessary. Thereby, the positive electrode active material layer 11 is formed on the surface of the positive electrode current collector 10, and the positive electrode 1 is manufactured.
Drying is performed in an atmosphere whose dew point is controlled at -50 ° C or lower. Examples of the atmosphere include vacuum, dry air, nitrogen, argon, helium and the like.

  The drying temperature is preferably 20 to 200 ° C. in consideration of the content of the high-boiling organic solvent in the pores of the porous positive electrode active material, the thermal stability of the dry polymer electrolyte, and the like. The drying time is 1 to 72 hours. By appropriately selecting the drying temperature and drying time from the above ranges, a desired amount of a high-boiling organic solvent can be contained in the pores of the porous positive electrode active material. When the atmosphere is vacuum, the content of the high-boiling organic solvent in the pores can be adjusted more finely by appropriately selecting the degree of vacuum together with the drying temperature and drying time.

[All-solid polymer battery]
The all solid-state polymer battery of the present invention can have the same configuration as the conventional all solid-state polymer battery except that the positive electrode of the present invention is used as the positive electrode.
FIG. 2 is a longitudinal sectional view schematically showing the configuration of the all solid-state polymer battery 2 which is one of the embodiments of the present invention. The all solid-state polymer battery 2 is a lithium battery including a positive electrode 1, a negative electrode 5, a solid electrolyte membrane 6, and a laminate outer package 7. The positive electrode 1 is the positive electrode of the present invention shown in FIG.

The negative electrode 4 includes a negative electrode current collector 12 and a negative electrode active material layer 13, and is provided to face the positive electrode 1 with the solid electrolyte membrane 6 interposed therebetween.
As the negative electrode current collector 12, those commonly used in the field of all solid-state polymer batteries can be used, and examples thereof include a metal sheet. The metal sheet-like material means, for example, a metal film, a metal foil, a metal fiber non-woven fabric, and the like. Examples of the metal contained in the metal sheet-like material include copper, nickel, palladium, and stainless steel. A metal can be used individually by 1 type or in combination of 2 or more types.

  The negative electrode active material layer 13 is provided so that one surface in the thickness direction is in contact with the negative electrode current collector 12 and the other surface is in contact with the solid electrolyte membrane 6. The negative electrode active material layer 13 is provided so as to face the positive electrode active material layer 11 with the solid electrolyte membrane 6 interposed therebetween. The negative electrode active material layer 13 contains a negative electrode active material. For example, lithium or a lithium alloy can be used as the negative electrode active material. As the lithium alloy, those commonly used in the field of all solid-state polymer batteries can be used. For example, Li—Si alloy, Li—Sn alloy, Li—Al alloy, Li—Ga alloy, Li—Mg alloy, Li— Examples include In alloys.

  As the solid electrolyte membrane 6, an electrolyte membrane made of a dry polymer electrolyte contained in the positive electrode of the present invention can be used. Components other than the dry polymer electrolyte may be added to the solid electrolyte membrane 6 as long as the characteristics are not impaired. As this component, the crystalline complex of Li salt and the solid of glymes is mentioned, for example. By adding this crystalline complex to the solid electrolyte membrane 6, the interaction between lithium ions and the polymer chain can be weakened, and the ionic conductivity of the fixed electrolyte membrane 6 can be further increased. In addition, an inorganic filler can be added for the purpose of improving the film strength, film quality uniformity, ion conductivity and the like. Examples of such an inorganic filler include fine particles such as alumina and silica.

The solid electrolyte membrane 6 is obtained, for example, by a method including a polymer electrolyte solution preparation step and a solid electrolyte membrane preparation step.
In the polymer electrolyte solution preparation step, a lithium salt is added to an organic solvent solution of the matrix polymer to prepare a polymer electrolyte solution. When a component other than the dry polymer electrolyte is used, it is preferable to add the component to the polymer electrolyte solution and dissolve or disperse the component. Here, the organic solvent is not particularly limited as long as it can dissolve the matrix polymer and is inert to the matrix polymer and the lithium salt, and a known one can be used. Specific examples of the organic solvent include nitriles such as acetonitrile, glymes such as methyl monoglyme, and NMP.

  In the production process of the solid electrolyte membrane, the polymer electrolyte solution is applied to the substrate surface, and the organic solvent in the solution is removed by drying to form the solid electrolyte membrane 6 made of the dry polymer electrolyte. This solid electrolyte membrane 6 is used after being peeled off from the substrate. If a battery electrode is used as the substrate and the solid electrolyte membrane 6 is formed on the active material layer surface of the electrode, it can be advantageously used as it is as a battery component.

  Further, in order to improve the mechanical strength and the like of the solid electrolyte membrane 6, a support not shown may be used. A support body is arrange | positioned so that the single side | surface or both surfaces of the thickness direction of the solid electrolyte 6 may be contact | connected, for example. Alternatively, the solid electrolyte membrane 6 may be produced by impregnating the support with a polymer electrolyte solution and removing the organic solvent by drying.

  Examples of the support include a porous sheet. Examples of the porous sheet include a nonwoven fabric and a microporous film. The nonwoven fabric is made of, for example, a synthetic resin such as polypropylene, polyethylene, polyethylene terephthalate, or polyphenylene sulfide, or a polymer compound such as cellulose. The microporous film is made of polyolefin such as polypropylene and polyethylene, for example.

  The laminate outer package 7 is a laminate of a metal film and a resin film, for example. As the laminate, those commonly used in this field can be used, for example, acid-modified polypropylene / polyethylene terephthalate (PET) / Al foil / PET laminate film, acid-modified polyethylene / polyamide / Al foil / PET laminate film. , Ionomer resin / Ni foil / polyethylene / PET laminate film, ethylene vinyl acetate / polyethylene / Al foil / PET laminate film, ionomer resin / PET / Al foil / PET laminate film, and the like.

  FIG. 3 is a longitudinal sectional view schematically showing a configuration of an all solid-state polymer battery 3 which is another embodiment of the present invention. The all-solid-state polymer battery 3 is similar to the all-solid-state polymer battery 2, and the corresponding parts are denoted by the same reference numerals and description thereof is omitted. The all-solid-state polymer battery 3 is characterized in that the sealing material 8 is attached to a portion where the positive electrode current collector 10 and the negative electrode current collector 12 are directly opposed to each other at the periphery without using the laminate outer body 7. And

  That is, the all solid-state polymer battery 3 includes the positive electrode 1, the negative electrode 5, the solid electrolyte membrane 6, and the sealing material 8. The positive electrode 1 includes a positive electrode current collector 10 and a positive electrode active material layer 11, the negative electrode 5 includes a negative electrode current collector 12 and a negative electrode active material layer 13, and the positive electrode active material layer 11 and the negative electrode active material layer 13 are solid. The positive electrode 1, the negative electrode 5, and the solid electrolyte membrane 6 are arranged so as to face each other with the electrolyte membrane 6 interposed therebetween. Further, in the peripheral portion of the all-solid-state polymer battery 3, the portion of the positive electrode current collector 10 where the positive electrode active material layer 11 is not formed and the portion of the negative electrode current collector 12 where the negative electrode active material layer 13 is not formed face each other directly. A sealing material 8 is attached to this portion. As the sealing material 8, for example, a synthetic resin material can be used.

The all solid-state polymer battery 3 is manufactured, for example, as follows.
First, the positive electrode active material layer 11 is formed on one surface of the positive electrode current collector 10 to produce the positive electrode 1. Further, the negative electrode active material layer (lithium-based active material layer) 13 and the solid electrolyte membrane 6 are laminated on one surface of the negative electrode current collector 12 in this order. Next, the positive electrode 1 and the negative electrode 4 are overlapped so that the positive electrode active material layer 11 and the negative electrode active material layer 13 are opposed to each other through the solid electrolyte membrane 6. Furthermore, the all-solid-state polymer battery 3 is obtained by attaching the sealing material 8 to the periphery of the positive electrode 1 and the negative electrode 4 and sealing the periphery.

  The all-solid-state polymer battery of the present invention can take various forms other than those shown in FIGS. 2 and 3, for example, flat, coin-type, cylindrical, square, and laminate forms. is there. In the all solid-state polymer battery of the present invention, the electrode group including the positive electrode, the negative electrode, and the solid electrolyte membrane can be configured, for example, as a stacked type, a wound type, or a bipolar type. Furthermore, the all solid-state polymer battery of the present invention can be configured as either a primary battery or a secondary battery.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
(Example 1 and Comparative Example 1)
The positive electrode for an all-solid-state polymer battery of the present invention , reference examples and comparative examples was produced by the following procedure.
(1) Production of porous positive electrode active material Electrolytic manganese dioxide (manufactured by Mitsui Mining & Smelting Co., Ltd.) having an average pore diameter of 5 μm, a pore volume of 0.039 cm ³ / g, and a volume average particle diameter of 40 μm at 400 ° C. Baked for hours. The obtained fired product was wet pulverized.

  A planetary ball mill apparatus (trade name: P-7 type, manufactured by Fritsch Japan Co., Ltd.) was used for the wet pulverization, and the rotation speed was 400 rpm. The solvent used was 2-propyl alcohol, the medium used was a φ5 mm zirconia ball, and the container used was a 250 cc container made of zirconia. After pulverization, the solvent was removed by vacuum drying at 60 ° C. for 5 hours, followed by hot air drying at 250 ° C. in dry air for 5 hours to produce porous manganese dioxide. In addition, the pulverization time was changed as shown in Table 1, and porous positive electrode active materials 1 to 6 which were six types of porous manganese dioxide were produced.

The average pore diameter, pore volume, and volume average particle diameter of the obtained porous positive electrode active materials 1 to 6 were measured as follows. The average pore diameter and pore volume were measured using a pore distribution measuring apparatus (trade name: ASAP2010, manufactured by Shimadzu Corporation) using nitrogen gas as an adsorption gas. Moreover, the volume average particle diameter of the porous manganese dioxide was measured using a flow type particle image analyzer (trade name: FPIA-3000S, manufactured by Sysmex Corporation). The results are shown in Table 1. In addition, the positive electrode using the porous positive electrode active material 1 is a reference example.

In addition, as the comparative positive electrode active materials 1 and 2, unground LiMn ₂ O ₄ (manufactured by Tosoh Corp.) and LiCoO ₂ (manufactured by Tanaka Chemical Laboratories) were also used in the same manner as described above, The pore volume and volume average particle size were measured. The results are shown in Table 1.

From Table 1, it can be seen that the longer the pulverization time, the smaller the volume average particle diameter of manganese dioxide, and conversely, the average pore diameter and pore volume increase. In addition, it can be seen that unmilled LiMn ₂ O ₄ and LiCoO ₂ have almost no pores and are not porous.

(2) Production of positive electrode for all solid-state polymer battery Using the porous positive electrode active materials 1 to 6 and the comparative positive electrode active materials 1 and 2 obtained above, a positive electrode for an all solid-state polymer battery was prepared as follows. Produced. The following operations were all performed in a dry air atmosphere whose dew point was controlled at −50 ° C. or lower. Hereinafter, unless otherwise specified, the porous positive electrode active materials 1 to 6 and the comparative positive electrode active materials 1 to 2 are collectively referred to as a positive electrode active material.

In a acetonitrile solution of polyethylene oxide (viscosity average molecular weight 100000, manufactured by Sigma-Aldrich), the molar ratio [Li] / [EO] of the lithium ion concentration [Li] and the ether oxygen concentration [EO] is 0.05. LiN (CF ₃ SO ₂ ) ₂ was added to a dry polymer electrolyte solution. The ether oxygen concentration [EO] is the molar concentration of ether oxygen contained in the ethylene oxide chain in polyethylene oxide.

  Next, the positive electrode active material, acetylene black (conductive material), and the dry polymer electrolyte solution obtained above were adjusted so that the positive electrode active material: acetylene black: polyethylene oxide = 80% by mass: 10% by mass: 10% by mass. Taking in a mortar and kneading. NMP was added to the obtained kneaded material so that the positive electrode active material: NMP = 1: 2 by mass ratio, and further kneaded in a mortar to prepare a positive electrode mixture paste.

The obtained positive electrode mixture paste was applied to one side of an aluminum foil (positive electrode current collector) having a thickness of 15 μm and vacuum-dried at 85 ° C. for 5 hours to form a positive electrode active material layer, thereby producing a positive electrode plate. The degree of vacuum was 1.0 × 10 ⁻³ mmHg. The positive electrode plate was cut into a 12 mm square with a tab, and then the positive electrode active material layer on the tab surface was peeled off. The remaining positive electrode active material layer was rolled with a hydraulic press, and the thickness of the positive electrode active material layer was 20 μm. A positive electrode was produced.

  About the positive electrode plate obtained by carrying out similarly to the above, the positive electrode active material layer was visually observed and the presence or absence of the coating unevenness was investigated. Moreover, the cross section of the thickness direction of a positive electrode active material layer was observed with the microscope, and the dispersion state of the positive electrode active material was investigated. The results are shown in Table 2. FIG. 4 is a scanning electron micrograph of a cross section in the thickness direction of the positive electrode plate including the positive electrode active material layer containing the porous positive electrode active material 4.

  About the positive electrode plate obtained by carrying out similarly to the above, the positive electrode active material layer was peeled from the aluminum foil. This positive electrode active material layer was subjected to thermal extraction GC / MS analysis, and the mass of NMP contained in the positive electrode active material was measured. For the measurement, a gas chromatograph analyzer (trade name: GCMS-QP2010 Plus, manufactured by Shimadzu Corporation) was used. Next, the mass of NMP contained in the positive electrode active material per unit mass was converted to the volume percentage of NMP with respect to the pore volume of the positive electrode active material. The results are shown in Table 2.

  From Table 2, it can be seen that uneven coating such as streaks occurs in the positive electrode active material layer using the porous positive electrode active materials 1 and 2 having a large volume average particle diameter. Moreover, it turns out that dispersion | distribution of a positive electrode active material is non-uniform | heterogenous. From Table 2 and FIG. 4, in the positive electrode active material layer using the porous positive electrode active materials 3 to 6 having a small volume average particle diameter, no coating unevenness is observed, and the positive electrode active material is uniformly dispersed. I understand. It can also be seen that even when the comparative positive electrode active materials 1 and 2 are used, there is no occurrence of uneven coating such as streaks, and a positive electrode active material layer in which the positive electrode active material is uniformly dispersed can be formed.

From the above results, it can be seen that when a positive electrode active material having a volume average particle diameter of 20 μm or less is used, there is no occurrence of coating unevenness and a positive electrode active material layer in which the positive electrode active material is uniformly dispersed can be formed.
Further, it can be seen from Table 2 that the amount of NMP with respect to the pore volume hardly changes regardless of the average pore diameter and pore volume of the porous positive electrode active material. On the other hand, since the comparative positive electrode active materials 1 and 2 have almost no pores therein, NMP could not be detected. From this, it is clear that NMP does not exist in the structure of the positive electrode active material layer but exists in the pores of the porous positive electrode active material.

(3) Preparation of negative electrode for all solid-state polymer battery This step, (4) preparation step of solid electrolyte membrane, and (5) assembly step of all solid-state polymer battery are all argon controlled at dew point below -60 ° C. I went in the glove box. A nickel lead was welded to a 20 mm square copper foil having a thickness of 10 μm. Next, a 20 mm square lithium foil having a thickness of 150 μm was pressure-bonded to the surface of the copper foil lead on which the lead was not welded to produce an all solid-state polymer battery negative electrode.

(4) Production of Solid Electrolyte Membrane A polymer solution was prepared by dissolving 20 g of polyethylene oxide (viscosity average molecular weight 100000, manufactured by Sigma-Aldrich) in 100 g of acetonitrile. LiN (CF ₃ SO ₂ ) ₂ was added to the obtained polymer solution so that the molar ratio [Li] / [EO] of the lithium ion concentration [Li] and the ether oxygen concentration [EO] was 0.05. A dry polymer electrolyte solution was obtained. The ether oxygen concentration [EO] is the concentration of ether oxygen contained in the ethylene oxide chain of polyethylene oxide.

  The obtained dry polymer electrolyte solution is applied to the surface of the negative electrode active material layer (lithium foil) of the negative electrode, vacuum-dried at room temperature for 48 hours, acetonitrile as a solvent is removed, and a 120 μm thick solid electrolyte membrane is formed. did. Thereby, the laminated body of the negative electrode and the solid electrolyte membrane was produced.

(5) Assembly of all solid-state polymer battery Using the positive electrode and laminate (a laminate of a negative electrode and a solid electrolyte membrane) obtained above, an all-solid polymer battery 4 shown in FIG. 5 was produced. FIG. 5 is a top view showing a simplified configuration of a laminate-type all solid-state polymer battery 4. The all solid-state polymer battery 4 includes an electrode group 15, a positive electrode lead 16, a negative electrode lead 17, and an outer case 18.

  The electrode group 15 is produced by disposing the positive electrode and the laminate obtained above so that the positive electrode active material layer and the negative electrode active material layer face each other with the solid electrolyte membrane interposed therebetween. The electrode group 15 is inserted into the outer case 18 made of metal laminate, the positive lead 16 and the negative lead 17 are led out from the opening of the outer case 18, and then the opening of the outer case 18 is fused and sealed. An all solid polymer battery 4 was produced.

(6) Evaluation of all-solid-state polymer battery The all-solid-state polymer battery 4 obtained above was aged at 60 degreeC for 1 day. Thereafter, a charge / discharge test was performed at an environmental temperature of 30 ° C. and a current density of 25 μA / cm ² . Here, the current density indicates a current value per positive electrode area. A battery in which the composition of the positive electrode active material is manganese dioxide and LiMn ₂ O ₄ is subjected to a discharge test under the condition of a final voltage of 1.8V, and a battery in which the composition of the positive electrode active material is LiCoO ₂ has a final voltage of 4.2V. After charging under conditions, a charge / discharge test was performed in which discharge was performed under the condition of a final voltage of 3.0V. Based on these tests, the battery capacity per unit mass of the positive electrode active material (mAh / g), the ratio between the battery capacity and the theoretical capacity [(battery capacity / theoretical capacity) × 100] (%), and the capacity after the storage test The maintenance rate (%) was determined. The results are shown in Table 3.

The battery capacity (mAh / g) and the ratio between the battery capacity and the theoretical capacity were determined from the capacity during discharge. In addition, after storing the all-solid-state polymer battery 4 before the discharge test using the porous positive electrode active materials 1 to 6 in a thermostatic bath at 60 ° C. for 60 days, the environmental temperature: 30 ° C., the current density: 25 μA / cm ² , A discharge test was conducted under the condition of final voltage: 1.8 V, the discharge capacity after 60 days storage was measured, and the capacity retention rate (%) after the storage test was determined as a percentage of the discharge capacity before 60 days storage. That is, capacity retention rate after storage test (%) = (discharge capacity after 60 days storage / discharge capacity before 60 days storage) × 100.

From Table 3, when a porous positive electrode active material having a composition of manganese dioxide is used, the battery capacity per mass of the positive electrode active material is 200 to 260 mAh / g, and LiMn ₂ O ₄ and LiCoO ₂ that are comparative positive electrode active materials. It can be seen that a higher capacity can be obtained than using. This is because the theoretical capacity of manganese dioxide is higher than that of LiMn ₂ O ₄ or LiCoO ₂ . However, as shown in the section of the prior art, in an all solid-state polymer battery, a high battery capacity cannot be obtained simply by using a positive electrode active material having a high theoretical capacity.

The present invention has a specific configuration in which a high-boiling organic solvent is present in the pores of a porous positive electrode active material. With this configuration, even when a porous positive electrode active material having a high theoretical capacity is used, a high-capacity all solid-state polymer battery close to the theoretical capacity of the active material can be produced. Assuming that the theoretical reaction of manganese dioxide is a one-electron reaction, the theoretical capacity is 308 mAh / g. Assuming that the theoretical reaction of LiMn ₂ O ₄ is a one-electron reaction, the theoretical capacity is 148 mAh / g. Assuming that the theoretical reaction of LiCoO ₂ is a 0.5 electron reaction, the theoretical capacity is 137 mAh / g.

Further, from Table 3, when porous positive electrode active materials 1 to 5 having an average pore diameter of 20 nm or less and a pore volume of 0.15 cm ³ / g or less are used, the capacity retention rate after storage is 80%. It turns out that it becomes the above. When the average pore diameter exceeds 20 nm and the pore volume exceeds 0.15 cm ³ / g as in the porous positive electrode active material 6, the reaction between the porous positive electrode active material and the solid electrolyte membrane proceeds excessively, and during storage It is considered that the capacity deterioration of the battery becomes large.

(Example 2)
An all solid-state polymer battery 4 was produced in the same manner as in Example 1 except that the porous positive electrode active material 4 was used and the vacuum drying time was changed from 5 hours to the time shown in Table 4. Here, the vacuum drying time is a time when the positive electrode mixture paste is applied to one side of an aluminum foil (positive electrode current collector) having a thickness of 15 μm and vacuum-dried at 85 ° C. The amount of NMP (volume%), the battery capacity (mAh / g) and the capacity retention rate (%) after the storage test with respect to the pore volume of the porous positive electrode active material 4 were determined in the same manner as in Example 1. The results are shown in Table 4. In Table 4, the values for the drying time of 5 hours are the values in Example 1 reprinted for comparison.

  From Table 4, it can be seen that the amount of NMP decreases as the drying time increases. From the results of the discharge test, it can be seen that a battery capacity of 200 mAh / g or more can be obtained when the NMP amount is 0.01% by volume or more. However, by comparing the results when the drying time is 0 hour and 1 hour, if the amount of NMP exceeds 0.5% by volume, the capacity retention rate after the storage test may decrease, and deterioration after storage may increase. I understand. This is presumably because NMP becomes excessive in the positive electrode, becomes free and moves to the negative electrode during storage, reacts with lithium in the negative electrode to form an insulating film, and the properties after storage deteriorate. . Moreover, since NMP is a free state, it is estimated that the reliability and safety | security of a battery are also falling.

(Example 3)
Changing the solvent for wet grinding of electrolytic manganese dioxide from 2-propanol (secondary alcohol) to 2-methyl-2-butanol (tertiary alcohol), water or ethanol (primary alcohol); and A positive electrode for an all solid polymer battery and an all solid polymer battery were produced in the same manner as in Example 1 except that the pulverization time was 12 hours.

The average pore diameter and pore volume of the porous positive electrode active material and the amount of NMP relative to the pore volume were measured in the same manner as in Example 1. The Mn valence was chemically titrated according to JIS-K1467, and the apparent Mn valence was calculated assuming that all impurities other than manganese dioxide were MnSO ₄ . The battery capacity was determined in the same manner as in Example 1. The results are shown in Table 5.

From Table 5, it can be seen that the battery capacity decreases when the porous positive electrode active materials 8 and 9 are used. The porous positive electrode active materials 8 and 9 are obtained by using ethanol or water as a grinding solvent during wet grinding. It has been found that when the grinding solvent is water or ethanol, the Mn valence decreases, and impurities such as Mn ₂ O ₃ and Mn ₃ O ₄ are generated. This is because water and primary alcohols are inferior in oxidation resistance compared to secondary alcohols and tertiary alcohols, so that the grinding solvent reacts with manganese dioxide during wet grinding to reduce manganese dioxide. It is thought that. For this reason, it is thought that a battery capacity falls rather than the case where secondary and tertiary alcohol are used.

  The present invention can provide an all solid-state polymer battery having a high battery capacity despite the use of a porous positive electrode active material having a large pore volume. And since there is no fear of liquid leakage, it is possible to provide a thin and flexible all solid-state polymer battery that has high reliability and safety and that takes advantage of the free shape of the polymer electrolyte. The all solid-state polymer battery of the present invention can be suitably used as a power source for thin and reliable devices such as portable information terminals, portable electronic devices, and medical devices.

It is a longitudinal cross-sectional view which simplifies and shows the structure of the positive electrode for all solid-state polymer batteries which is one of the embodiments of the present invention. It is a longitudinal cross-sectional view which shows typically the structure of the all-solid-state polymer battery which is one of the embodiments of this invention. It is a longitudinal cross-sectional view which shows typically the structure of the all-solid-state polymer battery which is other embodiment of this invention. It is a scanning electron micrograph of the cross section of the thickness direction of the positive electrode plate containing the positive electrode active material layer containing a porous positive electrode active material. It is a top view which simplifies and shows the structure of a laminate-type all-solid-state polymer battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode for all-solid-state polymer battery 2, 3, 4 All-solid-state polymer battery 5 Negative electrode 6 Solid electrolyte membrane 7 Laminate exterior body 8 Sealing material 10 Positive electrode collector 11 Positive electrode active material layer 12 Negative electrode collector 13 Negative electrode active material Layer 15 Electrode group 16 Positive electrode lead 17 Negative electrode lead 18 Exterior case

Claims (8)

A positive electrode current collector, and a positive electrode active material layer formed on the surface of the positive electrode current collector,
The positive electrode active material layer contains a porous positive electrode active material having pores, a conductive material and a dry polymer electrolyte,
The porous positive electrode active material is manganese dioxide,
The average pore diameter of the porous positive electrode active material is 10 to 20 nm, the pore volume is 0.03 to 0.15 cm ³ / g,
A positive electrode for an all solid-state polymer battery, wherein the porous positive electrode active material contains a high-boiling organic solvent having a boiling point of 150 ° C. or higher in the pores.   The positive electrode for an all-solid-state polymer battery according to claim 1, wherein the high-boiling organic solvent is at least one selected from N-methyl-2-pyrrolidone and glymes.   The positive electrode for an all solid-state polymer battery according to claim 1 or 2, wherein the porous positive electrode active material contains a high-boiling organic solvent having a pore volume of 0.01 to 3% by volume of the pore volume. A pulverizing step of pulverizing manganese dioxide to obtain a porous positive electrode active material having pores, an average pore diameter of 10 to 20 nm, and a pore volume of 0.03 to 0.15 cm ³ / g; ,
A paste preparation step of preparing a paste by mixing a porous positive electrode active material obtained in the pulverization step, a conductive material, a dry polymer electrolyte, and a high boiling point organic solvent having a boiling point of 150 ° C. or higher;
And an active material layer forming step of applying and drying the paste obtained in the paste preparation step on the surface of the positive electrode current collector and drying the positive electrode for an all solid-state polymer battery. The method for producing a positive electrode for an all solid-state polymer battery according to claim 4 , wherein the positive electrode active material is wet-pulverized in a solvent in the pulverization step.   The method for producing a positive electrode for an all solid-state polymer battery according to claim 5, wherein the solvent is a protic solvent.   The method for producing a positive electrode for an all solid-state polymer battery according to claim 6, wherein the protic solvent is at least one selected from a secondary alcohol and a tertiary alcohol.   The all-solid-state polymer battery containing the positive electrode for all-solid-state polymer batteries as described in any one of Claims 1-3, a negative electrode, and a solid electrolyte membrane.