JP5556969B2 - Laminated molded body for all solid state battery, all solid state battery and method for producing the same - Google Patents

Description

  The present invention relates to an all-solid battery laminated molded body, an all-solid battery, and a method for producing the same.

  In recent years, the demand for batteries as a power source for portable electronic devices such as mobile phones and portable personal computers has greatly increased. In a battery used for such an application, an electrolyte (electrolytic solution) such as an organic solvent has been conventionally used as a medium for moving ions.

  However, in the battery having the above configuration, there is a risk that the electrolyte solution leaks. Moreover, the organic solvent etc. which are used for electrolyte solution are combustible substances. For this reason, it is required to further increase the safety of the battery.

  Therefore, as one countermeasure for enhancing the safety of the battery, it has been proposed to use a solid electrolyte as the electrolyte instead of the electrolytic solution. Furthermore, development of an all-solid battery in which a solid electrolyte is used as an electrolyte and the other constituent elements are also made of solid is being promoted.

  For example, Japanese Patent Laid-Open No. 2007-5279 (hereinafter referred to as Patent Document 1) proposes a method for manufacturing an all-solid battery. According to the method for producing an all-solid battery disclosed in Patent Document 1, an active material containing a phosphoric acid compound and a solid electrolyte are dispersed in a solution containing a binder and a plasticizer, respectively, to prepare a slurry, An active material green sheet and a solid electrolyte green sheet obtained by molding these slurries are laminated and heat-treated to produce an all-solid battery laminate.

JP 2007-5279 A

  As a result of various studies on the manufacturing method of the all-solid battery as described in Patent Document 1, the inventors laminated green bodies before firing, a molded body such as a film, and heat-treated. In order to form a laminate constituting the power generation element, it has been found that a technique for completely removing organic compounds such as a binder and a plasticizer contained in the molded body by heat treatment is important. However, it has been found that the heat treatment for removing the organic compound also burns carbon as a conductive agent contained in the molded body before firing the electrode layer, which may cause deterioration of battery characteristics. The present invention has been made based on the above findings.

  Accordingly, an object of the present invention is to suppress burning of the conductive agent contained in a green sheet, a film or the like before firing the electrode layer, and to form a green sheet, a film or the like before firing the solid electrolyte layer. An object of the present invention is to provide a laminate for an all-solid battery capable of removing the contained binder, an all-solid battery, and a method for producing the same.

  As a result of various studies by the inventors in order to solve the above-described problems, an electrode layer having different binder species contained therein and a molded body before firing of the electrode layer and a molded body before firing of the solid electrolyte layer were used. It has been found that it is possible to suppress the burning of the conductive agent contained in the compact before firing the layer and to remove the binder contained in the compact before firing the solid electrolyte layer. Based on such knowledge of the inventors, the present invention has the following features.

  An all-solid battery laminate molded body according to the present invention includes a first molded body including an electrode active material of either a positive electrode active material or a negative electrode active material and a first polymer material, and a first molded body. And a second molded body including a solid electrolyte and a second polymer material. The decomposition temperature of the first polymer material is higher than the decomposition temperature of the second polymer material.

  In the all-solid-state battery laminate molded body of the present invention, the first and second polymer materials preferably have a molecular weight of 10,000 or more.

  In the all-solid battery laminated molded article of the present invention, the molded article may be in one form selected from the group consisting of a green sheet and a film.

  An all-solid-state battery manufacturing method according to one aspect of the present invention includes the following steps and features.

  (A) The 2nd shaping | molding containing the 1st molded object containing the electrode active material of either a positive electrode active material or a negative electrode active material, and a 1st polymeric material, and a solid electrolyte and a 2nd polymeric material. Process for producing a molded body

  (B) Laminated molded body forming step of laminating the first molded body and the second molded body to form a laminated molded body

  (C) A laminated fired body forming step of firing a laminated molded body to form a laminated fired body comprising an electrode layer and a solid electrolyte layer

  (D) The decomposition temperature of the first polymer material is higher than the decomposition temperature of the second polymer material.

  The manufacturing method of the all-solid-state battery according to another aspect of the present invention includes the following steps and features.

  (E) The process of producing the 1st solid-liquid mixture containing the electrode active material of either a positive electrode active material or a negative electrode active material, and a 1st polymeric material.

  (F) The process of producing the 2nd solid-liquid mixture containing a solid electrolyte and a 2nd polymeric material

  (G) The process of forming a 1st molded object from a 1st solid-liquid mixture.

  (H) Step of forming a second molded body from the second solid-liquid mixture

  (I) A step of firing the first molded body to form an electrode layer

  (J) A step of firing the second molded body to form a solid electrolyte layer

  (D) The decomposition temperature of the first polymer material is higher than the decomposition temperature of the second polymer material.

  In the method for manufacturing an all-solid battery according to another aspect of the present invention, the step (G) of forming the first molded body includes applying the first solid-liquid mixture to the solid electrolyte layer and then solid electrolyte layer. Forming a laminated body of the first molded body and firing the first molded body to form an electrode layer (I) firing the laminated body of the solid electrolyte layer and the first molded body. And forming a laminated fired body composed of a solid electrolyte layer and an electrode layer.

  Moreover, in the method for producing an all-solid battery according to another aspect of the present invention, the step (G) of forming the first molded body applies the first solid-liquid mixture to the second molded body. Forming a laminated molded body comprising the first molded body and the second molded body, firing the first molded body to form an electrode layer (I), and the second molded body The step (J) of forming a solid electrolyte layer by firing the substrate may include firing the laminated molded body to form a laminated fired body including the solid electrolyte layer and the electrode layer.

  The manufacturing method of the all-solid-state battery according to another situation of this invention is equipped with the following processes and characteristics.

  (K) The process of producing the solid-liquid mixture for positive electrodes containing a positive electrode active material and a 1st polymeric material.

  (L) The process of producing the solid-liquid mixture for negative electrodes containing a negative electrode active material and a 1st polymeric material.

  (M) The process of producing the solid-liquid mixture for solid electrolytes containing a solid electrolyte and a 2nd polymer material

  (N) A solid-liquid mixture for electrodes, either a solid-liquid mixture for positive electrodes or a solid-liquid mixture for negative electrodes, is applied to a substrate to form a first laminated molded body composed of the substrate and one-electrode molded body. Process

  (O) A step of firing the first laminated molded body to form a first laminated fired body comprising a base material and one electrode fired layer.

  (P) A step of applying a solid-liquid mixture for solid electrolyte to the first laminated fired body to form a second laminated molded body comprising the first laminated fired body and the solid electrolyte molded body.

  (Q) A step of firing the second laminated molded body to form a second laminated fired body comprising a substrate, one electrode fired layer, and a solid electrolyte layer.

  (R) A solid-liquid mixture for positive electrode or a solid-liquid mixture for negative electrode, which is the other solid-liquid mixture for electrode, is applied to the second laminated fired body, and consists of the second laminated fired body and the other electrode molded body. Step of forming the third laminated molded body

  (S) A step of firing the third laminated molded body to form a laminated fired body comprising a positive electrode layer, a solid electrolyte layer, and a negative electrode layer.

  (D) The decomposition temperature of the first polymer material is higher than the decomposition temperature of the second polymer material.

  In the manufacturing method of the all-solid-state battery of this invention, a solid-liquid mixture should just be one form chosen from the group which consists of a slurry, a paste, and a colloid.

  In the method for producing an all solid state battery of the present invention, the molded body may be in one form selected from the group consisting of a green sheet and a film.

  In the method for producing an all solid state battery of the present invention, the difference between the decomposition temperature of the first polymer material and the decomposition temperature of the second polymer material is preferably 50 ° C. or more and 500 ° C. or less, preferably 50 ° C. or more. More preferably, it is 200 ° C. or lower.

  Moreover, it is preferable that a 1st polymeric material and a 2nd polymeric material contain at least 1 sort (s) chosen from the group which consists of a polyvinyl acetal resin, a cellulose, an acrylic resin, and a urethane resin.

  Furthermore, the weight content ratio of the first polymer material in the first molded body and the second polymer material in the second molded body is 5 parts by weight or more and 35 parts by weight with respect to 100 parts by weight of the inorganic material. The following is preferable.

  The laminated fired body formed in the method for producing an all-solid battery of the present invention may include a laminated fired body having a single battery structure in which a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are laminated.

  Furthermore, the laminated fired body may include a laminated fired body in which a plurality of laminated fired bodies having a single battery structure are stacked with a current collector layer interposed.

  In the method for producing an all-solid battery of the present invention, the material forming at least one layer selected from the group consisting of a positive electrode layer, a solid electrolyte layer and a negative electrode layer is a solid electrolyte comprising a lithium-containing phosphate compound having a NASICON structure It is preferable to contain.

  In the method for producing an all-solid battery of the present invention, the material forming at least one layer selected from the group consisting of a positive electrode layer and a negative electrode layer preferably contains an electrode active material made of a lithium-containing phosphate compound.

  In the method for producing an all solid state battery of the present invention, the molecular weight of the first and second polymer materials is preferably 10,000 or more.

  The all solid state battery according to the present invention is manufactured by a manufacturing method having the above-described characteristics.

  When an all-solid battery is produced by firing the laminate for an all-solid battery of the present invention, combustion of the conductive agent can be suppressed and a dense solid electrolyte layer can be formed in the positive electrode layer or the negative electrode layer. Therefore, battery characteristics such as discharge capacity can be improved.

It is sectional drawing which shows typically the cross-section of the all-solid-state battery as one embodiment with which the manufacturing method of this invention is applied. It is sectional drawing which shows typically the cross-section of the all-solid-state battery as another embodiment with which the manufacturing method of this invention is applied.

  As shown in FIG. 1, a laminate 10 of an all-solid battery as one embodiment to which the manufacturing method of the present invention is applied is a single battery composed of a positive electrode layer 1, a solid electrolyte layer 2, and a negative electrode layer 3. Composed. The positive electrode layer 1 is disposed on one surface of the solid electrolyte layer 2, and the negative electrode layer 3 is disposed on the other surface opposite to the one surface of the solid electrolyte layer 2. In other words, the positive electrode layer 1 and the negative electrode layer 3 are provided at positions facing each other with the solid electrolyte layer 2 interposed therebetween.

  As shown in FIG. 2, an all-solid battery laminate 20 as another embodiment to which the manufacturing method of the present invention is applied includes a positive electrode layer 1, a solid electrolyte layer 2, and a negative electrode layer 3. A plurality of, for example, two unit cells are connected in series via the current collector layer 4. The current collector layer 4 disposed inside the laminate 20 of the all solid state battery is provided between the positive electrode layer 1 and the negative electrode layer 3.

  Each of the positive electrode layer 1 and the negative electrode layer 3 includes a solid electrolyte and an electrode active material, and the solid electrolyte layer 2 includes a solid electrolyte. At least one of the positive electrode layer 1 and the negative electrode layer 3 contains carbon or the like as a conductive agent.

  The all-solid battery laminate molded body used for producing the all-solid battery laminates 10 and 20 configured as described above includes an electrode active material of either a positive electrode active material or a negative electrode active material and a first active material. A first molded body including a polymer material; and a second molded body stacked on the first molded body and including a solid electrolyte and a second polymer material. The decomposition temperature of the first polymer material is higher than the decomposition temperature of the second polymer material.

  In order to manufacture the all-solid-state battery laminates 10 and 20 configured as described above, in one aspect of the present invention, first, an electrode active material of either the positive electrode active material or the negative electrode active material and the first A first molded body including the polymer material and a second molded body including the solid electrolyte and the second polymer material are manufactured (molded body manufacturing step). Next, the first molded body and the second molded body are laminated to form a laminated molded body (laminated molded body forming step). Then, the obtained laminated molded body is fired to form a laminated fired body including an electrode layer and a solid electrolyte layer (laminated fired body forming step). In this way, a molded body is formed from the solid-liquid mixture, the molded body of the positive electrode layer 1, the solid electrolyte layer 2 and the negative electrode layer 3 is laminated to form a laminated molded body, and this laminated molded body is fired. Alternatively, a laminated fired body of the positive electrode layer 1, the solid electrolyte layer 2, and the negative electrode layer 3 may be formed.

  Or in order to manufacture the laminated bodies 10 and 20 of the all-solid-state battery comprised as mentioned above, in another aspect of this invention, first, either the electrode active material of a positive electrode active material or a negative electrode active material and A first solid-liquid mixture containing the first polymer material is prepared. Next, a second solid-liquid mixture containing the solid electrolyte and the second polymer material is prepared. And a 1st molded object is formed from the obtained 1st solid-liquid mixture. A second molded body is formed from the obtained second solid-liquid mixture. Furthermore, the obtained 1st molded object is baked and the electrode layer, ie, the positive electrode layer 1, and the negative electrode layer 3, is formed. The obtained 2nd molded object is baked and the solid electrolyte layer 2 is formed. Thus, you may form each sintered compact of the positive electrode layer 1, the solid electrolyte layer 2, and the negative electrode layer 3 by forming a molded object from a solid-liquid mixture and baking the obtained molded object.

  In addition, a molded object should just be one form chosen from the group which consists of a green sheet and a film | membrane. The solid-liquid mixture may be in one form selected from the group consisting of slurry, paste and colloid.

  In the method for producing an all-solid battery according to another aspect of the present invention, the step of forming the first molded body includes the step of applying the first solid-liquid mixture to the solid electrolyte layer and the first step. Forming the electrode body by firing the first compact, and firing the solid electrolyte layer and the first compact to form the solid electrolyte layer. You may make it include forming the laminated fired body which consists of an electrode layer.

  Specifically, for example, first, a green sheet of a solid electrolyte material as a second molded body is formed from the second solid-liquid mixture. The green sheet of the solid electrolyte material is fired to produce the solid electrolyte layer 2. A slurry or paste of the positive electrode material as the first solid-liquid mixture is applied to one surface of the solid electrolyte layer 2, and the slurry of the negative electrode material as the first solid-liquid mixture is applied to the other surface opposite to the one surface. The paste is applied to form a positive electrode coating film as a first molded body and a laminate of the negative electrode coating film and the solid electrolyte layer 2. Then, the laminate may be fired to form a laminated fired body including the positive electrode layer 1, the solid electrolyte layer 2, and the electrode layer 3.

  In the all-solid-state battery manufacturing method according to another aspect of the present invention, the step of forming the first molded body includes the first solid-liquid mixture applied to the second molded body. Forming a laminated molded body composed of the molded body and the second molded body, firing the first molded body to form an electrode layer, firing the second molded body, and solid electrolyte The step of forming a layer may include firing the laminated molded body to form a laminated fired body including a solid electrolyte layer and an electrode layer.

  Specifically, for example, first, a green sheet of a solid electrolyte material as a second molded body is formed from the second solid-liquid mixture. The positive electrode material slurry or paste as the first solid-liquid mixture is applied to one surface of the green sheet of the solid electrolyte material, and the negative electrode material as the first solid-liquid mixture is applied to the other surface opposite to the one surface. The slurry or paste is applied to form a positive electrode coating film as a first molded body and a laminated molded body of a negative electrode coating film and a solid electrolyte green sheet as a second molded body. Then, the multilayer molded body may be fired to form a multilayer fired body including the positive electrode layer 1, the solid electrolyte layer 2, and the negative electrode layer 3.

  Alternatively, a positive electrode material slurry or paste as a first solid-liquid mixture is applied to one surface of a solid electrolyte material green sheet, and a positive electrode coating film as a first molded body and a second molded body as A laminated molded body with a solid electrolyte green sheet is formed. And this laminated molded body may be fired to form a laminated fired body comprising the positive electrode layer 1 and the solid electrolyte layer 2. In this case, a metal foil such as an alloy may be fixed as the negative electrode layer 3 on the other surface opposite to the one surface of the solid electrolyte layer 2.

  Furthermore, in the method for producing an all-solid battery according to another aspect of the present invention, first, a solid-liquid mixture for a positive electrode including a positive electrode active material and a first polymer material is prepared. A solid-liquid mixture for negative electrode containing a negative electrode active material and a first polymer material is prepared. A solid-liquid mixture for solid electrolyte containing the solid electrolyte and the second polymer material is prepared. Either the obtained solid-liquid mixture for positive electrode or solid-liquid mixture for negative electrode is applied to the base material to form a first laminated molded body composed of the base material and the one-electrode molded body. To do. The first laminated molded body is fired to form a first laminated fired body including a base material and one electrode fired layer. Next, a solid-liquid mixture for solid electrolyte is applied to the first laminated fired body to form a second laminated molded body composed of the first laminated fired body and the solid electrolyte molded body. Further, the second laminated molded body is fired to form a second laminated fired body composed of the base material, the one electrode fired layer, and the solid electrolyte layer. Then, either the obtained solid-liquid mixture for positive electrode or solid-liquid mixture for negative electrode is applied to the second laminated fired body, and the second laminated fired body, the other electrode molded body, A third laminated molded body is formed. Finally, the third laminated molded body is fired to form a laminated fired body including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. In this way, the positive electrode layer 1, the solid electrolyte layer 2, and the negative electrode layer 3 may be formed by sequentially coating, firing, and laminating.

  Specifically, for example, first, the positive electrode layer 1 is formed by applying a paste of a positive electrode material on a base material such as polyethylene terephthalate (PET) and baking it. The solid electrolyte layer 2 is formed by applying a paste of a solid electrolyte material on the obtained positive electrode layer 1 and baking it. A negative electrode material paste is applied on the obtained solid electrolyte layer 2 and baked to form the negative electrode layer 3. In this way, a laminated fired body composed of the positive electrode layer 1, the solid electrolyte layer 2, and the negative electrode layer 3 may be formed. In this case, you may form the negative electrode layer 3 previously on a base material.

  In the all-solid battery manufacturing method according to still another aspect of the present invention, first, a solid-liquid mixture for a positive electrode including a positive electrode active material and a first polymer material is prepared. A solid-liquid mixture for negative electrode containing a negative electrode active material and a first polymer material is prepared. A solid-liquid mixture for solid electrolyte containing the solid electrolyte and the second polymer material is prepared. The solid electrolyte layer 2 is formed by shaping and firing the obtained solid-liquid mixture for solid electrolyte. One electrode molded body is formed by molding any one of the obtained solid-liquid mixture for positive electrode or solid-liquid mixture for negative electrode. On the other hand, an electrode compact is laminated on one surface of the solid electrolyte layer to form a laminate. By firing this laminated body, a laminated fired body comprising a solid electrolyte layer and one electrode fired layer is formed. The other electrode molded body is formed by molding either the obtained solid-liquid mixture for positive electrode or solid-liquid mixture for negative electrode, which is the other solid-liquid mixture for electrode. The other electrode molded body is laminated on the other surface opposite to the one surface of the solid electrolyte layer to form a laminate. By firing this laminate, a laminate fired body composed of the positive electrode layer 1, the solid electrolyte layer 2, and the negative electrode layer 3 may be formed. In this way, a laminated fired body may be formed by sequentially laminating and firing the compacts of the positive electrode layer 1, the solid electrolyte layer 2, and the negative electrode layer 3 before firing.

  Although the various manufacturing methods of the all-solid-state battery of the present invention have been described, the manufacturing method of the all-solid-state battery of the present invention is not limited to the above-described manufacturing method.

  As described above, the all-solid-state battery laminate formed body of the present invention has a structure in which the respective pre-fired formed bodies of the positive electrode layer 1, the solid electrolyte layer 2, and the negative electrode layer 3 are laminated. The kind of the first polymer material contained in the molded body before firing of at least one of the positive electrode layer 1 and the negative electrode layer 3, and the second polymer material contained in the molded body before firing of the solid electrolyte layer 2 The type is different. The decomposition temperature of the first polymer material is higher than the decomposition temperature of the second polymer material. Thereby, in the positive electrode layer 1 or the negative electrode layer 3, a residue of the polymer material can be preferentially left, and necking between particles and burning of the conductive agent can be suppressed. On the other hand, in the solid electrolyte layer 2, it is possible to suppress the residue of the polymer material that inhibits ion conductivity, the voids after the removal of the polymer material, and the like, and to form a dense solid electrolyte layer, Furthermore, an internal short circuit due to a residue of the polymer material can be suppressed. Therefore, when the all-solid battery laminate molded body of the present invention is fired to produce an all-solid battery, battery characteristics such as discharge capacity can be improved.

  In the method for producing an all solid state battery of the present invention, the difference between the decomposition temperature of the first polymer material and the decomposition temperature of the second polymer material is preferably 50 ° C. or more and 500 ° C. or less, preferably 50 ° C. or more. More preferably, it is 200 ° C. or lower.

  When the difference between the decomposition temperature of the first polymer material and the decomposition temperature of the second polymer material is 50 ° C. or more and 500 ° C. or less, the above effect can be obtained more remarkably. More preferably, when the difference between the decomposition temperature of the first polymer material and the decomposition temperature of the second polymer material is 50 ° C. or higher and 200 ° C. or lower, the minimum necessary polymer material residue is used. Therefore, even in the positive electrode layer or the negative electrode layer containing a polymer material residue after firing, the densification of the positive electrode layer or the negative electrode layer is not hindered. Can increase the sex.

  In the method for producing an all-solid-state battery of the present invention, the first polymer material and the second polymer material are at least one selected from the group consisting of polyvinyl acetal resin, cellulose, acrylic resin, and urethane resin. It is preferable to include. By using such first and second polymer materials, it is possible to achieve both dispersibility and viscosity in a slurry or paste for producing a molded body.

  Furthermore, in the manufacturing method of the all-solid-state battery of this invention, each weight content ratio of the 1st polymeric material in a 1st molded object and the 2nd polymeric material in a 2nd molded object is 100 weight of inorganic materials. It is preferably 5 parts by weight or more and 35 parts by weight or less with respect to parts. Thus, by limiting the weight content ratio of the first and second polymer materials, the mechanical strength of the molded body can be maintained, and the adhesion between the molded bodies can be maintained when the molded bodies are laminated. it can.

  The molecular weight of the first and second polymer materials is preferably 10,000 or more.

  The laminated fired body may be a single battery structure laminated body 10 by laminating the positive electrode layer 1, the solid electrolyte layer 2 and the negative electrode layer 3, and the single battery structure laminated body with the current collector layer 4 interposed therebetween. A laminated body 20 in which a plurality of bodies 10 are laminated may be used. In this case, a plurality of laminates 10 having a single cell structure may be stacked electrically in series or in parallel.

  The method for forming the molded body is not particularly limited, but a die coater, a comma coater, screen printing, or the like can be used. The method of laminating the molded body is not particularly limited, but the molded body can be laminated using a hot isostatic press, a cold isostatic press, an isostatic press, or the like.

  A solid-liquid mixture for forming a molded body may be prepared by wet-mixing an organic vehicle in which a polymer material is dissolved in a solvent and a positive electrode active material, a negative electrode active material, a solid electrolyte, or a current collector material. it can. Media can be used in wet mixing, and specifically, a ball mill method, a viscomill method, or the like can be used. On the other hand, a wet mixing method that does not use media may be used, and a sand mill method, a high-pressure homogenizer method, a kneader dispersion method, or the like can be used.

  The solid-liquid mixture may contain a plasticizer. Although the kind of plasticizer is not particularly limited, phthalic acid esters such as dioctyl phthalate and diisononyl phthalate may be used.

  In the firing step, the atmosphere is not particularly limited, but it is preferably performed under conditions that do not change the valence of the transition metal contained in the electrode active material.

In addition, although the kind of electrode active material contained in the positive electrode layer 1 or the negative electrode layer 3 of the laminated bodies 10 and 20 of the all-solid-state battery to which the manufacturing method of the present invention is applied is not limited, as the positive electrode active material, Li ₃ V ₂ (PO ₄ ) _{3 and} other lithium-containing phosphate compounds having NASICON type structure, LiFePO ₄ and LiMnPO _{4 and} other olivine-type phosphate compounds, LiCoO ₂ , LiCo _1/3 Ni _1/3 Mn ₁ A layered compound such as _{/ 3} O ₂ and a lithium-containing compound having a spinel structure such as LiMn ₂ O ₄ and LiNi _0.5 Mn _1.5 O ₄ can be used.

As the negative electrode active material, MOx (M is at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, Nb and Mo, and x is 0.9 ≦ x ≦ 2.0. A compound having a composition represented by the following formula can be used. For example, it may be used a mixture prepared by mixing two or more active material having a composition represented by MOx containing different element M of such TiO ₂ and SiO _2. As the negative electrode active material, graphite-lithium compounds, lithium alloys such as Li-Al, oxidation of Li ₃ V ₂ (PO ₄ ) ₃ , Li ₃ Fe ₂ (PO ₄ ) ₃ , Li ₄ Ti ₅ O _12, etc. A thing etc. can be used.

Further, the type of solid electrolyte contained in the positive electrode layer 1, the negative electrode layer 3 or the solid electrolyte layer 2 of the laminates 10 and 20 of the all-solid battery to which the production method of the present invention is applied is not limited, A lithium-containing phosphate compound having a NASICON structure can be used. Lithium-containing phosphoric acid compound having a NASICON-type structure, the chemical formula _{Li x M y (PO 4)} 3 ( Formula, x 1 ≦ x ≦ 2, y is a number in the range of 1 ≦ y ≦ 2, M Is one or more elements selected from the group consisting of Ti, Ge, Al, Ga and Zr). In this case, part of P in the above chemical formula may be substituted with B, Si, or the like. For example, a mixture obtained by mixing two or more Nasicon-type lithium-containing phosphate compounds having different compositions such as Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ and Li _1.2 Al _0.2 Ti _1.8 (PO ₄ ) ₃ is used. It may be used.

  The lithium-containing phosphate compound having a NASICON structure used in the solid electrolyte is a compound containing a crystal phase of a lithium-containing phosphate compound having a NASICON structure or a lithium-containing phosphate having a NASICON structure by heat treatment. You may use the glass which precipitates the crystal phase of a phosphoric acid compound.

In addition, as a material used for said solid electrolyte, it is possible to use the material which has ion conductivity and is so small that electronic conductivity can be disregarded other than the lithium-containing phosphate compound which has a NASICON structure. Examples of such a material include lithium halide, lithium nitride, lithium oxyacid salt, and derivatives thereof. In addition, Li—PO compounds such as lithium phosphate (Li ₃ PO ₄ ), LIPON (LiPO _4−x N _x ) in which nitrogen is introduced into lithium phosphate, Li—Si— such as Li ₄ SiO ₄ O-based compounds, Li-P-Si-O based compounds, Li-V-Si-O based compounds, La _0.51 Li _0.35 TiO _2.94 , La _0.55 Li _0.35 TiO ₃ , Li _3x La _{2 / 3-x} TiO _3, etc. Examples thereof include compounds having a perovskite structure, compounds having a garnet structure having Li, La, and Zr.

  The material forming at least one of the positive electrode layer 1, the solid electrolyte layer 2 or the negative electrode layer 3 of the laminates 10 and 20 of the all-solid-state battery to which the manufacturing method of the present invention is applied is a lithium-containing phosphoric acid having a NASICON structure. It is preferable to include a solid electrolyte made of a compound. In this case, high ion conductivity that is essential for battery operation of an all-solid battery can be obtained. In addition, when glass or glass ceramics having a composition of a lithium-containing phosphate compound having a NASICON type structure is used as a solid electrolyte, a denser sintered body can be easily obtained due to the viscous flow of the glass phase in the firing step. It is particularly preferred to prepare the solid electrolyte starting material in the form of glass or glass ceramic.

  Moreover, the material which forms at least 1 layer of the positive electrode layer 1 or the negative electrode layer 3 of the laminated bodies 10 and 20 of the all-solid-state battery to which the manufacturing method of this invention is applied is an electrode active material which consists of a lithium containing phosphate compound. It is preferable to include. In this case, the phase change of the electrode active material in the firing step or the reaction of the electrode active material with the solid electrolyte can be easily suppressed by the high temperature stability of the phosphoric acid skeleton. The capacity can be increased. In addition, when an electrode active material composed of a lithium-containing phosphate compound and a solid electrolyte composed of a lithium-containing phosphate compound having a NASICON structure are used in combination, the reaction between the electrode active material and the solid electrolyte is suppressed in the firing step. It is particularly preferable to use a combination of the electrode active material and the solid electrolyte material as described above, since both of them can be obtained and good contact can be obtained.

  Furthermore, the current collector layer 4 of the laminate 20 of the all solid state battery to which the manufacturing method of the present invention is applied contains an electron conductive material. The electron conductive material preferably contains at least one selected from the group consisting of conductive oxides, metals and carbon materials.

  Next, examples of the present invention will be specifically described. In addition, the Example shown below is an example and this invention is not limited to the following Example.

  Hereinafter, Examples 1 to 5 and Comparative Examples of all solid state batteries manufactured according to the manufacturing method of the present invention will be described.

  (Production of organic vehicle)

  First, an organic vehicle was prepared by dissolving 20 parts by weight of various polymer materials having different decomposition temperatures shown in Table 1 below as binders in 100 parts by weight of a solvent. The decomposition temperature of the polymer material was judged at a temperature at which the weight loss rate of the polymer material exceeded 95% using a differential thermothermal gravimetric simultaneous measurement device (model number: TG-DTA7200) manufactured by Seiko Instruments Inc. . A urethane resin having a weight average molecular weight of 60,000 was used as urethane A, and a urethane resin having a weight average molecular weight of 200,000 was used as urethane B.

  (Preparation of slurry)

50 parts by weight of a glass powder of a lithium germanium-containing phosphate compound (LAGP: Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ ) having a NASICON type structure as a solid electrolyte, and Li ₃ V ₂ (PO ₄ ) as an electrode active material 45 parts by weight of a powder having a crystal phase of ₃ , 5 parts by weight of carbon powder as a conductive agent, and 120 parts by weight of an organic vehicle prepared as described above so as to include the polymer material A shown in Table 2 below. A spherical medium made of zirconia having a diameter of 1 mm was enclosed in a container and the container was rotated, and then the spherical medium was taken out to prepare an electrode slurry.

  A container containing 100 parts by weight of LAGP glass powder as a solid electrolyte and 120 parts by weight of an organic vehicle prepared as described above so as to contain the polymer material B shown in Table 2 below, together with a zirconia spherical medium having a diameter of 1 mm After enclosing in and rotating the container, the spherical media was taken out to produce a solid electrolyte slurry.

  Table 2 shows the difference in decomposition temperature of the polymer material (= (decomposition temperature Ta of polymer material A) − (decomposition temperature Tb of polymer material B)).

  (Green sheet production process)

  Each electrode slurry is coated on a polyethylene terephthalate (PET) film using a doctor blade method, formed into a sheet having a thickness of 50 μm, and punched into a disk having a diameter of 10 mm. Was made.

  The solid electrolyte slurry was coated on a PET film using a doctor blade method, formed into a sheet having a thickness of 30 μm, and punched into a disk having a diameter of 11 mm, thereby producing a solid electrolyte green sheet.

  (Laminate formation process)

  Four solid electrolyte green sheets peeled from the PET film were stacked and laminated, and a solid electrolyte layer was formed by pressurizing and pressure bonding at a temperature of 60 ° C. The reason for laminating a plurality of solid electrolyte green sheets is to give sufficient mechanical strength to the solid electrolyte layer after firing to facilitate the handling of the solid electrolyte layer in the process described later. There is no particular problem even if a solid electrolyte layer is formed without stacking a plurality of sheets.

  One electrode green sheet exfoliated from the PET film was laminated on one side of the solid electrolyte layer obtained above, and pressed at a temperature of 60 ° C. for pressure bonding to form a positive electrode layer. A negative electrode layer was formed by pressure-bonding two electrode sheets to the opposite surface of the solid electrolyte layer in the same manner. Thus, the green sheet laminated body for all-solid-state batteries was produced.

The reason for the difference in the number of electrode sheets used in the positive electrode layer and the negative electrode layer is that when Li ₃ V ₂ (PO ₄ ) ₃ is used as the positive electrode active material and the negative electrode active material, This is because the capacity per unit weight (gram) of Li ₃ V ₂ (PO ₄ ) ₃ differs by about twice. In addition, the thickness of a positive electrode layer and a negative electrode layer can be suitably changed according to the material of the electrode active material to be used.

  (Baking process)

  The obtained laminate was heat treated in an air atmosphere at a temperature of 500 ° C. to remove the polymer material (first firing step). Then, the all-solid-state battery was obtained by heat-processing in a nitrogen atmosphere at the temperature of 700 degreeC, and sintering the laminated body (2nd baking process).

  By observing the color of the solid electrolyte layer with an optical microscope, the residue of the polymer material contained in the solid electrolyte layer was confirmed on the fracture surface of the obtained all-solid-state battery. Moreover, the burning suppression effect of the electrically conductive agent contained in an electrode layer was confirmed by observing the color of an electrode layer with a scanning electron microscope. The results are shown in Table 3.

  Moreover, the obtained all-solid-state battery was sealed in a 2032 type coin-type battery, a charge / discharge test was performed, and the discharge amount was measured. The battery was charged until the voltage became 4.5 V with a charging current of 20 μA (the voltage was held for 3 hours at a voltage of 4.5 V after reaching the voltage of 4.5 V), and discharged until the voltage became 3 V with a discharging current of 20 μA. .

  As shown in Table 3, in the all solid state batteries of Examples 1 to 5, the color of the electrode layer is black, so that the combustion of carbon as a conductive agent is suppressed, and the color of the solid electrolyte layer is It turns out that there is no residue of a polymeric material by being white. On the other hand, in the all-solid battery of the comparative example, the color of the electrode layer is gray, so that the combustion of carbon as a conductive agent is not suppressed, and the color of the solid electrolyte layer is gray Thus, it can be seen that there is a residue of the polymer material. Moreover, as shown in Table 3, it was confirmed that the all-solid-state batteries of Examples 1 to 5 exhibit a higher discharge capacity than the all-solid-state battery of the comparative example.

In addition, the sealing method for comprising a battery is not specifically limited, You may seal the laminated body of the all-solid-state battery obtained by sintering with resin etc. For example, a paste obtained by applying or dipping an insulating paste such as Al ₂ O ₃ around the laminate may be sealed by heat treatment.

  In order to efficiently draw current from the positive and negative electrode layers, a conductive layer such as a metal layer may be formed on the positive and negative electrode layers by sputtering or the like. For example, the conductive layer may be formed by applying or dipping a metal paste or the like on the positive and negative electrode layers, followed by heat treatment.

  It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments and examples but by the claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the claims.

  When the all-solid battery laminated molded body of the present invention is baked to produce an all-solid battery, the positive electrode layer or the negative electrode layer can suppress the burning of the conductive agent and can form a dense solid electrolyte layer. Since battery characteristics such as discharge capacity can be improved, the present invention is particularly useful for the production of all-solid secondary batteries.

1: positive electrode layer, 2: solid electrolyte layer, 3: negative electrode layer, 4: current collector layer, 10, 20: laminate.

Claims (20)

A first molded body containing an electrode active material of either a positive electrode active material or a negative electrode active material and a first polymer material;
A second molded body that is laminated on the first molded body and includes a solid electrolyte and a second polymer material,
An all-solid battery multilayer molded article, wherein a decomposition temperature of the first polymer material is higher than a decomposition temperature of the second polymer material.   The multilayer molded body for an all-solid-state battery according to claim 1, wherein the molecular weight of the first and second polymer materials is 10,000 or more.   The multilayer molded body for an all-solid-state battery according to claim 1 or 2, wherein the molded body is one form selected from the group consisting of a green sheet and a film. A first molded body including an electrode active material of either a positive electrode active material or a negative electrode active material and a first polymer material; and a second molded body including a solid electrolyte and a second polymer material. A molded body production process to be produced;
A laminated molded body forming step of laminating the first molded body and the second molded body to form a laminated molded body;
A laminated fired body forming step of firing the laminated molded body to form a laminated fired body comprising an electrode layer and a solid electrolyte layer, and
An all-solid battery manufacturing method, wherein a decomposition temperature of the first polymer material is higher than a decomposition temperature of the second polymer material. Producing a first solid-liquid mixture comprising an electrode active material of either a positive electrode active material or a negative electrode active material and a first polymer material;
Producing a second solid-liquid mixture comprising a solid electrolyte and a second polymer material;
Forming a first molded body from the first solid-liquid mixture;
Forming a second molded body from the second solid-liquid mixture;
Firing the first molded body to form an electrode layer;
Firing the second molded body to form a solid electrolyte layer,
An all-solid battery manufacturing method, wherein a decomposition temperature of the first polymer material is higher than a decomposition temperature of the second polymer material. Forming the first molded body includes applying the first solid-liquid mixture to the solid electrolyte layer to form a laminate of the solid electrolyte layer and the first molded body;
The step of firing the first molded body to form an electrode layer includes laminating the solid electrolyte layer and the first molded body to form a laminated fired body comprising the solid electrolyte layer and the electrode layer. The manufacturing method of the all-solid-state battery of Claim 5 including forming. In the step of forming the first molded body, the first molded body and the second molded body are formed by applying the first solid-liquid mixture to the second molded body. Forming, and
The step of firing the first molded body to form an electrode layer and the step of firing the second molded body to form a solid electrolyte layer include firing the laminated molded body to form the solid electrolyte layer. The manufacturing method of the all-solid-state battery of Claim 5 including forming the laminated fired body which consists of and the said electrode layer. Producing a solid-liquid mixture for a positive electrode comprising a positive electrode active material and a first polymer material;
Producing a solid-liquid mixture for a negative electrode comprising a negative electrode active material and a first polymer material;
Producing a solid-liquid mixture for a solid electrolyte comprising a solid electrolyte and a second polymer material;
Either a solid-liquid mixture for a positive electrode or a solid-liquid mixture for a negative electrode is applied to a base material to form a first laminated molded body composed of the base material and a one-electrode molded body. And a process of
Firing the first laminated molded body to form a first laminated fired body comprising the base material and one electrode fired layer;
Applying the solid-liquid mixture for solid electrolyte to the first laminated fired body to form a second laminated molded body comprising the first laminated fired body and a solid electrolyte molded body;
Firing the second laminated molded body to form a second laminated fired body comprising the substrate, the one electrode fired layer, and a solid electrolyte layer;
From the second laminated fired body and the other electrode molded body, either the solid-liquid mixture for positive electrode or the solid-liquid mixture for negative electrode is applied to the second laminated fired body. Forming a third laminated molded body comprising:
Firing the third laminated molded body to form a laminated fired body comprising a positive electrode layer, a solid electrolyte layer, and a negative electrode layer,
An all-solid battery manufacturing method, wherein a decomposition temperature of the first polymer material is higher than a decomposition temperature of the second polymer material.   The manufacturing method of the all-solid-state battery of any one of Claim 5 to 8 whose said solid-liquid mixture is one form chosen from the group which consists of a slurry, a paste, and a colloid.   The manufacturing method of the all-solid-state battery of any one of Claim 4 to 9 whose said molded object is one form chosen from the group which consists of a green sheet and a film | membrane.   The difference between the decomposition temperature of the first polymer material and the decomposition temperature of the second polymer material is 50 ° C or more and 500 ° C or less, according to any one of claims 4 to 10. Of manufacturing all solid state battery.   The manufacturing method of the all-solid-state battery of Claim 11 whose difference of the decomposition temperature of the said 1st polymeric material and the decomposition temperature of the said 2nd polymeric material is 50 to 200 degreeC.   The first polymer material and the second polymer material include at least one selected from the group consisting of polyvinyl acetal resin, cellulose, acrylic resin, and urethane resin. The manufacturing method of the all-solid-state battery of any one.   The weight content ratio of the first polymer material in the first molded body and the second polymer material in the second molded body is 5 parts by weight or more and 35 parts by weight with respect to 100 parts by weight of the inorganic material. The manufacturing method of the all-solid-state battery of any one of Claim 4 to 13 which is below a weight part.   9. The laminated fired body according to claim 4, comprising a fired body having a single battery structure in which a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are laminated. Of manufacturing all solid state battery.   The method for manufacturing an all-solid battery according to claim 15, wherein the laminated fired body includes a laminated fired body in which a plurality of the laminated fired bodies having the single battery structure are laminated with a current collector layer interposed therebetween.   The material forming at least one layer selected from the group consisting of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer includes a solid electrolyte composed of a lithium-containing phosphate compound having a NASICON structure. Item 17. A method for producing an all solid state battery according to Item 16.   18. The material according to claim 15, wherein the material forming at least one layer selected from the group consisting of the positive electrode layer and the negative electrode layer includes an electrode active material made of a lithium-containing phosphate compound. The manufacturing method of the all-solid-state battery as described in 1 above.   The manufacturing method of the all-solid-state battery of any one of Claim 4 to 18 whose molecular weight of the said 1st and 2nd polymeric material is 10,000 or more.   The all-solid-state battery manufactured by the manufacturing method of any one of Claim 4-19.

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