JP2009104818A - All-solid battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an all-solid battery and its manufacturing method which achieve improvement of battery characteristics by not using polymer resin for a binder. <P>SOLUTION: In manufacturing at least one layer out of a cathode layer 2, a solid electrolyte layer 3, and an anode layer 4, a slurry with cathode active material particles dispersed in an alcohol solvent having metal alkoxide dissolved, in the case of manufacturing of the cathode layer, a slurry with anode active material particles dispersed in an alcohol solvent having metal alkoxide dissolved, in the case of manufacturing of the anode layer, and a slurry as an alcohol solvent having a metal alkoxide dissolved, in the case of manufacturing of the solid electrolyte layer, are coated on a base layer, which is then sintered. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an all-solid battery and a method for manufacturing the same, and more specifically to an all-solid battery used for a mobile phone, a notebook computer, and the like, and a method for manufacturing the same.

  In an era when portable electronic devices are diversified and various types of batteries are required, various types of batteries have been energetically improved in terms of weight reduction, size reduction, and high discharge capacity. Among them, the all-solid-state battery has a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, each of which is made of a solid, which can solve the safety problems associated with the electrolytic solution, and has been put to practical use for portable devices. . In particular, lithium-based all-solid-state batteries are of great interest because they can achieve a high energy density. However, there are many problems to be overcome in practical use in the case of an all-solid battery, regardless of the use of an electrolytic solution.

  One of the problems is improvement of ionic conductivity. For example, when a solid electrolyte layer is produced by a coating method, it is necessary to mix a polymer resin for binder and solid electrolyte particles. However, since the polymer resin does not have lithium ion conductivity, lithium ion conductivity is low. Be inhibited. That is, the polymer resin for the binder increases the internal resistance in the solid electrolyte layer, and further decreases the output characteristics in the all-solid lithium battery. In order to solve these problems, a method of manufacturing a solid electrolyte layer using a silicone resin as a polymer resin for a binder has been proposed using a coating method or a wet method (Patent Document 1). This patent document 1 discloses that by using a silicone resin as a binder resin and adopting a uniaxial press or a roller pressure treatment, the distribution of the binder resin can be made into a distribution form that is unlikely to be a significant obstacle to ionic conductivity. ing.

JP 2003-22841 A

  However, even if the distribution of the silicone resin for the binder can be controlled so as not to be a major obstacle to ionic conductivity, it is inevitable that the ionic conductivity will be lower than when there is no silicone resin. Moreover, since the silicone resin has a large elastic deformability, even if a uniaxial press or a roller pressurizing process is performed, voids having no ionic conductivity are likely to remain. Therefore, even if it is limited to the problem of improving ion conductivity, there is room for improvement in battery performance.

  An object of the present invention is to provide an all-solid-state battery in which battery characteristics are improved by not using a polymer resin for a binder and a method for producing the same.

  The manufacturing method of the all-solid-state battery of this invention is a manufacturing method of the all-solid-state battery provided with a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. In this production method, an alcohol solvent in which a metal alkoxide is dissolved is used in the production of at least one of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer. For the production of the positive electrode layer, a slurry in which the positive electrode active material particles are dispersed in an alcohol solvent in which the metal alkoxide is dissolved. In the case of the production of the negative electrode layer, the negative electrode active material particles in the alcohol solvent in which the metal alkoxide is dissolved. In the case of producing a dispersed slurry or a solid electrolyte layer, a slurry which is an alcohol solvent in which a metal alkoxide is dissolved is applied to a base, and then sintered.

  According to said structure, said at least 1 layer is formed with the metal alkoxide which gave ion conductivity, Therefore Ion conductivity can be improved and the output characteristic in an all-solid-state battery can be improved. All of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer may be manufactured by the above-described method, or any one layer may be manufactured by the above-described corresponding method. In addition, even if it is a case where a several layer is manufactured by the said method, it is usually sintered once. The all solid state battery may be a primary battery or a secondary battery.

  After the application and before or during sintering, a pressure treatment can be applied to the coating layer applied to each substrate. Thereby, since the at least one layer is easily plastically deformed, voids can be reduced and ionic conductivity can be increased. The hot pressing step (pressing step) and the sintering step may be performed in different steps, but for example, the hot pressing step and the sintering step are performed in one step by performing pressure treatment during the sintering. Can do.

  Water can be further added to the slurry. Thereby, the dispersibility of the solid particles in the slurry can be improved, and the viscosity of the slurry can be adjusted so that a coating layer can be easily formed, and a high-quality layer can be produced.

  Carbon particles can be further added to the slurry for producing the positive electrode layer or the negative electrode layer. Thereby, the electrical conductivity of a positive electrode layer or a negative electrode layer can be raised.

  In the production of all of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer, an alcohol solvent in which a metal alkoxide is dissolved is used, and the alcohol solvent in which the metal alkoxide is dissolved is La, Ti, Nb, Si, V, or Ta. At least one of each alkoxide and Li alkoxide, the positive electrode active material particles are oxide particles containing at least one of Co, Mn, and Ni and Li, and the negative electrode active material particles are The structure which is a particle | grain containing at least 1 of C, Si, and Sn can be taken. As a result, in the lithium-based all-solid-state battery, the above-mentioned metal alkoxide-derived oxide aggregates and sintered bodies of the respective active material particles in the respective electrode layers are formed by sintering without using a binder resin. . For this reason, the lithium ion conductivity of the lithium-based all-solid-state battery can be ensured, and voids can be easily removed with ease of plastic deformation. The reduction in voids also results in improved ionic conductivity.

  In the production of the solid electrolyte layer, ceramic particles may be further added to the slurry, and the ceramic particles may be oxide particles containing at least one of Al and Si. Thereby, the lithium ion conductivity in a lithium-type all-solid-state battery can be raised.

  The all-solid-state battery of the present invention is a battery manufactured using any one of the above-described all-solid battery manufacturing methods. Thereby, it is possible to obtain an all-solid-state battery having the operational effects in each of the above manufacturing methods.

  Another all-solid battery of the present invention is an all-solid battery comprising a positive electrode layer, a solid electrolyte layer and a negative electrode layer, and each of the positive electrode layer, the solid electrolyte layer and the negative electrode layer contains a metal oxide aggregate, It does not contain resin, and the positive electrode layer includes a sintered body of positive electrode active material particles, and the negative electrode layer includes a sintered body of negative electrode active material particles.

  Since the all-solid battery includes a metal oxide aggregate obtained by sintering a metal alkoxide without containing a binder resin, ionic conductivity can be ensured.

  The solid electrolyte layer may include a sintered body of insulating ceramic particles. Thereby, in the case of a lithium-type all-solid-state battery, lithium ion conductivity can be improved.

  The positive electrode layer and / or the negative electrode layer may contain carbon particles. Thereby, the electrical conductivity of a positive electrode layer or a negative electrode layer can be raised.

  According to the all solid state battery and the method for producing the same of the present invention, since no polymer resin is used for the binder, an all solid state battery having high ionic conductivity can be obtained.

  FIG. 1 is a cross-sectional view showing an all solid lithium battery according to an embodiment of the present invention. In FIG. 1, an all solid lithium battery main body 10 has a laminated structure of (current collector base material (positive electrode current collector) 1 / positive electrode layer 2 / solid electrolyte layer 3 / negative electrode layer 4 / negative electrode current collector 5). . Among these layers, (positive electrode layer 2 / solid electrolyte layer 3 / negative electrode layer 4) is formed using an alcohol solvent in which all layers are dissolved in a metal alkoxide. Among these, for the positive and negative electrode layers 2 and 4, slurry in which positive and negative electrode active materials are dispersed in the above solvent is used. In the solid electrolyte layer 3, an alcohol solvent in which the metal alkoxide is dissolved is often used as it is. However, in order to improve lithium ion conductivity, insulating ceramic particles may be added. Next, each layer will be described sequentially.

1. Positive electrode layer and positive electrode current collector (1) The current collector base material (primary layer base or positive electrode current collector) 1 on which the positive electrode layer 2 is applied has a thickness of 3 μm to 100 μm, particularly 5 μm to 25 μm. Good.
(2) The thickness of the positive electrode layer 2 is preferably 10 μm to 150 μm, particularly 50 μm to 100 μm.
(3) The material of the positive electrode current collector (current collector base material) 1 is preferably a metal foil such as Al, stainless steel, V, or Ni.
(4) Coating slurry for positive electrode layer (A) As positive electrode active material particles, positive electrode active material particles such as LiMn ₂ O ₄ , LiCoO ₂ , MnO ₂ , FeS, FeS ₂ , V ₂ O ₃ , and TiS ₂ are used. It is good.
(B) The conductive material or conductive aid may contain carbon particles such as acetylene black, ketjen black, and artificial graphite.
(C) The alcohol solvent is preferably an alcohol solvent such as ethanol, methanol, or propanol.
(D) The metal alkoxide is dissolved in the above solvent, and after coating, drying and sintering, a single alkoxide or a lithium ion conductive oxide having a concentration such that the lithium ion conductive oxide is obtained. It is preferable to dissolve a plurality of alkoxides having a concentration ratio of For example, the following (D1) or (D2) is a preferred example.
(D1) For example, when dissolved in (Li ethoxide) :( pentaethoxy Nb) = 1: 1 (molar ratio), it becomes a lithium ion conductive oxide of LiNbO ₃ after sintering.
(D2) As another example, when dissolved in (La isopropoxide) :( Li ethoxide) :( Ti isopropoxide) = 1: 1: 2 (molar ratio), La _0.5 Li _0.5 TiO ₂ after sintering Lithium ion conductive oxide.
(E) Mixing ratio The value of (E1) (total molar amount of metal alkoxide) :( active material molar amount) is preferably in the range of 2: 8 to 6: 4.
(E2) The conductive auxiliary is preferably 2 to 10% by weight based on the amount of active material.
(E3) The amount of the solvent is preferably adjusted so that the slurry viscosity is 0.1 to 5 Pa · s.
(F) Others: It is preferable to add 1 to 10 wt% water to the ethanol solvent because the dispersibility of the solid particles in the slurry is improved. Viscosity can be adjusted by adding water.

2. Negative electrode layer and negative electrode current collector (1) The thickness of the negative electrode layer 4 is preferably 10 μm to 150 μm, particularly 50 μm to 100 μm.
(2) The thickness of the negative electrode current collector 5 is preferably 1 μm to 100 μm, particularly 3 μm to 25 μm.
(3) The material of the negative electrode current collector 5 is preferably a metal foil such as Cu, stainless steel, Ni, or V.
(4) Coating slurry for negative electrode layer (A) For the negative electrode active material particles, active material particles such as C, Sn, SiO _x , and Si may be used.
The items (B) to (F) regarding the coating slurry for the positive electrode layer may be applied to the coating slurry for the negative electrode layer.

3. Solid Electrolyte Layer (1) The thickness of the solid electrolyte layer 3 is preferably 3 μm to 100 μm, particularly 5 μm to 50 μm.
(2) The components of the coating slurry for the solid electrolyte layer 3 need only be (C) a solvent and (D) a metal alkoxide. And about (C) solvent and (D) metal alkoxide, it can be made the same as the case of the said positive electrode layer and negative electrode layer. However, by including insulating ceramic particles such as alumina and silica, the lithium ion conductivity after sintering is improved more than the metal alkoxide alone. The insulating ceramic particles can be in a molar ratio of 10% to 50% with respect to the number of moles of the metal alkoxide.
(F) In the case of a slurry for a solid electrolyte layer, it is preferable to adjust the viscosity to 0.1 Pa · s to 5 Pa · s by adding water.

  In the positive electrode layer 2 or the negative electrode layer 4, a sintered body of positive electrode active material particles or negative electrode active material particles is formed, and metal oxide aggregates derived from metal alkoxide are disposed on the sintered body. Even when pressure treatment is applied, the fine voids generated during sintering cannot be completely eliminated and remain. When carbon particles are included as the conductive material, the carbon particles are disposed in the sintered body. The solid electrolyte layer 3 is formed of a metal oxide aggregate formed by sintering from a metal alkoxide. Fine voids generated during sintering remain without being completely eliminated. When insulating ceramic particles are used to improve lithium ion conductivity, the insulating ceramic particles are arranged in the metal oxide aggregate.

Next, the point of the manufacturing method of the all-solid-state battery of this invention is demonstrated.
1. As a method for applying the slurry, any of a knife roll method, a die coating method, a dip coating method, and a spin coating method may be used.
2. The alcohol solvent is dried in the atmosphere. Drying conditions are carried out below the boiling point of the solvent.
3. The sintering temperature is preferably 200 ° C to 450 ° C. The sintering time is preferably within 5 to 60 minutes.
4). It is preferable to perform a pressure treatment such as hot pressing at a temperature equal to or lower than the sintering temperature after application and before sintering.

  The all-solid-state battery manufactured by the above manufacturing method and material does not use a polymer resin for the binder, and the metal oxide aggregate derived from metal alkoxide having ion conductivity, particularly lithium ion conductivity, plays the role of the binder. Fulfill. For this reason, it is possible to obtain an all solid state battery having high ionic conductivity and thus high discharge capacity.

  Next, the effects of the present invention will be described with reference to examples. The specimens used were Invention Example A and Comparative Example, all of which were all solid state batteries. For the evaluation of these all solid state batteries, the discharge capacity of all the solid state batteries was measured.

1. Invention Example A
(Positive electrode layer: see FIG. 2) 10 g of Li ethoxide and 67 g of pentaethoxy Nb were dissolved in 100 g of dehydrated ethanol, and 60 g of LiCoO ₂ active material powder having a particle size of 10 μm was added. While stirring well, water was added with a dropper to adjust the slurry viscosity to 1 Pa · s. This slurry was applied to stainless steel (corresponding to JIS SUS) foil 1 by a knife roll method and dried to prepare a positive electrode layer 2. When the thickness of the positive electrode layer 2 was measured with a micrometer, the coating thickness was 100 μm.

(Solid electrolyte layer: see FIG. 3) 10 g of Li ethoxide and 67 g of pentaethoxy Nb were dissolved in 50 g of dehydrated ethanol, and 20 g of alumina powder having a particle size of 0.5 μm was added. While stirring well, water was added with a dropper to adjust the slurry viscosity to 1 Pa · s. This slurry was applied onto the positive electrode layer 2 by a knife roll method and dried to prepare a solid electrolyte layer 3. The thickness of the solid electrolyte layer 3 measured with a micrometer was 30 μm.

(Negative electrode layer: see FIG. 4) 10 g of Li ethoxide and 67 g of pentaethoxy Nb were dissolved in 50 g of dehydrated ethanol, and 40 g of carbon powder having a particle size of 3 μm was added. While stirring well, water was added with a dropper to adjust the slurry viscosity to 1 Pa · s. This slurry was applied onto the solid electrolyte layer 3 by a knife roll method and dried to prepare the negative electrode layer 4. When the thickness of the negative electrode layer 4 was measured with a micrometer, the coating thickness was 100 μm.

(Negative electrode current collector: see FIG. 5) Stainless steel (corresponding to JIS SUS) foil 5 was laminated as a negative electrode current collector on these layers, and the whole was hot pressed at 150 ° C. under the condition of 50 Pa × 1 minute. Thereafter, sintering was performed at 400 ° C. for 1 hour in the atmosphere. Thereafter, the battery was sealed in an aluminum laminate bag in an argon atmosphere with a dew point of -70 ° C. to obtain a lithium secondary battery having a power generation area of 10 cm ² .
(Measurement of discharge capacity) When charge / discharge was carried out at a current of 10 mA, a discharge capacity of 40 mAh was obtained.

2. Comparative Example (Positive Electrode Layer) A total of 20 g of a two-part silicone resin was dissolved in dehydrated hexane at a predetermined ratio, 60 g of LiCoO ₂ active material powder having a particle size of 10 μm was added, and the slurry viscosity was 1 Pa · s. Further, 5 g of acetylene black was added as a conductive assistant. This slurry was applied to a stainless steel (SUS equivalent) foil by a knife roll method, then cured in argon at 150 ° C. for 30 minutes, dried and measured for thickness with a micrometer, resulting in a coating thickness of 100 μm.

(Solid electrolyte layer) A total of 20 g of a two-component silicone resin is dissolved in dehydrated hexane at a predetermined ratio, 60 g of a Li ₄ P ₂ S ₇ sulfide solid electrolyte powder having a particle size of 1 μm is added, and the slurry viscosity is 1 Pa · s. This slurry was applied on the positive electrode by a knife roll method, cured in argon at 150 ° C. for 30 minutes, dried, and measured for thickness with a micrometer, resulting in a coating thickness of 30 μm.

(Negative electrode layer) A total of 20 g of a two-component silicone resin was dissolved in dehydrated hexane at a predetermined ratio, and 40 g of a carbon active material powder having a particle size of 3 μm was added to make the slurry viscosity 1 Pa · s. The slurry was applied on the solid electrolyte by a knife roll method, cured at 150 ° C. for 30 minutes, dried, and measured for thickness with a micrometer, resulting in a coating thickness of 100 μm.

(Negative Electrode Current Collector) A stainless steel (SUS equivalent) foil was laminated as a negative electrode current collector on these layers, and the whole was hot pressed at 150 ° C. for 50 Pa × 1 minute. Thereafter, the battery was sealed in an aluminum laminate bag in an argon atmosphere with a dew point of -70 ° C. to obtain a lithium secondary battery having a power generation area of 10 cm ² .
(Measurement of discharge capacity) When the battery was charged / discharged at a current of 10 mA, a discharge capacity of 12 mAh was obtained.

  According to the measurement results of the above discharge capacity, the discharge capacity of Example A of the present invention is 3.3 times that of the comparative example, which is dramatically improved, and the performance of the all solid state battery of the present invention is excellent. It was confirmed that

  In the above embodiments and examples, a method for producing all the positive electrode layer, negative electrode layer, and solid electrolyte layer of an all-solid battery using an alcohol solvent in which a metal alkoxide is dissolved has been described. One layer or two layers may be manufactured by the above method (wet method), and the other layer may be manufactured by another manufacturing method, for example, a gas phase method such as a laser ablation method. In consideration of battery performance, work efficiency (economic efficiency), etc., it is preferable to use a manufacturing method in which appropriate methods are combined.

  In the above embodiments and examples, only the lithium-based all-solid battery has been described. However, the all-solid-state battery of the present invention and the manufacturing method thereof are not limited to the lithium-based all-solid battery, and a metal alkoxide is dissolved. Any all solid state battery is included as long as it is an all solid state battery manufactured by a coating method using an alcohol solvent. Moreover, it is contained regardless of a primary battery or a secondary battery.

  Although the embodiments and examples of the present invention have been described above, the embodiments and examples of the present invention disclosed above are merely examples, and the scope of the present invention is the implementation of these inventions. It is not limited to the form. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  According to the all solid state battery and the method of manufacturing the same of the present invention, a metal alkoxide having high lithium ion conductivity is used as a binder and no polymer resin is used, so that an all solid state battery having high ion conductivity and discharge capacity can be obtained. it can.

It is sectional drawing which shows the all-solid-state battery in embodiment of this invention. It is sectional drawing of the step which produced the positive electrode layer in the Example. It is sectional drawing of the step which produced the solid electrolyte layer. It is sectional drawing of the step which produced the negative electrode layer. It is a figure of the step of hot-pressing, after laminating | stacking a negative electrode current collection layer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Current collector base material (positive electrode current collector), 2 Positive electrode layer, 3 Solid electrolyte layer, 4 Negative electrode layer, 5 Negative electrode current collector, 10 All-solid battery main body.

Claims (10)

A method for producing an all-solid battery comprising a positive electrode layer, a solid electrolyte layer and a negative electrode layer,
In the production of at least one of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer, an alcohol solvent in which a metal alkoxide is dissolved is used.
In the case of preparing the positive electrode layer, a slurry in which positive electrode active material particles are dispersed in an alcohol solvent in which the metal alkoxide is dissolved is used. In the case of preparing the negative electrode layer, a negative electrode is used in an alcohol solvent in which the metal alkoxide is dissolved. A slurry in which active material particles are dispersed, or in the case of producing the solid electrolyte layer, a slurry that is an alcohol solvent in which the metal alkoxide is dissolved is applied to a base, and then sintered. The manufacturing method of an all-solid-state battery.   2. The all-solid-state battery according to claim 1, wherein after the coating and before or during the sintering, a pressure treatment is applied to the coating layer applied to each of the bases. Manufacturing method.   The method for producing an all-solid-state battery according to claim 1, wherein water is further added to the slurry.   The method for producing an all solid state battery according to claim 1, wherein carbon particles are further added to the slurry for producing the positive electrode layer or the negative electrode layer.   For the production of all of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer, an alcohol solvent in which a metal alkoxide is dissolved is used, and the alcohol solvent in which the metal alkoxide is dissolved is La, Ti, Nb, Si, V, Ta. At least one of each alkoxide and Li alkoxide, and the positive electrode active material particles are oxide particles containing at least one of Co, Mn, and Ni and Li, and the negative electrode active material particles Is a particle containing at least one of C, Si, and Sn, The manufacturing method of the all-solid-state battery in any one of Claims 1-4 characterized by the above-mentioned.   2. In the production of the solid electrolyte layer, ceramic particles are further added to the slurry, and the ceramic particles are oxide particles containing at least one of Al and Si. The manufacturing method of the all-solid-state battery in any one of -5.   An all-solid-state battery manufactured using the method for producing an all-solid-state battery according to claim 1. An all-solid battery comprising a positive electrode layer, a solid electrolyte layer and a negative electrode layer,
Any of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer includes a metal oxide aggregate, does not include a resin,
The all-solid-state battery, wherein the positive electrode layer includes a sintered body of positive electrode active material particles, and the negative electrode layer includes a sintered body of negative electrode active material particles.   The all-solid-state battery according to claim 8, wherein the solid electrolyte layer includes a sintered body of insulating ceramic particles. The all-solid-state battery according to claim 8 or 9, wherein the positive electrode layer and / or the negative electrode layer contains carbon particles.

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