JP2010248044A - LiNbO3 glass, method for producing the same, and nonaqueous electrolyte battery using LiNbO3 glass - Google Patents

Abstract

LiNbO ₃ glass manufacturing method, LiNbO ₃ glass, and solid electrolyte membrane that can be synthesized by firing at a temperature that does not change composition, is amorphous, has little residual carbon, and does not burn carbonaceous matter A positive electrode for a non-aqueous electrolyte battery and a non-aqueous electrolyte battery are provided.
A sol solution adjusting step for preparing a sol solution containing equimolar lithium alkoxide and niobium alkoxide and using an alcohol as a solvent, and the obtained sol solution is mixed with an alcohol in an atmosphere having a predetermined relative humidity. A method for producing LiNbO ₃ glass, comprising: a gelling step of heating and concentrating and gelling at a temperature below the boiling point; and a firing step of firing the obtained gel at a temperature of 250 ° C. or higher and lower than 350 ° C. Lithium ion conductive solid electrolyte film mainly made of LiNbO ₃ glass, the grain boundaries of the positive electrode active material particles, a non-aqueous electrolyte battery using the positive electrode and the solid electrolyte film or the positive electrode containing LiNbO ₃ glass.
[Selection] Figure 1

Description

The present invention relates to a nonaqueous electrolyte battery using a LiNbO ₃ glass and LiNbO ₃ glass, particularly excellent in lithium ion (Li ⁺⁾ conductive, with less LiNbO ₃ glass carbon residue as well as their preparation and LiNbO ₃ glass solid The present invention relates to an electrolyte membrane, a positive electrode, and a nonaqueous electrolyte battery.

LiNbO ₃ glass, which is a Li ⁺ conductor, has attracted attention as a material for a solid electrolyte membrane of a non-aqueous electrolyte battery using a solid electrolyte (hereinafter also referred to as “solid electrolyte battery”).

In addition, since LiNbO ₃ glass has high chemical stability with respect to a positive electrode active material such as lithium cobaltate (LiCoO ₂ ), it can be added to the positive electrode as a positive electrode material that improves Li ⁺ conductivity in the positive electrode. Attention has been paid.

Such LiNbO ₃ glass is generally synthesized by a melt quenching method (Non-patent Document 1). In the case of the melt quench method, a high temperature of 1550 ° C. or higher is required. For this reason, composition fluctuations easily occur due to the vapor pressure of the material during firing. That is, since Li having a high vapor pressure evaporates during firing, Li deficiency is likely to occur in the product, and as a result, the Li ⁺ conductivity of the product may be lowered. In addition, niobium (Nb) is easily reduced, and there is a possibility that the product may exhibit electronic conductivity or lose chemical stability against LiCoO ₂ . Further, when firing, an expensive crucible made of Pt that can withstand high temperatures and does not react with the material must be used, resulting in poor productivity.

In recent years, as a method of synthesizing LiNbO ₃ that eliminates the disadvantages of the melt quenching method, a synthesis method of baking at 400 ° C. using a sol-gel method (Patent Document 1, Non-Patent Document 2) that performs reflux and partial hydrolysis or a spray method ( Non-patent document 3) has been developed.

JP-A-63-238282

“Ionic Conductivity of Quenched Alkaline Niobate and Tantalate Glasses” Appl. Phys. 49 (9), September (1978) 4808-4811. Synthesis of LiNbO3 Thin Films by Sol-Gel Method Electronic Ceramics '91 September 20-25 “LiNbO3-coated LiCoO2 as cathode material for all solid-state lithium secondary batteries” Electrochem. Comm. 9 (2007) 1486-1490

However, LiNbO ₃ synthesized by a conventional sol-gel method cannot be said to be suitable as a material for a solid electrolyte. That is, those heated at a temperature of 250 ° C. or higher are crystalline without Li ⁺ conductivity, and those heated at a temperature lower than 250 ° C. are amorphous and have Li ⁺ conductivity, but the residual Since it contains carbon, it exhibits electronic conductivity and cannot be used as a solid electrolyte.

  Moreover, it cannot be said that the synthesis method using the spray method is suitable for a positive electrode material. That is, when the positive electrode is baked at 400 ° C., the carbonaceous conductive additive such as acetylene carbon added to the positive electrode may be burned out, which hinders the addition of the conductive additive.

Therefore, the present invention provides a LiNbO ₃ glass that can be synthesized by firing at a temperature that does not change composition, suppresses crystallization, has excellent Li ⁺ conductivity, has little residual carbon, and does not burn down carbonaceous matter, and its production It is an object of the present invention to provide a method, a solid electrolyte membrane using such LiNbO ₃ glass, a positive electrode for a nonaqueous electrolyte battery, and a nonaqueous electrolyte battery.

  In view of the above problems, the present inventors have found out a method for solving the above problems by the following means as a result of intensive studies and have reached the present invention. The invention of each claim will be described below.

The method for producing LiNbO ₃ glass according to the present invention is as follows:
A method for producing LiNbO ₃ glass using a sol-gel method,
A sol solution adjusting step for adjusting a sol solution containing equimolar lithium alkoxide and niobium alkoxide and using alcohol as a solvent;
A gelling step of concentrating and gelling the obtained sol solution by heating at a temperature below the boiling point of the alcohol in an atmosphere having a predetermined relative humidity;
And a firing step of firing the obtained gel at a temperature of 250 ° C. or higher and lower than 350 ° C.

In the present invention, since the sol-gel method is used, LiNbO ₃ glass having no composition fluctuation can be produced. In addition, a sol solution containing lithium alkoxide, for example, ethoxylithium (LiOEt) and niobium alkoxide, for example, pentaethoxyniobium (Nb (OEt) ₅ ), for example, ethanol (EtOH) as a solvent, in an atmosphere having a predetermined relative humidity. In order to heat at a temperature below the boiling point of the alcohol, crystallization is suppressed even when firing at an unprecedented high temperature of 250 ° C. or more and less than 350 ° C., and LiNbO ₃ glass excellent in Li ⁺ conductivity is produced. Can do.

That is, in the case of a conventional method for producing LiNbO ₃ using a sol-gel method, for example, water is added to an ethanol solution of ethoxylithium and pentaethoxyniobium and refluxed to perform concentration after hydrolyzing. However, in the case of the present invention, the sol solution of ethoxylithium and pentaethoxyniobium is heated in an atmosphere having a predetermined relative humidity. Hydrolysis is performed by gradually taking the water contained therein into the sol solution. Moreover, rapid concentration is suppressed by heating at a temperature below the boiling point of ethanol as a solvent, and hydrolysis and concentration are performed simultaneously. For this reason, the colloidal constituent unit can be miniaturized, and as a result, crystallization can be suppressed even when firing at an unprecedented high temperature, and LiNbO ₃ glass excellent in Li ⁺ conductivity can be produced. .

  In the present invention, since the firing is performed at a temperature of 250 ° C. or higher, the carbon derived from the alcohol or the like used in the production is sufficiently removed, the residual carbon of the product is reduced, and the electron conductivity is expressed. Can be suppressed. On the other hand, since the firing is performed at a temperature of less than 350 ° C., when applied to the material of the positive electrode of the solid electrolyte battery, there is no possibility that the carbon added as a conductive additive to the positive electrode is burned out during the firing.

  Examples of the alkoxide used in the production method of the present invention include ethoxide such as ethoxylithium, methoxide such as methoxylithium, various propoxides such as propoxylithium and butoxylithium, and butoxide. Examples of the alcohol include methanol, various propanols, butanol and the like in addition to the above ethanol.

  Further, in the present invention, an atmosphere under “atmosphere having a predetermined relative humidity” means that moisture can be contained in the alcohol solution from the atmosphere so that hydrolysis can be performed at an appropriate reaction rate suitable for industrial production. Refers to an atmosphere containing an amount of water necessary to be taken in at a sufficient rate, and specifically, a relative humidity of 15 to 75 RH% is preferable.

  Further, the heating temperature in the gelation step of the present invention is preferably 50 ° C. or more for promoting the gelation reaction, and preferably 75 ° C. or less for preventing bumping.

Next, the LiNbO ₃ glass according to the present invention is
Characterized in that it is a glass manufactured by the manufacturing method of said LiNbO ₃ glass.

Since the LiNbO ₃ glass according to the present invention is manufactured by the above-described LiNbO ₃ glass manufacturing method, the crystallization is surely suppressed, the Li ⁺ conductivity is excellent, the residual carbon is reduced, and the electron conductivity is expressed. LiNbO ₃ glass can be provided which has no fear of being lost.

Next, the solid electrolyte membrane according to the present invention is:
The main feature is the LiNbO ₃ glass according to the invention.

In the LiNbO ₃ glass used for the solid electrolyte membrane according to the present invention, crystallization is suppressed and residual carbon is reduced. For this reason, it is possible to provide a solid electrolyte membrane that is excellent in Li ⁺ conductivity and has no fear of developing electron conductivity.

  A small amount of an electrically insulating filler such as ceramic particles may be added to the solid electrolyte membrane.

Next, the positive electrode for a non-aqueous electrolyte battery according to the present invention is:
It consists of a molded body of particles mainly composed of positive electrode active material particles,
The grain boundary of the positive electrode active material particles contains the LiNbO ₃ glass according to the present invention.

In the present invention, since the LiNbO ₃ glass according to the present invention is included in the grain boundary of the positive electrode active material particles, a positive electrode for a non-aqueous electrolyte battery with excellent Li ⁺ movement in the positive electrode and excellent performance is provided. can do. In particular, the electrolyte does not penetrate to the grain boundaries of the positive electrode particles, and exhibits an excellent effect as a positive electrode for a non-aqueous electrolyte battery using a solid electrolyte that is liable to hinder Li ⁺ migration at the grain boundaries.

Furthermore, the positive electrode containing LiNbO ₃ glass at the grain boundary of the positive electrode active material particles is mixed with the positive electrode active material particles when the lithium and niobium alkoxide sol solution is prepared, and gelled. It can be easily manufactured by firing to produce LiNbO ₃ glass. Further, when adjusting the sol solution, carbon particles may be added and mixed as a conductive aid. Since the firing temperature for generating LiNbO ₃ glass is less than 350 ° C., the added carbon particles as a conductive additive there is no fear of burned during calcination.

Further, the positive electrode active material powder used in the present invention is represented by a general formula LiMO ₂ or LiM ₂ O ₄ (where M includes one or more of Mn, Fe, Co, Ni, Al). A lithium composite oxide powder can be preferably used. Specifically, LiCoO ₂ , LiNiO ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiMn ₂ O ₄ , LiMn _1.9 Mention may be made of powders such as Co _0.1 O ₄ and LiFePO ₄ .

Next, the non-aqueous electrolyte battery according to the present invention is:
A non-aqueous electrolyte battery having a laminate of a positive electrode, a solid electrolyte membrane, and a negative electrode,
The solid electrolyte membrane according to the present invention is used as the solid electrolyte membrane of the laminate.

In the present invention, since a solid electrolyte membrane excellent in Li ⁺ conductivity is used, a nonaqueous electrolyte battery having low internal resistance and excellent characteristics can be provided. Moreover, there is no fear of a short circuit due to the solid electrolyte membrane exhibiting electron conductivity.

  In general, the solid electrolyte membrane is formed by forming a gel film on the surface of the positive electrode and then firing, but the solid electrolyte membrane according to the present invention is fired at a temperature of less than 350 ° C. Even if baking is performed after forming the gel film on the surface, there is no fear that the carbon particles, which are conductive assistants added to the positive electrode, are burned out.

Next, the non-aqueous electrolyte battery according to the present invention is:
The positive electrode for a nonaqueous electrolyte battery according to the invention is used.

  In the present invention, since the positive electrode for a non-aqueous electrolyte battery according to the above-described invention is used, a non-aqueous electrolyte battery having a small internal resistance and excellent characteristics can be provided. In particular, a remarkable effect is exhibited in a non-aqueous electrolyte battery using a solid electrolyte.

In addition, in the case of the non-aqueous electrolyte battery according to the present invention, in addition to the solid electrolyte film mainly composed of the LiNbO ₃ glass according to the present invention, Li—P—S composed of sulfides, for example, Li, P, S, and O. -O and Li ₂ S and _P 2 _{S 5} Metropolitan Li-P-S amorphous film or polycrystalline film such as made of is preferably used.

According to the present invention, there is no composition variation, crystallization is suppressed, Li ⁺ conductivity is excellent, residual carbon is low, and the LiNbO ₃ glass that can be synthesized by firing at a temperature at which the carbonaceous material does not burn out and its A production method, a solid electrolyte membrane using such LiNbO ₃ glass, a positive electrode for a non-aqueous electrolyte battery, and a non-aqueous electrolyte battery can be provided.

It is a diagram showing a procedure of manufacturing the LiNbO ₃ glass according to one embodiment of the present invention. It is an X-ray diffraction pattern of LiNbO ₃ baked at each temperature of 300 ° C., 350 ° C., and 400 ° C. Is a diagram showing the complex impedance measurements at room temperature of the LiNbO ₃ glass of Example 2. It is a graph showing the results of Arrhenius plot of the conductivity of LiNbO ₃ glass of Example 2. 6 is a diagram showing a procedure for producing a positive electrode for a solid electrolyte battery of Example 3. FIG. It is a figure which shows typically the structure of the laminated body of the nonaqueous electrolyte battery using a solid electrolyte.

  Hereinafter, the present invention will be described based on embodiments. Note that the present invention is not limited to the following embodiments. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

(Procedure for producing LiNbO ₃ glass)
First, the procedure for producing LiNbO ₃ glass will be described with reference to FIG. FIG. 1 is a diagram showing a procedure for producing LiNbO ₃ glass according to one embodiment of the present invention.

(1) Mixing First, equimolar ethoxylithium (LiOEt), pentaethoxyniobium (Nb (OEt) ₅ ) and a predetermined amount of ethanol (EtOH) are weighed and mixed in a dry atmosphere having a dew point of −50 ° C. or less. Adjust the sol solution. The water content of the raw materials LiOEt, Nb (OEt) ₅ and EtOH is preferably 0.01 wt% or less.

(2) Hydrolysis and concentration Next, the container containing the sol solution is transferred to an atmosphere in which the relative humidity is controlled to 20 to 30 RH%, and the temperature below the boiling point of EtOH, for example 60, while stirring the sol solution. Heat to ~ 70 ° C. During this time, gaseous water contained in the atmosphere is taken into the sol liquid and hydrolysis occurs, and at the same time, EtOH evaporates and the sol solution is concentrated and gelation proceeds. When the viscosity of the sol solution reaches a predetermined viscosity suitable for film formation by coating or the like, for example, about 500 mPa · s, heating is stopped.

(3) Application on base material A sol solution in which gelation is in progress is applied to the base material to form a gel film having a predetermined thickness on the base material.

(4) Firing Next, the obtained gel film is not crystallized, and the temperature at which EtOH and H ₂ O remaining between the molecules can be sufficiently removed, specifically 250 ° C. or more and less than 350 ° C. It is baked for about 0.5 hours to be amorphous, and LiNbO ₃ glass is produced. In the present embodiment, for example, by using a positive electrode for a solid electrolyte battery as a base material, a solid electrolyte film made of LiNbO ₃ glass is formed on the surface of the positive electrode.

In addition, after application | coating on a base material as shown in FIG. 1 (before baking), it forms on a base material as needed so that it may have a predetermined shape and size and a denser LiNbO ₃ glass may be obtained. For example, the gel film is dried at 25 ° C. for about 12 hours, EtOH other than EtOH remaining between the molecules is removed, and then pressure-molded at a pressure of about 50 MPa.

Next, the present invention will be described specifically by way of examples. In the examples described below, a method for producing LiNbO ₃ glass by a sol-gel method using LiOEt and Nb (Et) ₅ as a raw material is examined, and the synthesis method established as a result of the study is used for producing a positive electrode of a nonaqueous electrolyte battery. This is an applied example.

In this example, a method for producing LiNbO ₃ glass by a sol-gel method, in particular, an example in which the influence of the firing temperature on the quality of LiNbO ₃ was examined.
(1) Preparation and gelation of sol solution In a dry air having a dew point of −60 ° C., 1.23 g of ethoxylithium (LiOEt), 7.50 g of pentaethoxyniobium (Nb (OEt) ₅ ), ethanol (EtOH) 23. 28 g of each was weighed, put into a beaker (volume 50 ml), and stirred with a magnetic stirrer for 10 minutes to obtain a sol solution.

  Thereafter, the beaker containing the sol solution was transferred to air controlled at a temperature of 25 ° C. and a relative humidity of 30%, and the beaker was heated in a temperature range of 60 to 70 ° C. while stirring with a magnetic stirrer with a heating mechanism. At the time of heating for 60 minutes, the amount of the sol solution decreased to 30% of the initial value, and when the viscosity was measured, the viscosity was 500 mPa · s, which was suitable for the production of a gel film.

(2) Production of gel film When the amount of the sol solution was reduced to 30% of the original, a gel film of LiNbO ₃ was formed on each of the four quartz plates by dipping.

(3) Firing Four quartz plates having a LiNbO ₃ gel film formed on the surface were fired at temperatures of 200 ° C., 300 ° C., 350 ° C., and 400 ° C. for 30 minutes in an electric furnace, respectively, and the surface of the quartz plate was LiNbO _Three films were produced.

(4) Evaluation of crystallinity and residual alcohol of the produced LiNbO ₃ film a. Crystallinity The crystallinity of four samples with different heat treatment temperatures was analyzed by X-ray diffraction. Among these, the analysis result of three types of samples whose heat treatment temperatures are 300 ° C, 350 ° C, and 400 ° C is shown in FIG. From FIG. 2, it can be seen that those heat-treated at 350 ° C. and 400 ° C. are crystallized, but those heat-treated at 300 ° C. are maintained in an amorphous state. Although not shown, it was confirmed that the amorphous state was maintained even for the sample having a heat treatment temperature of 200 ° C. From this result, it can be seen that heat treatment must be performed at a temperature lower than 350 ° C. in order to maintain the amorphous state.

B. Residual alcohol In order to determine the amount of residual ethyl alcohol in two types of samples with heat treatment temperatures of 200 ° C. and 300 ° C. that have been confirmed to maintain an amorphous state, infrared absorption specified in JIS Z-2615 The amount of residual carbon was measured by the method. The measurement result showed that the residual carbon content of the sample heat-treated at 200 ° C. was 1.8%, whereas the residual carbon content of the sample heat-treated at 300 ° C. was 100 ppm. From this result, it was found that the amount of residual ethyl alcohol can be reduced to a sufficiently low value by heat treatment at 300 ° C.

In this example, a film-like LiNbO ₃ glass was produced by baking at 300 ° C., and the denseness and ionic conductivity were evaluated.
(1) Production of LiNbO ₃ Glass Example 1 except that a quartz plate on which a gold comb-shaped electrode was formed was used as a base material for forming a LiNbO ₃ gel film, and the firing temperature was fixed at 300 ° C. LiNbO ₃ glass was produced in the same manner as described above.

(2) Evaluation of denseness and ionic conductivity of LiNbO ₃ glass a. Denseness and film thickness The prepared film-like sample was observed with a Nomarski optical microscope, and it was confirmed that a dense LiNbO ₃ film was formed. Moreover, the film thickness was measured by a palpation-type level difference meter, and it was confirmed that the film thickness of the generated LiNbO ₃ film was 0.5 μm.

B. Ion conductivity and activation energy The complex impedance at each temperature of the sample heat treated at 300 ° C. was measured in the frequency range of 5 Hz to 13 MHz with a complex impedance measuring apparatus with a heating mechanism. FIG. 3 shows the measurement results of the complex impedance at room temperature. Li ⁺ conductivity at each temperature was obtained from the measurement result of the complex impedance, and activation energy was obtained from the result of the Arrhenius plot. FIG. 4 is a graph showing the results of performing an Arrhenius plot of the conductivity of the LiNbO ₃ glass according to this example. FIG. 4 shows that the Li ⁺ conductivity of this sample at room temperature is on the order of 10 ⁻⁶ S / cm. Moreover, it has confirmed that the activation energy was 49 kJ / mole (0.51 eV) from the inclination of the straight line of FIG. As a result, the Li ⁺ conductivity is higher than that of a Li ₂ O—SiO ₂ film (ion conductivity of 10 ⁻⁹ S / cm level, activation energy of 0.7 eV or more), which is a representative film of a sol-gel oxide solid electrolyte. It turns out that it is improving dramatically.

In this example, LiNbO ₃ glass is applied to a positive electrode for a solid electrolyte battery.
(1) Production of positive electrode Hereinafter, production of a positive electrode for a solid electrolyte battery will be described with reference to FIG. FIG. 5 is a diagram showing a procedure for producing a positive electrode for a solid electrolyte battery according to this example.

I. Mixing, hydrolysis and concentration 10 g of LiCoO ₂ powder having an average particle size of 1.2 μm, 0.163 g of acetylene black as a conductive auxiliary agent, and 24.39 g of the sol solution used in Example 1 were placed in a beaker (volume 50 ml) and mixed. In the air controlled at a temperature of 25 ° C and a relative humidity of 30%, while stirring with a magnetic stirrer with a heating mechanism, heat the beaker in a temperature range of 60-70 ° C and concentrate at the same time as hydrolysis to proceed with gelation I let you. And it heated for 60 minutes until the amount of sol liquid reduced to 30% of the initial stage like Example 1, and the viscosity became 1000 mPa * s.

B. Coating on substrate and pressure forming On the stainless steel substrate (diameter: 15.5 mm, thickness: 0.5 mm, material: Kovar), a sol solution in progress of gelation is applied by a mask method to form a coating film having a thickness of 50 μm. Formed. After the application, in the state where the ethyl alcohol component in the coating film remained and the sol state was maintained, it was pressure-molded with a hydraulic press at a pressure of 1 MPa.

C. Firing After pressure molding, heat treatment was performed in an air atmosphere at a temperature of 300 ° C. for 30 minutes using an electric furnace to obtain a positive electrode for a non-aqueous electrolyte battery.

D. Observation of positive electrode The cross-sectional structure of the obtained positive electrode was observed by FIB-SIM. As a result, it was found that LiCoO ₂ particles were dispersed in the positive electrode, and a dense LiNbO ₃ layer containing acetylene black powder with a thickness of 0.5 to 1 μm was present at the LiCoO ₂ grain boundary. .

(2) Production of All Solid Type Nonaqueous Electrolyte Battery Next, production of an all solid type nonaqueous electrolyte battery using the positive electrode will be described with reference to FIG. FIG. 6 is a diagram schematically showing a configuration of a laminate of a nonaqueous electrolyte battery using a solid electrolyte. In FIG. 6, 1 is a positive electrode, 2 is a solid electrolyte membrane, and 3 is a negative electrode.

I. Thickness 10μm by evaporation to form the prepared surface of the positive electrode 1 of the solid electrolyte _Li w _-P x _-S y -O _z were formed (wherein w + x + y + z = 1) based solid electrolyte membrane 2. In addition, it was confirmed by measurement using XPS that the values of w, x, y, and z were 0.27, 0.17, 0.49, and 0.07, respectively.

B. Formation of Negative Electrode Next, a mask having a hole having a diameter of 10 mm was placed on the surface of the solid electrolyte, and a metal lithium film having a thickness of 5 μm was formed by a vapor deposition method to obtain negative electrode 3.

C. Assembling the battery Next, the battery was sealed in a coin-type container in a glove box with an argon gas atmosphere having a dew point of −90 ° C. to produce an all-solid-state nonaqueous electrolyte battery.

(3) Performance evaluation a. Test Method The produced battery was charged and discharged under the conditions of a temperature of 25 ° C., a cut-off voltage of 4.2 V to 2.5 V, and a current density of 1 mA / cm ² to evaluate the charge / discharge capacity density and the cycle performance. In addition, charging / discharging was once stopped after charge of the 1st cycle, the complex impedance was measured in the range of frequency 100kHz-10mHz using the complex impedance measuring apparatus, and the total resistance of the battery was calculated | required.

B. Test results a. Charge / Discharge Capacity Density The charge / discharge capacity density is as high as 2.2 mAh / cm ^{2 in} terms of unit area based on the active area and 120 mAh / g in terms of unit weight of LiCoO ₂ of the positive electrode. It was confirmed that the LiCoO ₂ contained was almost active.

b. Cycle test results The charge / discharge efficiency was about 60 to 90% in the initial few cycles, but then became almost 100%, and the cycle was stably driven for 300 cycles or more.

c. Total resistance of the battery The total resistance showed a sufficiently low resistance value of 50 Ωcm ^{2 in} terms of unit area based on the active area.

In the all-solid-state nonaqueous electrolyte of this example, the total resistance was low and excellent charge / discharge characteristics were obtained because a dense LiNbO ₃ layer was present at the LiCoO ₂ grain boundary of the positive electrode. This is because the Li ⁺ conductivity in the positive electrode is improved.

1 Positive electrode 2 Solid electrolyte membrane 3 Negative electrode

Claims (6)

A method for producing LiNbO ₃ glass using a sol-gel method,
A sol solution adjusting step for adjusting a sol solution containing equimolar lithium alkoxide and niobium alkoxide and using alcohol as a solvent;
A gelling step of concentrating and gelling the obtained sol solution by heating at a temperature below the boiling point of the alcohol in an atmosphere having a predetermined relative humidity;
A method for producing LiNbO ₃ glass, comprising a firing step of firing the obtained gel at a temperature of 250 ° C. or higher and lower than 350 ° C. LiNbO ₃ glass, characterized in that the glass produced by the production method of the LiNbO ₃ glass according to claim 1. A solid electrolyte membrane comprising the LiNbO ₃ glass according to claim 2 as a main component. It consists of a molded body of particles mainly composed of positive electrode active material particles,
A positive electrode for a non-aqueous electrolyte battery, comprising the LiNbO ₃ glass according to claim 2 at a grain boundary of the positive electrode active material particles. A non-aqueous electrolyte battery having a laminate of a positive electrode, a solid electrolyte membrane, and a negative electrode,
A nonaqueous electrolyte battery, wherein the solid electrolyte membrane according to claim 3 is used as the solid electrolyte membrane of the laminate.   A nonaqueous electrolyte battery comprising the positive electrode for a nonaqueous electrolyte battery according to claim 4.

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