JP5678736B2 - Method for producing solid electrolyte precursor solution and method for producing solid electrolyte - Google Patents

Description

  The present invention relates to a method for producing a solid electrolyte precursor solution and a method for producing a solid electrolyte.

  Lithium batteries (including primary batteries and secondary batteries) are used as a power source for many electric devices including portable information devices. The lithium battery includes a positive electrode layer, a negative electrode layer, and an electrolyte layer that is disposed between these layers and mediates conduction of lithium ions while maintaining electrical insulation. In recent years, the energy density of lithium batteries has dramatically improved. At the same time, however, there has been an increased risk of electrolyte smoking and ignition. Therefore, a safer lithium battery with a non-flammable organic electrolyte used in the electrolyte layer has been developed. The demand is growing.

  As a lithium battery that achieves both high energy density and safety, an all-solid-state lithium battery that does not use an organic electrolyte for conducting lithium between the positive and negative electrodes has been proposed (see, for example, Patent Document 1). . All-solid-state lithium batteries use a solid electrolyte to conduct lithium ions between the positive and negative electrodes, and problems associated with using organic solvent-based electrolytes, such as safety problems due to electrolyte leakage, The problem of heat resistance caused by volatilization of the organic electrolyte exceeding its boiling point at high temperatures can be solved.

As such a solid electrolyte, oxide-based solid electrolyte particles having high lithium ion conductivity, excellent insulating properties, and high chemical stability are widely known. As oxide-based solid electrolyte particles, lithium lanthanum titanate-based materials have a high lithium ion conductivity that should be noted, and are expected to be applied to batteries.
By the way, the above-mentioned solid electrolyte particles are often formed into a shape that matches the shape to be used by compression molding. However, since most of the solid electrolyte particles are very hard, the contact between the electrolyte particles in the molded product (solid electrolyte) is insufficient, and the grain boundary resistance increases, and the lithium ion conductivity of the molded product tends to decrease. is there.

Therefore, a solid electrolyte is obtained by performing sintering at a temperature of 1000 ° C. or more after compression molding. In a lithium battery, the electrolyte in the layer and the positive electrode active material are separated by the heat of sintering. There is a problem that the chemical reaction is easy, and a problem that the ionic conductivity is likely to decrease due to volatilization and reduction of lithium from the electrolyte.
As a method of avoiding such a problem, by setting the particle size of at least primary particles of the solid electrolyte particles to the nanometer order, the contact property is improved, and the sintering temperature is set to 600 ° C. or lower where heat diffusion is inactive. Can be expected. For this reason, there is a need for a method capable of miniaturizing at least primary particles while precisely controlling the composition of the solid electrolyte particles.

  Further, as a method for forming a solid electrolyte, a synthetic system using a liquid phase material, particularly a sol-gel method may be employed. In the sol-gel method, a compound composed of an organic functional group and an inorganic element is subjected to a process involving a hydrolysis reaction or a dehydration condensation reaction in a solution system to form a gel-like constituent element network, which is then calcined to obtain a predetermined content. This is a technique for forming a crystal structure of The sol-gel method can be applied to forming an electrolyte layer by coating, or can be sprayed into a high-temperature gas to obtain fine particles.

  In order to form a solid electrolyte by such a sol-gel method, for example, a method such as Patent Document 2 relating to the production of lithium lanthanum titanate is known. That is, first, a metal alkoxide for constituting a target solid electrolyte is dissolved in an alcohol solution. Next, this alcohol solution is made into a sol at 25 to 80 ° C., for example. Next, the sol is applied to the electrode surface, and is left to gel for about 1 day to 1 week at 25 to 120 ° C., for example. Then, a solid electrolyte is formed on an electrode by performing baking for about 1 hour at 800-900 degreeC.

JP 2009-215130 A JP 2003-346895 A

Journal of Sol-Gel Science and Technology 22, 33-40, 2001

However, the supply source of the constituent metal elements, that is, the alcohol solution of the metal alkoxide has a characteristic that it easily forms insoluble components such as hydroxides and oxides due to moisture absorption and contact with oxygen. For this reason, the composition of the crystal of the solid electrolyte changes, and the ionic conductivity tends to decrease. For example, Li _3X La _{2/3 -X} TiO ₃ has a lithium ion conductivity of approximately 10 ⁻³ S / cm when x = 0.12, but lithium ions when x = 0.1 and 0.15. The conductivity is about 10 ⁻⁵ S / cm. Thus, since the composition in the crystal of the solid electrolyte greatly affects the lithium ion conductivity, a forming method capable of precisely controlling the composition is required. In addition, when oxide crystal particles having a complicated composition are formed from a liquid material, constituent elements are easily segregated, and thus the function as an electrolyte may not be exhibited. Furthermore, since a large amount of organic solvent is used for the raw material solution, there is a concern about adverse effects on manufacturing workers and the environment.
Therefore, the present invention has been conceived under such circumstances, and is a method for producing a precursor solution of a solid electrolyte that is excellent in controlling an atomic ratio in a crystal of a solid electrolyte and that is suitable for atomization. Another object is to provide a method and a method for producing a solid electrolyte.

[Aspect 1]
In order to achieve the above object, a precursor solution of a solid electrolyte according to an embodiment of the present invention is an aqueous solution formed from hydrogen peroxide, ammonia, and a specific raw material, and the specific raw material is (a Peroxytitanic acid, (b) a water-soluble salt containing at least lithium, (c) a chelating agent containing an unbonded functional group in the molecule, and (d) the chelating agent in at least two locations in one molecule. A crosslinking agent having a characteristic group that causes a condensation reaction, and the number of moles of the unbonded functional group of (c) in the aqueous solution is at least equal to or less than the number of moles of (d). Features.

  If it is such a structure, peroxotitanic acid aqueous solution can be prepared with hydrogen peroxide and ammonia, and titanium can be handled as a water-soluble compound. Thereby, the chemical stability with respect to water and oxygen increases as compared with the case where alkoxide or the like is used, and the control of the composition and particle size of the target product is facilitated. Further, an aqueous solution in which a salt of an A-site substitution element, a chelating agent containing an unbonded functional group in the molecule, and a crosslinking agent having a condensation reactive group in at least two locations in the molecule are added to the precursor solution. Thus, the A site substitution element, the chelating agent, and the cross-linking agent are dispersed in the precursor solution without phase separation, and the deviation from the target composition due to segregation can be reduced, and a solid electrolyte having excellent ion conductivity can be obtained. .

In the above configuration, the salt of (b) that can be used as the A-site substitution element contains at least lithium, which includes alkali rare earths such as lanthanum and cerium, alkali metals such as sodium and potassium, zirconium, silver and the like. By selecting and using any water-soluble salt from elements such as transition metals, aluminum, silicon, germanium, phosphorus, etc., for example, a titanic acid-based oxide solid such as Li _3X La _{2 / 3-X} TiO ₃ Electrolyte crystals can be obtained. These can be used in combination of two or more elements in order to improve ion conductivity and potential window characteristics. For the same purpose, those in which the anion is substituted with fluorine or the like can also be used.

  When the number of moles of unbonded functional groups in the molecule of (c) is equal to the number of moles of (d) in the precursor solution composed of these raw materials, the chelate molecule and the crosslinking agent of (c) are alternately linked. Since the crosslinked structure is adopted, an electrolyte having a desired crystal composition can be obtained even by heat treatment at a temperature lower than that of the conventional example. On the other hand, when the number of moles of (d) is excessive, the distance between chelate molecules increases, so that the interatomic distances of (a) and (b) become long, and a high temperature is required for the formation of the target product. Become. Further, when the number of moles of (d) is insufficient, the isotropic dispersibility of the element is lowered as the cross-linked structure is reduced, and oxide segregation is likely to occur.

[Aspect 2]
The precursor solution of the solid electrolyte includes a step of obtaining a complex aqueous solution by adding the chelating agent to a peroxotitanic acid aqueous solution containing the peroxotitanic acid, the hydrogen peroxide, and the ammonia; and A step of adding a water-soluble salt, adding the water-soluble salt and then adding the crosslinking agent, and gelling the aqueous solution by a polyesterification or amidation reaction, and gelling the aqueous solution The pH of the aqueous solution may be adjusted to 5.0 or more and 6.0 or less.

  If it is such a structure, stability in the aqueous solution of a titanium atom can be increased by complexing peroxotitanic acid and the chelating agent which consists of hydroxycarboxylic acid or aminocarboxylic acid, for example. In addition, the unbonded functional group in the complex molecule generates a polyester compound by a condensation reaction with the cross-linking agent, thereby suppressing the thermal diffusion of the constituent elements of the target crystal composition during the heating process, and reducing the amount of impurities such as titanium dioxide. The effect of suppressing life can be obtained.

  In the above structure, chelating agents that can be used include glycolic acid, lactic acid, hydroxybutyric acid, glyceric acid, malic acid, tartaric acid, citric acid, salicylic acid, and other hydroxycarboxylic acids, and 2-aminoethanoic acid and 3-aminopropion. Examples thereof include aminocarboxylic acids including amino acids such as acid, 4-aminobutanoic acid, 5-aminopentanoic acid, 6-aminohexanoic acid, 7-aminoheptanoic acid and 8-aminooctanoic acid.

Moreover, according to said structure, after adding the salt of A site substitution element to a precursor solution, the production | generation of a cubic perovskite crystal | crystallization can be accelerated | stimulated by keeping pH of a solution to the weak acidity of 5-6. . At this time, if the pH is too lower than the described range, precipitates are likely to be generated when ammonia is desorbed in the gelation step, causing segregation. Similarly, if the pH is too higher than the stated range, peroxotitanic acid tends to precipitate as a polyanion, and segregation of TiO ₂ or the like tends to occur after firing. These phenomena are due to the properties of peroxotitanic acid. For example, the properties are described in Non-Patent Document 1 described above. In particular, in a combination of two or more A-site elements and a large difference in ion radius, this tendency tends to be remarkable.

[Aspects 3 and 4]
In the solid electrolyte precursor solution, the cross-linking agent may be an organic compound molecule containing at least 2 and at most 20 carbon atoms. Further, the organic compound molecule may have 8 or less carbon atoms.
With such a configuration, an effect of easily obtaining cubic perovskite crystal particles having a uniform particle diameter while maintaining the target composition is exhibited. This is because the cross-linking agent has the effect of suppressing the thermal diffusion of atoms as described above, and in the polymer gel after the cross-linking reaction, the A-site substituted atoms diffuse mainly in the water-soluble complex of peroxotitanic acid. This is to form fine particles as nuclei.

  At this time, when the number of carbon atoms of the crosslinking agent is 2 to 20, an ideal dispersion state of atoms is formed. However, when a crosslinking agent having a larger number of carbon atoms is used, the solubility of the crosslinking agent itself is lowered. Therefore, the number of carbon atoms in the crosslinking agent is preferably 20 or less. Further, methanediol, which is a cross-linking agent having 1 carbon atom, is unstable, so that not only segregation is likely to occur but also harmful formaldehyde is generated, which is dangerous. Therefore, the cross-linking agent having a carbon number of 2 or more that can stably prevent the fusion of peroxotitanate complexes is used. However, when the number of carbons increases, in addition to the above-described decrease in dispersibility due to the decrease in solubility, the decomposition and removal efficiency of organic components due to thermal decomposition and the like decrease, and the crosslinking agent remains in the final product (ie, solid electrolyte). There is a risk that. Accordingly, the carbon number of the crosslinking agent is desirably 20 or less, more preferably 8 or less.

Examples of such crosslinking agents include 1,2-ethylene glycol, 1,3-propanediol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol and other aliphatic 1, n-alkanediols represented by the formula HO— (CH ₂ ) _n —OH, and diethylene glycol, triethylene glycol, tetraethylene glycol and other formulas HO— _(C 2 _H 4 _-O) oligoethylene glycols represented by n -H, ethylenediamine, expressed in propanediamine, butanediamine, pentanediamine, etc. hexanediamine rational formula _{H 3 N- (CH 2) -NH} 3 Examples thereof include aliphatic 1, n-alkanediamines and derivatives thereof.

[Aspect 5]
According to another aspect of the present invention, a method for producing a precursor solution of a solid electrolyte includes adding a chelating agent having an unbonded functional group in a molecule to a peroxotitanic acid aqueous solution containing peroxotitanic acid, hydrogen peroxide, and ammonia. A step of obtaining an aqueous complex solution, and adding a water-soluble salt containing at least lithium to the aqueous complex solution, and then adding the water-soluble salt, and then causing a condensation reaction with the chelating agent in at least two places in one molecule A step of gelling the aqueous solution by a polyesterification or amidation reaction, and the number of moles of unbonded functional groups of the chelating agent in the aqueous solution is at least the number of moles of the crosslinking agent. Is less than or equal to.

  According to such a manufacturing method, as described above, chemical stability against water and oxygen is increased, and control of the composition and particle size of the target product is facilitated. Furthermore, the A site substitution element, the chelating agent, and the cross-linking agent are dispersed in the precursor solution without phase separation, and a deviation from the target composition due to segregation can be reduced to obtain a solid electrolyte excellent in ionic conductivity. In addition, the unbonded functional group in the complex molecule generates a polyester compound by a condensation reaction with the cross-linking agent, thereby suppressing the thermal diffusion of the constituent elements of the target crystal composition during the heating process, and reducing the amount of impurities such as titanium dioxide. Can suppress life.

[Aspect 6]
The method for producing a precursor solution of the solid electrolyte may be characterized in that, in the step of gelling the aqueous solution, the pH of the aqueous solution is adjusted to 5.0 or more and 6.0 or less. According to such a manufacturing method, as described above, the production of cubic perovskite crystals can be promoted.

[Aspects 7 and 8]
The method for producing a precursor solution of the solid electrolyte may be characterized in that an organic compound molecule containing at least 2 and at most 20 carbon atoms is used as the crosslinking agent. Further, the organic compound molecule may have 8 or less carbon atoms. If it is such a manufacturing method, as above-mentioned, carbon number in the organic compound molecule | numerator which is a crosslinking agent is 20 or less, More preferably, it is 2-8, A uniform particle size, maintaining a target composition The cubic perovskite type crystal particles can be easily obtained. In addition, it is possible to suppress a decrease in solubility of the crosslinking agent itself and a decrease in decomposition / removal efficiency of the organic component, and it is possible to prevent the crosslinking agent from remaining in the final product.

[Aspects 9 and 10]
A method for producing a solid electrolyte according to still another aspect of the present invention is a method for producing a solid electrolyte using the above precursor solution, wherein the precursor solution is heated at a temperature of 300 ° C. or more and 500 ° C. or less. Including a step of performing. Furthermore, in the step of heating the precursor solution, the precursor solution may be heated at a temperature of 350 ° C. or lower.

If it is such a manufacturing method, the average particle diameter of the primary particle whose composition was well controlled by heating the precursor solution within a range of 500 ° C. or less, more preferably within a range of 300 to 350 ° C. is, for example, 10 to 10 ° C. An oxide-based solid electrolyte fine particle having a thickness of 50 nm can be obtained. This is because the formation temperature of the solid electrolyte, which required a high temperature of 900 ° C. or higher in the conventional method, is lowered to 300 to 500 ° C. due to the effects of the above aspects 1 to 4. At this time, if heating is performed at 550 ° C. or higher, thermal diffusion of the element proceeds and particles are likely to grow. Further, when the heating temperature is 300 ° C. or lower, the target product is hardly formed, and the thermal decomposition of the chelating agent or the crosslinking agent added to the raw material does not proceed, so that the purity of the target product is lowered.
In the present invention, the method for heating the precursor solution involved in fine particle formation is not particularly limited, and any mode may be used as long as electrolyte particles having a small primary particle diameter can be obtained. For example, if a crosslinked gel-like precursor solution is heated in a container, an aggregate of fine primary particles can be obtained. Moreover, a primary particle simple substance can also be disperse | distributed using a spray pyrolysis apparatus.

The flowchart which shows the formation procedure of the solid electrolyte particulates concerning 1st Example The figure which shows the analysis result by X-ray diffraction of the powder obtained in 1st Example. The figure which shows the analysis result by X-ray diffraction of the crystal seed | species obtained in 2nd Example. The figure which shows the analysis result by X-ray diffraction of the crystal seed | species obtained by the 1st comparative example.

Embodiments of the present invention will be described below with reference to the drawings.
(1) 1st Example FIG. 1: is a flowchart which shows the formation procedure of the solid electrolyte particulates concerning 1st Example. Here, Li _0.35 La _0.55 TiO ₃ fine particles were formed as the solid electrolyte fine particles. The formation procedure will be described below.

First, a peroxotitanic acid aqueous solution was prepared from a titanium source. As the titanium source, titanium metal powder, titanium dioxide powder, or the like can be used. Peroxotitanium (including peroxotitanic acid, hydrogen peroxide, and ammonia) was prepared by dissolving 0.1M equivalent of the titanium source powder in 30% hydrogen peroxide water while cooling with water, and adding 35% ammonia water. An acid aqueous solution was prepared (steps (S) 1 and 2).
As a titanium source in this step, any raw material may be used as long as it is a titanium compound that induces peroxotitanic acid. However, when the above-described titanium metal powder and titanium dioxide powder are used as raw materials, A high-purity solution containing no compound other than peroxotitanic acid can be prepared.

  As the next step, citric acid monohydrate was dissolved in the peroxotitanic acid aqueous solution as a chelating agent. Here, citric acid monohydrate was dissolved so as to have a mole number of 1.9 times the mole number of titanium atoms in the peroxotitanic acid aqueous solution. The peroxotitanic acid aqueous solution becomes a peroxotitanic acid citric acid complex aqueous solution by complexing peroxotitanic acid and citric acid (step (S) 3). In this case, the unbonded functional group of the chelating agent is a carboxyl group. The carboxyl group is coordinated to the metal atom.

Was then dissolved with stirring LiNO ₃ and La _{(NO 3)} 3 · 6 to hydrate for each mole of titanium atoms become moles of 0.035 and 0.055 times with a magnetic stirrer. When this solution was stirred with a magnetic stirrer for 30 minutes, a pale orange peroxotitanate citric acid complex aqueous solution was obtained (step S (4)).
Next, 1,6-hexanediol as a cross-linking agent was dissolved to 0.19 M in the above-mentioned aqueous solution of peroxotitanate citrate complex. That is, 1,6-hexanediol was dissolved so that the number of moles of titanium was 1.9 times the number of moles of titanium atoms in the aqueous solution of peroxotitanic acid-citrate complex. Moreover, it adjusted using pH adjusters, such as nitric acid and aqueous ammonia, so that pH might be set to 5.5, and stirred at 60 degreeC for 1 hour. By this step, a dark red aqueous solution was obtained (step (S) 5).

  This dark red aqueous solution is a precursor solution of solid electrolyte fine particles. As described above, the amount of citric acid monohydrate, which is a chelating agent, and the amount of 1,6-hexanediol, which is a cross-linking agent, are respectively defined with respect to the number of moles of titanium atoms. The number of moles of unbound functional groups of citric acid in the aqueous solution is at least equal to or less than the number of moles of 1,6-hexanediol, and is substantially zero.

  Next, this aqueous solution (that is, the precursor solution) was gelled. In this gelation step, the pH of the precursor solution is adjusted within the range of 5.0 to 6.0 with the pH adjuster described above. In this step, the precursor solution having a pH of 5.0 to 6.0 was heated to 120 ° C. while stirring with a magnetic stirrer and held for 20 minutes to 1 hour. By this operation, a dark orange viscous gel was obtained (step (S) 6).

Next, solid electrolyte fine particles were formed using this gelled precursor solution. In the fine particle forming step, the gel was heated in a Petri dish in an air atmosphere. The heating temperature was 350 ° C., and this temperature was maintained for about 3 hours. After heating for 3 hours, a white powder was obtained (step S (7)). This powder was analyzed using a powder X-ray diffractometer (PANnal X'Pert PRO) to examine the crystal phase of the powder. The analysis result is shown in FIG. In FIG. 2, the horizontal axis represents the diffraction angle 2θ [°], and the vertical axis represents the diffraction line intensity [arb. unit].
As shown in FIG. 2, a peak derived from diffraction of Li _0.35 La _0.55 TiO ₃ crystal was detected in the powder obtained in Example 1, and a single crystal of Li _0.35 La _0.55 TiO ₃ crystal was detected. It was found that a single phase was generated. Further, when the particle size was compared with Li _0.35 La _0.55 TiO ₃ having the same composition obtained by the solid phase reaction method by the Scherrer method, the particle size of the primary particles was 20 nm.

(2) Second Embodiment Next, a second embodiment of the present invention will be described. Here, synthesis according to Example 1 was carried out using 1,10-decanediol having 10 carbon atoms as a crosslinking agent. However, in the gelation step of the precursor solution, it did not gel by heating at 120 ° C. for 1 hour, but changed from a dark red to a yellow solid. When this solid was heated at 350 ° C., it changed from brownish brown to dark brown granules. When the granules were further heated at 550 ° C. for 3 hours, they turned into white powders. The composition of this powder was examined by a powder X-ray diffractometer. The analysis result is shown in FIG. In FIG. 3, the horizontal axis indicates the diffraction angle 2θ [°], and the vertical axis indicates the diffraction line intensity [arb. unit].
As shown in FIG. 3, no peak derived from diffraction of Li _0.35 La _0.55 TiO ₃ crystal was detected in the powder obtained in the second example. This is thought to be because the formation temperature of the oxide increases due to the increase in the alkyl chain of the crosslinking agent, and the target Li _0.35 La _0.55 TiO ₃ could not be obtained by heating at 550 ° C.

(3) First Comparative Example Next, a first comparative example of the present invention will be described. Here, lithium acetate, lanthanum acetate hemihydrate and titanium tetraisopropoxide are dissolved in a solvent containing acetic acid and isopropanol at a ratio of 0.35: 0.55: 1.0 and gelled at 100 ° C. And then fired at 1000 ° C. XRD analysis was performed on the white powder obtained by these steps. The analysis result is shown in FIG. In FIG. 4, the horizontal axis indicates the diffraction angle 2θ [°], and the vertical axis indicates the diffraction line intensity [arb. unit].

As shown in FIG. 4, in the powder obtained in the first comparative example, peaks of Li _0.35 La _0.55 TiO ₃ as well as La ₂ Ti ₂ O ₇ were detected, and Li _0.35 La ₀ It was found that a heterogeneous phase other than _0.55 TiO ₃ was formed. This is thought to be segregated by the precipitation of titanium tetraisopropoxide as TiO ₂ or Ti (OH) ₄ . Moreover, according to the Scherrer method, it was shown that the particle size of a primary particle is about 500 nm.

(4) Summary According to the first embodiment of the present invention, it is possible to obtain a precursor solution that is hardly denatured by moisture absorption or oxygen exposure and has high chemical stability. According to this method, it is possible to prevent the raw material added to the precursor solution from forming as an insoluble oxide or hydroxide and precipitating as a by-product as an unreacted segregated product as in the conventional example. For this reason, it becomes easy to obtain a solid electrolyte having desired electrical characteristics by controlling the element ratio. In addition, as described above, in the precursor solution, the number of moles of unbonded functional groups of the chelating agent is at least the number of moles of the crosslinking agent, so that the dispersibility of the elements and the reactivity in heat treatment are improved. This makes it easier to obtain a desired crystal composition at a lower temperature than the conventional example.

According to the first embodiment of the present invention, the chelating agent is coordinated to peroxotitanic acid, so that the water solubility is improved and the stability and dispersibility of the solution can be improved. Furthermore, the chelating agent coordinated to the metal atom in the solution is crosslinked to form a gel, whereby heat treatment can be performed while maintaining the dispersed state of the elements in the precursor solution. For this reason, it becomes easier to maintain the target composition than the conventional example in which segregation or the like is likely to occur after the volatilization of the solvent.
Furthermore, according to the first embodiment of the present invention, since the metal complex in the precursor solution is isolated by the crosslinking agent, fine particles can be obtained. At this time, when the alkyl chain carbon number of the cross-linking agent is 6 to 8, fine particles can be suitably formed while maintaining the reactivity with which crystals are formed at a low temperature.

In addition, according to the first embodiment of the present invention, the precursor solution is heated at, for example, 350 ° C., thereby forming solid electrolyte fine particles (crystals) and volatilization / decomposition of organic matter. Or has an effect of preventing the particle size from being increased due to sintering between the fine particles.
The present invention is not limited to the above-described embodiments, and can be applied without departing from the gist of the present invention.
(5) Application Examples The precursor solution, the manufacturing method thereof, and the solid electrolyte manufacturing method described above can be applied to an electrolyte for an all-solid lithium battery as an application example. In addition, the present invention can also be applied to fuel cell electrolytes, superconducting materials, and dielectric materials.

  S1-S7 step

Claims (4)

Adding a chelating agent containing an unbonded functional group in the molecule to a peroxotitanic acid aqueous solution containing peroxotitanic acid, hydrogen peroxide and ammonia to obtain an aqueous complex solution;
After adding a water-soluble salt containing at least lithium to the aqueous complex solution, and adding the water-soluble salt, a crosslinking agent having a characteristic group that causes a condensation reaction with the chelating agent is added to at least two locations in one molecule. A step of gelling the aqueous solution by a polyesterification or amidation reaction,
The number of moles of non-bonded functional group of the chelating agent in the aqueous solution, the method for manufacturing a precursor solution of the solid electrolyte, characterized in that the pre-Symbol is less than the number of moles of crosslinking agent.   The method for producing a precursor solution of a solid electrolyte according to claim 1, wherein in the step of gelling the aqueous solution, the pH of the aqueous solution is adjusted to 5.0 or more and 6.0 or less. A method for producing a solid electrolyte by using a precursor solution according to the production method according to claim 1 or 2,
A step of heating the precursor solution at a temperature of 300 ° C. or more and 500 ° C. or less.   The method for producing a solid electrolyte according to claim 3, wherein in the step of heating the precursor solution, the precursor solution is heated at a temperature of 350 ° C. or less.

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