CN112768752B

CN112768752B - Method for improving discoloration and gelation of solid electrolyte, preparation method of solid electrolyte and solid electrolyte

Info

Publication number: CN112768752B
Application number: CN202011564152.6A
Authority: CN
Inventors: 陈规伟; 黄科程; 冀亚娟; 刘金成; ***
Original assignee: Eve Energy Co Ltd
Current assignee: Eve Energy Co Ltd
Priority date: 2020-12-25
Filing date: 2020-12-25
Publication date: 2022-07-12
Anticipated expiration: 2040-12-25
Also published as: CN112768752A

Abstract

The invention discloses a method for improving solid electrolyte discoloration and gelation of a solid electrolyte and the solid electrolyte. The method comprises the following steps: mixing inorganic solid electrolyte, lithium salt, PVDF and an organic solvent I to prepare a glue solution, wherein the surface of the inorganic solid electrolyte has residual alkali, and pretreating the inorganic solid electrolyte by adopting a solution of an acidic substance before preparing the glue solution, or adding the acidic substance in the mixing process. The method effectively solves the problems of uneven coating and reduced lithium ion conductivity caused by discolored gel and the like, and improves the coating uniformity when the glue solution is adopted for coating and the ionic conductivity of the solid electrolyte obtained after coating and drying.

Description

Method for improving discoloration and gelation of solid electrolyte, preparation method of solid electrolyte and solid electrolyte

Technical Field

The invention relates to the technical field of solid batteries, and relates to a method for improving discoloration and gelation of a solid electrolyte, a preparation method of the solid electrolyte and the solid electrolyte.

Background

Benefiting from a series of subsidy policies of the state on the electric vehicle industry, the domestic electric vehicle market is developed rapidly. The energy density of the single battery reaches 400 and 500Wh/kg by 2025 and 2030, but the energy density and the safety performance of the battery after 2025 cannot meet the national requirements based on the existing liquid electrolyte lithium ion power battery system. The use of a nonflammable solid electrolyte instead of a conventional liquid electrolyte can increase the energy density of the battery by about 66% while securing the safety performance of the battery, and thus the solid battery is considered to be an important direction of the next-generation battery technology.

Many solid electrolyte systems are currently being investigated. The inorganic solid electrolyte has high room-temperature ionic conductivity, good thermal stability, wide electrochemical window, high hardness, poor flexibility, poor interface contact and high preparation cost; the organic solid electrolyte has good flexibility and elasticity, good interface contact, mature preparation process and low cost, but has lower room temperature ionic conductivity. The organic/inorganic composite system can take advantages of both inorganic solid electrolytes and organic solid electrolytes, and is considered to have potential for practical application. The PVDF/oxide solid electrolyte composite system has high ionic conductivity, good mechanical property and high thermal stability, and has a relatively wide application prospect in organic/inorganic composite systems. However, in the electrolyte preparation process, the PVDF is subjected to a phenomenon of discoloration and gelation, which leads to the reduction of the production quality of the electrolyte membrane and the reduction of the ionic conductivity, and seriously deteriorates the performance of the electrolyte.

According to studies, the cause of the discoloration gel phenomenon is mainly weak alkalinity of the oxide solid electrolyte. Lithium hydroxide or lithium carbonate is generally used as a lithium source in the synthesis of the oxide solid electrolyte. Meanwhile, in order to reduce the influence of lithium volatilization phenomenon in the high-temperature calcination process on the synthesis effect, the lithium hydroxide or lithium carbonate is excessive by 10-15%. Therefore, a small amount of alkaline substances remains in the finally synthesized garnet powder. Part of oxide electrolyte (such as lithium lanthanum zirconium oxygen) has general stability to air, and a layer of alkalescent lithium carbonate is slowly generated on the surface of the oxide electrolyte in the air, and the thickness of the oxide electrolyte can reach dozens of microns. Therefore, the oxide solid electrolyte powder is generally weakly alkaline. In the process of preparing the PVDF/oxide solid electrolyte composite electrolyte membrane, the PVDF and the oxide solid electrolyte are simultaneously dispersed in an organic solvent to form stable and uniform glue solution. Because of the addition of oxide electrolyte, the whole glue solution is weakly alkaline. PVDF can undergo irreversible HF elimination reaction under an alkaline environment to generate carbon-carbon conjugated double bonds, so that the glue solution is red. Secondly, carbon-carbon double bonds can be crosslinked in the stirring process of the glue solution, so that the PVDF glue solution is gelatinized and becomes a jelly-like substance. PVDF crosslinking causes difficulty in movement of lithium ions in the polymer electrolyte membrane and decreases ion conductivity. The jellified gel can cause the glue solution to be difficult to coat, the uniformity and consistency of the electrolyte membrane are greatly reduced, and the mass production is not facilitated.

According to the analysis, the phenomenon of PVDF glue solution discoloration and gelation can be effectively solved by removing weak base in the oxide solid electrolyte. In a method (patent No. CN201810861866.X) for preventing PVDF slurry of lithium lanthanum zirconium tantalum oxygen from discoloring gel, weak alkali is removed by washing or coating. The washing method is a method of removing a trace amount of weak base from the oxide electrolyte by washing with a large amount of organic solvent, and has a long treatment time, an extended overall production time, and difficulty in completely removing the weak base adhering to the surface of the oxide electrolyte. The coating method is to coat an organic layer on the surface of the oxide electrolyte, so that weak base cannot contact with the glue solution, thereby solving the problem of color-changing gel, but the coating has certain influence on the ion conductivity of the oxide electrolyte and the process is complex.

Disclosure of Invention

In view of the above circumstances, an object of the present invention is to provide a method for improving discoloration and gelation of a solid electrolyte, a method for producing a solid electrolyte, and a solid electrolyte.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method of improving solid electrolyte discoloration, gelation, said method comprising: mixing inorganic solid electrolyte, lithium salt, PVDF and organic solvent I to prepare a glue solution, wherein the surface of the inorganic solid electrolyte has residual alkali,

before preparing the glue solution, the solution of the acidic substance is adopted to carry out pretreatment on the inorganic solid electrolyte, or the acidic substance is added in the mixing process.

The invention discloses a method for inhibiting PVDF glue solution discoloration gel by using an acidic substance, wherein the using amount of the acidic substance can be determined according to the residual alkali amount on the surface of an inorganic solid electrolyte, so that the problems of nonuniform coating and reduced lithium ion conductivity caused by discoloration gel and the like are effectively solved, the coating uniformity when the glue solution is used for coating is improved, and the ion conductivity of the solid electrolyte obtained after coating and drying is improved.

The method is simple and rapid to operate and is suitable for industrial production.

In the present invention, the determination method of the residual alkali amount on the surface of the inorganic solid electrolyte is the prior art, and the detection or calculation can be performed by those skilled in the art by referring to the methods disclosed in the prior art, and will not be described herein again.

The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.

Preferably, the inorganic solid electrolyte is at least one of an oxide solid electrolyte and a derivative thereof.

Preferably, the oxide solid state electrolyte comprises at least one of a lithium lanthanum zirconium oxide solid state electrolyte, a lithium titanium aluminum phosphate solid state electrolyte, a lithium germanium aluminum phosphate solid state electrolyte, and a lithium lanthanum titanate solid state electrolyte.

Preferably, the lithium salt includes lithium hydrosulfide, LiN (CN)₂、Li(CF₃SO₂)₃C、LiC₄F₉SO₃、LiN(SO₂CF₂CF₃)₂、LiB(C₂O₄)₂Lithium bis (oxalato) borate, LiBF₄、LiBF₃(C₂F₅) Lithium difluoro (oxalato) borate, lithium oxalato difluoroborate, lithium bis (trifluoromethanesulfonyl) imide, lithium bis (fluorosulfonyl) imide (, LiN (SO)₂F)₂)、LiCF₃SO₃、LiAsF₆、LiSbF₆And LiClO₄At least one of (1).

In the invention, the molecular formula of the lithium cyanide sulfide is LiSCN; lithium bis (oxalate) borate is abbreviated as LiBOB; lithium difluoro (oxalate) borate is abbreviated as LiDFOB; lithium oxalyldifluorophosphate is abbreviated as LIODFB; the molecular formula of lithium bis (trifluoromethanesulfonyl) imide is LiN (SO)₂CF₃)₂Abbreviated as LiTFSI; the molecular formula of lithium bis (fluorosulfonyl) imide is LiN (SO)₂F)₂Abbreviated to LiFSI.

Preferably, the mass-to-volume ratio of the inorganic solid electrolyte to PVDF is 1 g/70-120 mL, such as 1g/70mL, 1g/75mL, 1g/80mL, 1g/85mL, 1g/90mL, 1g/100mL, 1g/110mL, or 1g/120mL, etc.

Preferably, the organic solvent i includes at least one of N-methylpyrrolidone, dimethylformamide and dimethylacetamide.

Preferably, the mixing mode is as follows: and adding the inorganic solid electrolyte into the organic solvent I, performing ultrasonic dispersion, then adding PVDF and lithium salt, and stirring to obtain a glue solution. The inorganic solid electrolyte is mixed according to the mode of the preferred technical scheme, so that the good dispersibility of the inorganic solid electrolyte can be better ensured, the uniform distribution of the inorganic solid electrolyte in the whole organic/inorganic composite electrolyte membrane is facilitated, and the good ionic conductivity is ensured.

Preferably, the stirring is magnetic stirring.

Preferably, the stirring time is 6h to 15h, such as 6h, 7h, 8h, 10h, 12h or 15h, and the like.

When an acidic substance is introduced in the mixing process, the stirring mode is combined, so that the good dispersibility of the inorganic solid electrolyte can be better ensured, the effect of acid on removing residual alkali can be better exerted, the uniform distribution of the inorganic solid electrolyte in the whole organic/inorganic composite electrolyte membrane and the removal effect of the residual alkali are facilitated, and the good ionic conductivity and the good coating uniformity are ensured.

As a preferred technical solution of the method of the present invention, the pretreatment comprises:

(1) dissolving the acidic substance in an organic solvent II to obtain a low-concentration acid solution with the concentration of 0.5-10 mu mol/L;

(2) and (2) adding the inorganic solid electrolyte into the low-concentration acid solution obtained in the step (1), and performing solid-liquid separation after reaction to obtain the inorganic solid electrolyte after alkali removal.

In this preferred embodiment, the concentration of the low-concentration acid solution in step (1) is 0.005mol/L to 0.1mol/L, for example, 0.005mol/L, 0.007mol/L, 0.008mol/L, 0.01mol/L, 0.012mol/L, 0.015mol/L, 0.02mol/L, 0.023mol/L, 0.026mol/L, 0.03mol/L, 0.035mol/L, 0.04mol/L, 0.045mol/L, 0.05mol/L, 0.055mol/L, 0.06mol/L, 0.065mol/L, 0.07mol/L, 0.08mol/L, 0.085mol/L, or 0.1 mol/L.

In this preferred technical scheme, the solid-liquid separation mode in step (2) is not limited, and those skilled in the art can select the solid-liquid separation mode according to needs, for example, the inorganic solid electrolyte on the filter element can be removed by suction filtration with a water pump, or the inorganic solid electrolyte can be separated from the acid solution by high-speed centrifugation.

According to the preferred technical scheme, the inorganic solid electrolyte is quickly treated by using an acidic substance, residual alkali in the inorganic solid electrolyte is removed, and then the inorganic solid electrolyte is used for preparing the solid electrolyte.

Preferably, the acidic substance in step (1) includes at least one of hydrochloric acid, oxalic acid, sulfuric acid, acetic acid and nitric acid.

Preferably, the organic solvent II in the step (1) is alcohol, preferably ethanol.

Preferably, the concentration of the low-concentration acid solution in the step (1) is 0.008 mol/L-0.02 mol/L.

Preferably, the mass of the acidic substance in the low-concentration acid solution in the step (1) is 1.02 to 1.05 times, for example, 1.02, 1.03, 1.04, 1.05 or the like, preferably 1.03 to 1.04 times the mass of the residual alkali on the surface of the inorganic solid electrolyte.

Preferably, the reaction of step (2) is carried out under ultrasonic conditions.

Preferably, the time of the ultrasound is 5min to 10min, such as 5min, 6min, 8min or 10 min.

Preferably, the pretreatment process further comprises the step (3) after the step (2): and heating the inorganic solid electrolyte after alkali removal, thereby removing the organic solvent II remained on the surface of the inorganic solid electrolyte.

In this preferred embodiment, the heating temperature may be selected according to the kind of the organic solvent ii, as long as the organic solvent ii can be removed from the surface of the inorganic solid electrolyte. For example, ethanol may be removed from the surface of the inorganic solid electrolyte by drying at 100 ℃ for 12 hours, or may be removed from the surface of the inorganic solid electrolyte by drying at 200 ℃ for 30 minutes.

As another preferred embodiment of the method of the present invention, the acidic substance is added in an amount of 0.5. mu. mol/L to 10. mu. mol/L, for example, 0.5. mu. mol/L, 0.6. mu. mol/L, 0.7. mu. mol/L, 1. mu. mol/L, 1.3. mu. mol/L, 1.6. mu. mol/L, 2. mu. mol/L, 2.5. mu. mol/L, 3. mu. mol/L, 3.5. mu. mol/L, 4. mu. mol/L, 4.5. mu. mol/L, 5. mu. mol/L, 5.5. mu. mol/L, 6. mu. mol/L, 6.5. mu. mol/L, 7. mu. mol/L, 7.5. mu. mol/L, 8. mu. mol/L, 9. mu. mol/L or 10. mu. mol/L, etc., preferably 0.5. mu. mol/L to 1.5. mu. mol/L, per 1mL of the organic solvent I.

The glue solution is prepared by adding an acidic substance in the mixing process of the glue solution preparation, namely mixing the inorganic solid electrolyte, the lithium salt, the PVDF, the acidic substance and the organic solvent I. In the glue solution preparation process, the acidic substance neutralizes the alkalinity of the glue solution, PVDF discoloration gel can be effectively inhibited in an express way, the coating uniformity when the glue solution is adopted for coating is improved, and the ion conductivity of the solid electrolyte obtained after coating and drying is improved. The above-mentioned preferable amount of the acidic substance can more effectively remove the residual alkali and improve the performance of the solid electrolyte.

In a second aspect, the present invention provides a method for preparing a solid electrolyte, wherein the glue solution prepared by the method of the first aspect is coated on a substrate and dried to obtain the solid electrolyte.

The method of application is not limited in the present invention, and the dope may be applied to the surface of the substrate by, for example, casting.

Preferably, the substrate is an aluminum foil or a glass plate.

Preferably, the drying temperature is 55 ℃ to 70 ℃, such as 55 ℃, 60 ℃, 65 ℃, or 70 ℃ and the like; the drying time is 8h to 15h, such as 8h, 9h, 10h, 11h, 12h, 13h or 15 h.

In a third aspect, the present invention provides a solid electrolyte prepared by the method of the second aspect.

Compared with the prior art, the invention has the following beneficial effects:

(1) the method has simple and effective process and low cost, and can quickly remove weak alkaline substances in inorganic solid electrolytes such as oxide solid electrolytes and the like;

(2) the method successfully solves the difficult problem of gelation in the process of preparing the glue solution by the solid electrolyte, such as the difficult problem of coating caused by the gelation of the PVDF/oxide solid electrolyte glue solution, thereby leading the prepared organic/inorganic composite electrolyte membrane to be more uniform and obviously improving the consistency.

(3) The method successfully solves the problem of the reduction of the ionic conductivity of the electrolyte membrane caused by the gelation of the glue solution of the solid electrolyte (such as PVDF/oxide solid electrolyte).

Drawings

FIG. 1 is an optical photograph of an organic/inorganic composite electrolyte prepared in comparative example 1;

FIG. 2 is an optical photograph of the organic/inorganic composite electrolyte prepared in example 1;

FIG. 3 is an optical photograph of the dope prepared in comparative example 1;

FIG. 4 is an optical photograph of the dope prepared in example 2;

fig. 5 is an EIS result comparison of organic/inorganic composite electrolytes prepared in comparative example 1 and example 1.

Fig. 6 is an EIS result comparison of organic/inorganic composite electrolytes prepared in comparative example 1 and example 2.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

Example 1

The embodiment provides a method for improving solid electrolyte discoloration and gelation, which comprises the following steps:

1. adding 500 mu L of 1mol/L hydrochloric acid into 50mL of alcohol, diluting to 0.01mol/L acid solution, adding 5g of LLZTO into the solution, performing ultrasonic treatment for 10min, wherein the mass of an acid substance in the acid solution is 1.03 times of that of residual alkali on the surface of the inorganic solid electrolyte. After the sonication was completed, alcohol was separated from the oxide electrolyte using suction filtration. And then drying at 100 ℃ for 12h to obtain the treated LLZTO.

2. 0.1g of the treated LLZTO powder was added to 8mL NMP (N-methylpyrrolidone) and sonicated for 10min to ensure that the LLZTO powder was uniformly dispersed in NMP.

3. 0.33g of LiTSI and 1g of PVDF were added to the LLZTO/NMP dispersion and stirred magnetically for 12 hours to ensure that the above materials form a homogeneous gel.

4. The above-mentioned glue solution was applied to the surface of a glass plate using a doctor blade with a thickness of 400. mu.m. After finishing the blade coating, putting the glass plate into a vacuum drying oven, drying for 12h at the temperature of 60 ℃, and removing the NMP solvent to obtain the organic/inorganic composite electrolyte.

TABLE 1

Note: the numbers in the table represent parallel tests performed according to the conditions of example 1, with results within error.

Example 2

1. adding 5 mu L of hydrochloric acid (1mol/L) and 0.1g of LLZTO into 8mL of NMP solvent, wherein the mass of an acidic substance is 1.04 times of the mass of residual alkali on the surface of the inorganic solid electrolyte, uniformly dispersing by ultrasonic treatment for 10min, and simultaneously removing the residual alkali by acid-base reaction.

2. 0.33g of LiTFSI and 1g of PVDF were added to the LLZTO/NMP dispersion and stirred magnetically for 12 hours to ensure that the material formed a homogeneous gel.

3. The above-mentioned glue solution was applied to the surface of a glass plate using a doctor blade with a thickness of 400. mu.m. After finishing the blade coating, putting the glass plate into a vacuum drying oven, drying for 12h at the temperature of 60 ℃, and removing the NMP solvent to obtain the organic/inorganic composite electrolyte.

TABLE 2

Note: the numbers in the table represent parallel tests performed according to the conditions of example 2, with results within error.

Example 3

The difference from example 1 is that the volume of alcohol used in step 1 is 20mL, the concentration of the acid solution is 0.025mol/L, and the ratio of the mass of the acidic substance in the acid solution to the residual alkali on the surface of the inorganic solid electrolyte is the same as example 1.

TABLE 3

Note: the numbers in the table represent parallel tests performed according to the conditions of comparative example 1.

Example 4

The difference from example 1 is that the volume of alcohol used in step 1 is 10mL, the concentration of the acid solution is 0.05mol/L, and the ratio of the mass of the acidic substance in the acid solution to the residual alkali on the surface of the inorganic solid electrolyte is the same as example 1.

TABLE 4

As can be seen from comparison between example 1 and examples 3 to 4, the ion conductivity of the entire product tends to decrease as the concentration of the acidic solution increases. This is because Li of an oxide solid electrolyte is in contact with an acidic solution⁺Will react with H in the solution⁺Lithium hydrogen exchange occurs therebetween, resulting in a breakdown of a lithium ion transport path of the oxide electrolyte and a decrease in ion conductivity. For the oxide electrolyte/PVDF composite electrolyte, the oxide electrolyte takes charge of a part of ion transport, and the decrease of the ion conductivity thereof directly affects the ion conductivity of the composite electrolyte. Therefore, the concentration of the acidic solution is notPreferably too high to prevent a significant negative impact on the ionic conductivity of the product.

Example 5

The difference from example 1 is that the volume of hydrochloric acid used in step 1 was adjusted to 1mL, and under the conditions, the concentration of the acid solution was 0.02mol/L, and the ratio of the mass of the acidic substance in the acid solution to the residual alkali on the surface of the inorganic solid electrolyte was 2 times that of example 1.

TABLE 5

As can be seen from a comparison between example 1 and example 5, the ratio of the mass of the acidic substance in the acid solution to the residual alkali on the surface of the inorganic solid electrolyte was 2 times that of example 1, that is, the mass of the acidic substance in the acid solution was 2.06 times that of the residual alkali on the surface of the inorganic solid electrolyte. Too much acid addition negatively affects the ionic conductivity of the electrolyte. The reason is in two ways: firstly, excessive acid addition can cause more serious lithium/hydrogen exchange and influence the intrinsic ion conductivity of the inorganic solid electrolyte; secondly, acid is an impurity without ion transport capacity in the electrolyte system, and excessive acid-base reaction residual products influence the overall ionic conductivity of the electrolyte membrane. Therefore, the amount of the acid added should not be too high.

Example 6

The difference from example 2 is that the acid was added in a volume of 50. mu.L in step 1.

TABLE 6

Note: the numbers in the table represent parallel tests performed according to the conditions of comparative example 1,

it is understood from a comparison between example 2 and example 6 that an excessive amount of acid added adversely affects the ionic conductivity of the electrolyte. The reason is twofold: firstly, excessive acid addition can cause more serious lithium/hydrogen exchange and influence the intrinsic ionic conductivity of the inorganic solid electrolyte; secondly, acid is an impurity without ion transmission capability in the electrolyte system, and excessive acid-base reaction residual products influence the overall ion conductivity of the electrolyte membrane. Therefore, the amount of the acid added should not be too high.

Example 7

The difference from example 2 is that hydrochloric acid, LLZTO, LiTSi and PVDF are mixed in one step.

Such mixing can lead to maldistribution of the material, particularly inorganic solid electrolyte, which can lead to membrane curling and local ionic conductivity reduction.

Comparative example 1

The difference from example 1 is that step 1 is not carried out and the untreated LLZTO powder is used directly in step 2.

TABLE 7

Since the acid treatment is not performed, the gum solution is solidified to become jelly-like, so that the uniformity is poor, and the prepared product has low ionic conductivity.

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. A method of improving discoloration and gelation of a solid electrolyte gel solution, said method comprising: mixing inorganic solid electrolyte, lithium salt, PVDF and organic solvent I to prepare a glue solution, wherein the surface of the inorganic solid electrolyte has residual alkali,

before preparing glue solution, adopting solution of acidic substance to pretreat inorganic solid electrolyte, wherein the pretreatment comprises the following steps: (1) dissolving an acidic substance in an organic solvent II to obtain a low-concentration acid solution, wherein the concentration of the low-concentration acid solution is 0.008 mol/L-0.05 mol/L, and the mass of the acidic substance in the low-concentration acid solution in the step (1) is 1.02 times-1.05 times of the mass of residual alkali on the surface of the inorganic solid electrolyte; (2) adding an inorganic solid electrolyte into the low-concentration acid solution obtained in the step (1), and performing solid-liquid separation after reaction to obtain the inorganic solid electrolyte after alkali removal;

or adding an acidic substance in the mixing process, wherein the mixing mode is as follows: adding an inorganic solid electrolyte into an organic solvent I, performing ultrasonic dispersion, then adding PVDF and lithium salt, and stirring to obtain a glue solution; wherein, the amount of the acidic substance added is 0.5-6.25 mu mol per 1mL of the organic solvent I.

2. The method for improving discoloration and gelation of a solid electrolyte glue solution according to claim 1, wherein said inorganic solid electrolyte is at least one of an oxide solid electrolyte and its derivatives.

3. The method of improving the discoloration and gelation of a solid electrolyte cement according to claim 2, wherein said oxide solid electrolyte comprises at least one of a lithium lanthanum zirconium oxide solid electrolyte, a lithium titanium aluminum phosphate solid electrolyte, a lithium germanium aluminum phosphate solid electrolyte and a lithium lanthanum titanate solid electrolyte.

4. The method of claim 1, wherein the lithium salt comprises lithium sulfocyanide, LiN (CN)₂、Li(CF₃SO₂)₃C、LiC₄F₉SO₃、LiN(SO₂CF₂CF₃)₂、LiB(C₂O₄)₂Lithium bis (oxalato) borate, LiBF₄、LiBF₃(C₂F₅) Lithium difluoro (oxalato) borate, lithium oxalato difluoroborate, lithium bis (trifluoromethanesulfonyl) imide, lithium bis (fluorosulfonyl) imide (, LiN (SO)₂F)₂)、LiCF₃SO₃、LiAsF₆、LiSbF₆And LiClO₄At least one of (1).

5. The method for improving discoloration and gelation of a solid electrolyte gel according to claim 1, wherein said organic solvent I comprises at least one of N-methylpyrrolidone, dimethylformamide and dimethylacetamide.

6. The method for improving the discoloration and gelation of a solid electrolyte gum solution according to claim 1, wherein said stirring is magnetic stirring.

7. The method for improving the discoloration and gelation of the solid electrolyte glue solution according to claim 1, wherein the stirring time is 6-15 hours.

8. The method for improving discoloration and gelation of a solid electrolyte glue solution according to claim 1, wherein said acidic substance of step (1) comprises at least one of hydrochloric acid, oxalic acid, sulfuric acid, acetic acid and nitric acid.

9. The method for improving the discoloration and gelation of a solid electrolyte glue solution according to claim 1, wherein said organic solvent II in step (1) is alcohol.

10. The method for improving discoloration and gelation of a solid electrolyte glue solution according to claim 9, wherein said organic solvent ii in step (1) is ethanol.

11. The method for improving the discoloration and gelation of the solid electrolyte glue solution according to claim 1, wherein the concentration of the low-concentration acid solution in the step (1) is 0.008mol/L to 0.02 mol/L.

12. The method for improving the discoloration and gelation of the solid electrolyte glue solution according to claim 1, wherein the mass of the acidic substance in the low-concentration acid solution in the step (1) is 1.03 to 1.04 times of the mass of the residual alkali on the surface of the inorganic solid electrolyte.

13. The method for improving the discoloration and gelation of a solid electrolyte glue solution according to claim 1, wherein said reaction of step (2) is carried out under ultrasonic conditions.

14. The method for improving the color change and the gelation of the solid electrolyte glue solution according to claim 13, wherein the time of the ultrasonic treatment is 5-10 min.

15. The method for improving the discoloration and gelation of a solid electrolyte glue solution according to claim 1, wherein step (3) is performed after step (2) in the pretreatment process: and heating the inorganic solid electrolyte after alkali removal.

16. The method for improving the discoloration and gelation of the solid electrolyte glue solution according to claim 1, wherein the amount of the acidic substance added is 0.5 to 1.5 μmol per 1mL of the organic solvent I.

17. A method for preparing a solid electrolyte, characterized in that the glue solution prepared by the method of any one of claims 1 to 16 is coated on a substrate and dried to obtain the solid electrolyte.

18. The method of producing a solid electrolyte according to claim 17, wherein the substrate is an aluminum foil or a glass plate.

19. The method for preparing the solid electrolyte according to claim 17, wherein the drying temperature is 55 ℃ to 70 ℃ and the drying time is 8h to 15 h.

20. A solid electrolyte prepared by the method of claim 17.