Low-moisture solid-state electrolyte material and preparation method and application thereof

Abstract

The application discloses a kind of low moisture solid electrolyte material and its preparation method and application, belong to lithium ion battery technical field. After solid electrolyte powder is uniformly dispersed in the mixed solution of anhydrous ethanol / deionized water, γ-glycidyl ether oxypropyl trimethoxysilane (KH-560) is added, condensation reflux is carried out, and preliminary modified solid electrolyte material is obtained by fully reacting;The preliminary modified solid electrolyte material is uniformly dispersed in N, N-dimethylformamide (DMF) with polyhedral oligomeric silsesquioxane (POSS), condensation reflux is carried out, and low moisture solid electrolyte material is obtained by fully reacting.The moisture value of the final obtained solid electrolyte material is less than 1000ppm.The application uses the above method, by changing the addition amount of KH-560 and POSS, to realize the adjustment of the moisture of solid electrolyte material, thereby reducing the storage cost of solid electrolyte material, and improving the safety stability and cycle life of lithium ion battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a low-moisture solid-state electrolyte material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of new energy industry, lithium ion batteries, as the most promising energy storage system, have attracted widespread attention. This makes the new energy market and researchers have more stringent requirements for the performance of energy density, safety and stability, and cycle life of lithium ion batteries. However, the existing liquid lithium ion battery system cannot simultaneously meet the high energy density and high safety and stability. Therefore, in recent years, solid-state electrolyte materials have become the focus of research.

[0003] Solid-state electrolyte materials mainly include the following types: garnet type, NASICON type, perovskite type, LISICON type, etc., which can be used as the ion transport layer of solid-state batteries, have high ionic conductivity and electronic insulation, and play a key role in the overall performance of the battery. It mainly has three forms in solid-state batteries, including positive and negative electrode particle coating, positive and negative electrode sheet mixing, and separator coating.

[0004] However, solid-state electrolyte materials are a strong hydrophilic material, and there are a large number of hydrophilic groups on the surface. The stability to air and water at room temperature is poor. At the same time, the moisture content is an important indicator in the production process of lithium ion batteries. When the moisture content of the production raw materials exceeds the standard or excessive moisture is introduced during the production process, a large amount of HF will be generated in the battery, thereby reducing the safety and cycle life of the battery.

[0005] The main solution to the above problems is: (1) remove the hydrophilic groups on the surface of the solid-state electrolyte material, such as the treatment method for solving the high moisture problem of nano solid-state electrolyte disclosed in Chinese patent CN117352828A, which reduces the impurities and adsorbed crystal water on the surface of the nano solid-state electrolyte through low-temperature sintering, to obtain a solid-state electrolyte material with low moisture and low impurity content; (2) reduce the proportion of small particle size particles, such as the low-moisture nano solid-state electrolyte powder material, preparation method and application disclosed in Chinese patent CN18553993A, which separates the nano solid-state electrolyte by centrifugation to obtain a powder material without small particles with a particle size of less than 250 nm, thereby reducing the moisture content of the material. The above methods are physical methods, and the powder obtained by using the two methods cannot be stable to air and water at room temperature, so the use environment needs to strictly control the humidity.

[0006] Therefore, the present application proposes a low-moisture solid-state electrolyte material and a preparation method, which has good stability to air and water at room temperature, and is beneficial to improve the safety and stability and cycle life of lithium ion batteries. SUMMARY

[0007] The application aims to provide a low-moisture solid-state electrolyte material and a preparation method and application thereof, which is modified by KH-560 and POSS, and a low-surface-energy polymer is coated on the surface of the solid-state electrolyte material, so that the solid-state electrolyte material has good stability to air and water at room temperature, and the problems in the background art are solved.

[0008] To achieve the above-mentioned purpose, the application provides a preparation method of a low-moisture solid-state electrolyte material, which specifically comprises the following steps:

[0009] S1, uniformly dispersing a solid-state electrolyte powder into a mixed solution of anhydrous ethanol / deionized water, adding acid to adjust the pH value, and then adding KH-560 to obtain a mixed solution;

[0010] S2, condensing and refluxing the mixed solution obtained in S1, fully reacting, cooling to room temperature after the reaction is completed, washing, and drying to obtain a preliminarily treated powder;

[0011] S3, dispersing the powder obtained in S2 into DMF and adding POSS to obtain a mixed solution;

[0012] S4, condensing and refluxing the mixed solution obtained in S3, fully reacting, cooling to room temperature after the reaction is completed, washing, and drying to obtain a low-moisture solid-state electrolyte material.

[0013] Preferably, the solid-state electrolyte powder is one of a garnet-type solid-state electrolyte, a NASICON-type solid-state electrolyte, a perovskite-type solid-state electrolyte, a LISICON-type solid-state electrolyte, and a derivative material thereof.

[0014] Preferably, the garnet-type solid-state electrolyte has a chemical general formula of Li7A3B2O 12 , wherein A is one or more of La, Ca, Sr, Ba, and K; B is one or more of Zr, Ta, Nb, and Hf;

[0015] The NASICON-type solid-state electrolyte has a chemical general formula of AM2(BO4)3, wherein A is one or more of Li, Na, and K, M is one or more of Ge, Ti, and Zr, and B is one or more of P and V;

[0016] The perovskite-type solid-state electrolyte has a chemical general formula of ABX3, wherein A is one or more of Nd, Ba, Sr, and La, and B is one or more of Ti and Al;

[0017] The LISICON-type solid-state electrolyte has a chemical general formula of Li 14G(HO4)4, where G is one or more of Zr, Cr, and Sn, and H is one or more of Si, S, and P.

[0018] Preferably, in S1, the mass ratio of solid electrolyte powder to KH-560 is 3:1; the volume ratio of anhydrous ethanol to deionized water in the mixed solution of anhydrous ethanol / deionized water is 4:1; the acid is one of hydrochloric acid, sulfuric acid, nitric acid, citric acid, and tartaric acid, and the pH value is adjusted to 3-5.

[0019] Preferably, in step S2, the reflux temperature is 60-100℃, the reaction time is 4-10h, the washing solvent is one or both of anhydrous ethanol and deionized water, the washing is performed 3-6 times, and the drying temperature is 40-80℃.

[0020] Preferably, in step S3, the mass ratio of POSS to powder is 1:1; POSS is POSS silanol, or [(RSiO] 1.5 )4(RXSiO 1.0 )3] Σ7 silicon oxides, polysilsesquioxanes [(RSiO 1.5 ) n ] Σ# and POSS fragment [(RSiO 1.5 ) m (RXSiO 1.0 ) n ] Σ# One of them, wherein X is OH or OR, and R is one of hydrocarbon, silane or siloxy group.

[0021] Preferably, in step S4, the reflux temperature is 60-100℃, the reaction time is 4-10h, the washing solvent is one or more of DMF, anhydrous ethanol, and deionized water, the washing is performed 3-6 times, and the drying temperature is 40-80℃.

[0022] The present invention also provides a low-moisture solid electrolyte material prepared by the above preparation method.

[0023] This invention also provides the application of the above-mentioned solid electrolyte material in the preparation of lithium-ion secondary batteries.

[0024] Therefore, the low-moisture solid electrolyte material, its preparation method, and its application disclosed in this invention have the following beneficial effects:

[0025] (1) This invention utilizes KH-560 and POSS to perform composite modification on solid electrolyte materials. A layer of POSS with a nanoscale organic-inorganic structure and low surface energy is coated on the surface of the solid electrolyte material. Its hydrophobic groups can prevent further water penetration and greatly improve the hydrophobicity of the material. At the same time, the spatial characteristics of POSS material can form a rough structure on the surface of the solid electrolyte material, further enhancing the hydrophobic properties of the material, thereby achieving a low moisture effect.

[0026] (2) This invention reduces the environmental requirements for solid electrolyte materials during use and storage by coating and modifying them;

[0027] (3) Lithium-ion batteries using the low-moisture solid electrolyte material prepared by the present invention can improve safety stability and cycle life.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 SEM image of the low-moisture LATP prepared in Example 1;

[0030] Figure 2 The XRD pattern of the low-moisture LATP prepared in Example 1. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0032] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0033] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0034] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art.

[0035] Example 1

[0036] This embodiment provides a method for preparing a low-moisture solid electrolyte material, the specific steps of which are as follows:

[0037] 1.5g of Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) was dispersed in 250 ml of ethanol / water (V:V = 200 / 50) mixed solution by sonication for 1 h. The pH was adjusted to 4.5 with HCl solution (1M). 0.5 g of γ-glycidoxypropyltrimethoxysilane was slowly added, and the mixture was sonicated for 0.5 h to obtain a mixed solution. The solution was then transferred to a 500 ml three-necked flask and refluxed in an oil bath at 80 °C for 6 h. After cooling to room temperature, the reaction product was repeatedly washed four times by centrifugation with anhydrous ethanol and deionized water, and then vacuum dried at 60 °C for 12 h to obtain the pre-treated powder.

[0038] The powder obtained in the previous step was ultrasonically dispersed in 150 ml of DMF, and then 1.5 g of aminopropyl isobutyl polyhedrally siloxane was added. The mixture was then transferred to a 500 ml three-necked flask and refluxed in an oil bath at 85 °C for 6 h. After cooling to room temperature, the reaction product was repeatedly centrifuged and washed five times with DMF, anhydrous ethanol, and deionized water, and then vacuum dried at 60 °C for 12 h to obtain a low-moisture solid electrolyte material.

[0039] SEM image of the low-moisture LATP prepared in Example 1 is shown below. Figure 1 As shown, the XRD pattern is as follows Figure 2 As shown. By Figure 1 It can be seen that the surface of the low-moisture LATP material prepared in this embodiment has a distinct rough coating layer, which should be the composite coating of KH-560 and aminopropyl isobutyl polyhedrally siloxane in this scheme. Figure 2 It can be seen that the main phase of the low-moisture LATP material prepared by this method is consistent with the phase of the 35-0754 card, and there are no obvious impurities.

[0040] Example 2

[0041] This embodiment provides a method for preparing a low-moisture solid electrolyte material, the specific steps of which are as follows:

[0042] 1.5g of Li7La3Zr2O 12 (LLZO) was ultrasonically dispersed in 250 ml of an ethanol / water (V:V = 200 / 50) mixed solution for 1 h. The pH was adjusted to approximately 4.5 with HCl solution (1M). 0.5 g of γ-glycidoxypropyltrimethoxysilane was slowly added, and the mixture was ultrasonicated for 0.5 h to obtain a mixed solution. The solution was then transferred to a 500 ml three-necked flask and refluxed in an oil bath at 80 °C for 6 h. After cooling to room temperature, the reaction product was repeatedly centrifuged and washed four times with anhydrous ethanol and deionized water. It was then vacuum dried at 60 °C for 12 h to obtain the pre-treated powder.

[0043] The powder obtained in the previous step was ultrasonically dispersed in 150 ml of DMF, and then 1.5 g of aminopropyl isobutyl polyhedrally siloxane was added. The mixture was then transferred to a 500 ml three-necked flask and refluxed in an oil bath at 85 °C for 6 h. After cooling to room temperature, the reaction product was repeatedly centrifuged and washed five times with DMF, anhydrous ethanol, and deionized water, and then vacuum dried at 60 °C for 12 h to obtain a low-moisture solid electrolyte material.

[0044] Example 3

[0045] This embodiment provides a method for preparing a low-moisture solid electrolyte material, the specific steps of which are as follows:

[0046] 1.5g of Li 0.33 La 0.56 TiO3 (LLTO) was ultrasonically dispersed in 250 ml of an ethanol / water (V:V = 200 / 50) mixed solution for 1 h. The pH was adjusted to approximately 4.5 with HCl solution (1M). 0.5 g of γ-glycidoxypropyltrimethoxysilane was slowly added, and the mixture was ultrasonicated for 0.5 h to obtain a mixed solution. This solution was then transferred to a 500 ml three-necked flask and refluxed in an oil bath at 80 °C for 6 h. After cooling to room temperature, the reaction product was repeatedly centrifuged and washed four times with anhydrous ethanol and deionized water. It was then vacuum dried at 60 °C for 12 h to obtain the pre-treated powder.

[0047] The powder obtained in the previous step was ultrasonically dispersed in 150 ml of DMF, and then 1.5 g of aminopropyl isobutyl polyhedrally siloxane was added. The mixture was then transferred to a 500 ml three-necked flask and refluxed in an oil bath at 85 °C for 6 h. After cooling to room temperature, the reaction product was repeatedly centrifuged and washed five times with DMF, anhydrous ethanol, and deionized water, and then vacuum dried at 60 °C for 12 h to obtain a low-moisture solid electrolyte material.

[0048] Comparative Example 1

[0049] The material used in this comparative example is unmodified LATP material.

[0050] Comparative Example 2

[0051] The material used in this comparative example is unmodified LLZO material.

[0052] Comparative Example 3

[0053] The material used in this comparative example is unmodified LLTO material.

[0054] The moisture content of the materials in the above embodiments and comparative examples was tested, and the results are shown in Table 1. The moisture content was measured using a Karl Fischer moisture analyzer, with titration conducted continuously at 150°C for 10 minutes.

[0055] Table 1. Moisture content test results of the examples and comparative examples.

[0056]

[0057] As shown in Table 1, the moisture content of the modified LATP, LLZO and LATP powders was reduced to below 1400 ppm. The composite modification of POSS and KH560 has a significant effect on reducing the moisture content of solid electrolyte materials, and it can prevent solid electrolyte materials from adsorbing moisture from the environment.

[0058] The solid electrolyte materials of the above embodiments and comparative examples were used for positive electrode mixing. In this scheme, NCM523 was used as the positive electrode active material. During the positive electrode homogenization process, the ratio of added substances NCM523: solid electrolyte material: SP: PVDF was 96.3%: 0.5%: 2%: 2.2%.

[0059] A 2032 coin cell was assembled using the above positive electrode. In an argon glove box with an oxygen content below 0.01 ppm, the prepared solid electrolyte-blended NCM523 was used as the positive electrode, lithium metal sheets as the negative electrode, and 1 M LiPF6 dissolved in a ethylene carbonate (EC) / dimethyl carbonate (DMC) / diethyl carbonate (EMC) mixture (volume ratio 1:1:1) was used as the electrolyte. Polypropylene was used as the separator. The cells were charged and discharged at voltages ranging from 2.5 to 4.25 V. The electrochemical performance data of the coin cells are shown in Table 2.

[0060] Table 2 Electrochemical performance data of coin cells assembled with co-coated cathodes

[0061]

[0062] The comparison of the electrochemical performance of the coin cells in the examples and comparative examples in Table 2 shows that the solid electrolyte material prepared by the present invention has better cycle performance. This is because the mixed electrode using the low-moisture solid electrolyte has a lower moisture value, and the HF generated by moisture inside the cell will also be reduced, a series of side reactions will also be reduced, and the cycle life of the cell will be improved.

[0063] Therefore, this invention proposes a low-moisture solid electrolyte material and its preparation method. By using KH-560 and POSS to perform composite modification on the solid electrolyte material, good stability against air and water at room temperature is achieved, thereby reducing storage costs and improving the safety, stability and cycle life of lithium-ion batteries.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a low-moisture solid electrolyte material, characterized in that, Specifically, the following steps are included: S1. Disperse the solid electrolyte powder evenly in a mixed solution of anhydrous ethanol / deionized water, adjust the pH value with acid, and then add KH-560 to obtain a mixed solution. The mass ratio of solid electrolyte powder to KH-560 is 3:1; S2. The mixed solution obtained in S1 is refluxed under condenser to allow it to react completely. After the reaction is complete, it is cooled to room temperature, washed, and dried to obtain the pre-treated powder. S3. Disperse the powder obtained in S2 into DMF, add POSS, and obtain a mixed solution; The mass ratio of POSS to powder is 1:1; POSS is POSS silanol, formula [(RSiO 1.5 )4(RXSiO 1.0 )3] Σ7 silicon oxides, polysilsesquioxanes [(RSiO 1.5 ) n ] Σ# and POSS fragment [(RSiO 1.5 ) m (RXSiO 1.0 ) n ] Σ# One of them, wherein X is OH or OR, and R is one of hydrocarbon, silane or silyloxy group; S4. The mixed solution obtained in S3 is refluxed and allowed to react completely. After the reaction is complete, it is cooled to room temperature, washed, and dried to obtain a low-moisture solid electrolyte material.

2. The method for preparing a low-moisture solid electrolyte material according to claim 1, characterized in that: The solid electrolyte powder is one of the following: garnet-type solid electrolyte, NASICON-type solid electrolyte, perovskite-type solid electrolyte, LISICON-type solid electrolyte, and their derivative materials.

3. The method for preparing a low-moisture solid electrolyte material according to claim 2, characterized in that: The chemical formula of the garnet-type solid electrolyte is Li7A3B2O. 12 Where A is one or more of La, Ca, Sr, Ba, and K; and B is one or more of Zr, Ta, Nb, and Hf. The general chemical formula of the NASICON-type solid electrolyte is AM2(BO4)3, wherein A is one or more of Li, Na, and K, M is one or more of Ge, Ti, and Zr, and B is one or more of P and V; The perovskite-type solid electrolyte has the general chemical formula ABX3, wherein A is one or more of Nd, Ba, Sr, and La, and B is one or more of Ti and Al; The chemical formula of the LISICON solid electrolyte is Li 14 G(HO4)4, where G is one or more of Zr, Cr, and Sn, and H is one or more of Si, S, and P.

4. The method for preparing a low-moisture solid electrolyte material according to claim 1, characterized in that: In S1, the volume ratio of anhydrous ethanol to deionized water in the mixed solution of anhydrous ethanol / deionized water is 4:1; the acid is one of hydrochloric acid, sulfuric acid, nitric acid, citric acid, and tartaric acid, and the pH value is adjusted to 3-5.

5. The method for preparing a low-moisture solid electrolyte material according to claim 1, characterized in that: In S2, the reflux temperature is 60-100℃, the reaction time is 4-10h, the washing solvent is one or both of anhydrous ethanol and deionized water, the washing is performed 3-6 times, and the drying temperature is 40-80℃.

6. The method for preparing a low-moisture solid electrolyte material according to claim 1, characterized in that: In step S4, the reflux temperature is 60-100℃, the reaction time is 4-10h, the washing solvent is one or more of DMF, anhydrous ethanol, and deionized water, the washing is performed 3-6 times, and the drying temperature is 40-80℃.

7. A low-moisture solid electrolyte material, characterized in that: The low-moisture solid electrolyte material is prepared using any one of the preparation methods of claims 1-6.

8. The application of the low-moisture solid electrolyte material as described in claim 7, characterized in that: The low-moisture solid electrolyte material is used in the preparation of lithium-ion secondary batteries.

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