Solid-state polymer electrolyte containing two-dimensional nanometer additives and preparation method and application thereof

Abstract

The application discloses a solid-state polymer electrolyte containing two-dimensional nano additives and a preparation method and application thereof, and belongs to the technical field of lithium metal batteries. The preparation method of the solid-state polymer electrolyte is as follows: transition metal phosphorus sulfide precursors, lithium salt and polymer are added into a dispersing agent, stirring is conducted to strip the transition metal phosphorus sulfide and lithiumize, and a polymer electrolyte precursor solution is formed; and stirring is finished to obtain a mixture slurry; wherein the transition metal phosphorus sulfide precursors include one or more of FePS3, MnPS3, CdPS3 and ZnPS3; the mixture slurry is coated on a mold, and drying is conducted to obtain the solid-state polymer electrolyte containing two-dimensional nano additives. The preparation method is a one-step lithiumization method for preparing two-dimensional nano additives, is more simple than a two-step alkali metal ion lithiumization method, has no adverse effect on the performance of lithium batteries, and can avoid the introduction of impurity water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium metal battery, more particularly to a solid-state polymer electrolyte containing two-dimensional nano additive, and a preparation method and application thereof. BACKGROUND

[0002] Unlike lithium-ion batteries and lithium-ion polymer batteries, a solid-state battery is a battery using solid electrodes and solid electrolytes. A solid-state polymer battery matching a lithium metal negative electrode is a hotspot in the field of next-generation battery research. A solid-state electrolyte is a core part of a solid-state battery, which plays a role of isolating electrons and conducting ions between the positive and negative electrodes, and has an extremely important influence on the capacity, working temperature, working voltage range, cycle stability and safety performance of the battery. The solid-state electrolyte can be divided into inorganic and organic solid-state electrolytes, and among them, the inorganic solid-state electrolyte is composed of two systems of oxides and sulfides; the organic solid-state electrolyte is mainly a solid-state electrolyte taking polymer as a basic material. The polymer solid-state electrolyte is mainly composed of a polymer matrix and a lithium salt, and its main characteristics are high high-temperature ionic conductivity, a larger electrochemical stability window, good compatibility with electrodes, etc.; due to the film-forming characteristics of the polymer, it is easy to process.

[0003] In addition to having a quite high theoretical specific energy density and high safety, the solid-state polymer battery still has a serious interface stability problem. There are serious side reactions between the polymer electrolyte and the positive and negative electrodes, which leads to lithium dendrite growth and irreversible decay of the positive electrode capacity, and thus seriously limits the cycle life of the battery. Therefore, a large number of research and development of additives are carried out to improve the electrochemical performance and interface stability of the solid-state polymer electrolyte, among which two-dimensional nano additives based on transition metal phosphorus sulfides can effectively inhibit the growth of lithium dendrites. However, the exfoliation and lithiumation method thereof is relatively complex, and it is difficult to avoid the introduction of impurity water, which has certain side reactions and safety hazards.

[0004] Therefore, it is necessary to develop an exfoliation and lithiumation method of transition metal phosphorus sulfide, which simplifies the preparation method without affecting the battery performance and avoids the introduction of water. SUMMARY

[0005] In view of the above problems, the present application provides a solid-state polymer electrolyte containing two-dimensional nano additive, and a preparation method and application thereof. Compared with the two-step non-in-situ exfoliation and lithiumation method reported at present, the one-step method provided by the present application is more simple, saves raw materials, and avoids the introduction of impurity water, thereby avoiding the side reactions and performance degradation caused by water. The two-dimensional nano additive obtained by lithiumation of the transition metal phosphorus sulfide precursor provided by the present application is uniformly dispersed in the solid-state polymer electrolyte, and can mechanically inhibit the growth of lithium dendrites.

[0006] The first objective of this invention is to provide a method for preparing a solid polymer electrolyte containing two-dimensional nano-additives, which is carried out according to the following steps:

[0007] Transition metal phosphorus sulfide precursor, lithium salt and polymer are added to a dispersant and stirred to allow the transition metal phosphorus sulfide to be delithiated and to form a polymer electrolyte precursor solution; after stirring, a slurry is obtained; wherein, the transition metal phosphorus sulfide precursor includes one or more of FePS3, MnPS3, CdPS3 and ZnPS3.

[0008] The mixture slurry was coated onto a mold and dried to obtain a solid polymer electrolyte containing two-dimensional nano-additives.

[0009] Preferably, the stirring temperature is 25-200℃ and the stirring time is 1-48h; wherein, the ratio of transition metal phosphorus sulfide precursor to dispersant is 1g:1-1000ml, the mass ratio of transition metal phosphorus sulfide precursor to lithium salt is 1:0.05-20, and the mass ratio of transition metal phosphorus sulfide precursor to polymer is 1:0.01-100.

[0010] Preferably, the dispersant is one or more of ethanol, isopropanol, water, dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, acetonitrile, and xylene.

[0011] Preferably, the lithium salt is one or more selected from LiF, LiPF6, LiTFSI, LiFSI, LiCl, Li2O, Li3N, Li2CO3, LiOH, LiBF4, LiBOB, LiDFOB, and LiClO4.

[0012] Preferably, the polymer is one or more selected from polyethylene glycol diacrylate, polymethyl methacrylate, polybutyl acrylate, polyfluorobutyl acrylate, polyvinyl carbonate, polyethylene glycol, polyethylene oxide, carboxymethyl cellulose, triethyl cellulose, chitosan, polyvinylidene fluoride, polytetrafluoroethylene, and polytetrahydrofuran.

[0013] Preferably, the drying method is blower drying or vacuum drying, the drying temperature is 25-200℃, and the drying time is 4-48h.

[0014] A second objective of this invention is to provide a solid polymer electrolyte containing two-dimensional nano-additives prepared by the above-described preparation method.

[0015] A third objective of this invention is to provide the application of the above-mentioned solid polymer electrolyte containing two-dimensional nano-additives in lithium metal batteries.

[0016] Mechanism of the invention: The invention uses water or organic solvent as a dispersant, adds a transition metal phosphorus sulfide precursor, lithium salt and polymer, and stirs. During the stirring process, the transition metal phosphorus sulfide is uniformly dispersed in the dispersant and fully mixed with the lithium salt. During the stirring process, lithium ions are intercalated and lithiated between the transition metal phosphorus sulfide layers, and the transition metal phosphorus sulfide is peeled off into few-layer or single-layer two-dimensional sheets. Moreover, a fully lithiated two-dimensional nano-additive can be obtained in one peeling lithiation process, and a polymer electrolyte precursor solution is formed simultaneously. At the same time, the lithiated two-dimensional nano-additive and the composite polymer electrolyte precursor solution are obtained.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The one-step stripping lithiation method provided by the present invention is much simpler than the two-step method reported so far. It can also obtain a solid polymer electrolyte precursor solution at the same time. After drying, a composite solid polymer electrolyte can be obtained, avoiding multi-step operations of non-in-situ preparation and saving raw materials.

[0019] (2) The one-step stripping lithiation method provided by the present invention has no adverse effect on the electrochemical performance of the composite electrolyte compared with the currently reported two-step method;

[0020] (3) The one-step stripping lithiation method provided by the present invention avoids the introduction of impurity water in the lithiation operation, and avoids side reactions and safety hazards compared with the two-step method reported so far. Attached Figure Description

[0021] Figure 1 The cycling performance of the solid polymer electrolyte lithium metal symmetric batteries containing two-dimensional nano-additives prepared in Example 1 and Comparative Example 1 is shown.

[0022] Figure 2 The cycling performance of the solid polymer electrolyte lithium metal symmetric batteries containing two-dimensional nano-additives prepared in Example 2 and Comparative Example 2 is shown.

[0023] Figure 3 This is a scanning electron microscope cross-sectional image of the solid polymer electrolyte containing two-dimensional nano-additives prepared in Example 3. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials can be obtained commercially.

[0026] Example 1

[0027] (1) Weigh 2g CdPS3, 0.9g triethylcellulose, and 0.2g LiBF4 lithium salt, add them to 20mL dimethylformamide solution, and stir at 30℃ for 24h;

[0028] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 60°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0029] Example 2

[0030] (1) Weigh 0.1g MnPS3, 0.8g polytetrahydrofuran, 0.2g LiTFSI and 0.2g LiBOB lithium salt, add them to 20mL dimethylformamide solution, and stir at 30℃ for 24h;

[0031] (2) The slurry is coated on a polytetrafluoroethylene mold and dried at 120°C for 48 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0032] Example 3

[0033] (1) Weigh 0.5g MnPS3, 1.0g polyvinylidene fluoride, 0.2g LiBF4 and 0.2g LiPF6 lithium salt, add them to 25mL N-methylpyrrolidone solution, and stir at 60℃ for 24h.

[0034] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 80°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0035] Example 4

[0036] (1) Weigh 0.01g ZnPS3, 1.0g polyethylene glycol diacrylate, and 0.2g LiF lithium salt, add them to 10mL acetonitrile solution, and stir at 30℃ for 24h;

[0037] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 30°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0038] Example 5

[0039] (1) Weigh 0.97g of transition metal phosphorus sulfide precursor (FePS3 and MnPS3 in a mass ratio of 1:1), 1.0g of polymer (polymethyl methacrylate and triethyl cellulose in a volume ratio of 1:100), and 0.1g of LiFSI lithium salt, add them to 20mL of dimethylformamide solution, and stir at 30℃ for 24h.

[0040] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 180°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0041] Example 6

[0042] (1) Weigh 0.16g FePS3, 0.8g polymer (the volume ratio of polybutyl acrylate and polytetrafluoroethylene is 1:20), and 0.16g LiCl lithium salt, add them to 20mL dimethylformamide solution, and stir at 30℃ for 24h.

[0043] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 30°C for 48 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0044] Example 7

[0045] (1) Weigh 0.1g CdPS3, 1.0g polyfluorinated butyl acrylate, and 0.3g LiClO4 lithium salt, add them to 20mL of dispersant solution (the volume ratio of dimethylformamide to water is 1:1), and stir at 30℃ for 24h.

[0046] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 30°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0047] Example 8

[0048] (1) Weigh 0.64g of transition metal phosphorus sulfide precursor (CdPS3 and MnPS3 in a mass ratio of 1:10), 0.8g of polymer (polyethylene carbonate and carboxymethyl cellulose in a volume ratio of 1:50), and 0.4g of LiDFOB, add them to 20mL of dimethylformamide solution, and stir at 30℃ for 24h.

[0049] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 200°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0050] Example 9

[0051] (1) Weigh 0.81g CdPS3, 0.0081g polyethylene glycol, and 0.36g electrolyte salt (Li2O and LiF mass ratio is 1:20) lithium salt, add them to 20mL dispersant solution (ethanol, isopropanol and water volume ratio is 1:1:1), and stir at 30℃ for 24h.

[0052] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 30°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0053] Example 10

[0054] (1) Weigh 0.05g CdPS3, 1.0g polyethylene oxide, and 0.1g lithium salt (Li3N and LiFSI mass ratio is 1:100), add them to 20mL isopropanol solution, and stir at 100℃ for 5h.

[0055] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 30°C for 12 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0056] Example 11

[0057] (1) Weigh 0.24g of transition metal phosphorus sulfide precursor (FePS3 and CdPS3 in a mass ratio of 1:5), 0.8g of carboxymethyl cellulose, and 0.04g of lithium salt (LiCl and LiF in a mass ratio of 1:50), add them to 20mL of tetrahydrofuran solution, and stir at 40℃ for 32h.

[0058] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 80°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0059] Example 12

[0060] (1) Weigh 0.45g CdPS3, 0.9g chitosan, and 9g lithium salt (LiBF4, LiPF6 and Li2CO3 in a mass ratio of 1:80:50) and add them to 20mL xylene solution. Stir at 25℃ for 48h.

[0061] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 200°C for 4 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0062] Example 13

[0063] (1) Weigh 0.6g FePS3, 1.0g polymer (the volume ratio of polytetrafluoroethylene, triethyl cellulose and chitosan is 1:1:1), and 0.03g LiOH lithium salt, add them to 0.6mL of water, and stir at 200℃ for 1h;

[0064] (2) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 25°C for 48 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0065] Comparative Example 1

[0066] (1) Disperse 1g CdPS3 in 100mL of deionized water, add 0.1g potassium chloride, and stir at room temperature for 24h. Filter the dispersion using a cellulose membrane, wash with deionized water, and dry the product at 30℃ for 4h.

[0067] (2) Disperse the dried product in 100 mL of deionized water, add 0.1 g of lithium chloride, and stir at room temperature for 24 h. Then place it in an ultrasonic crusher and crush it at 600 W for 10 min. Centrifuge the obtained product at 10000 rpm for 15 min. Filter the supernatant obtained by vacuum filtration through a polycarbonate filter membrane. Dry the product at 30 °C for 24 h to obtain the two-dimensional nano additive.

[0068] (3) Weigh 2g of two-dimensional nano additives, 0.9g of triethyl cellulose, and 0.2g of LiBF4 lithium salt, add them to 20mL of dimethylformamide solution, and stir at 30℃ for 24h.

[0069] (4) The slurry is coated on a polytetrafluoroethylene mold and dried under vacuum at 60°C for 24 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0070] Comparative Example 2

[0071] (1) Disperse 0.5g MnPS3 in 200mL of deionized water, add 2g potassium chloride, and stir at room temperature for 24h. Filter the dispersion using a cellulose membrane, wash with deionized water, and dry the product at 30℃ for 4h.

[0072] (2) Disperse the dried product in 200 mL of deionized water, add 2 g of lithium chloride, and stir at room temperature for 24 h. Then place it in an ultrasonic crusher and crush it at 300 W for 30 min. Centrifuge the obtained product at 10000 rpm for 30 min. Filter the supernatant obtained by vacuum filtration through a polycarbonate filter membrane. Dry the product at 30 °C for 24 h to obtain the two-dimensional nano additive.

[0073] (3) Weigh 0.1g of two-dimensional nano additives, 0.8g of polytetrahydrofuran, 0.2g of LiTFSI and 0.2g of LiBOB lithium salt, add them to 20mL of dimethylformamide solution, and stir at 30℃ for 24h.

[0074] (4) The slurry is coated on a polytetrafluoroethylene mold and dried at 120°C for 48 hours to obtain a polymer solid electrolyte membrane with uniformly dispersed two-dimensional nano-additives.

[0075] Figure 1 The cycling performance of the solid polymer electrolyte lithium metal symmetric batteries containing two-dimensional nano-additives prepared in Example 1 and Comparative Example 1 was compared. Figure 1 It is evident that the one-step stripping of lithiation does not affect the electrochemical performance of symmetric batteries, and the cycle performance of both is similar.

[0076] Figure 2 The cycle performance of the solid polymer electrolyte lithium metal symmetric batteries containing two-dimensional nano-additives prepared in Example 2 and Comparative Example 2 is compared; Figure 2 It is evident that the one-step stripping of lithiation has no impact on the capacity and cycle performance of the full cell, and the electrochemical performance of the two is similar.

[0077] Figure 3 This is a scanning electron microscope cross-sectional image of the solid polymer electrolyte containing two-dimensional nano-additives prepared in Example 3; (The image is from...) Figure 3 It is evident that the two-dimensional nano-additive is dispersed relatively uniformly within the polymer matrix, with no obvious agglomeration observed.

[0078] It should be noted that when numerical ranges are mentioned in the claims of this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0079] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a solid polymer electrolyte containing two-dimensional nano-additives, characterized in that, Prepare according to the following steps: A transition metal phosphorus sulfide precursor, lithium salt, and polymer are added to a dispersant, and the mixture is stirred to allow the transition metal phosphorus sulfide to be delithiated and to form a polymer electrolyte precursor solution. After stirring, a slurry is obtained. The transition metal phosphorus sulfide precursor includes one or more of FePS3, MnPS3, CdPS3, and ZnPS3. The stirring temperature is 25-200℃, the ratio of transition metal phosphorus sulfide precursor to dispersant is 1g:1-1000ml, and the mass ratio of transition metal phosphorus sulfide precursor to lithium salt is 1:0.05-20. The mixture slurry was coated onto a mold and dried to obtain a solid polymer electrolyte containing two-dimensional nano-additives.

2. The method for preparing a solid polymer electrolyte containing two-dimensional nano-additives according to claim 1 is characterized in that, The stirring time is 1-48h; wherein the mass ratio of transition metal phosphorus sulfide precursor to polymer is 1:0.01-100.

3. The method for preparing a solid polymer electrolyte containing two-dimensional nano-additives according to claim 1, characterized in that, The dispersant is one or more of ethanol, isopropanol, water, dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, acetonitrile, and xylene.

4. The method for preparing a solid polymer electrolyte containing two-dimensional nano-additives according to claim 1, characterized in that, The lithium salt is one or more of LiF, LiPF6, LiTFSI, LiFSI, LiCl, Li2O, Li3N, Li2CO3, LiOH, LiBF4, LiBOB, LiDFOB, and LiClO4.

5. The method for preparing a solid polymer electrolyte containing two-dimensional nano-additives according to claim 1, characterized in that, The polymer is one or more of the following: polyethylene glycol diacrylate, polymethyl methacrylate, polybutyl acrylate, polyfluorobutyl acrylate, polyvinyl carbonate, polyethylene glycol, polyethylene oxide, carboxymethyl cellulose, triethyl cellulose, chitosan, polyvinylidene fluoride, polytetrafluoroethylene, and polytetrahydrofuran.

6. The method for preparing a solid polymer electrolyte containing two-dimensional nano-additives according to claim 1, characterized in that, The drying method is blower drying or vacuum drying, the drying temperature is 25-200℃, and the drying time is 4-48h.

7. A solid polymer electrolyte containing two-dimensional nano-additives prepared by the preparation method according to any one of claims 1-6.

8. The application of the solid polymer electrolyte containing two-dimensional nano-additives as described in claim 7 in lithium metal batteries.

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