A polymer for a sulfide solid-state electrolyte and a preparation method, application thereof

Abstract

The present application relates to a kind of polymer for sulfide solid electrolyte and its preparation method, application.The preparation method of the polymer of the present application is emulsion polymerization method, lithium perfluoro vinyl ether sulfonate, dodecylfluoroheptyl methacrylate, emulsifier is added to deionized water, heated in butadiene atmosphere, then initiator is added to carry out polymerization reaction, the polymer is obtained, then it is blended with sulfide, and form a kind of polymer sulfide mixed electrolyte.The present application builds effective hydrophobic barrier network in mixed electrolyte by the synergistic effect of fluorinated group contained in lithium perfluoro vinyl ether sulfonate and dodecylfluoroheptyl methacrylate in polymer chain segment.This makes the preparation and short-time operation of mixed electrolyte slurry can be carried out in lower dew point dry room environment, reduces the dependence on strict inert atmosphere protection, thereby greatly reduces the production environment control cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of all-solid-state lithium batteries, in particular to a polymer for sulfide solid electrolyte and a preparation method and application thereof. BACKGROUND

[0002] All-solid-state lithium batteries have become the focus of the next generation of energy storage technology due to their high energy density, intrinsic safety (avoiding the risk of liquid electrolyte leakage), and excellent ability to inhibit lithium dendrites. However, its industrialization process is still limited by the performance bottleneck and large-scale preparation difficulties of the core material-solid-state electrolyte. Although the current mainstream sulfide solid electrolyte (such as argyrodite Li6PS5Cl) has a relatively high room temperature ionic conductivity (usually >10 -3 S·cm -1 ), it still faces the following key challenges in practical application:

[0003] 1. Poor environmental stability: sulfides are highly sensitive to air (especially moisture) and easily react to generate toxic H2S gas, leading to material structure degradation. The preparation process needs to rely on strict inert atmosphere protection, significantly increasing the process complexity and cost. 2. Insufficient interface compatibility: sulfides are prone to adverse chemical / electrochemical reactions when in contact with lithium metal anodes, resulting in a significant increase in interface impedance. 3. High overall cost: sulfide electrolytes rely on high-purity raw materials (such as Li2S, P2S5) and complex synthesis processes (such as high-energy ball milling, high-temperature sintering), making large-scale production cost prohibitive.

[0004] To overcome the above challenges, the strategy of combining polymer materials with sulfide electrolytes to construct a hybrid electrolyte system is considered effective. This strategy aims to synergistically leverage the advantages of both components: the polymer component can improve the flexibility of the hybrid electrolyte and improve the electrode / electrolyte interface contact, thereby reducing the required working pressure for battery assembly; at the same time, the hydrophobic nature of the polymer can effectively block the direct contact between the sulfide and moisture in the air, reducing the risk of H2S generation; while the high ionic conductivity of the sulfide electrolyte can effectively compensate for the low room temperature conductivity of the polymer electrolyte. In addition, the raw material cost of the polymer material is usually significantly lower than that of the sulfide electrolyte, providing a feasible path to reduce the overall manufacturing cost of all-solid-state batteries. SUMMARY

[0005] Therefore, the present application provides a polymer for sulfide solid electrolyte and a preparation method and application thereof. The preparation method of the polymer of the present application is emulsion polymerization, and the polymer is blended with sulfide to form a polymer-sulfide hybrid electrolyte.

[0006] The object of the present application can be achieved by the following scheme:

[0007] The application provides a polymer for sulfide solid electrolyte, which is prepared by the following method:

[0008] The lithium perfluoro vinyl ether sulfonate, dodecafluoroheptyl methacrylate and emulsifier are added into deionized water, heated in a butadiene atmosphere, and then the initiator is added for polymerization reaction, and the polymer is obtained after demulsification.

[0009] As an embodiment of the application, the mass percentage of lithium perfluoro vinyl ether sulfonate and dodecafluoroheptyl methacrylate is 10-20:10-20, preferably 10-17:10-17, and more preferably 14-16:14-16.

[0010] As an embodiment of the application, the mass ratio of lithium perfluoro vinyl ether sulfonate, dodecafluoroheptyl methacrylate and deionized water is 10-20:10-20:200, preferably 15:15:200.

[0011] As an embodiment of the application, the mass ratio of lithium perfluoro vinyl ether sulfonate, dodecafluoroheptyl methacrylate, emulsifier and initiator is 10-20:10-20:4-6:0.4-0.6, preferably 10-15:13-15:5:0.5.

[0012] As an embodiment of the application, the emulsifier comprises ammonium perfluoro-2-methyl-3-oxa hexanoate. Preferably, a fluorine-containing emulsifier is used to ensure the stability of the polymerization system and the performance of the product.

[0013] As an embodiment of the application, the initiator comprises one or more of ammonium sulfate and potassium persulfate. Preferably, a persulfate initiator is used in the application.

[0014] As an embodiment of the application, the temperature of the polymerization reaction is 65-75°C, and the time is 4-5h, preferably the temperature is 70°C, and the time is 4h.

[0015] As an embodiment of the application, the pressure of the butadiene atmosphere during the polymerization reaction is 0.5-0.7 mpa, preferably 0.55-0.65 mpa, and more preferably 0.6 mpa. The higher the pressure, the greater the solubility of butadiene in the solution. By controlling the pressure, the concentration of butadiene in the concentrated solution is controlled, the polymerization reaction is ensured, and the reaction time is further controlled to control the content of butadiene structure in the polymer.

[0016] As an embodiment of the application, demulsification is carried out by using a calcium chloride solution. After demulsification, the polymer is obtained by filtration, washing and drying. The drying is carried out at 60°C under vacuum for 24 hours.

[0017] As an embodiment of the present application, the structure of the obtained polymer is as follows:

[0018] ,

[0019] wherein a, b, c are the proportions of each monomer, wherein the proportions of each monomer in the copolymer are adjusted according to the target performance.

[0020] The present application provides a preparation method of a polymer sulfide hybrid electrolyte, comprising the following steps:

[0021] The polymer is dissolved in a solvent to form a polymer solution, and then the sulfide solid electrolyte powder is dispersed in the polymer solution to form a slurry, which is coated on a substrate, and the solvent is removed to form a polymer sulfide hybrid electrolyte (hybrid electrolyte film).

[0022] As an embodiment of the present application, the solvent includes one or more of toluene, xylene, dibromomethane, and isobutyl isobutyrate. The solvent of the present application is preferably selected from aprotic, nonpolar or weakly polar solvents to minimize chemical attack on the sulfide electrolyte.

[0023] As an embodiment of the present application, the sulfide solid electrolyte includes argyrodite-type sulfide electrolyte.

[0024] As an embodiment of the present application, the mass ratio of the polymer to the sulfide solid electrolyte is 10-25:75-90, preferably 10-15:85-90.

[0025] As an embodiment of the present application, the amount ratio of the polymer to the solvent is 0.15 g:10 ml.

[0026] As an embodiment of the present application, the solvent is removed by standing and drying the coated slurry. The standing time is 2-4 h, and the drying temperature is 55-65°C, and the time is 10-15 h. The present application is placed at room temperature to volatilize most of the solvent, and then transferred to a vacuum oven for drying to completely remove the residual solvent.

[0027] Compared with the prior art, the present application has the following remarkable beneficial effects:

[0028] (1) By the synergistic effect of the fluorinated groups contained in the lithium perfluoro vinyl ether sulfonate and the methyl dodecafluoroheptyl methacrylate in the polymer chain segment, an effective hydrophobic barrier network is constructed in the hybrid electrolyte. This makes the preparation and short-time operation of the hybrid electrolyte slurry can be carried out in a lower dew point dry room environment, reducing the dependence on strict inert atmosphere protection, thereby greatly reducing the production environment control cost.

[0029] (2) The introduction of the polymer component significantly improves the flexibility and machinability of the mixed electrolyte, enabling good contact between the electrode / electrolyte interface at a relatively low working pressure, which is beneficial to reducing the internal resistance of the battery and improving the cycle stability.

[0030] (3) The raw material cost and production cost of the polymer are generally lower than that of high-performance sulfide solid-state electrolyte. The use of the polymer described in the present application to partially replace expensive sulfide electrolyte provides a feasible technical path for reducing the overall manufacturing cost of the all-solid-state lithium battery. BRIEF DESCRIPTION OF DRAWINGS

[0031] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the following drawings:

[0032] Figure 1 Infrared spectrum of P-1 polymer prepared for Example 1. DETAILED DESCRIPTION

[0033] The present application will be described in detail below with reference to the accompanying drawings and specific examples. The following examples are implemented under the technical scheme of the present application, providing detailed implementation and specific operation process, which will help those skilled in the art to further understand the present application. It should be pointed out that the protection scope of the present application is not limited to the following examples, and several adjustments and improvements made under the concept of the present application also belong to the protection scope of the present application.

[0034] Example 1

[0035] Into a reaction kettle equipped with a stirrer, a thermometer, a gas inlet and a condenser, 200 g of deionized water and 5 g of perfluoro-2-methyl-3-oxa hexanoic acid ammonium salt, 15 g of lithium perfluoro vinyl ether sulfonate, 15 g of methyl methacrylate dodecafluoroheptyl ester were added, the butadiene gas was replaced three times by vacuum, then the temperature was raised to 70°C, the butadiene pressure was maintained at 0.6 mpa, 0.5 g of ammonium persulfate (APS) initiator (dissolved in 10 g of water) was injected to start the polymerization reaction for 4 hours, after the reaction was completed, it was cooled to room temperature, calcium chloride solution was added to break the emulsion, the precipitate was filtered and washed with deionized water several times, the obtained polymer was dried at 60°C under vacuum for 24 hours to obtain polymer P-1, the infrared spectrum is shown in Figure 1

[0036] Wet blending:

[0037] In a glove box, 0.1 g of polymer P-1 was weighed and dissolved in 10 mL of anhydrous toluene, and magnetically stirred until completely dissolved. 0.9 g of argyrodite sulfide electrolyte powder (Li 10 GeP2S​12 ) ), slowly add the sulfide powder into the above polymer solution. Stir for 2 hours to get a uniform slurry, pour the slurry M-1 into a polytetrafluoroethylene mold, let it stand at room temperature for 2 hours to evaporate most of the solvent, then transfer it to a vacuum oven at 60 °C to dry for 12 hours to completely remove the residual solvent, to get a self-supporting hybrid electrolyte film S-1.

[0038] Example 2

[0039] Into a reaction kettle equipped with a stirrer, a thermometer, a gas inlet and a condenser, add 200 g of deionized water and 5 g of ammonium perfluoro-2-methyl-3-oxahexanoate, lithium perfluoro vinyl ether sulfonate 10 g, dodecafluoroheptyl methacrylate 13 g, replace butadiene gas three times by vacuum, then heat to 70 °C, maintain butadiene pressure at 0.58 mpa, inject 0.5 g of ammonium persulfate (APS) initiator (dissolved in 10 g of water) to start the polymerization reaction for 4 hours, after the reaction is completed, cool to room temperature, add calcium chloride solution to break the emulsion, filter, wash the precipitate with deionized water several times, dry the obtained polymer at 60 °C under vacuum for 24 hours to obtain polymer P-2.

[0040] Wet blending:

[0041] In a glove box, weigh 0.1 g of polymer P-1, dissolve in 10 mL of anhydrous p-xylene, and stir magnetically until dissolved. Weigh 0.9 g of argyrodite sulfide electrolyte powder, slowly add the sulfide powder into the above polymer solution. Stir for 2 hours to get a uniform slurry, pour the slurry M-1 into a polytetrafluoroethylene mold, let it stand at room temperature for 2 hours to evaporate most of the solvent, then transfer it to a vacuum oven at 60 °C to dry for 12 hours to completely remove the residual solvent, to get a self-supporting hybrid electrolyte film S-2.

[0042] Example 3

[0043] Into a reaction kettle equipped with a stirrer, a thermometer, a gas inlet and a condenser, add 200 g of deionized water and 5 g of ammonium perfluoro-2-methyl-3-oxahexanoate, lithium perfluoro vinyl ether sulfonate 13 g, dodecafluoroheptyl methacrylate 14 g, replace butadiene gas three times by vacuum, then heat to 70 °C, maintain butadiene pressure at 0.58 mpa, inject 0.5 g of ammonium persulfate (APS) initiator (dissolved in 10 g of water) to start the polymerization reaction for 4 hours, after the reaction is completed, cool to room temperature, add calcium chloride solution to break the emulsion, filter, wash the precipitate with deionized water several times, dry the obtained polymer at 60 °C under vacuum for 24 hours to obtain polymer P-3.

[0044] wet-blending:

[0045] In a glove box, 0.15 g of polymer P-1 was weighed and dissolved in 10 mL of anhydrous isobutyl isobutyrate with magnetic stirring until dissolved. 0.85 g of argyrodite sulfide electrolyte powder was weighed and slowly added to the above polymer solution. The mixture was stirred for 2 hours to obtain a uniform slurry, which was cast on a polytetrafluoroethylene (PTFE) mold and left to stand at room temperature for 2 hours to allow most of the solvent to evaporate. The slurry was then transferred to a vacuum oven at 60 °C for 12 hours to dry and completely remove the residual solvent, obtaining a self-supporting mixed electrolyte film S-3.

[0046] Example 4

[0047] Into a reaction kettle equipped with a stirrer, thermometer, gas inlet and condenser, 200 g of deionized water, 5 g of ammonium perfluoro-2-methyl-3-oxahexanoate, 15 g of lithium perfluoro vinyl ether sulfonate, 15 g of dodecafluoroheptyl methacrylate were added. The butadiene gas was replaced three times by vacuum, then the temperature was raised to 70 °C, maintaining the butadiene pressure at 0.6 mpa, 0.5 g of ammonium persulfate (APS) initiator (dissolved in 10 g of water) was injected to start the polymerization reaction for 4 hours. After the reaction was completed, it was cooled to room temperature, calcium chloride solution was added to break the emulsion, and the precipitate was filtered and washed several times with deionized water. The obtained polymer was dried at 60 °C under vacuum for 24 hours to obtain polymer P-4.

[0048] wet-blending:

[0049] In a glove box, 0.15 g of polymer P-1 was weighed and dissolved in 10 mL of anhydrous isobutyl isobutyrate with magnetic stirring until dissolved. 0.85 g of argyrodite sulfide electrolyte powder was weighed and slowly added to the above polymer solution. The mixture was stirred for 2 hours to obtain a uniform slurry, which was cast on a polytetrafluoroethylene (PTFE) mold and left to stand at room temperature for 2 hours to allow most of the solvent to evaporate. The slurry was then transferred to a vacuum oven at 60 °C for 12 hours to dry and completely remove the residual solvent, obtaining a self-supporting mixed electrolyte film S-3.

[0050] Example 5

[0051] The preparation method is basically the same as that of Example 1, except that 12 g of lithium perfluoro vinyl ether sulfonate and 12 g of dodecafluoroheptyl methacrylate were used, obtaining a self-supporting mixed electrolyte film S-5.

[0052] Example 6

[0053] The preparation method is basically the same as that of example 1, except that lithium perfluorovinyl ether sulfonate 18g, dodecafluoroheptyl methacrylate 18g are used, to obtain a self-supporting mixed electrolyte membrane S-6.

[0054] Example 7

[0055] The preparation method is basically the same as that of example 1, except that the butadiene pressure is 0.5mpa, to obtain a self-supporting mixed electrolyte membrane S-7.

[0056] Example 8

[0057] The preparation method is basically the same as that of example 1, except that the butadiene pressure is 0.7mpa, to obtain a self-supporting mixed electrolyte membrane S-8.

[0058] Performance test:

[0059] Ion conductivity test method

[0060] The ion conductivity test method uses an alternating current impedance method, 100mg is taken in a pressure cell mold, and then pressurized to 30MPa. The test parameters of the electrochemical workstation are set as follows: alternating current impedance test frequency range 1MHz~1Hz, test is carried out, after the test is completed, the thickness of the film is measured, and the calculation formula is as follows: σLi + =L / RS, wherein R is the alternating current impedance value, L is the film thickness, and S is the film area. The conductivity test results are shown in Tables 1 and 2.

[0061] Table 1 Change of conductivity of mixed sulfide electrolyte in dry room

[0062]

[0063] The longer the exposure time, the less the conductivity decreases, indicating that the longer the window time left for processing.

[0064] Table 2 Conductivity of mixed sulfide electrolyte prepared at different pressures in dry room

[0065]

[0066] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or modifications within the scope of the claims, which does not affect the essential content of the present application.

Claims

1. A polymer for use in sulfide solid electrolytes, characterized in that, It is prepared by the following method: Lithium perfluorovinyl ether sulfonate, dodecafluoroheptyl methacrylate, and emulsifier are added to deionized water, heated in a butadiene atmosphere, and then an initiator is added to carry out a polymerization reaction. After demulsification, the polymer is obtained. The ratio of lithium perfluorovinyl ether sulfonate, dodecafluoroheptyl methacrylate, emulsifier, and initiator is 10-20:10-20:4-6:0.4-0.6; During the polymerization reaction, the pressure of the butadiene atmosphere is 0.5-0.7 MPa; The polymerization reaction is carried out at a temperature of 65-75°C for 4-5 hours.

2. The polymer for a sulfide solid electrolyte according to claim 1, characterized in that, The mass ratio of lithium perfluorovinyl ether sulfonate, dodecafluoroheptyl methacrylate, and deionized water is 10-20:10-20:

200.

3. The polymer for a sulfide solid electrolyte according to claim 1, characterized in that, The emulsifier includes ammonium perfluoro-2-methyl-3-oxahexanoate; And / or, the initiator includes one or more of ammonium sulfate and potassium persulfate.

4. A method for preparing a polymer sulfide mixed electrolyte, characterized in that, Includes the following steps: The polymer as described in claim 1 is dissolved in a solvent to form a polymer solution. The sulfide solid electrolyte powder is then dispersed in the polymer solution to form a slurry, which is then coated onto a substrate. The solvent is removed to form a polymer-sulfide mixed electrolyte.

5. The preparation method according to claim 4, characterized in that, Solvents include one or more of toluene, xylene, dibromomethane, and isobutyl isobutyrate.

6. The preparation method according to claim 4, characterized in that, The sulfide solid electrolyte includes a sulfide electrolyte of the sulfide type.

7. The preparation method according to claim 4, characterized in that, The mass ratio of polymer to sulfide solid electrolyte is 10-25:75-90.

8. The use of the polymer as described in claim 1 in the preparation of lithium batteries.

Images