Positive electrode binder for solid-state battery, corresponding battery and preparation method

Abstract

The invention belongs to a supramolecular positive electrode composite binder for a solid-state lithium battery, a corresponding battery and a preparation method, and the preparation method of the positive electrode composite binder for the solid-state lithium battery comprises the following steps: complexing a supramolecular macrocyclic host, a polymer molecule guest and a lithium salt according to a certain proportion, according to the positive electrode binder, the mechanical stability of a positive electrode can be guaranteed, a good lithium ion channel can be constructed in the positive electrode, the cycle rate performance of a solid-state battery is effectively improved, and the preparation method is simple and suitable for large-scale industrial application.

Description

Technical Field

[0001] The present invention belongs to the field of new energy batteries, and specifically relates to a preparation method of a positive electrode supramolecular composite binder for a solid-state battery, a positive electrode sheet prepared by using this method, and a corresponding battery. Background Art

[0002] With the advancement of environmental protection goals, solid-state batteries with high energy density and high safety are regarded as the core of the next-generation energy storage technology. As a key component of solid-state batteries, the ion transport efficiency and interface stability inside the positive electrode directly restrict the overall performance of solid-state batteries. However, traditional positive electrode binders (such as polyvinylidene fluoride) are difficult to meet the dual requirements of solid-state batteries for multi-scale ion transport networks and mechanical stability due to problems such as low ionic / electronic conductivity and insufficient interfacial adhesion. How to design a new type of binder with both high ion conduction ability and dynamic interface adaptability has become a key challenge to break through the performance bottleneck of solid-state batteries.

[0003] At present, certain progress has been made in the design of positive electrode binders for solid-state batteries. For example, a dry composite process based on lithium-ion conductive ionomers (such as tetrafluoroethylene copolymers) significantly improves the lithium-ion transport efficiency of the electrode by constructing continuous ion channels (ACS Energy Letters 2022, 7, 1092.). The introduction of functional functional groups (such as -OH, -COO-) has been proven to optimize the desolvation behavior at the electrode-electrolyte interface and reduce the interfacial impedance (Advanced Functional Materials, 2023, 202305974.). However, the existing binder systems still face significant defects: firstly, there is an inherent contradiction between high ionic conductivity and strong adhesion, and it is difficult for traditional polymers to balance the two; secondly, the mechanical stress caused by the rigid interface easily leads to the collapse of the electrode structure; thirdly, the chemical compatibility problem between the binder and the solid-state electrolyte has not been completely solved, and the interface deterioration caused by side reactions severely restricts the battery cycle life.

[0004] Improvement of positive electrode binders in the prior art: CN116814200A uses a polymer containing cyano, carboxyl, and pyrrole rings. The ionic conductivity is improved by the dipole interaction between cyano and lithium ions, the adhesion is enhanced by carboxyl, and the pyrrole ring provides an electron transport channel. The synergistic effect of the three functional groups requires strict control of the ratio, the process complexity is high, and performance fluctuations are likely to occur in actual production.

[0005] The present invention aims to provide a preparation method of a positive electrode supramolecular composite binder for a solid-state battery that can effectively promote the lithium-ion transport inside the positive electrode, simultaneously reduce the interfacial impedance between the positive electrode and the solid-state electrolyte, effectively improve the cycle rate performance of the solid-state battery, and the preparation method is simple and suitable for large-scale industrial application. Summary of the Invention

[0006] To overcome the problems of insufficient battery performance, complex preparation process, and excessively high cost of existing solid-state batteries, this application proposes a cathode supramolecular composite binder for solid-state batteries, a corresponding battery with a cathode sheet, and a preparation method. By constructing a stable ion transport network inside the cathode, the cycle life of the solid-state battery is significantly improved.

[0007] In the first aspect, the present invention provides a method for preparing a cathode supramolecular composite binder for a solid-state battery, the method comprising the following steps: (1) Select a predetermined content of supramolecular macrocycle A and polymer molecule B; Further, the supramolecular macrocycle A in step (1) is: crown ether, cyclodextrin, calixarene, calixpyrrole, calixcarbazole, cucurbituril, pillararene, or one or more of them; the polymer B is a linear molecule; specifically, the polymer B is one or more of polyacrylic acid, sodium carboxymethyl cellulose, polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polyacrylate, etc.; the mass ratio of the supramolecular macrocycle host A to the linear molecule polymer B is 0.01 to 10.

[0008] (2) Add the supramolecular macrocycle A and the polymer molecule B to a solvent and mix to form a homogeneous solution C; Further, the solvent in step (2) is one or more of deionized water, acetonitrile, N,N-dimethylformamide, tetrahydrofuran, ethylene glycol dimethyl ether, N-methylpyrrolidone, dimethyl sulfoxide, acetone.

[0009] Further, the mass concentration of the supramolecular macrocycle host A and the linear molecule polymer B in the homogeneous solution C in step (2) is 1 wt% to 30 wt%.

[0010] Further, when the supramolecular macrocycle A and the polymer molecule B are mixed in step (2), the stirring time is 1 to 24 hours, and the heating temperature is 25 to 60 °C.

[0011] (3) Add a lithium salt to the homogeneous solution C, heat and stir thoroughly to mix evenly to obtain the cathode supramolecular composite binder.

[0012] Further, the lithium salt in step (3) is one or more of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium nitrate, lithium bis(oxalato)borate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide.

[0013] Further, the stirring time in step (3) is 1 to 24 hours, and the heating temperature is 25 to 60 °C.

[0014] Further, the molar concentration of the lithium salt in step (3) is 0.5 to 2 mol L-1 。

[0015] In the second aspect, the present invention also provides a positive electrode supramolecular composite binder for a solid-state battery, which is specifically prepared by the method described in the first aspect.

[0016] In the third aspect, the present invention also provides a positive electrode sheet using the positive electrode supramolecular composite binder described in the second aspect, which includes components with the following mass percentages, based on a total of 100%; Conductive agent: 0.5 - 10%; Positive electrode supramolecular composite binder: 5 - 10%; The balance is positive electrode active material; Further, the conductive agent is acetylene black.

[0017] Further, the positive electrode active material is one or more of lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt manganese oxide, lithium manganese oxide, etc.

[0018] In the fourth aspect, the present invention also provides a method for preparing the solid-state battery positive electrode sheet as described above, which includes the following steps: uniformly mixing the positive electrode active substance, the conductive agent and the positive electrode supramolecular composite binder, coating it on the surface of the current collector, drying, and cutting to obtain the solid-state battery positive electrode sheet: The drying temperature of the solid-state battery positive electrode sheet is 60°C - 110°C, and the drying time is 6 - 24 h.

[0019] Further, the positive electrode active material is: one or more of lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt manganese oxide, lithium manganese oxide, etc.

[0020] Further, the positive electrode active substance, the conductive agent and the positive electrode supramolecular composite binder are uniformly mixed by ball milling; Further, the ball milling time is 1 - 6 hours.

[0021] Further, the thickness of the coating applied on the surface of the current collector is 20 - 150 microns.

[0022] In the fifth aspect, the present invention also provides a battery, which includes the solid-state battery positive electrode sheet described in the third aspect, a negative electrode composed of lithium metal, and a polyethylene oxide solid electrolyte.

[0023] The present invention has the following advantages: 1) The positive electrode supramolecular composite binder for a solid-state battery, the battery corresponding to the positive electrode sheet, and the preparation method thereof of the present invention combine the advantages of macrocyclic supramolecules and linear molecules as the positive electrode binder for a solid-state battery. The macrocyclic supramolecules and linear molecules can provide multiple synergistic ion transport channels inside the positive electrode, promote the transport of lithium ions inside the positive electrode, and effectively stabilize the electrode-solid electrolyte interface through hydrogen bonding, effectively reducing the interface impedance to improve the cycle and rate performance of the solid-state battery.

[0024] 2) The positive electrode supramolecular composite binder for a solid-state battery, the battery corresponding to the positive electrode sheet, and the preparation method thereof of the present invention. First, the preparation process of the supramolecular composite binder is simple, easy to operate, low in cost, and can be mass-produced. Second, the structure of the positive electrode sheet with the positive electrode supramolecular composite binder is stable, and high reversible capacity and cycle performance can be achieved under a high areal loading electrode. Description of the Drawings

[0025] Figure 1 Figure is the scanning electron microscope (SEM) image of the lithium iron phosphate positive electrode using only polyvinylidene fluoride binder for Comparative Example 1; Figure 2 Figure is the SEM image of the lithium iron phosphate positive electrode using the binder prepared in Example 1; Figure 3 Figure is the SEM image of the lithium iron phosphate positive electrode using the binder prepared in Example 2; Figure 4 Figure is the SEM image of the lithium iron phosphate positive electrode using the binder prepared in Example 3 Figure 5 Figure is the cycle performance test chart of all-solid-state batteries assembled with different examples and Comparative Example 1 at a rate of 0.5C and 60 °C; Figure 6 The cycle performance chart of the lithium iron phosphate positive electrode using the binder prepared in Example 2 at a high loading of 7.5 mg cm -2 0.1C. Detailed Embodiments

[0026] To better understand the present invention, the following examples further illustrate the present invention, but the content of the present invention is not limited to the following examples only. Example 1

[0027] (1) Weigh the supramolecular macrocycle β-cyclodextrin and the polymer molecule polyethylene oxide with a mass ratio of 1:100 and add them to a beaker containing the solvent acetonitrile, heat and stir well at 60 °C for 6 h to mix evenly, forming a homogeneous solution with a mass concentration of 30 wt%.

[0028] (2) Add lithium bis(trifluoromethanesulfonyl)imide to the homogeneous solution C, with a concentration of 0.01 mol L -1, heat and stir well at 60 °C until evenly mixed to obtain the positive electrode supramolecular composite binder.

[0029] (3) Take lithium iron phosphate as the positive electrode active material, acetylene black as the conductive agent, the positive electrode supramolecular composite binder prepared in the above step (2) as the binder, and acetonitrile as the solvent. Grind in a ball mill for 3 hours according to a mass ratio of 8:1:1 to obtain the mixed slurry D.

[0030] (4) Coat the mixed slurry D on the carbon-coated aluminum foil, and the coating thickness is about 25 microns to ensure uniform distribution.

[0031] (5) Dry the coated aluminum foil in a vacuum environment at a drying temperature of 60 °C for 6 hours to ensure complete volatilization of the solvent and obtain the solid-state battery positive electrode sheet.

[0032] (6) Weigh polyethylene oxide and lithium bis(trifluoromethanesulfonyl)imide according to a molar ratio of 16:1, dissolve them in an appropriate amount of acetonitrile, stir at 60 °C for 6 h until the slurry becomes viscous. Then put the slurry into a polytetrafluoroethylene mold on non-woven fabric, and then transfer it to a vacuum drying oven. Dry at 60 °C for 12 h, and cut the dried product into pieces with a diameter of 16 mm for standby to obtain the polyethylene oxide polymer solid electrolyte membrane.

[0033] (7) Use a lithium metal sheet as the negative electrode, the solid-state battery positive electrode sheet prepared in steps 1-5, and the solid electrolyte membrane prepared in step 6 as the electrolyte to assemble a 2025-type button solid-state battery in a super purification glove box (the water and oxygen content are both lower than 0.1 ppm). Example 2

[0034] (1) Weigh supramolecular macrocycle β-cyclodextrin, polymer molecule polyethylene oxide and polyvinylidene fluoride with a mass ratio of 3:40:60, add them to a beaker containing acetonitrile and N-methylpyrrolidone, heat and stir well at 60 °C for 12 h until evenly mixed to form a homogeneous solution with a mass concentration of 5 wt%.

[0035] (2) Add lithium bis(trifluoromethanesulfonyl)imide to the homogeneous solution C, with a concentration of 0.025 mol L -1 , heat and stir well at 60 °C until evenly mixed to obtain the positive electrode supramolecular composite binder.

[0036] (3) Take lithium iron phosphate as the positive electrode active material, acetylene black as the conductive agent, the positive electrode supramolecular composite binder prepared in the above step (2) as the binder, and acetonitrile as the solvent. Grind in a ball mill for 5 hours according to a mass ratio of 8:1:1 to obtain the mixed slurry D.

[0037] (4) Coat the mixed slurry D on the carbon-coated aluminum foil, and the coating thickness is about 50 microns to ensure uniform distribution.

[0038] (5) Dry the coated aluminum foil in a vacuum environment at a drying temperature of 60 °C for 12 hours to ensure complete volatilization of the solvent, obtaining the positive electrode sheet of the solid-state battery.

[0039] (6) Weigh polyethylene oxide and lithium bis(trifluoromethanesulfonyl)imide according to a molar ratio of 16:1, dissolve them in an appropriate amount of acetonitrile, stir at 60 °C for 6 h until the slurry becomes viscous. Then place the slurry into a polytetrafluoroethylene mold on non-woven fabric, and then transfer it to a vacuum drying oven, dry at 60 °C for 12 h, and after drying, cut it into a size with a diameter of 16 mm with a cutting machine for standby, obtaining the polyethylene oxide polymer solid electrolyte membrane.

[0040] (7) Other assembly steps of the solid-state battery are the same as those in Example 1. Example 3

[0041] (1) Weigh supramolecular macrocycle β-cyclodextrin and polymer molecule polyethylene oxide with a mass ratio of 3:25, add them to a beaker containing the solvent acetonitrile, heat and stir thoroughly at 60 °C for 6 h to mix evenly, forming a homogeneous solution with a mass concentration of 5 wt%.

[0042] (2) Add lithium bis(trifluoromethanesulfonyl)imide to the homogeneous solution C with a concentration of 0.03 mol L -1 , heat and stir thoroughly at 60 °C to mix evenly, obtaining the positive electrode supramolecular composite binder.

[0043] (3) Use lithium iron phosphate as the positive electrode active material, acetylene black as the conductive agent, the positive electrode supramolecular composite binder prepared in the above step (2) as the binder, and acetonitrile as the solvent, and grind them in a ball mill at a mass ratio of 8:1:1 for 3 hours to obtain the mixed slurry D.

[0044] (4) Coat the mixed slurry D on the carbon-coated aluminum foil, and the coating thickness is about 25 microns to ensure uniform distribution.

[0045] (5) Dry the coated aluminum foil in a vacuum environment at a drying temperature of 60 °C for 6 hours to ensure complete volatilization of the solvent, obtaining the positive electrode sheet of the solid-state battery.

[0046] (6) Weigh polyethylene oxide and lithium bis(trifluoromethanesulfonyl)imide according to a molar ratio of 16:1, dissolve them in an appropriate amount of acetonitrile, stir at 60 °C for 6 h until the slurry becomes viscous. Then place the slurry into a polytetrafluoroethylene mold on non-woven fabric, and then transfer it to a vacuum drying oven, dry at 60 °C for 12 h, and after drying, cut it into a size with a diameter of 16 mm with a cutting machine for standby, obtaining the polyethylene oxide polymer solid electrolyte membrane.

[0047] (7) Using a lithium metal sheet as the negative electrode, the solid-state battery positive electrode sheet prepared in steps 1-5, and the solid-state electrolyte membrane prepared in step 6 as the electrolyte, assemble a 2025-type button solid-state battery in a super purification glove box (with water and oxygen content both below 0.1 ppm). Example 4

[0048] (1) Weigh supramolecular macrocyclic cucurbituril and polymer molecule polyethylene oxide with a mass ratio of 100:1, add them to a beaker containing N,N-dimethylformamide, heat and stir thoroughly at 60 °C for 8 h to mix evenly, and form a homogeneous solution with a mass concentration of 10 wt%.

[0049] (2) Add lithium bis(trifluoromethanesulfonyl)imide to the homogeneous solution C with a concentration of 0.02 mol L -1 , heat and stir thoroughly at 60 °C to mix evenly, and thus obtain the positive electrode supramolecular composite binder.

[0050] (3) Use lithium iron manganese phosphate as the positive electrode active material, acetylene black as the conductive agent, the positive electrode supramolecular composite binder prepared in the above step (2) as the binder, and N,N-dimethylformamide as the solvent. Grind them in a ball mill at a mass ratio of 8:1:1 for 5 hours to obtain a mixed slurry D.

[0051] (4) Coat the mixed slurry D on the carbon-coated aluminum foil, and the coating thickness is about 100 microns to ensure uniform distribution.

[0052] (5) Dry the coated aluminum foil in a vacuum environment at a drying temperature of 60 °C for 12 hours to ensure complete volatilization of the solvent and obtain the solid-state battery positive electrode sheet.

[0053] (6) Weigh polyethylene oxide and lithium bis(trifluoromethanesulfonyl)imide according to a molar ratio of 16:1, dissolve them in an appropriate amount of acetonitrile, stir at 60 °C for 6 h until the slurry becomes viscous. Then put the slurry into a polytetrafluoroethylene mold on non-woven fabric, and transfer it to a vacuum drying oven. Dry it at 60 °C for 12 h, and after drying, cut it into a size with a diameter of 16 mm with a cutter for standby, and obtain a polyethylene oxide polymer solid-state electrolyte membrane.

[0054] (7) Other assembly steps of the solid-state battery are the same as those in Example 1. Example 5

[0055] (1) Weigh crown ether, polymer molecule polyethylene oxide, and polymer molecule polyvinylidene fluoride with a mass ratio of 1:100:100, add them to a beaker containing the solvent acetonitrile, heat and stir thoroughly at 60 °C for 6 h to mix evenly, and form a homogeneous solution with a mass concentration of 10 wt%.

[0056] (2) Add lithium bis(trifluoromethanesulfonyl)imide to the homogeneous solution C at a concentration of 0.01 mol L -1 , heat and stir well at 60 °C until evenly mixed to obtain the positive electrode supramolecular composite binder.

[0057] (3) Take lithium iron phosphate as the positive electrode active material, acetylene black as the conductive agent, the positive electrode supramolecular composite binder prepared in the above step (2) as the binder, and acetonitrile as the solvent, and grind in a ball mill at a mass ratio of 8:1:1 for 3 hours to obtain a mixed slurry D.

[0058] (4) Coat the mixed slurry D on the carbon-coated aluminum foil with a coating thickness of about 25 microns to ensure uniform distribution.

[0059] (5) Dry the coated aluminum foil in a vacuum environment at a drying temperature of 60 °C for 6 hours to ensure complete volatilization of the solvent and obtain the positive electrode sheet of the solid-state battery.

[0060] (6) Weigh polyethylene oxide and lithium bis(trifluoromethanesulfonyl)imide at a molar ratio of 16:1, dissolve them in an appropriate amount of acetonitrile, stir at 60 °C for 6 h until the slurry becomes viscous. Then put the slurry into a polytetrafluoroethylene mold on non-woven fabric, and then transfer it to a vacuum drying oven, dry at 60 °C for 12 h, and cut the dried product into pieces with a diameter of 16 mm for standby to obtain a polyethylene oxide polymer solid electrolyte membrane.

[0061] (7) Other assembly steps of the solid-state battery are the same as those in Example 1.

[0062] (1) Only add the polymer molecule polyvinylidene fluoride as a component to a beaker containing N-methylpyrrolidone, heat and stir well at 60 °C for 12 h until evenly mixed to form a binder with a mass concentration of 5 wt%.

[0063] (2) Take lithium manganese iron phosphate as the positive electrode active material, acetylene black as the conductive agent, the binder prepared in the above step (1) as the binder, and N-methylpyrrolidone as the solvent, and grind in a ball mill at a mass ratio of 8:1:1 for 5 hours to obtain a mixed slurry.

[0064] (4) Coat the mixed slurry on the carbon-coated aluminum foil with a coating thickness of about 50 microns to ensure uniform distribution.

[0065] (5) Dry the coated aluminum foil in a vacuum environment at a drying temperature of 60 °C for 12 hours to ensure complete volatilization of the solvent and obtain the positive electrode sheet of the solid-state battery.

[0066] (6) Weigh polyethylene oxide and lithium trifluoromethylsulfonyl imide in a molar ratio of 16:1, dissolve in an appropriate amount of acetonitrile, and stir at 60°C for 6 h until the slurry becomes viscous. Then put the slurry into a polytetrafluoroethylene mold on a non-woven fabric, transfer it to a vacuum drying oven, and dry it at 60°C for 12 h. After drying, use a cutting machine to cut it into a size of 16 mm in diameter for use, thereby obtaining a polyethylene oxide polymer solid electrolyte membrane.

[0067] (7) The other assembly steps of the solid-state battery are the same as those in Example 1.

[0068] Figures 1-4 The surface morphology of lithium iron phosphate positive electrode sheets using different binders. A good ion transport network is constructed inside the positive electrode through the binder.

[0069] from Figure 5 It can be seen that the batteries of Examples 1, 2 and Comparative Example 1 have discharge specific capacities of 145.6, 156.2 and 134.5 mAh / g, respectively, after cycling 100 times at 0.5C. The capacity retention rate of Example 1 after 100 cycles is 88.2%, the capacity retention rate of Example 2 after 100 cycles is 96.1%, and the capacity retention rate of Comparative Example 1 after 100 cycles is only 85.3%. By comparison, it can be seen that the binder positive electrode prepared in Example 2 has good cycle stability.

[0070] In addition, if Figure 6 As shown in Figure 2, the battery prepared in Example 2 has a high surface capacity of 7.5 mg cm -2 After running stably for 30 cycles at a rate of 0.1C, it still has a high discharge capacity of 139.2 mAh / g. The all-solid-state battery assembled with the lithium iron phosphate positive electrode prepared by this binder has a discharge capacity of not less than 160 mAh / g at a rate of 0.2C, a discharge capacity of not less than 150 mAh / g at a rate of 0.5C, and a discharge capacity of not less than 135 mAh / g at a rate of 2C.

[0071] The embodiments described above are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A preparation method of a cathode supramolecular composite binder for a solid-state lithium battery, characterized in that, The synthesis method comprises the following steps: (1) Select supramolecular macrocycle A and polymer molecule B with predetermined contents; (2) Add A and B into a solvent and mix evenly to form a homogeneous solution C; (3) Add a lithium salt into the homogeneous solution C and mix evenly to obtain the positive electrode supramolecular composite binder; The supramolecular macrocycle A is one or more of: crown ether, cyclodextrin, calixarene, calixpyrrole, calixcarbazole, cucurbituril, pillararene; The polymer molecule B is one or more of: polyacrylic acid, sodium carboxymethyl cellulose, polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polyacrylate, etc.; The solvent is one or more of deionized water, acetonitrile, N,N-dimethylformamide, tetrahydrofuran, ethylene glycol dimethyl ether, N-methylpyrrolidone, dimethyl sulfoxide, acetone.

2. The preparation method of a positive electrode supramolecular composite binder for a solid-state lithium battery according to claim 1, characterized in that, The mass ratio of the supramolecular macrocycle host A to the linear molecular polymer B is 0.01 - 10.

3. The preparation method of a positive electrode supramolecular composite binder for a solid-state lithium battery according to claim 1, characterized in that, The supramolecular macrocycle host and the linear molecular polymer are added into a solvent to form a homogeneous solution C, wherein the mass concentration of the supramolecular macrocycle host A and the linear molecular polymer B in the homogeneous solution C is 1 wt% - 30 wt%.

4. The preparation method of a positive electrode supramolecular composite binder for a solid-state lithium battery according to any one of claims 1 to 3, characterized in that, In steps (2) and (3), the stirring time is 1 - 24 hours and the heating temperature is 25 - 60 °C.

5. A preparation method of a positive electrode supramolecular composite binder according to any one of claims 1-3, characterized in that, The lithium salt is one or more of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium nitrate, lithium bis(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide; the concentration of the lithium salt is 0.01 to 0.1 mol / L -1 .

6. A positive electrode sheet for a solid-state lithium battery, characterized in that: It comprises components with the following mass percentages, based on the total amount being 100%: 0.5 - 10% of conductive agent; 5 - 10% of the positive electrode supramolecular composite binder prepared by the method according to any one of claims 1 - 5; the balance is the positive electrode active material.

7. The positive electrode sheet for a solid-state lithium battery according to claim 6, characterized in that: The positive electrode active material is selected from one or more of lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt manganese oxide, lithium manganate, etc.; the conductive agent is acetylene black.

8. A method for preparing a positive electrode sheet for a solid-state lithium battery according to any one of claims 6-7, characterized in that: It comprises the following steps: Mix the positive electrode active material, the conductive agent and the positive electrode supramolecular composite binder prepared by the method according to any one of claims 1 - 5 evenly, coat it on the surface of the current collector, dry it, and cut it to obtain the positive electrode sheet; The drying temperature is 60 °C - 110 °C and the drying time is 6 - 24 h.

9. A method for preparing a positive electrode sheet for a solid-state lithium battery as claimed in claim 8, wherein the thickness of the coating coated on the surface of the current collector is 20 - 150 microns.

10. A battery, characterized in that, The battery is composed of the positive electrode sheet for a solid-state lithium battery as claimed in claims 6 - 7 or the positive electrode sheet for a solid-state lithium battery prepared by the method of claims 8 - 9, a negative electrode composed of lithium metal, and a polyethylene oxide solid electrolyte.

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