Solid-state battery and preparation method thereof

Abstract

The invention relates to the technical field of solid-state batteries, in particular to a solid-state battery and a preparation method thereof. The preparation method of the solid-state battery comprises the following steps: S1, preparing a positive pole piece; s2, preparing a negative pole piece; s3, preparing solid electrolyte slurry; s4, preparing a solid electrolyte membrane; and S5, assembling and formation: assembling the positive electrode and the negative electrode prepared in the step S4 into a battery cell in a positive and negative alternating lamination mode, and performing charging formation treatment on the battery at the high temperature of 70100 DEG C to finish the preparation so as to obtain the solid-state battery. According to the preparation method of the solid-state battery, by optimizing the material ratio and the production process, the performance and safety of the battery are improved, the production process is simplified, the environmental friendliness is improved, and reliable technical support is provided for application of the high-performance solid-state battery.

Description

Technical Field

[0001] The present application relates to the technical field of solid-state batteries, and in particular to a solid-state battery and a method for preparing the same. Background Art

[0002] With the rapid development of new energy vehicles and intelligent equipment, the market demand for secondary batteries has exploded, and people are demanding the development of energy storage devices with high energy density and high safety. Battery energy density is constantly improving and breaking through with the needs of production and life.

[0003] In the existing technology, from the perspective of the proportion of commercial batteries, lithium-ion batteries still use flammable and explosive liquid organic matter as electrolyte, and most commercial batteries are liquid batteries. Due to its inherent chemical properties, liquid lithium-ion batteries will produce lithium dendrites during the charging and discharging process, leading to a series of safety problems such as explosions and spontaneous combustion. For example, spontaneous combustion accidents occurred when new energy vehicles were charging or at high temperatures. In the existing technology, solid electrolytes are used to replace existing liquid electrolytes. The electrolytes of solid-state batteries are first prepared separately, and then solid-solid pressed with the electrodes. The solid-solid contact interface impedance will be greater, and some voids and gaps will inevitably exist. Especially inside the electrode of the mixed positive electrode material, the density of the heterogeneous interface here is much larger than the macroscopic pole piece / electrolyte, and the problem of solid-solid contact is particularly prominent. Due to the lack of electrolyte infiltration buffering, the stress generated by the continuous contact of the solid electrolyte on the electrode-electrolyte interface greatly reduces the cycle life of the battery. The electrolyte and electrodes of the solid-state battery are both solid, the degree of wetting of the contact surface becomes low, and the contact resistance and heat are easily increased due to the reaction during the charging and discharging process.

[0004] Therefore, it is imperative to develop a method for preparing solid-state batteries to improve the electrochemical performance and cycle stability of the batteries. Summary of the invention

[0005] In order to solve the above problems, the present application provides a solid-state battery and a method for preparing the same. The solid-state battery prepared by the present application has a higher contact area, is tightly fitted, is not easy to peel off during the charge and discharge process, and has good cycle stability. It can also solve the problem of the thickness of conventional solid electrolyte membranes and save weight and volume.

[0006] In a first aspect, the present application provides a method for preparing a solid-state battery, using the following technical solution: A method for preparing a solid-state battery comprises the following steps: S1. Preparation of positive electrode sheet: mixing positive electrode active material, conductive agent and binder evenly, coating and rolling to form positive electrode; S2. Preparation of negative electrode sheet: carbon nanotubes, binder, dispersant and additives are made into slurry, stirred evenly, coated and rolled to form negative electrode; S3, preparation of solid electrolyte slurry: dissolving the polymer solid electrolyte in a solvent with a low melting point according to the mass fraction, then adding the modified sulfide solid electrolyte, stirring evenly, and degassing to obtain a solid electrolyte slurry; S4, preparing a solid electrolyte membrane: evenly coating the solid electrolyte slurry on the surface of the positive electrode to obtain a solid electrolyte membrane with a thickness of 3-10 microns, setting the temperature between 110-120°C, drying, rolling, and collecting the coiled material for use in the next process; evenly coating the solid electrolyte slurry on the surface of the negative electrode to obtain a solid electrolyte membrane with a thickness of 3-10 microns, setting the temperature between 110-120°C, drying, rolling, and collecting the coiled material for use in the next process; S5, assembly and formation: The positive and negative electrodes prepared in step S4 are assembled into a battery cell by stacking them in an alternating positive and negative manner, and the battery is charged and formed at a high temperature of 70-100° C. to complete the preparation and obtain a solid-state battery.

[0007] By adopting the above technical scheme, the solid-state battery preparation method of the present application realizes the production of high-performance, high-safety and environmentally friendly solid-state batteries through the synergistic effect of multiple steps. S1, preparation of positive electrode sheet, fully mix the positive electrode active material, conductive agent and binder to ensure the uniformity and electrochemical properties of the material. A uniform positive electrode sheet is formed by coating and rolling process to ensure the consistency of thickness and density. Provide a uniform base layer for subsequent solid electrolyte coating to ensure that the electrolyte membrane can be evenly attached to the positive electrode surface. S2, preparation of negative electrode sheet, mix carbon nanotubes, binder, dispersant and additives into a uniform slurry. A uniform negative electrode sheet is formed by coating and rolling process to ensure the consistency of thickness and density. The high porosity and ultra-thin characteristics of carbon nanotubes provide a larger sodium and lithium storage space, which improves the energy density of the battery. The introduction of lithium nitrate inhibits the growth of lithium and sodium dendrites and improves the safety of the battery. S3, preparation of solid electrolyte slurry, dissolve the polymer solid electrolyte in a low melting point solvent, add the modified sulfide solid electrolyte, stir evenly and degas. The combination of polymer solid electrolyte and modified sulfide solid electrolyte forms a stable lithium-conducting support network, which improves the ionic conductivity and stability of the electrolyte membrane. S4, prepare the solid electrolyte membrane, and evenly apply the solid electrolyte slurry to the surface of the positive and negative electrodes to form a solid electrolyte membrane with a thickness of 3-10 microns. After drying between 110-120°C, roll it to ensure the flatness and tight fit of the electrolyte membrane. The solid electrolyte membrane not only provides good ionic conductivity, but also has excellent mechanical strength and flexibility, and plays the role of a traditional battery separator. It avoids the flammability problem of traditional electrolytes and improves the safety of the battery. S5, assembly and formation, the positive and negative electrodes are stacked and assembled into a battery cell in an alternating positive and negative manner. The battery is charged and formed at a high temperature of 70-100°C to complete the preparation. The high-temperature formation process ensures the stability of the solid electrolyte at high temperatures and avoids decomposition and short circuit problems. It simplifies the production process and improves production efficiency and environmental friendliness. In summary, this application achieves the following goals by optimizing material ratios and production processes: 1. Improving battery performance and safety: Using solid electrolyte membranes instead of traditional electrolytes avoids flammability problems and short circuit problems caused by lithium dendrites piercing the diaphragm. 2. Simplifying the production process: Eliminating the use of diaphragms and electrolytes reduces production processes and reduces production costs. 3. Environmental friendliness: Alleviates the pressure on environmental protection and safety supervision in production workshops, and improves environmental safety and environmental friendliness. 4. High energy density and high power density: The introduction of carbon nanotubes as negative electrode materials provides larger sodium and lithium storage space, which is suitable for high energy density batteries; at the same time, it has electronic, ionic and thermal conductivity, which is suitable for high power density batteries.5. Cycle stability and electrochemical performance: The combination of polymer solid electrolyte and modified sulfide solid electrolyte improves the ionic conductivity and stability of the electrolyte membrane, effectively improving the cycle stability and electrochemical performance of the solid-state battery. The synergistic effect of these steps makes the solid-state battery preparation method of this application have significant advantages in terms of technological advancement, economic feasibility and environmental friendliness.

[0008] Preferably, in step S1, the mass ratio of each material is positive electrode active material: conductive agent: binder = 92:4:4; the positive electrode active material is one or more of oxide-based positive electrode material, lithium manganese oxide and lithium cobalt oxide; the conductive agent is at least one of conductive carbon black, carbon nanotubes and graphene; the binder is PTFE.

[0009] Preferably, in step S2, the diameter of the carbon nanotubes is 60-100 nm, and the length is 5-30 μm; the mass ratio of each material is carbon nanotubes: binder: dispersant: additive = 72:20:5:3; the solid content of the slurry is 10%; the additive is lithium nitrate; the binder is PVDF; and the dispersant is PVP.

[0010] Preferably, in step S3, the mass ratio of the modified sulfide solid electrolyte to the polymer solid electrolyte is (90-95):(5-10).

[0011] Preferably, in step S3, the preparation method of the modified sulfide solid electrolyte is: 2-4g of tridecafluorooctyltriethoxysilane, 100g of sulfide solid electrolyte and 0.6L of anhydrous acetonitrile are added to a reactor, reacted at 80°C in a nitrogen atmosphere for 8 hours, then centrifuged to collect the solid, and washed the solid three times with anhydrous acetonitrile, and dried at 50°C in vacuum for 12 hours to obtain a modified sulfide solid electrolyte.

[0012] By adopting the above technical scheme, the prepared modified sulfide solid electrolyte has the following effects and synergistic effects: Improve interfacial compatibility: By grafting and modifying the surface of the sulfide solid electrolyte with tridecafluorooctyl triethoxysilane, the interfacial compatibility between the polymer solid electrolyte and the sulfide solid electrolyte particles can be significantly improved. This improved compatibility helps the sulfide particles to be more evenly distributed in the polymer matrix, thereby improving the overall performance of the solid-state battery. Optimize mechanical properties: Through the interaction between the modified sulfide solid electrolyte and the polymer solid electrolyte, a solid-state battery with good mechanical properties can be prepared. This membrane can withstand higher operating pressures and can effectively buffer volume expansion and contraction during charging and discharging, thereby effectively improving the cycle stability, safety and electrochemical performance of the solid-state battery. Improve ionic conductivity: The modified sulfide solid electrolyte is filled between the lithium-conducting support network formed by the ion-conducting polymer. Such a structural design helps to shorten the transmission distance of lithium ions and reduce the transfer impedance between electrolyte particles, thereby improving ionic conductivity. This is crucial to improving the charging and discharging efficiency and cycle stability of the battery. Synergistic effect: The combination of modified sulfide solid electrolyte and polymer solid electrolyte not only plays the advantages of each, but also produces a synergistic effect. The polymer provides flexibility and processability, while the modified sulfide contributes high ionic conductivity and good thermal stability. This combination makes the final solid-state battery have excellent physical properties while maintaining high ionic conductivity.

[0013] Preferably, the sulfide solid electrolyte is Li6PS5Cl, Li6PS5Br and Li 10 SnP2S 12 At least one of the sulfide solid electrolytes has a D50 of 3-5 μm.

[0014] Preferably, in step S3, the polymer solid electrolyte is composed of polyethylene oxide and an ion-conducting polymer in a mass ratio of 1:3.

[0015] By adopting the above technical solution, the polymer solid electrolyte is composed of polyethylene oxide (PEO) and ion conductive polymer in a mass ratio of 1:3. This combination makes full use of the characteristics of the two materials to achieve high performance of solid-state batteries. Polyethylene oxide (PEO) is a commonly used polymer matrix material with good mechanical properties and chemical stability. As a polymer matrix, PEO provides good structural support and stability for solid-state batteries. At the same time, PEO also has a certain ion conductivity, which can improve the ion conductivity of solid-state batteries to a certain extent. Ion conductive polymer is a special polymer with high ion conductivity and good chemical stability. The ion conductive polymer and PEO are cross-linked to form a lithium conductive support network. This network structure helps the transmission of lithium ions, shortens the transmission distance of lithium ions, and reduces the transfer impedance between electrolyte particles, thereby improving the ion conductivity of solid-state batteries. In addition, the ion conductive polymer also has high mechanical strength, which can improve the compressive strength of solid-state batteries, enabling them to withstand higher operating pressures.

[0016] Preferably, the method for preparing the ion-conducting polymer comprises the following steps: S81, weighing styrene sulfonic acid and lithium hydroxide in a molar ratio of 1:1, respectively dissolving them in deionized water to obtain an 8 wt % styrene sulfonic acid aqueous solution and an 8 wt % lithium hydroxide aqueous solution, respectively, adding the lithium hydroxide aqueous solution dropwise to the styrene sulfonic acid aqueous solution, fully neutralizing the reaction, drying to remove water, and obtaining lithium p-styrene sulfonate; S82. Weigh lithium p-styrene sulfonate, styrene and azobisisobutyronitrile in a molar ratio of 1:1:0.005 respectively, dissolve lithium p-styrene sulfonate and styrene in N,N-dimethylformamide, add azobisisobutyronitrile, thermally polymerize at 65°C for 6 hours, and purify by recrystallization with methanol and ethyl ether to obtain an ion-conducting polymer.

[0017] By adopting the above technical scheme, the ion-conducting polymer is prepared by cross-linking the ion-conducting polymers to form a lithium-conducting support network, and the modified sulfide solid electrolyte is filled between the lithium-conducting support networks. The formation of the lithium-conducting support network can effectively conduct lithium ions, shorten the transmission distance of lithium ions, reduce the transfer impedance between electrolyte particles, and improve the ion conductivity. The solid-state battery can withstand higher operating pressure, improve the stability of the solid-state battery, enable it to buffer the volume expansion and contraction during the charge and discharge process, and effectively improve the cycle stability, safety and electrochemical performance of the solid-state battery.

[0018] Preferably, in step S3, the solvent with a low melting point is at least one of acetone, isopropanol and tetrahydrofuran.

[0019] In a second aspect, the present application provides a solid-state battery, which adopts the following technical solution: As a general technical concept, the present application also provides a solid-state battery, which is manufactured using the above-mentioned solid-state battery preparation method.

[0020] In summary, the beneficial technical effects of this application are: 1. Improve battery safety: By using a solid electrolyte membrane instead of traditional electrolyte, the problem of electrolyte flammability is avoided, greatly improving the safety of the battery. At the same time, the elimination of traditional PE or PP separators further improves the safety of the battery and avoids short circuit problems caused by lithium or sodium dendrites piercing the separator.

[0021] 2. Improved production efficiency: This application reduces the production process, no longer requires diaphragms and electrolytes, simplifies the production process, improves production efficiency, and reduces production costs.

[0022] 3. Improve battery performance: By optimizing the material ratio and production process, not only the performance and safety of the battery are improved, but also the environmental friendliness is improved. Introducing carbon nanotubes as negative electrode materials to prepare high-porosity, ultra-thin negative electrode layers has a larger sodium and lithium storage space than traditional silicon, silicon carbon, and graphite, and is more suitable for high-energy density batteries. At the same time, carbon nanotubes have electronic, ionic and thermal conductivity, which is more suitable for high-power density batteries.

[0023] 4. Improve battery cycle stability and electrochemical performance: Use polymer solid electrolytes to cross-link with each other to form a lithium-conducting support network, and fill the modified sulfide solid electrolyte between the lithium-conducting support networks. The formation of the lithium-conducting support network can effectively conduct lithium ions, shorten the transmission distance of lithium ions, reduce the transfer impedance between electrolyte particles, and improve the ion conductivity. The solid electrolyte membrane can withstand higher operating pressures, improve the stability of the solid electrolyte membrane, and enable it to buffer the volume expansion and contraction during the charge and discharge process, effectively improving the cycle stability, safety and electrochemical performance of the solid-state battery.

[0024] 5. Improve environmental protection and safety: By eliminating the use of electrolyte, the environmental protection and safety supervision pressure of the production workshop is reduced, and the environmental protection and safety of the production environment are improved.

[0025] 6. Good high temperature stability: Since the solid electrolyte can remain stable at high temperatures and does not decompose, the solid-state battery can be formed at a high temperature of 70-100°C. At the same time, the solid electrolyte can withstand high pressure, so that the solid-state battery can remain stable when it is formed under high pressure conditions without short circuit problems. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0027] In the following examples, 1 part means 100 g, and the weight average molecular weight of polyethylene oxide is 150W.

[0028] Preparation Example 1 Preparation of ion-conducting polymer The method for preparing an ion-conducting polymer comprises the following steps: S81, weighing styrene sulfonic acid and lithium hydroxide in a molar ratio of 1:1, respectively dissolving them in deionized water to obtain an 8 wt % styrene sulfonic acid aqueous solution and an 8 wt % lithium hydroxide aqueous solution, respectively, adding the lithium hydroxide aqueous solution dropwise to the styrene sulfonic acid aqueous solution, fully neutralizing the reaction, drying to remove water, and obtaining lithium p-styrene sulfonate; S82. Weigh lithium p-styrene sulfonate, styrene and azobisisobutyronitrile in a molar ratio of 1:1:0.005 respectively, dissolve lithium p-styrene sulfonate and styrene in N,N-dimethylformamide, add azobisisobutyronitrile (the amount of azobisisobutyronitrile added is 2% of the mass of lithium p-styrene sulfonate), thermally polymerize at 65°C for 6 hours, and purify by recrystallization method using methanol and ethyl ether to obtain an ion-conducting polymer.

[0029] Example 1 A method for preparing a solid-state battery comprises the following steps: S1. Preparation of positive electrode sheet: mixing materials with a mass ratio of positive electrode active material: conductive agent: binder = 92:4:4, coating and rolling to form a positive electrode; the positive electrode active material is lithium manganese oxide; the conductive agent is conductive carbon black; the binder is PTFE; S2. Preparation of negative electrode sheet: Make a slurry with a mass ratio of carbon nanotubes: binder: dispersant: additive = 72:20:5:3, stir evenly, apply and roll to make a negative electrode; wherein the diameter of the carbon nanotubes is 60-100nm and the length is 5-30μm; the solid content of the slurry is 10%; the additive is lithium nitrate; the binder is PVDF; and the dispersant is PVP; S3. Preparation of solid electrolyte slurry: dissolve 5 parts of polymer solid electrolyte in 800 parts of acetone according to mass fraction, then add 95 parts of modified sulfide solid electrolyte, stir evenly, degas, and prepare solid electrolyte slurry; the polymer solid electrolyte is composed of polyethylene oxide and ion conductive polymer in a mass fraction ratio of 1:3; the preparation method of the modified sulfide solid electrolyte is: add 2g of tridecafluorooctyl triethoxysilane, 100g of Li6PS5Cl powder with D50 of 3μm and 0.6L of anhydrous acetonitrile into a reactor, react at 80°C in a nitrogen atmosphere for 8 hours, then centrifuge to collect the solid, wash the solid three times with anhydrous acetonitrile, and dry at 50°C in vacuum for 12h to obtain a modified sulfide solid electrolyte; S4, preparation of solid electrolyte membrane: the solid electrolyte slurry is evenly coated on the surface of the positive electrode to obtain a solid electrolyte membrane with a thickness of 3 microns, the temperature is set to 110°C, after drying, it is rolled and rolled, and it is used in the next process; the solid electrolyte slurry is evenly coated on the surface of the negative electrode to obtain a solid electrolyte membrane with a thickness of 10 microns, the temperature is set to 110°C, after drying, it is rolled and rolled, and it is used in the next process; S5, assembly and formation: the positive and negative electrodes prepared in step S4 are assembled into a battery cell by stacking them in an alternating positive and negative manner, and the battery is charged and formed at a high temperature of 70°C. Formation: charging to 4.3V and discharging to 3.0V at current rates of 0.05C, 0.1C, and 0.5C respectively, to complete the preparation and obtain a solid-state battery.

[0030] Example 2 A method for preparing a solid-state battery comprises the following steps: S1. Preparation of positive electrode sheet: mixing materials with a mass ratio of positive electrode active material: conductive agent: binder = 92:4:4, coating and rolling to form a positive electrode; the positive electrode active material is lithium manganese oxide; the conductive agent is carbon nanotubes; the binder is PTFE; S2. Preparation of negative electrode sheet: Make a slurry with a mass ratio of carbon nanotubes: binder: dispersant: additive = 72:20:5:3, stir evenly, apply and roll to make a negative electrode; wherein the diameter of the carbon nanotubes is 60-100nm and the length is 5-30μm; the solid content of the slurry is 10%; the additive is lithium nitrate; the binder is PVDF; and the dispersant is PVP; S3. Preparation of solid electrolyte slurry: Dissolve 10 parts of polymer solid electrolyte in 800 parts of isopropanol according to mass fraction, then add 90 parts of modified sulfide solid electrolyte, stir evenly, degas, and obtain solid electrolyte slurry; the polymer solid electrolyte is composed of polyethylene oxide and ion conductive polymer in a mass fraction ratio of 1:3; the preparation method of the modified sulfide solid electrolyte is: add 2g of tridecafluorooctyl triethoxysilane, 100g of Li6PS5Br powder with a D50 of 5μm and 0.6L of anhydrous acetonitrile into a reactor, react at 80°C in a nitrogen atmosphere for 8 hours, then centrifuge to collect the solid, wash the solid three times with anhydrous acetonitrile, and dry at 50°C in vacuum for 12h to obtain a modified sulfide solid electrolyte; S4, preparation of solid electrolyte membrane: the solid electrolyte slurry is evenly coated on the surface of the positive electrode to obtain a solid electrolyte membrane with a thickness of 10 microns, the temperature is set to 120°C, after drying, it is rolled and rolled, and it is used in the next process; the solid electrolyte slurry is evenly coated on the surface of the negative electrode to obtain a solid electrolyte membrane with a thickness of 3 microns, the temperature is set to 120°C, after drying, it is rolled and rolled, and it is used in the next process; S5, assembly and formation: the positive and negative electrodes prepared in step S4 are assembled into a battery cell by stacking them in an alternating positive and negative manner, and the battery is charged and formed at a high temperature of 100°C. Formation: charging to 4.3V and discharging to 3.0V at current rates of 0.05C, 0.1C, and 0.5C respectively, to complete the preparation and obtain a solid-state battery.

[0031] Example 3 A method for preparing a solid-state battery comprises the following steps: S1. Preparation of positive electrode sheet: mixing materials with a mass ratio of positive electrode active material: conductive agent: binder = 92:4:4, coating and rolling to form a positive electrode; the positive electrode active material is lithium manganese oxide; the conductive agent is conductive carbon black; the binder is PTFE; S2. Preparation of negative electrode sheet: Make a slurry with a mass ratio of carbon nanotubes: binder: dispersant: additive = 72:20:5:3, stir evenly, apply and roll to make a negative electrode; wherein the diameter of the carbon nanotubes is 60-100nm and the length is 5-30μm; the solid content of the slurry is 10%; the additive is lithium nitrate; the binder is PVDF; and the dispersant is PVP; S3, solid electrolyte slurry preparation: according to the mass fraction, 7 parts of polymer solid electrolyte are dissolved in 800 parts of tetrahydrofuran, and then 93 parts of modified sulfide solid electrolyte are added, stirred evenly, and degassed to obtain solid electrolyte slurry; the polymer solid electrolyte is composed of polyethylene oxide and ion conductive polymer in a mass fraction ratio of 1:3; the preparation method of the modified sulfide solid electrolyte is: 2g of tridecafluorooctyl triethoxysilane, 100g of Li 10 SnP2S 12 The powder and 0.6L of anhydrous acetonitrile were added into a reactor, reacted at 80°C in a nitrogen atmosphere for 8 hours, and then centrifuged to collect the solid, washed the solid three times with anhydrous acetonitrile, and dried at 50°C in vacuum for 12 hours to obtain a modified sulfide solid electrolyte; S4, preparation of solid electrolyte membrane: the solid electrolyte slurry is evenly coated on the surface of the positive electrode to obtain a solid electrolyte membrane with a thickness of 6.5 microns, the temperature is set to 115°C, after drying, it is rolled and rolled, and it is used in the next process; the solid electrolyte slurry is evenly coated on the surface of the negative electrode to obtain a solid electrolyte membrane with a thickness of 6.5 microns, the temperature is set to 115°C, after drying, it is rolled and rolled, and it is used in the next process; S5, assembly and formation: assemble the positive and negative electrodes prepared in step S4 into a battery cell by stacking them in an alternating positive and negative manner, and charge and form the battery at a high temperature of 90°C; formation: charge to 4.3V and discharge to 3.0V at current rates of 0.05C, 0.1C, and 0.5C, respectively, to complete the preparation and obtain a solid-state battery.

[0032] The solid-state battery prepared in the above-mentioned Examples 1 to 3 is BT120888699, with a capacity of 600Ah and a top head length of 1200mm, wherein the main body is 888mm, the airbag part is 318mm, the width is 10mm, the size of the positive electrode sheet is: 876mm (W) * 663mm (L) with four corners in arc shape, and the size of the negative electrode is: 880mm (W) * 667mm (L) solid-state lithium battery. The performance differences between the product and the manufacturing method of the present application and the traditional product and the manufacturing method are shown in Table 1 below: Table 1 Performance differences project This application product Traditional products Process flow reduce normal Positive electrode length and width 876*663mm 876*663mm Negative electrode length and width 880*667mm 880*667mm Diaphragm none have Electrolyte none have acupuncture pass NG Cycle life 35% longer normal Comparative Example 1 The same as Example 3, except that: in step S3, the polymer solid electrolyte is polyethylene oxide.

[0033] Comparative Example 2 The same as Example 3, except that: in step S3, the polymer solid electrolyte is an ion-conducting polymer.

[0034] Comparative Example 3 The same as Example 3, except that in step S3, an equal amount of Li with a D50 of 4 μm is used. 10 SnP2S 12 Powder replaces modified sulfide solid electrolyte.

[0035] Performance Testing The solid-state batteries prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were sampled respectively, and their initial efficiency was tested by cyclic discharge at 0.1C, and the capacity retention rate was tested by 50 cycles. The test results are shown in Table 2.

[0036] Ion conductivity test: The solid electrolyte slurries prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were coated on the surface of the PET release film, dried in a vacuum oven at 120° C. for 16 hours, and then the PET release film was removed to obtain a solid electrolyte membrane with a thickness of 20 μm. Test method: Use the Transmission Power 1260A impedance / gain-phase analyzer to perform AC impedance test, with a frequency range of 1mHz-0.1Hz. Cut the solid electrolyte membrane into 10mm diameter discs, attach carbon-coated aluminum foil on both sides, place it in the mold battery PEEK sleeve, and then insert stainless steel columns on both sides to block the electrodes. Test under a pressure of 360MPa and calculate the ionic conductivity of the solid electrolyte membrane.

[0037] Table 2 Electrochemical performance test results Analyzing the data in Table 2, we can see that: 1) The solid-state batteries prepared in Examples 1 to 3 have a higher contact area and are tightly fitted. They are not easily peeled off during the charge and discharge process and have good cycle stability, thereby improving the safety performance of the battery.

[0038] 2) The performance comparison analysis of the solid-state batteries prepared in combination with Example 3 and Comparative Examples 1-2 shows that the polymer solid electrolyte is composed of polyethylene oxide and ion-conducting polymer in a mass ratio of 1:3. By utilizing the synergistic effect between them, the ion-conducting polymer and polyethylene oxide are cross-linked to form a lithium-conducting support network. This network structure helps the transmission of lithium ions, shortens the transmission distance of lithium ions, and reduces the transfer impedance between electrolyte particles, thereby improving the ion conductivity of the solid-state battery. In addition, the ion-conducting polymer also has a high mechanical strength, which can improve the compressive strength of the solid-state battery, enabling it to withstand higher operating pressures.

[0039] 3) The performance comparison analysis of the solid-state battery prepared in combination with Example 3 and Comparative Example 3 shows that the modified sulfide solid electrolyte prepared in the present application is grafted and modified on the surface of the sulfide solid electrolyte by tridecafluorooctyl triethoxysilane, which can significantly improve the interfacial compatibility between the polymer solid electrolyte and the sulfide solid electrolyte particles. This improved compatibility helps the sulfide particles to be more evenly distributed in the polymer matrix, thereby improving the overall performance of the solid-state battery. Through the interaction between the modified sulfide solid electrolyte and the polymer solid electrolyte, a solid-state battery with good mechanical properties can be prepared. This membrane can withstand higher operating pressures and can effectively buffer volume expansion and contraction during charge and discharge, thereby effectively improving the cycle stability, safety and electrochemical performance of the solid-state battery. The modified sulfide solid electrolyte is filled between the lithium-conducting support network formed by the ion-conducting polymer. Such a structural design helps to shorten the transmission distance of lithium ions and reduce the transfer impedance between the electrolyte particles, thereby improving the ionic conductivity. This is crucial for improving the charge and discharge efficiency and cycle stability of the battery.

[0040] The above embodiments are only used to explain the technical solutions of the present application rather than to limit them. Although the above embodiments provide a specific description of the present application, relevant technical personnel should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents, and any modifications and equivalent replacements that do not depart from the spirit and scope of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a solid-state battery, characterized in that: The following steps are involved: S1. Preparation of positive electrode sheet: mixing positive electrode active material, conductive agent and binder evenly, coating and rolling to form positive electrode; S2. Preparation of negative electrode sheet: carbon nanotubes, binder, dispersant and additives are made into slurry, stirred evenly, coated and rolled to form negative electrode; S3, preparation of solid electrolyte slurry: dissolving the polymer solid electrolyte in a solvent with a low melting point according to the mass fraction, then adding the modified sulfide solid electrolyte, stirring evenly, and degassing to obtain a solid electrolyte slurry; S4, preparing a solid electrolyte membrane: evenly coating the solid electrolyte slurry on the surface of the positive electrode to obtain a solid electrolyte membrane with a thickness of 3-10 microns, setting the temperature between 110-120°C, drying, rolling, and collecting the coiled material for use in the next process; evenly coating the solid electrolyte slurry on the surface of the negative electrode to obtain a solid electrolyte membrane with a thickness of 3-10 microns, setting the temperature between 110-120°C, drying, rolling, and collecting the coiled material for use in the next process; S5, assembly and formation: The positive and negative electrodes prepared in step S4 are assembled into a battery cell by stacking them in an alternating positive and negative manner, and the battery is charged and formed at a high temperature of 70-100° C. to complete the preparation and obtain a solid-state battery.

2. The method for preparing a solid-state battery according to claim 1, characterized in that: In step S1, the mass ratio of each material is positive electrode active material: conductive agent: binder = 92:4:4; the positive electrode active material is one or more of oxide-based positive electrode material, lithium manganese oxide and lithium cobalt oxide; the conductive agent is at least one of conductive carbon black, carbon nanotubes and graphene; the binder is PTFE.

3. The method for preparing a solid-state battery according to claim 1, characterized in that: In step S2, the diameter of the carbon nanotubes is 60-100 nm, and the length is 5-30 μm; the mass ratio of each material is carbon nanotubes: binder: dispersant: additive = 72:20:5:3; the solid content of the slurry is 10%; the additive is lithium nitrate; the binder is PVDF; and the dispersant is PVP.

4. The method for preparing a solid-state battery according to claim 1, characterized in that: In step S3, the mass ratio of the modified sulfide solid electrolyte to the polymer solid electrolyte is (90-95):(5-10).

5. The method for preparing a solid-state battery according to claim 1, characterized in that: In step S3, the preparation method of the modified sulfide solid electrolyte is: 2-4g of tridecafluorooctyltriethoxysilane, 100g of sulfide solid electrolyte and 0.6L of anhydrous acetonitrile are added to a reactor, reacted at 80°C in a nitrogen atmosphere for 8 hours, then centrifuged, the solid is collected, and the solid is washed three times with anhydrous acetonitrile, and dried at 50°C in vacuum for 12 hours to obtain a modified sulfide solid electrolyte.

6. A method for preparing a solid-state battery according to claim 5, characterized in that: The sulfide solid electrolyte is Li6PS5Cl, Li6PS5Br and Li 10 SnP2S 12 At least one of the sulfide solid electrolytes has a D50 of 3-5 μm.

7. The method for preparing a solid-state battery according to claim 1, characterized in that: In step S3, the polymer solid electrolyte is composed of polyethylene oxide and an ion-conducting polymer in a mass ratio of 1:

3.

8. A method for preparing a solid-state battery according to claim 7, characterized in that: The method for preparing the ion-conducting polymer comprises the following steps: S81, weighing styrene sulfonic acid and lithium hydroxide in a molar ratio of 1:1, respectively dissolving them in deionized water to obtain an 8 wt % styrene sulfonic acid aqueous solution and an 8 wt % lithium hydroxide aqueous solution, respectively, adding the lithium hydroxide aqueous solution dropwise to the styrene sulfonic acid aqueous solution, fully neutralizing the reaction, drying to remove water, and obtaining lithium p-styrene sulfonate; S82. Weigh lithium p-styrene sulfonate, styrene and azobisisobutyronitrile in a molar ratio of 1:1:0.005 respectively, dissolve lithium p-styrene sulfonate and styrene in N,N-dimethylformamide, add azobisisobutyronitrile, thermally polymerize at 65°C for 6 hours, and purify by recrystallization with methanol and ethyl ether to obtain an ion-conducting polymer.

9. The method for preparing a solid-state battery according to claim 1, characterized in that: In step S3, the solvent with a low melting point is at least one of acetone, isopropanol and tetrahydrofuran.

10. A solid-state battery, characterized in that: The solid-state battery is prepared by the preparation method of any one of claims 1 to 9.

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