Positive electrode for sulfide all-solid-state lithium battery, preparation method and battery

Abstract

The invention provides a positive electrode for a sulfide all-solid-state lithium battery, a preparation method and a battery, the positive electrode comprises a high-nickel ternary positive electrode material layer and a positive electrode protection layer covering the high-nickel ternary positive electrode material layer, the positive electrode protection layer is obtained by a protection layer slurry volatilization solvent and ultraviolet aging treatment, the protection layer slurry contains lithium salt, an organic solvent and nitrile rubber, and the organic solvent is an organic solvent. And the molar ratio of the nitrile rubber to the lithium salt in the protective layer slurry is (0.5-5): 1. The positive electrode protective layer contains cross-linked aged nitrile rubber, lithium salt and a part of organic solvent, the organic solvent can form a stable complex with the lithium salt to construct a high-concentration lithium salt complex system, CN <-> in the nitrile rubber can be coordinated with Li < + > in the high-concentration lithium salt complex to construct a continuous Li < + > transmission channel, so that the lithium ion battery can be used for a lithium ion battery. And the nitrile rubber is dense and hard after cross-linking and aging, so that the positive electrode protection layer effectively improves the safety performance and the cycle performance of the battery and ensures that the battery has good rate capability.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a positive electrode, preparation method, and battery for a sulfide all-solid-state lithium battery. Background Technology

[0002] All-solid-state lithium batteries offer advantages such as no leakage risk and excellent safety due to the use of solid electrolytes instead of traditional liquid electrolytes. Especially when using high-nickel ternary cathodes, they achieve extremely high energy density, making them a core development direction for next-generation energy storage devices. Among these, sulfide solid electrolytes are widely used in all-solid-state lithium battery systems due to their high ionic conductivity and good machinability.

[0003] However, existing sulfide-based all-solid-state lithium batteries still face key technical challenges that limit their application: First, when the sulfide solid electrolyte comes into direct contact with the high-nickel ternary cathode, side reactions are prone to occur, damaging the electrolyte and electrode materials, consuming active materials, causing a sharp increase in interfacial impedance, and degrading cycle performance; Second, the high-nickel ternary cathode material easily releases active oxygen at high temperatures, which diffuses rapidly and reacts with the sulfide solid electrolyte, triggering violent exothermic reactions and accelerating battery thermal runaway. Summary of the Invention

[0004] The purpose of this invention is to provide a cathode, preparation method, and battery for sulfide all-solid-state lithium batteries, in order to solve the problems in the prior art.

[0005] The technical solution adopted in this invention includes: a positive electrode for a sulfide all-solid-state lithium battery, the positive electrode comprising a high-nickel ternary positive electrode material layer and a positive electrode protective layer covering thereon, the positive electrode protective layer being obtained by evaporating solvent from protective layer slurry and undergoing ultraviolet aging treatment, the protective layer slurry containing lithium salt, organic solvent and nitrile rubber.

[0006] Preferably, the molar ratio of nitrile rubber to lithium salt in the protective layer slurry is (0.5~5):1.

[0007] Preferably, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorophosphate, lithium perchlorate, and lithium chloride.

[0008] Preferably, the concentration of lithium salt in the protective layer slurry is 1~3 mol / L.

[0009] Preferably, the organic solvent includes at least one selected from acetonitrile, propionitrile, N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, carbon tetrachloride, 1,2-dichloroethane, cyclohexanone, γ-butyrolactone, tetrahydrofuran, dioxane, butyl acetate, hexyl butyrate, dibutyl phthalate, toluene, and xylene.

[0010] The technical solution of the present invention also includes: a method for preparing the above-mentioned positive electrode for sulfide all-solid-state lithium batteries, comprising the steps of:

[0011] Nitrile rubber, lithium salt and organic solvent are mixed in a certain proportion to obtain a protective layer slurry;

[0012] A protective layer slurry is coated onto a high-nickel ternary cathode material layer, and then heated to evaporate some of the organic solvent, resulting in a coated electrode sheet.

[0013] The positive electrode is obtained by cross-linking and aging the nitrile rubber in the coated electrode using an ultraviolet environment.

[0014] Preferably, the conditions for heating to cause partial evaporation of the organic solvent are: heating temperature of 40~80℃ and heating time of 2~48h.

[0015] Preferably, the conditions for aging the nitrile rubber in the coated electrode using ultraviolet light are: ultraviolet light irradiation power of 0.5~1.5W / m2 and ultraviolet light irradiation time of 10~150min.

[0016] Preferably, the step of mixing nitrile rubber, lithium salt, and organic solvent in a specified ratio includes:

[0017] (1) Using molecular sieves to remove water from organic solvents;

[0018] (2) Use nitrile rubber and lithium salt in the specified proportions;

[0019] (3) Mix the substances obtained in steps (1) and (2) in the correct proportions.

[0020] The technical solution of the present invention also includes: a sulfide all-solid-state lithium battery, wherein the above-mentioned positive electrode is configured in the sulfide all-solid-state lithium battery.

[0021] The beneficial effects of this invention are as follows: The positive electrode provided by this invention contains a positive electrode protective layer, which contains cross-linked aged nitrile rubber, lithium salt, and a portion of organic solvent. The organic solvent can form a stable complex with the lithium salt, thereby constructing a high-concentration lithium salt complex system. The CN content in the nitrile rubber... - It can form a complex with Li in high-concentration lithium salts. + Coordination occurs, constructing continuous Li + Transmission channel, reducing Li + The migration barrier of nitrile rubber is dense and hard after cross-linking and aging. Therefore, the positive electrode protective layer can effectively isolate the high-nickel ternary positive electrode material layer from the sulfide solid electrolyte while having good ion conduction performance. It can not only prevent the high-nickel ternary positive electrode material and the active oxygen it releases from the sulfide solid electrolyte from undergoing side reactions, thus improving the safety and cycle performance of the battery, but also ensure that the battery has good rate performance. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a positive electrode for a sulfide all-solid-state lithium battery, a method for preparing the positive electrode, and a sulfide all-solid-state lithium battery equipped with the positive electrode. To facilitate a concise and clear introduction to the technical solution of this invention, the following description follows in the order of preparation method, positive electrode, and battery.

[0024] The method for preparing the positive electrode of a sulfide-based all-solid-state lithium battery provided in this invention includes the following steps:

[0025] S1. Mix nitrile rubber, lithium salt and organic solvent in a certain proportion to obtain a protective layer slurry;

[0026] S2. The protective layer slurry is coated onto the high-nickel ternary cathode material layer, and heated to evaporate some of the organic solvent, thus obtaining the coated electrode sheet;

[0027] S3. Use ultraviolet light to crosslink and age the nitrile rubber in the coated electrode to obtain the positive electrode.

[0028] The positive electrode sheet prepared by the above method includes a high-nickel ternary positive electrode material layer and a positive electrode protective layer coated thereon. As mentioned above, the positive electrode protective layer is obtained by evaporating the solvent from the protective layer slurry and performing ultraviolet aging treatment. The resulting positive electrode protective layer contains cross-linked aged nitrile rubber, lithium salt, and some organic solvent. Among them, the organic solvent can form a stable complex with the lithium salt, thereby constructing a high-concentration lithium salt complex system. The CN in the nitrile rubber... - It can form a complex with Li in high-concentration lithium salts. + Coordination occurs, constructing continuous Li + Transmission channel, reducing Li + The migration barrier of nitrile rubber is dense and hard after cross-linking and aging. Therefore, the positive electrode protective layer can effectively isolate the high-nickel ternary positive electrode material layer from the sulfide solid electrolyte while having good ion conduction performance. It can not only prevent the high-nickel ternary positive electrode material and the active oxygen it releases from the sulfide solid electrolyte from undergoing side reactions, thus improving the safety and cycle performance of the battery, but also ensure that the battery has good rate performance.

[0029] The above step S1 specifically includes:

[0030] (1) Using molecular sieves to remove water from organic solvents: During operation, add molecular sieves to the organic solvent, store it in a glove box, and then filter to remove the molecular sieves;

[0031] Preferably, the molecular sieve has a radius of 3~5mm, a type of 4Å, a static water adsorption capacity (25℃, saturated saline, 24h) ≥22.5%, a static water adsorption capacity (35℃, saturated saline, 24h) ≥22%, a crushing resistance ≥80N, a particle size (gravimetric method) ≥98%, and a spherical shape.

[0032] Preferably, the settling conditions for the organic solvent and molecular sieve mixture in the glove box are: argon gas filling, O2 < 0.5 ppm, H2O < 0.5 ppm, and settling time of 48 h.

[0033] Optionally, the organic solvent includes at least one of acetonitrile, propionitrile, N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, carbon tetrachloride, 1,2-dichloroethane, cyclohexanone, γ-butyrolactone, tetrahydrofuran, dioxane, butyl acetate, hexyl butyrate, dibutyl phthalate, toluene, and xylene.

[0034] (2) Take nitrile rubber and lithium salt in the following proportion: During operation, put nitrile rubber and lithium salt into a container with a magnetic stir bar in a molar ratio of (0.5~5):1. The magnetic stir bar is a polytetrafluoroethylene magnetic stir bar and the container is a silicate transparent glass bottle.

[0035] Optionally, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorophosphate, lithium perchlorate, and lithium chloride.

[0036] (3) Mix the substances obtained in steps (1) and (2) in proportion: During operation, according to the concentration of lithium salt in the protective layer slurry being 1~3 mol / L, add the dehydrated organic solvent to the container in step (2), start magnetic stirring, and stir the resulting mixture evenly to form a clear and transparent gel-like liquid, which is the protective layer slurry.

[0037] The above-mentioned step S2 specifically includes: during operation, a protective layer slurry is coated on the surface of the high-nickel ternary cathode material layer to form a uniform transparent liquid layer on the surface of the high-nickel ternary cathode material layer; the transparent liquid layer is heated for a period of time to allow the organic solvent to partially evaporate, thereby obtaining a coating layer containing some organic solvent, which is a coated electrode sheet containing the coating layer and the high-nickel ternary cathode material layer.

[0038] Preferably, the conditions for heating to cause partial evaporation of the organic solvent are: heating temperature of 40~80℃ and heating time of 2~48h.

[0039] The above-mentioned step S3 specifically includes: during operation, the coated electrode is placed under ultraviolet light for a period of time to allow the nitrile rubber in the coating to crosslink and age, thus obtaining the positive electrode.

[0040] Preferably, the conditions for crosslinking and aging the nitrile rubber in the coated electrode using ultraviolet light are: ultraviolet light irradiation power of 0.5~1.5W / m 2 The ultraviolet light irradiation time is 10~150min.

[0041] This invention also provides a sulfide-based all-solid-state lithium battery assembled using the aforementioned positive electrode. This sulfide-based all-solid-state lithium battery exhibits excellent safety and electrochemical performance: the cross-linked and aged nitrile rubber possesses good mechanical strength, is uniform and dense, effectively suppressing the diffusion of active oxygen and preventing side reactions between the high-nickel ternary positive electrode material and its released active oxygen and the sulfide solid electrolyte. This increases the battery's thermal runaway initiation temperature and reduces the peak thermal runaway temperature, ensuring good cycle life and thermal safety. Furthermore, the continuous Li-type lithium battery composed of nitrile rubber, organic solvent, and lithium salt... + The transmission channel ensures that the battery has good rate performance.

[0042] The following are specific embodiments and comparative examples of the present invention, wherein: experimental methods not specifically described in terms of operation steps are performed in accordance with the corresponding product instructions; instruments, reagents, and consumables used, unless otherwise specified, can be purchased from commercial companies. There are no particular restrictions on the source of any raw materials used in the present invention; they can be purchased from the market and prepared using conventional methods well known to those skilled in the art. There are no particular restrictions on the purity of any raw materials used in the present invention; however, analytical grade or conventional purity in the lithium battery field is preferred.

[0043] Example 1

[0044] Step 1: Prepare a high-nickel ternary cathode material layer.

[0045] The high-nickel ternary cathode material was mixed with the halide electrolyte LiInCl3, the conductive agent acetylene black, and the binder PTFE in a mass ratio of 80:17:1:2. Under argon protection, the mixture was ball-milled at 300 r / min for 3 h. The mixed powder was then transferred to a mold and unidirectionally cold-pressed using a hydraulic press to form an electrolyte-high-nickel ternary cathode material composite layer.

[0046] Step 2: Preparation of the cathode for sulfide-based all-solid-state lithium batteries

[0047] S1. Preparation of protective layer slurry:

[0048] (1) Add molecular sieve to 500 mL of hexyl butyrate (organic solvent), let stand in a glove box for 48 h, and then filter to remove the molecular sieve;

[0049] (2) Place 0.5 mol of nitrile rubber and 0.5 mol of LiFSI (lithium salt) into a silicate transparent glass bottle containing a polytetrafluoroethylene magnetic stir bar;

[0050] (3) Add hexyl butyrate dehydrated in step (1) to the silicate transparent glass bottle in step (2), start magnetic stirring, stir the resulting mixture evenly to form a clear and transparent gel-like liquid, which is the protective layer slurry.

[0051] S2. Preparation of coated electrode sheets:

[0052] The protective layer slurry is coated onto the surface of the electrolyte-high nickel ternary cathode material composite layer, forming a uniform transparent liquid layer on the surface of the electrolyte-high nickel ternary cathode material composite layer;

[0053] The transparent liquid layer is heated at 60°C for 24 hours to partially evaporate the hexyl butyrate, resulting in a coating containing a portion of hexyl butyrate (appearing as a viscous and transparent layer), thus obtaining a coated electrode containing a coating and an electrolyte-high nickel ternary cathode material composite layer.

[0054] S3. Preparation of the positive electrode sheet:

[0055] The coated electrode was placed under ultraviolet light at a rate of 0.8 W / m. 2 Irradiate with high power for 30 minutes to cause the nitrile rubber in the coating to crosslink and age, thus obtaining the positive electrode sheet.

[0056] Example 2

[0057] Step 1: Prepare a high-nickel ternary cathode material layer.

[0058] The high-nickel ternary cathode material was mixed with the halide electrolyte LiInCl3, the conductive agent acetylene black, and the binder PTFE in a mass ratio of 80:17:1:2. Under argon protection, the mixture was ball-milled at 300 r / min for 3 h. The mixed powder was then transferred to a mold and unidirectionally cold-pressed using a hydraulic press to form an electrolyte-high-nickel ternary cathode material composite layer.

[0059] Step 2: Preparation of the cathode for sulfide-based all-solid-state lithium batteries

[0060] S1. Preparation of protective layer slurry:

[0061] (1) Add molecular sieve to 500 mL of hexyl butyrate (organic solvent), let stand in a glove box for 48 h, and then filter to remove the molecular sieve;

[0062] (2) Place 1 mol of nitrile rubber and 0.5 mol of LiFSI (lithium salt) into a silicate transparent glass bottle containing a polytetrafluoroethylene magnetic stir bar;

[0063] (3) Add hexyl butyrate dehydrated in step (1) to the silicate transparent glass bottle in step (2), start magnetic stirring, stir the resulting mixture evenly to form a clear and transparent gel-like liquid, which is the protective layer slurry.

[0064] S2. Preparation of coated electrode sheets:

[0065] The protective layer slurry is coated onto the surface of the electrolyte-high nickel ternary cathode material composite layer, forming a uniform transparent liquid layer on the surface of the electrolyte-high nickel ternary cathode material composite layer;

[0066] The transparent liquid layer is heated at 60°C for 24 hours to partially evaporate the hexyl butyrate, resulting in a coating containing a portion of hexyl butyrate (appearing as a viscous and transparent layer), thus obtaining a coated electrode containing a coating and an electrolyte-high nickel ternary cathode material composite layer.

[0067] S3. Preparation of the positive electrode sheet:

[0068] The coated electrode was placed under ultraviolet light at a rate of 0.8 W / m. 2 Irradiate with high power for 30 minutes to cause the nitrile rubber in the coating to crosslink and age, thus obtaining the positive electrode sheet.

[0069] Example 3

[0070] Step 1: Prepare a high-nickel ternary cathode material layer.

[0071] The high-nickel ternary cathode material was mixed with the halide electrolyte LiInCl3, the conductive agent acetylene black, and the binder PTFE in a mass ratio of 80:17:1:2. Under argon protection, the mixture was ball-milled at 300 r / min for 3 h. The mixed powder was then transferred to a mold and unidirectionally cold-pressed using a hydraulic press to form an electrolyte-high-nickel ternary cathode material composite layer.

[0072] Step 2: Preparation of the cathode for sulfide-based all-solid-state lithium batteries

[0073] S1. Preparation of protective layer slurry:

[0074] (1) Add molecular sieve to 500 mL of hexyl butyrate (organic solvent), let stand in a glove box for 48 h, and then filter to remove the molecular sieve;

[0075] (2) Place 0.5 mol of nitrile rubber and 0.5 mol of LiFSI (lithium salt) into a silicate transparent glass bottle containing a polytetrafluoroethylene magnetic stir bar;

[0076] (3) Add hexyl butyrate dehydrated in step (1) to the silicate transparent glass bottle in step (2), start magnetic stirring, stir the resulting mixture evenly to form a clear and transparent gel-like liquid, which is the protective layer slurry.

[0077] S2. Preparation of coated electrode sheets:

[0078] The protective layer slurry is coated onto the surface of the electrolyte-high nickel ternary cathode material composite layer, forming a uniform transparent liquid layer on the surface of the electrolyte-high nickel ternary cathode material composite layer;

[0079] The transparent liquid layer is heated at 60°C for 24 hours to partially evaporate the hexyl butyrate, resulting in a coating containing a portion of hexyl butyrate (appearing as a viscous and transparent layer), thus obtaining a coated electrode containing a coating and an electrolyte-high nickel ternary cathode material composite layer.

[0080] S3. Preparation of the positive electrode sheet:

[0081] The coated electrode was placed under ultraviolet light at a rate of 1.0 W / m 2 Irradiate with high power for 30 minutes to cause the nitrile rubber in the coating to crosslink and age, thus obtaining the positive electrode sheet.

[0082] Example 4

[0083] Step 1: Prepare a high-nickel ternary cathode material layer.

[0084] The high-nickel ternary cathode material was mixed with the halide electrolyte LiInCl3, the conductive agent acetylene black, and the binder PTFE in a mass ratio of 80:17:1:2. Under argon protection, the mixture was ball-milled at 300 r / min for 3 h. The mixed powder was then transferred to a mold and unidirectionally cold-pressed using a hydraulic press to form an electrolyte-high-nickel ternary cathode material composite layer.

[0085] Step 2: Preparation of the cathode for sulfide-based all-solid-state lithium batteries

[0086] S1. Preparation of protective layer slurry:

[0087] (1) Add molecular sieve to 500 mL of hexyl butyrate (organic solvent), let stand in a glove box for 48 h, and then filter to remove the molecular sieve;

[0088] (2) Place 0.5 mol of nitrile rubber and 0.5 mol of LiFSI (lithium salt) into a silicate transparent glass bottle containing a polytetrafluoroethylene magnetic stir bar;

[0089] (3) Add hexyl butyrate dehydrated in step (1) to the silicate transparent glass bottle in step (2), start magnetic stirring, stir the resulting mixture evenly to form a clear and transparent gel-like liquid, which is the protective layer slurry.

[0090] S2. Preparation of coated electrode sheets:

[0091] The protective layer slurry is coated onto the surface of the electrolyte-high nickel ternary cathode material composite layer, forming a uniform transparent liquid layer on the surface of the electrolyte-high nickel ternary cathode material composite layer;

[0092] The transparent liquid layer is heated at 60°C for 24 hours to partially evaporate the hexyl butyrate, resulting in a coating containing a portion of hexyl butyrate (appearing as a viscous and transparent layer), thus obtaining a coated electrode containing a coating and an electrolyte-high nickel ternary cathode material composite layer.

[0093] S3. Preparation of the positive electrode sheet:

[0094] The coated electrode was placed under ultraviolet light at a rate of 0.8 W / m. 2 Irradiate with high power for 60 minutes to cause the nitrile rubber in the coating to crosslink and age, thus obtaining the positive electrode sheet.

[0095] Example 5

[0096] After ball milling Li6PS5Cl powder at 200 r / min for 2 h, it was transferred to a mold and subjected to a pressure of 200 MPa at room temperature for 15 min to obtain a solid electrolyte layer.

[0097] A 20Ah-level sulfide all-solid-state lithium battery was fabricated by stacking, packaging, baking, sealing, settling, forming, and capacity testing of a commercial silicon-carbon anode, a separator obtained in Example 5, and a positive electrode obtained in Example 1.

[0098] Example 6

[0099] After ball milling Li6PS5Cl powder at 200 r / min for 2 h, it was transferred to a mold and subjected to a pressure of 200 MPa at room temperature for 15 min to obtain a solid electrolyte layer.

[0100] A 20Ah-level sulfide all-solid-state lithium battery was fabricated by stacking, packaging, baking, sealing, settling, forming, and capacity testing of a commercial silicon-carbon anode, a separator obtained in Example 6, and a positive electrode obtained in Example 2.

[0101] Example 7

[0102] After ball milling Li6PS5Cl powder at 200 r / min for 2 h, it was transferred to a mold and subjected to a pressure of 200 MPa at room temperature for 15 min to obtain a solid electrolyte layer.

[0103] Commercial silicon-carbon anodes, the separator obtained in Example 7, and the positive electrode obtained in Example 3 were stacked, packaged, baked, sealed, left to stand, formed, and tested to produce a 20Ah-level sulfide all-solid-state lithium battery.

[0104] Example 8

[0105] After ball milling Li6PS5Cl powder at 200 r / min for 2 h, it was transferred to a mold and subjected to a pressure of 200 MPa at room temperature for 15 min to obtain a solid electrolyte layer.

[0106] Commercial silicon-carbon anodes, the separator obtained in Example 8, and the positive electrode obtained in Example 4 were stacked, packaged, baked, sealed, left to stand, formed, and tested to produce a 20Ah-level sulfide all-solid-state lithium battery.

[0107] Comparative Example 1

[0108] The high-nickel ternary cathode material was mixed with the halide electrolyte LiInCl3, the conductive agent acetylene black, and the binder PTFE in a mass ratio of 80:17:1:2. Under argon protection, the mixture was ball-milled at 300 r / min for 3 h. The mixed powder was then transferred to a mold and unidirectionally cold-pressed using a hydraulic press to form an electrolyte-high-nickel ternary cathode material composite layer.

[0109] After ball milling Li6PS5Cl powder at 200 r / min for 2 h, it was transferred to a mold and subjected to a pressure of 200 MPa at room temperature for 15 min to obtain a solid electrolyte layer.

[0110] Using the electrolyte-high nickel ternary cathode material composite layer prepared in Comparative Example 1 as the cathode electrode, the commercial silicon-carbon anode, the cathode electrode obtained in Comparative Example 1, and the separator were stacked, packaged, baked, sealed, left to stand, formed, and tested to produce a 20Ah-level sulfide all-solid-state lithium battery.

[0111] Performance testing:

[0112] The sulfide all-solid-state lithium batteries obtained in Examples 5-8 and Comparative Example 1 were tested under the following conditions:

[0113] (1) Specific energy test: 0.2C charge and discharge at 25℃.

[0114] (2) Needle penetration test: When the battery is fully charged (100% SOC), use a steel needle with a diameter of 3 mm and a taper of 30° to radially penetrate the battery at a speed of 40 mm / s. The steel needle stays in the battery for 1 hour.

[0115] (3) 180℃ hot box test: Measure the battery voltage V1 when the battery is fully charged (100% SOC); place the battery in an environment of 180℃±2℃ for 24h, then transfer the battery to an environment of 25℃±2℃ for 4h, then check the battery status and measure the battery voltage V2.

[0116] The above-mentioned needle penetration test passed when the battery did not catch fire, and the hot box test passed when the battery voltage change V1-V2 did not exceed 0.2V. The test results are shown in the table below:

[0117] Battery source Specific energy (Wh / kg) Needle prick test pass rate 180℃ hot box test pass rate Example 5 300 8 / 10 8 / 10 Example 6 300 9 / 10 8 / 10 Example 7 300 8 / 10 9 / 10 Example 8 300 9 / 10 9 / 10 Comparative Example 1 300 4 / 10 6 / 10

[0118] In the table above, n / 10 indicates that n out of 10 battery samples in each batch pass the test. The table shows that the cathode prepared using this invention can effectively improve the safety performance of sulfide-based all-solid-state lithium batteries and maintain good electrochemical performance.

[0119] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the claims, or equivalent forms of such scope and boundaries.

Claims

1. A positive electrode for a sulfide-based all-solid-state lithium battery, characterized in that, The positive electrode includes a high-nickel ternary positive electrode material layer and a positive electrode protective layer covering it. The positive electrode protective layer is obtained by evaporating solvent from the protective layer slurry and performing ultraviolet aging treatment. The protective layer slurry contains lithium salt, organic solvent and nitrile rubber.

2. The positive electrode for a sulfide-based all-solid-state lithium battery according to claim 1, characterized in that, The molar ratio of nitrile rubber to lithium salt in the protective layer slurry is (0.5~5):

1.

3. The positive electrode for a sulfide-based all-solid-state lithium battery according to claim 2, characterized in that, Lithium salts include at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorophosphate, lithium perchlorate, and lithium chloride.

4. The positive electrode for a sulfide-based all-solid-state lithium battery according to any one of claims 1-3, characterized in that, The concentration of lithium salt in the protective layer slurry is 1~3 mol / L.

5. The positive electrode for a sulfide-based all-solid-state lithium battery according to claim 4, characterized in that, Organic solvents include at least one of acetonitrile, propionitrile, N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, carbon tetrachloride, 1,2-dichloroethane, cyclohexanone, γ-butyrolactone, tetrahydrofuran, dioxane, butyl acetate, hexyl butyrate, dibutyl phthalate, toluene, and xylene.

6. A method for preparing the positive electrode for a sulfide all-solid-state lithium battery according to any one of claims 1-5, characterized in that, Including the following steps: Nitrile rubber, lithium salt and organic solvent are mixed in a certain proportion to obtain a protective layer slurry; A protective layer slurry is coated onto a high-nickel ternary cathode material layer, and then heated to evaporate some of the organic solvent, resulting in a coated electrode sheet. The positive electrode is obtained by cross-linking and aging the nitrile rubber in the coated electrode using an ultraviolet environment.

7. The method for preparing the positive electrode for a sulfide-based all-solid-state lithium battery according to claim 6, characterized in that, Conditions for heating to evaporate some of the organic solvent: heating temperature 40~80℃, heating time 2~48h.

8. The method for preparing the positive electrode for a sulfide-based all-solid-state lithium battery according to claim 6, characterized in that, The conditions for aging the nitrile rubber in the coated electrode using ultraviolet light are: ultraviolet light irradiation power of 0.5~1.5W / m. 2 The ultraviolet light irradiation time is 10~150min.

9. The method for preparing the positive electrode for a sulfide-based all-solid-state lithium battery according to claim 6, characterized in that, The step of mixing nitrile rubber, lithium salt, and organic solvent in a specific ratio includes: (1) Using molecular sieves to remove water from organic solvents; (2) Use nitrile rubber and lithium salt in the specified proportions; (3) Mix the substances obtained in steps (1) and (2) in the correct proportions.

10. A sulfide-based all-solid-state lithium battery, characterized in that, The sulfide all-solid-state lithium battery is configured with a positive electrode as described in any one of claims 1-5.