Sulfide solid-state battery and application of preparation method thereof
By using conductive rubber materials and conductive agents in sulfide solid-state batteries to form a highly conductive electrode structure, the problem of poor interface contact between the electrode and the solid electrolyte is solved, and the battery's cycle performance and safety performance are improved.
Patent Information
- Application Number
- CN202510862782.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-25
- Publication Date
- 2025-09-26
AI Technical Summary
Existing sulfide solid-state batteries have problems such as poor interface contact between electrodes and solid electrolytes and poor conductivity, resulting in poor capacity and cycle performance.
Conductive rubber materials are used to add conductive agents and electrolytes to the positive and negative electrode material layers to form a highly conductive electrode structure. Conductive glue is prepared through a wet process to evenly wrap the main material to form a stable electron ion network.
The interfacial contact stability between the electrode and the electrolyte is significantly improved, and the cycle performance, rate performance and safety performance of the battery are improved.
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Figure CN120709455A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of battery technology, and in particular to a sulfide solid-state battery and an application of a preparation method thereof. Background Art
[0002] As lithium-ion batteries become ubiquitous in all areas of production and life, people are placing higher demands on their energy density and safety performance. Liquid lithium batteries operating at high currents may produce lithium dendrites, causing battery short circuits. Furthermore, organic liquid electrolytes are prone to side reactions, oxidative decomposition, gas generation, and even thermal runaway at high temperatures, which can easily lead to serious safety issues. Compared to liquid batteries, solid-state lithium batteries use solid electrolytes to directly replace electrolytes with flammable and volatile organic liquids as solvents. Among them, solid-state batteries, represented by sulfide solid-state lithium batteries, have higher energy density and safety performance, and are one of the main development trends of the next generation of energy storage systems.
[0003] However, on the one hand, the interface contact between the electrode and the solid electrolyte in sulfide solid-state lithium batteries is different from the solid-liquid contact between the electrode and the electrolyte in liquid batteries; on the other hand, the conductivity of the active material commonly used in sulfide solid-state batteries is also poor. For example, the main material of the negative electrode uses SiO2, which is more mature. x In order to match higher energy density, the negative electrode of sulfide solid-state battery uses micron / nano silicon with higher specific capacity as the main material, which directly results in the inability to build a complete ion-electron three-phase contact network structure in the solid-state battery electrode.
[0004] In summary, the existing sulfide solid-state battery system has poor capacity and cycle performance due to large contact impedance and low particle electronic conductivity.
[0005] In view of this, the present invention is proposed. Summary of the Invention
[0006] An object of the present invention is to provide a sulfide solid-state battery having the characteristics of small polarization impedance, high capacity and excellent cycle performance.
[0007] Another object of the present invention is to provide a method for preparing a sulfide solid-state battery, which is simple, easy to implement and environmentally friendly.
[0008] Another object of the present invention is to provide an electrical device.
[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted: A sulfide solid-state battery comprises a positive electrode sheet, a negative electrode sheet, and an electrolyte layer; the positive electrode sheet comprises a positive electrode material layer, the negative electrode sheet comprises a negative electrode material layer, and the positive electrode material layer and / or the negative electrode material layer comprise a conductive rubber material; the conductive rubber material has a mass content of 2% to 4% in the positive electrode material layer, and a mass content of 1% to 3% in the negative electrode material layer.
[0010] In some embodiments, the conductive rubber materials in the positive electrode material layer and the negative electrode material layer independently include at least one of conductive silicone rubber, conductive perfluororubber, conductive tetrafluoropropylene rubber, conductive chloroprene rubber, conductive polyurethane rubber, conductive acrylic rubber, conductive carbon black nitrile rubber and conductive ethylene acrylate rubber.
[0011] In some embodiments, the positive electrode material layer further includes a positive electrode material, a first sulfide electrolyte, and a first conductive agent, and the mass ratio of the positive electrode material, the first sulfide electrolyte, and the first conductive agent is (8-12): (2-5): (0.1-0.5).
[0012] In some embodiments, the negative electrode material layer further includes a negative electrode material, a second sulfide electrolyte, and a second conductive agent, and the mass ratio of the negative electrode material, the second sulfide electrolyte, and the second conductive agent is (8~12):(2~5):(0.1~0.5).
[0013] In some embodiments, the first conductive agent and the second conductive agent each independently include at least one of acetylene black, carbon black, graphite, nano-carbon fiber, carbon nanotube, and graphene.
[0014] In some embodiments, the first conductive agent and the second conductive agent are each independently selected from a conductive agent A, a conductive agent B, and a conductive agent C, the conductive agent A is nano-carbon fiber, the conductive agent B is a carbon nanotube, and the conductive agent C is at least one of acetylene black, carbon black, graphite, and graphene, and the mass ratio of the conductive agent A, the conductive agent B, and the conductive agent C is (3~5):2:1.
[0015] In some embodiments, the positive electrode material includes at least one of lithium iron phosphate, lithium manganese oxide, and nickel cobalt manganese material.
[0016] In some embodiments, the negative electrode material comprises SiO x , at least one of silicon carbon, micron silicon and nano silicon.
[0017] In some embodiments, the electrolyte layer includes a sulfide electrolyte and a binder, and the mass content of the binder in the electrolyte layer is 3% to 6%; the binder includes at least one of SBS, NBR, SEBS and SBR.
[0018] The method for preparing the sulfide solid-state battery as described above comprises the following steps: Obtain a conductive adhesive solution formed by a conductive rubber material and a solvent.
[0019] A positive electrode slurry and a negative electrode slurry are obtained, wherein the positive electrode slurry and / or the negative electrode slurry contain the conductive glue.
[0020] The positive electrode slurry further includes an organic solvent, a first sulfide electrolyte, a positive electrode material and a first conductive agent; the positive electrode slurry is coated on the surface of the positive electrode current collector to obtain a positive electrode sheet.
[0021] The negative electrode slurry further includes an organic solvent, a second sulfide electrolyte, a negative electrode material and a second conductive agent; the negative electrode slurry is coated on the surface of the negative electrode current collector to obtain a negative electrode sheet.
[0022] Obtain electrolyte slurry, apply the electrolyte slurry to at least one side of the positive electrode sheet and / or the negative electrode sheet to obtain a composite positive electrode sheet and / or a composite negative electrode sheet, and then perform lamination processing to obtain a sulfide solid-state battery.
[0023] In some embodiments, the solid content of the conductive adhesive is 2% to 6%.
[0024] In some embodiments, the method for preparing the positive electrode slurry specifically includes: first mixing the conductive glue and the solvent, second mixing with the first sulfide electrolyte, third mixing with the positive electrode material, and fourth mixing with the first conductive agent.
[0025] In some embodiments, the first mixing, the second mixing, and the third mixing independently include sequentially performing a low-speed treatment and a high-speed treatment, wherein the low-speed treatment is performed at a speed of 700 to 1000 rpm for a time of 3 to 6 minutes, and the high-speed treatment is performed at a speed of 1500 to 2500 rpm for a time of 8 to 15 minutes; In some embodiments, the method for preparing the negative electrode slurry specifically includes: first mixing the conductive glue and the solvent, second mixing with the second sulfide electrolyte, third mixing with the negative electrode material, and fourth mixing with the second conductive agent.
[0026] In some embodiments, the first mixing, the second mixing, and the third mixing each independently include sequentially performing low-speed processing and high-speed processing, the low-speed processing speed is 700-1000 rpm, the low-speed processing time is 3-6 minutes, the high-speed processing speed is 1500-2500 rpm, and the high-speed processing time is 8-15 minutes.
[0027] In some embodiments, the preparation of the electrolyte slurry specifically includes: mixing a binder and a solvent to obtain a mixed system with a solid content of 40% to 50%, and then mixing with a sulfide electrolyte to obtain an electrolyte slurry.
[0028] An electrical device comprises the sulfide solid-state battery.
[0029] Compared with the prior art, the present invention has the following beneficial effects: (1) The conductive rubber material network of the present invention tightly wraps and crosslinks the active material, conductive agent, and electrolyte together to form an electrode with high conductivity. This effectively avoids the problem of uneven dispersion of the current polymer rubber binder itself, which makes it difficult to achieve uniform mixing of the slurry components. It also effectively alleviates the problem of large expansion rate of the active material, such as the current high-expansion silicon negative electrode, which has a reduced contact area due to volume expansion during the charge and discharge cycle and severe cycle attenuation. The present invention uses a suitable proportion of conductive rubber material to significantly improve the interfacial contact stability between the electrode and the electrolyte, maintain a good conductive network, and thus enhance the cycle performance, rate performance, and safety performance of the battery.
[0030] (2) The preparation method of the sulfide solid-state battery of the present invention is that when the conductive glue is prepared by a wet process, the conductive agent and the polymer material in the conductive glue can be dissolved in a solvent in a uniformly distributed state to form a conductive glue. When preparing the positive and negative electrode slurries, the main material is added to the glue. The conductive agent in the conductive glue is evenly wrapped around the main material under the action of the polymer material, so that the main material particles, the conductive agent, and the binder in the positive and negative electrodes form a better electron ion network in the sulfide solid phase system, which is beneficial to reducing the battery polarization impedance, increasing the positive and negative electrode capacity, and improving the battery cycle performance.
[0031] (3) The battery of the present invention has excellent cycle performance, rate performance and safety performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0033] Figure 1 Graph showing the cycle performance of the soft-pack batteries obtained in Examples 1 to 3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION
[0034] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.
[0035] According to one aspect of the present invention, the present invention relates to a sulfide solid-state battery, comprising a positive electrode sheet, a negative electrode sheet and an electrolyte layer; the positive electrode sheet comprises a positive electrode material layer, the negative electrode sheet comprises a negative electrode material layer, and the positive electrode material layer and / or the negative electrode material layer comprise a conductive rubber material; the conductive rubber material has a mass content of 2% to 4% in the positive electrode material layer, and a mass content of 1% to 3% in the negative electrode material layer.
[0036] The conductive rubber material of the present invention is a conductive carbon black or conductive fiber and other media are evenly dispersed in a polymer material to form a stable two-phase distributed conductive adhesive material. The conductive rubber material can be dissolved in a solvent in a uniformly distributed state to form a conductive glue. The active material, conductive agent and electrolyte are tightly wrapped and cross-linked together through the conductive rubber material network to form an electrode with high conductivity. This can effectively avoid the problem that the current polymer rubber adhesive itself cannot achieve the mixing of slurry components due to uneven dispersion. At the same time, it can also effectively alleviate the problem of large expansion rate of active materials, such as the current high-expansion silicon negative electrode, which has a reduced contact area due to volume expansion during the charge and discharge cycle and severe cycle attenuation. The present invention adopts a suitable proportion of conductive rubber material, such as 1%, 2%, 3%, etc., which can significantly improve the interface contact stability of the electrode and the electrolyte, maintain a good conductive network, and thus improve the cycle performance, rate performance and safety performance of the battery.
[0037] In some embodiments, the positive electrode sheet includes a current collector and a positive electrode material layer located on at least one side of the positive electrode current collector. The positive electrode current collector includes aluminum foil or aluminum alloy foil.
[0038] In some embodiments, the negative electrode sheet includes a current collector and a negative electrode material layer located on at least one side of the negative electrode current collector. The negative electrode current collector includes copper foil.
[0039] In some embodiments, the conductive rubber material in the positive electrode material layer and the negative electrode material layer independently includes at least one of conductive silicone rubber, conductive perfluororubber, conductive tetrafluoroethylene rubber, conductive chloroprene rubber, conductive polyurethane rubber, conductive acrylic rubber, conductive carbon black nitrile rubber, and conductive ethylene acrylate rubber. The present invention employs one or more of the above-mentioned conductive rubber materials, such as a combination of conductive tetrafluoroethylene rubber and conductive chloroprene rubber, a combination of conductive acrylic rubber and conductive ethylene acrylate rubber, and the like. The conductive rubber material itself forms a continuous elastic conductive matrix that can form a complementary network with conventional conductive agents. When the first conductive agent or the second conductive agent is displaced due to changes in the electrode volume, the conductive network of the conductive rubber material can prevent the conductive path from being interrupted. In addition, it can evenly disperse the electrolyte and conductive agent around the positive and negative electrode main materials, thereby improving the electrochemical performance of the positive and negative electrode material layers.
[0040] In some embodiments, the conductive silicone rubber is derived from Anhui Mingyi Silicon Industry Co., Ltd., and is an addition-type liquid silicone rubber functional additive.
[0041] In some embodiments, a method for preparing a conductive perfluororubber comprises: plasticizing a fluororubber raw rubber and softening it at a roller temperature of 40-60° C. on an open mill; adding an acid scavenger, magnesium oxide, and a processing aid, stearic acid, and mixing them evenly; adding a conductive filler, acetylene black, in portions to avoid agglomeration, and controlling the temperature to be less than 100° C. to prevent scorching; and finally adding a vulcanizing agent, bisphenol AF, wherein the mass ratio of the acid scavenger, processing aid, conductive filler, and vulcanizing agent is (15-18):(1-3):(45-55):(2-4), mixing evenly, and then discharging the glue.
[0042] In some embodiments, the preparation method of the conductive perfluororubber in a specific embodiment includes: plasticizing the fluororubber raw rubber and softening it at a roller temperature of 50°C on an open mill; adding an acid scavenger magnesium oxide and a processing aid stearic acid and mixing them evenly; adding the conductive filler acetylene black in three times (the same amount is added each time) to avoid agglomeration, and controlling the temperature to 85°C; finally, adding the vulcanizing agent bisphenol AF, with the mass ratio of the acid scavenger, processing aid, conductive filler, and vulcanizing agent being 16:2:50:3, mixing and then draining the glue.
[0043] In some embodiments, the method for preparing the conductive tetrafluoroethylene rubber comprises: (1) Emulsion polymerization tetrafluoroethylene rubber: Monomers: tetrafluoroethylene (TFE) and propylene (P), molar ratio 70:30~80:20.
[0044] Curing site monomer: bromine / iodine-containing olefins (such as perfluoroethyl iodide vinyl ether, perfluoro-4-iodo-1-butene), added in an amount of 0.1% to 3% (based on monomer mass), providing peroxide curing crosslinking sites. Chain transfer agent: I(CF2) nI (n=2~6, such as perfluorobutyl diiodide), dosage 0.3%~1.2%, to regulate molecular weight distribution and reduce Mooney viscosity.
[0045] Initiator system: redox type (potassium persulfate + ammonium persulfate + sodium metabisulfite, mass ratio 1:1:2), dosage 0.4%~0.6%.
[0046] Conditions: temperature 85~95℃, pressure 0.8~1.2 MPa, reaction time is maintained by adding monomers to maintain constant pressure.
[0047] Post-treatment: coagulation with magnesium chloride solution, washing with water, and vacuum drying at 90℃.
[0048] (2) Mixing.
[0049] Stage 1: A mixture of tetrafluoroethylene rubber, carbon black, coal powder and sodium stearate was banburying at 110° C., with the mass ratio of tetrafluoroethylene rubber, carbon black, coal powder and sodium stearate being 100:20:15:1.5, to obtain a first system.
[0050] Stage 2: The first system is parked for 12 hours, and silver-plated nickel powder, TAIC (triallyl isocyanurate), and DCP (dicumyl peroxide) are added to the mill in a mass ratio of 5:6:1.5, and thin sheets are produced.
[0051] (3) Vulcanization: Molding (170℃ for 10 min, 15 MPa); oven two-stage vulcanization (230℃ for 4 h).
[0052] In some embodiments, a method for preparing conductive chloroprene rubber comprises: Neoprene was plasticized, and antioxidants and processing aids were added. The antioxidants included anti-ozonant RD (anti-cracking) and thermal oxidation inhibitor 4010NA. Stearic acid was used as a processing aid. Conductive filler (acetylene black) was added in batches. Magnesium oxide and zinc oxide were added to absorb acid and prevent scorching. The mass ratio of antioxidant, processing aid, conductive filler, magnesium oxide and zinc oxide was (1-3): (1.5-3.5): (25-35): (3-5): (3-5). Staged vulcanization was performed: stage one vulcanization was performed in a flat vulcanizing press (temperature of 150-160°C, pressure of 10-15 MPa, and time of 15-30 min); stage two vulcanization was performed in an oven (temperature of 70-90°C, and time of 4-8 h. Stage two vulcanization can eliminate stress and stabilize conductivity.
[0053] In some embodiments, the method for preparing the conductive chloroprene rubber in a specific embodiment includes: Neoprene was plasticized, and antioxidants and processing aids were added. The antioxidants included anti-ozonant RD (anti-cracking) and thermal oxidation inhibitor 4010NA. Stearic acid was used as a processing aid. Conductive filler (acetylene black) was added in batches. Magnesium oxide and zinc oxide were added to absorb acid and prevent scorching. The mass ratio of antioxidant, processing aid, conductive filler, magnesium oxide and zinc oxide was 1.5:2:30:4:4. Stage vulcanization was performed: stage one vulcanization was performed in a flat vulcanizing press (temperature 155°C, pressure 12 MPa, time 20 min); stage two vulcanization was performed in an oven (temperature 80°C, time 6 h).
[0054] In some embodiments, the method for preparing the conductive polyurethane rubber comprises: The polyol PPG is dehydrated, and diisocyanate is added. The reaction is carried out at 75-85°C for 2 hours to form a prepolymer. The filler (graphene), solvent (DMF), and coupling agent (silane KH550) are ultrasonically dispersed for 1 hour, and then added to the prepolymer with high-speed stirring to form a conductive paste. The conductive paste is then added with a chain extender (MOCA) and vacuum degassed for 10 minutes before being vulcanized in stages. The mass ratio of PPG, diisocyanate, graphene, DMF, KH550, and MOCA is 100:2:30:40:3:15. The staged vulcanization process includes a first stage vulcanization at 100-120°C for 2-6 hours (at atmospheric pressure) and a second stage vulcanization at 80°C for 24 hours to increase the degree of crosslinking.
[0055] In some embodiments, the method for preparing the conductive acrylic rubber comprises: The matrix was prepared by emulsion polymerization. Acrylate monomer, acetylene black, sodium dodecylsulfonate, and potassium persulfate were reacted at 80°C for 3 hours in a ratio of 100:25:2:05. The emulsion was broken, washed, and dried to obtain the matrix rubber. Filler (acetylene black) and silane coupling agent KH550 were added and mixed in an internal mixer. The filler mass was 20% of the matrix rubber mass, and the silane coupling agent KH550 mass was 2% of the matrix rubber mass. The temperature did not exceed 70°C, and the product was vulcanized in stages. The staged vulcanization process included: compression vulcanization at 170°C for 10 minutes (pressure 10 MPa); and a second stage oven vulcanization at 150°C for 4 hours (to stabilize the conductive network).
[0056] In some embodiments, a method for preparing a conductive ethylene acrylate rubber comprises: Put the ethylene-acrylate rubber into the internal mixer for plastication at a temperature not exceeding 60°C. The mass ratio of rubber to acetylene black is 4:1. Add the conductive agent into the internal mixer in three times (the amount is the same for each time), heat it to 100-110°C and mix it for 10 minutes, and then vulcanize it in sections. The section vulcanization includes: one stage of molding: treatment at 170°C for 10 minutes (pressure is 15MPa); the second stage of oven: treatment at 150°C for 4 hours to eliminate internal stress and stabilize conductivity.
[0057] In some embodiments, the method for preparing the conductive carbon black nitrile rubber comprises: At a roll temperature of 40-50°C, add NBR and thinly mix for 3 minutes. Add conductive carbon black in three batches (2 minutes between each addition), thinning until free of particles. Add zinc oxide, stearic acid, sulfur, and an accelerator (DM) and mix for 5 minutes. Remove from heat and perform a staged vulcanization. The mass ratio of NBR, conductive carbon black, zinc oxide, stearic acid, sulfur, and accelerator is 100:30:5:1:1.5:1.2. The staged vulcanization process includes: compression vulcanization at 160°C for 8 minutes (10 MPa pressure) and a second stage vulcanization at 100°C for 2 hours to stabilize performance.
[0058] In some embodiments, the conductive rubber materials in the positive electrode material layer and the negative electrode material layer are each independently selected from a first material, a second material, and a third material. The first material is selected from conductive silicone rubber, the second material is selected from at least one of conductive perfluororubber, conductive tetrafluoroethylene rubber, and conductive chloroprene rubber, and the third material is selected from at least one of conductive polyurethane rubber, conductive acrylate rubber, conductive ethylene acrylate rubber, conductive nitrile rubber, conductive ethylene propylene rubber, and conductive butyl rubber. The mass ratio of the first material, the second material, and the third material is 1:(2-4):1. The present invention utilizes an appropriate ratio of the first, second, and third materials to enhance the stability and electrochemical performance of the positive electrode material layer and the material layer.
[0059] In some embodiments, the positive electrode material layer further includes a positive electrode material, a first sulfide electrolyte, and a first conductive agent, and the mass ratio of the positive electrode material, the first sulfide electrolyte, and the first conductive agent is (8~12):(2~5):(0.1~0.5), for example, 8:2:0.1, 9:3:0.2, 9:4:0.3, 11:4:0.4, 12:5:0.5, etc.
[0060] In some embodiments, the negative electrode material layer further includes a negative electrode material, a second sulfide electrolyte, and a second conductive agent, and the mass ratio of the negative electrode material, the second sulfide electrolyte, and the second conductive agent is (8~12):(2~5):(0.1~0.5), for example, 8:2:0.1, 9:3:0.2, 9:4:0.3, 11:4:0.4, 12:5:0.5, etc.
[0061] In some embodiments, the first conductive agent and the second conductive agent each independently include at least one of acetylene black, carbon black, graphite, carbon nanofibers, carbon nanotubes, and graphene, such as a combination of carbon black and graphite, a combination of carbon nanofibers and carbon nanotubes, or a combination of carbon nanofibers, carbon nanotubes, and graphene. The present invention improves electronic conductivity by using conductive agents of appropriate types and proportions.
[0062] In some embodiments, the first and second conductive agents are each independently selected from conductive agent A, conductive agent B, and conductive agent C, wherein conductive agent A is carbon nanofiber having a diameter of 120-180 nm and a length of 10-40 μm, conductive agent B is carbon nanotubes, and conductive agent C is at least one of acetylene black, carbon black, graphite, and graphene, and the mass ratio of conductive agent A, conductive agent B, and conductive agent C is (3-5):2:1. The present invention utilizes the above-described specific composition of the first and second conductive agents to form a more effective synergistic effect with the conductive rubber material. The appropriate proportion of carbon nanofibers helps resist fracture caused by volume deformation and provides a good skeletal support effect. The appropriate proportion of carbon nanotubes can form super electron channels and a three-dimensional network. The appropriate proportion of conductive agent C can be filled between conductive agent A and conductive agent B to achieve synergistic effects.
[0063] In some embodiments, the positive electrode material includes one or a combination of lithium iron phosphate, lithium manganese oxide, and nickel cobalt manganese materials.
[0064] In some embodiments, the negative electrode material comprises SiO x , silicon carbon, micron silicon and nano silicon, or a combination of the two.
[0065] In some embodiments, the first sulfide electrolyte and the second sulfide solid electrolyte each independently include lithium germanium phosphosulfur, lithium silicon phosphosulfur chlorine, and argyrodite-type Li6PS5X, where X is at least one of Cl, Br, or I.
[0066] In some embodiments, the electrolyte layer includes a sulfide electrolyte and a binder, and the mass content of the binder in the electrolyte layer is 3% to 6%, for example, 3%, 4%, %, 6%, etc.; the binder includes at least one of SBS, NBR, SEBS and SBR.
[0067] According to another aspect of the present invention, the present invention also relates to a method for preparing the sulfide solid-state battery as described above, comprising the following steps: Obtain a conductive adhesive solution formed by a conductive rubber material and a solvent.
[0068] A positive electrode slurry and a negative electrode slurry are obtained, wherein the positive electrode slurry and / or the negative electrode slurry contain the conductive glue.
[0069] The positive electrode slurry further includes an organic solvent, a first sulfide electrolyte, a positive electrode material and a first conductive agent; the positive electrode slurry is coated on the surface of the positive electrode current collector to obtain a positive electrode sheet.
[0070] The negative electrode slurry further includes an organic solvent, a second sulfide electrolyte, a negative electrode material and a second conductive agent; the negative electrode slurry is coated on the surface of the negative electrode current collector to obtain a negative electrode sheet.
[0071] Obtain electrolyte slurry, apply the electrolyte slurry to at least one side of the positive electrode sheet and / or the negative electrode sheet to obtain a composite positive electrode sheet and / or a composite negative electrode sheet, and then perform lamination processing to obtain a sulfide solid-state battery.
[0072] The preparation method of the sulfide solid-state battery of the present invention is as follows: when preparing the conductive adhesive by a wet process, the conductive agent and the polymer material in the conductive adhesive can be dissolved in a solvent in a uniformly distributed state to form the conductive adhesive; when preparing the positive and negative electrode slurries, the main material is added to the adhesive, and the conductive agent in the conductive adhesive is uniformly wrapped around the main material under the action of the polymer material, so that the main material particles, the conductive agent, and the binder in the positive and negative electrodes form a good electron ion network in the sulfide solid phase system, which is beneficial to reducing the battery polarization impedance, increasing the positive and negative electrode capacity, and improving the battery cycle performance.
[0073] In some embodiments, the conductive adhesive has a solid content of 2% to 6%, such as 2%, 3%, 4%, 4.5%, 5%, 5.5%, or 6%. Conductive adhesive with an appropriate solid content is more conducive to mixing materials and ensuring the performance of the slurry.
[0074] In some embodiments, the method for preparing the positive electrode slurry specifically comprises: first mixing the conductive glue and solvent, then mixing with the first sulfide electrolyte, then mixing with the positive electrode material, and finally mixing with the first conductive agent. The present invention employs this specific order of addition to better ensure the performance of the positive electrode slurry, resulting in a positive electrode material layer with excellent structural stability and conductivity.
[0075] In some embodiments, during the preparation of the positive electrode slurry, the first mixing, the second mixing, and the third mixing each independently include sequentially performing a low-speed treatment and a high-speed treatment, wherein the low-speed treatment has a speed of 700-1000 rpm (e.g., 700 rpm, 800 rpm, 900 rpm, or 1000 rpm), and the low-speed treatment duration is 3-6 minutes (e.g., 3 minutes, 4 minutes, 5 minutes, or 6 minutes), and the high-speed treatment has a speed of 1500-2500 rpm (e.g., 1500 rpm, 1800 rpm, 2000 rpm, 2200 rpm, or 2500 rpm), and the high-speed treatment duration is 8-15 minutes (e.g., 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, or 15 minutes). In some embodiments, the speed ratio of the low-speed treatment to the high-speed treatment is 0.3-0.5, e.g., 0.3, 0.35, 0.4, or 0.5. The time ratio of the low-speed treatment to the high-speed treatment is 0.4 to 0.75, for example, 0.4, 0.5, 0.6, 0.7 or 0.75, etc. The present invention adopts appropriate first mixing, second mixing and third mixing conditions to ensure better mixing, connection and distribution of materials, thereby ensuring the performance of the positive electrode slurry and improving the conductivity, mechanical strength and electrochemical performance of the positive electrode material layer.
[0076] In some embodiments, the negative electrode slurry preparation method specifically includes: first mixing the conductive glue and solvent, then mixing with the second sulfide electrolyte, then mixing with the negative electrode material, and finally mixing with the second conductive agent. The negative electrode slurry preparation method of the present invention, using this specific addition order, is more conducive to ensuring the performance of the negative electrode slurry and improving the stability and electrochemical performance of the negative electrode material layer.
[0077] In some embodiments, the first mixing, the second mixing and the third mixing each independently include sequentially performing low-speed processing and high-speed processing, the speed of the low-speed processing is 700~1000rpm, the time of the low-speed processing is 3~6min, the speed of the high-speed processing is 1500~2500rpm, and the time of the high-speed processing is 8~15min. In some embodiments, the speed ratio of the low-speed processing and the high-speed processing is 0.3~0.5, such as 0.3, 0.35, 0.4, 0.45 or 0.5. The time ratio of the low-speed processing and the high-speed processing is 0.4~0.75, such as 0.4, 0.5, 0.6, 0.65, 0.7 or 0.75. In the preparation process of the negative electrode slurry of the present invention, appropriate first mixing, second mixing and third mixing conditions are adopted, thereby ensuring that the materials are better mixed, connected and distributed, thereby ensuring the performance of the negative electrode slurry and improving the conductivity, mechanical strength and electrochemical properties of the negative electrode material layer.
[0078] In some embodiments, the preparation of the electrolyte slurry specifically includes: mixing a binder and a solvent to obtain a mixed system with a solid content of 40% to 50% (e.g., 40%, 45% or 50%), and then mixing it with a sulfide electrolyte to obtain an electrolyte slurry.
[0079] In some embodiments, the solvent of the present invention includes at least one of a benzene solvent such as xylene, an ether solvent such as anisole, and an alkane solvent such as dodecane.
[0080] According to another aspect of the present invention, the present invention also relates to an electrical device comprising the above-mentioned sulfide solid-state battery.
[0081] The battery of the present invention has excellent cycle performance, rate performance and safety performance.
[0082] The following is further explained with reference to specific embodiments and comparative examples.
[0083] Example 1 A method for preparing an all-solid-state battery comprises the following steps: (a) Conductive carbon black nitrile rubber was dissolved in xylene to prepare a conductive nitrile rubber liquid (conductive rubber liquid) with a solids content of 4%. The preparation method of the conductive carbon black nitrile rubber comprises: adding NBR to a mill roll at a temperature of 45°C and thinly mixing for 3 minutes; adding the conductive carbon black in three equal batches (2 minutes apart each time) and thinning until no particles are present; then adding zinc oxide, stearic acid, sulfur, and an accelerator (DM) and mixing for 5 minutes; sheeting; and vulcanizing in stages. The mass ratio of NBR, conductive carbon black, zinc oxide, stearic acid, sulfur, and accelerator is 100:30:5:1:1.5:1.2. The staged vulcanization includes: compression vulcanization at 160°C for 8 minutes (pressure 10 MPa); and secondary vulcanization at 100°C for 2 hours.
[0084] (b) Preparation of positive electrode sheet: 14.6 g of the above-mentioned conductive glue was weighed, 5 g of xylene solvent was added, and the mixture was stirred in a mixer at 800 rpm for 5 min and 2000 rpm for 10 min. Then, 3 g of sulfide electrolyte Li6PS5Cl was added, and the mixture was stirred in a mixer at 800 rpm for 5 min and 2000 rpm for 10 min to obtain mixture a. Then, 10.5 g of nickel-cobalt-manganese (NCM811) ternary positive electrode active material was added to the above-mentioned mixture a, and the mixture was continued to be stirred at 800 rpm for 5 min and 2000 rpm for 10 min to obtain mixture b. 0.3 g of conductive agent (multi-walled carbon nanotubes) was weighed and added to the above-mentioned mixture b to obtain a positive electrode system with a network conductive connection; then, the positive electrode sheet was obtained by coating and baking.
[0085] (c) Preparation of negative electrode sheet: 7.95 g of the above-mentioned conductive glue was weighed, 27.8 g of xylene solvent was added, and the mixture was stirred in a mixer at 800 rpm for 5 min and 2000 rpm for 10 min. Then, 3.45 g of sulfide electrolyte Li6PS5Cl was added, and the mixture was stirred in a mixer at 800 rpm for 5 min and 2000 rpm for 10 min to obtain mixture c. Then, 10.5 g of silicon dioxide active material was added to the above mixture c, and the mixture was stirred at 800 rpm for 5 min and 2000 rpm for 10 min to obtain mixture d. 0.3 g of conductive agent (multi-walled carbon nanotubes) was weighed and added to the above mixture d to obtain a positive electrode system with a network conductive connection; then, the negative electrode sheet was obtained by coating and baking.
[0086] (d) Preparation of electrolyte membrane slurry: Nitrile rubber was dissolved in xylene to prepare a 4% solids solution. 7.65 g of the mixed solution was added with 34.9 g of xylene solvent to adjust the solid electrolyte slurry to 45% solids. The mixture was stirred at 800 rpm for 5 min and 2000 rpm for 10 min. Then, 15 g of sulfide electrolyte Li6PS5Cl was added and stirred at 800 rpm for 5 min and 2000 rpm for 10 min to prepare a sulfide electrolyte membrane slurry.
[0087] (e) Preparation of all-solid-state batteries: After the above-mentioned negative electrode sheet is rolled and compacted, the electrolyte membrane slurry is coated on the negative electrode sheet with a 200μm scraper to obtain a composite electrode sheet, and a 45*58mm double-layer composite electrode sheet is cut; after the positive electrode sheet is rolled, a 43*56mm positive electrode sheet is cut, and the positive and negative electrodes are welded to the tabs and then stacked and packaged. After isostatic pressing at 500MPa, a sulfide all-solid-state battery is prepared.
[0088] Example 2 A method for preparing an all-solid-state battery comprises the following steps: (a) Conductive silicone rubber is dissolved in xylene to prepare a conductive silicone rubber adhesive (conductive adhesive) having a solid content of 4%.
[0089] (b) Preparation of positive electrode sheet: Weigh 14.6 g of the above-mentioned conductive glue, add 5 g of xylene solvent, and stir with a mixer: 800 rpm for 5 min, 2000 rpm for 10 min, add 3 g of sulfide electrolyte Li6PS5Cl, and stir with a mixer: 800 rpm for 5 min, 2000 rpm for 10 min to obtain mixture a, then add 10.5 g of nickel cobalt manganese (NCM811) ternary positive electrode active material to the above-mentioned mixture a, continue stirring: 800 rpm for 5 min, 2000 rpm for 10 min to obtain mixture b; weigh 0.3 g of multi-walled carbon nanotubes and add them to the above-mentioned mixture b to obtain a positive electrode system with a network conductive connection, which is then coated and baked to obtain a positive electrode sheet.
[0090] (c) Negative Electrode Preparation: 7.95 g of the conductive adhesive was weighed, 27.8 g of xylene solvent was added, and the mixture was stirred in a mixer at 800 rpm for 5 minutes and 2000 rpm for 10 minutes. Then, 3.45 g of the sulfide electrolyte Li6PS5Cl was added and stirred in a mixer at 800 rpm for 5 minutes and 2000 rpm for 10 minutes to obtain mixture c. 10.5 g of silicon dioxide active material was added to mixture c and stirred at 800 rpm for 5 minutes and 2000 rpm for 10 minutes to obtain mixture d. 0.3 g of multi-walled carbon nanotubes was weighed and added to mixture d to form a network-like conductively connected positive electrode system. The negative electrode sheet was then coated and baked.
[0091] (d) Preparation of electrolyte membrane slurry: Silicone rubber was dissolved in xylene to prepare a 4% solids solution. 7.65 g of the mixed slurry was added with 34.9 g of xylene solvent to adjust the solid electrolyte slurry to 45% solids. The mixture was stirred at 800 rpm for 5 min and 2000 rpm for 10 min. Then, 15 g of sulfide electrolyte Li6PS5Cl was added and the mixture was stirred at 800 rpm for 5 min and 2000 rpm for 10 min to obtain a sulfide electrolyte membrane slurry.
[0092] (e) Preparation of all-solid-state batteries: After the above-mentioned negative electrode sheet is rolled and compacted, the electrolyte membrane slurry is coated on the negative electrode sheet with a 200μm scraper to obtain a composite electrode sheet, and a 45*58mm double-layer composite electrode sheet is cut; after the positive electrode sheet is rolled, a 43*56mm positive electrode sheet is cut, and the positive and negative electrodes are welded to the tabs and then stacked and packaged. After isostatic pressing at 500MPa, a sulfide all-solid-state battery is prepared.
[0093] Example 3 A method for preparing an all-solid-state battery, which differs from Example 1 in that: In step (a), the conductive rubber material is selected from conductive silicone rubber and conductive perfluororubber (mass ratio is 1:2).
[0094] Example 4 A method for preparing an all-solid-state battery, which differs from Example 1 in that: In step (a), conductive silicone rubber, conductive perfluororubber and conductive ethylene acrylate rubber (mass ratio is 1:3:1).
[0095] The conductive agents in step (b) and step (c) are each independently selected from conductive agent A, conductive agent B and conductive agent C, conductive agent A is nano-carbon fiber, conductive agent B is multi-walled carbon nanotube, conductive agent C is graphene, and the mass ratio of conductive agent A, conductive agent B and conductive agent C is 4:2:1.
[0096] Example 5 A method for preparing an all-solid-state battery, which differs from Example 1 in that: In step (a), conductive silicone rubber, conductive perfluororubber and conductive ethylene acrylate rubber (mass ratio is 1:2:1).
[0097] The conductive agents in step (b) and step (c) are each independently selected from conductive agent A, conductive agent B and conductive agent C, conductive agent A is nano-carbon fiber, conductive agent B is multi-walled carbon nanotube, conductive agent C is acetylene black, and the mass ratio of conductive agent A, conductive agent B and conductive agent C is 5:2:1.
[0098] Comparative Example 1 A method for preparing an all-solid-state battery comprises the following steps: (a) dissolving nitrile rubber in xylene to prepare a rubber solution having a solid content of 4%; (b) Preparation of positive electrode sheet: except that 14.15 g of the glue solution of this comparative example was used, 3 g of sulfide electrolyte Li6PS5Cl and 0.45 g of SPLi were added, and other conditions were the same as those in Example 1.
[0099] (c) Preparation of negative electrode sheet: except that 7.5 g of the glue solution of this comparative example was used, 3.45 g of sulfide electrolyte Li6PS5Cl and 0.45 g of SPLi were added, and other conditions were the same as those in Example 1.
[0100] (d) Preparation of electrolyte membrane slurry: same as in Example 1. (e) Preparation of all-solid-state battery: Except for using the positive electrode sheet and negative electrode sheet of this comparative example, other conditions are the same as those of Example 1.
[0101] Comparative Example 2 A method for preparing an all-solid-state battery comprises the following steps: (a) Dissolving silicone rubber in xylene to prepare a rubber solution having a solid content of 4%; (b) Preparation of positive electrode sheet: except that 14.15 g of the glue solution of this comparative example was used, 3 g of sulfide electrolyte Li6PS5Cl and 0.45 g of SPLi were added, and other conditions were the same as those in Example 2.
[0102] (c) Preparation of negative electrode sheet: except that 7.5 g of the glue solution of this comparative example was used, 3.45 g of sulfide electrolyte Li6PS5Cl and 0.45 g of SPLi were added, and other conditions were the same as those in Example 2.
[0103] (d) Preparation of electrolyte membrane slurry: same as in Example 2. (e) Preparation of all-solid-state battery: Except for using the positive electrode sheet and negative electrode sheet of this comparative example, other conditions are the same as those of Example 2.
[0104] Experimental example 1. The capacity of the main materials in the positive and negative electrode formulas Test conditions: cut-off voltage of 2.5~4.0 V, charge and discharge at a rate of 0.1 C.
[0105] The test results are shown in Table 1 and Table 2.
[0106] Table 1 Performance data of positive electrode formula main material mold battery
[0107] Table 2 Performance data of negative electrode formula main material mold battery
[0108] It can be seen from Tables 1 and 2 that after using the conductive binder, the specific capacity of the positive and negative electrodes are significantly improved. It can be seen that during wet mixing, by using the glue prepared by the conductive binder, the conductive agent can be evenly dispersed around the positive and negative electrode main materials, thereby greatly improving the conductivity of the system and improving the capacity of the positive and negative electrode materials.
[0109] 2. All-solid-state sulfide battery cycle Figure 1 The full-battery soft-pack cycle decay curves of Examples 1 to 3 and Comparative Example 1 show that the three groups of examples show a stable cycle trend, while the comparative example shows obvious decay. This shows that the conductive rubber material of the present invention can be used to prepare soft-pack batteries with excellent performance.
[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A sulfide solid-state battery, characterized in that: It includes a positive electrode sheet, a negative electrode sheet and an electrolyte layer; the positive electrode sheet contains a positive electrode material layer, the negative electrode sheet contains a negative electrode material layer, and the positive electrode material layer and / or the negative electrode material layer contain a conductive rubber material; the mass content of the conductive rubber material in the positive electrode material layer is 2% to 4%, and the mass content of the conductive rubber material in the negative electrode material layer is 1% to 3%.
2. The sulfide solid-state battery according to claim 1, characterized in that The conductive rubber materials in the positive electrode material layer and the negative electrode material layer independently include at least one of conductive silicone rubber, conductive perfluororubber, conductive tetrafluoroethylene rubber, conductive chloroprene rubber, conductive polyurethane rubber, conductive acrylic rubber, conductive carbon black nitrile rubber and conductive ethylene acrylate rubber.
3. The sulfide solid-state battery according to claim 1, characterized in that The positive electrode material layer further includes a positive electrode material, a first sulfide electrolyte and a first conductive agent, wherein the mass ratio of the positive electrode material, the first sulfide electrolyte and the first conductive agent is (8-12): (2-5): (0.1-0.5); And / or, the negative electrode material layer further includes a negative electrode material, a second sulfide electrolyte and a second conductive agent, and the mass ratio of the negative electrode material, the second sulfide electrolyte and the second conductive agent is (8-12): (2-5): (0.1-0.5).
4. The sulfide solid-state battery according to claim 2, characterized in that The first conductive agent and the second conductive agent each independently include at least one of acetylene black, carbon black, graphite, nano-carbon fiber, carbon nanotube and graphene; Preferably, the first conductive agent and the second conductive agent are each independently selected from a conductive agent A, a conductive agent B, and a conductive agent C, the conductive agent A is carbon nanofiber, the conductive agent B is carbon nanotube, and the conductive agent C is at least one of acetylene black, carbon black, graphite, and graphene, and the mass ratio of the conductive agent A, the conductive agent B, and the conductive agent C is (3-5):2:1; And / or, the positive electrode material includes at least one of lithium iron phosphate, lithium manganese oxide and nickel cobalt manganese material; And / or, the negative electrode material includes SiO x , at least one of silicon carbon, micron silicon and nano silicon.
5. The sulfide solid-state battery according to claim 1, characterized in that The electrolyte layer includes a sulfide electrolyte and a binder, wherein the binder has a mass content of 3% to 6% in the electrolyte layer; and the binder includes at least one of SBS, NBR, SEBS, and SBR.
6. The method for preparing a sulfide solid-state battery according to any one of claims 1 to 5, wherein: The following steps are involved: Obtaining a conductive adhesive solution formed by a conductive rubber material and a solvent; Obtaining positive electrode slurry and negative electrode slurry, wherein the positive electrode slurry and / or the negative electrode slurry contains the conductive glue; The positive electrode slurry further comprises an organic solvent, a first sulfide electrolyte, a positive electrode material and a first conductive agent; the positive electrode slurry is coated on the surface of the positive electrode current collector to obtain a positive electrode sheet; The negative electrode slurry further comprises an organic solvent, a second sulfide electrolyte, a negative electrode material and a second conductive agent; the negative electrode slurry is coated on the surface of the negative electrode current collector to obtain a negative electrode sheet; Obtain electrolyte slurry, apply the electrolyte slurry to at least one side of the positive electrode sheet and / or the negative electrode sheet to obtain a composite positive electrode sheet and / or a composite negative electrode sheet, and then perform lamination processing to obtain a sulfide solid-state battery.
7. The method for preparing a sulfide solid-state battery according to claim 6, characterized in that: Contains at least one of the following features (1) to (2): (1) The solid content of the conductive adhesive is 2% to 6%; (2) The preparation method of the positive electrode slurry specifically comprises: first mixing the conductive glue and the solvent, second mixing with the first sulfide electrolyte, third mixing with the positive electrode material, and fourth mixing with the first conductive agent; Preferably, the first mixing, the second mixing and the third mixing each independently include performing low-speed treatment and high-speed treatment in sequence, the speed of the low-speed treatment is 700~1000rpm, the time of the low-speed treatment is 3~6min, the speed of the high-speed treatment is 1500~2500rpm, and the time of the high-speed treatment is 8~15min.
8. The method for preparing a sulfide solid-state battery according to claim 6, wherein: The method for preparing the negative electrode slurry specifically comprises: first mixing the conductive glue and the solvent, second mixing with the second sulfide electrolyte, third mixing with the negative electrode material, and fourth mixing with the second conductive agent; Preferably, the first mixing, the second mixing and the third mixing each independently include performing low-speed treatment and high-speed treatment in sequence, the speed of the low-speed treatment is 700~1000rpm, the time of the low-speed treatment is 3~6min, the speed of the high-speed treatment is 1500~2500rpm, and the time of the high-speed treatment is 8~15min.
9. The method for preparing a sulfide solid-state battery according to claim 6, wherein: The preparation of the electrolyte slurry specifically includes: mixing a binder and a solvent to obtain a mixed system with a solid content of 40% to 50%, and then mixing it with a sulfide electrolyte to obtain an electrolyte slurry.
10. An electrical device, characterized in that: A sulfide solid-state battery comprising the sulfide solid-state battery according to any one of claims 1 to 5.