Sulfide solid-state battery, and preparation method and application of sulfide solid-state battery

Abstract

The invention discloses a sulfide solid-state battery and a preparation method and application of the sulfide solid-state battery, and relates to the technical field of batteries, the sulfide solid-state battery comprises a positive electrode, an electrolyte membrane and a negative electrode, the positive electrode comprises a positive electrode active material, a sulfide electrolyte, a conductive agent and a first binder; the electrolyte membrane comprises an amorphous sulfide electrolyte and a second binder, the negative electrode comprises a current collector, a first negative electrode layer and a second negative electrode layer, the first negative electrode layer and the second negative electrode layer are sequentially arranged on the surface of the current collector, and the sulfide solid-state battery is assembled by configuring the proportion and the combination mode of all the components in the positive electrode, the electrolyte membrane and the negative electrode. The amorphous flexible sulfide electrolyte and the high-ionic-conductivity electrolyte are compounded with the positive electrode, the amorphous flexible electrolyte is adopted to adapt to the volume change of the positive electrode and the negative electrode, good contact of interfaces of the positive electrode and the negative electrode is maintained, and the first effect of the battery is improved by adopting a pre-lithiated double-layer structure at the negative electrode; therefore, the prepared battery has long-term stability.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly relates to a sulfide solid-state battery, a preparation method and application of the sulfide solid-state battery. Background Art

[0002] Sulfide solid-state batteries have higher energy density, longer cycle life and better safety. Sulfide solid-state batteries mainly use sulfide as the solid electrolyte, which has high ionic conductivity and low interfacial resistance, avoiding the leakage and short-circuit problems of liquid electrolytes, thus reducing the risks of fire and explosion. This kind of battery can maintain stable performance in high-temperature or low-temperature environments, improving the overall safety.

[0003] In some related technologies, silicon-containing anodes are usually used in combination with high-nickel ternary cathodes in sulfide solid-state batteries. During the charge and discharge process, the volume changes of the cathode and anode, as well as the poor contact between the cathode and anode and the interface, lead to internal contact failure of the battery, interface deterioration, rapid capacity decay, resulting in a significant reduction in the long-term stability of the battery and a shortened service life. Summary of the Invention

[0004] To solve at least one of the problems mentioned in the above background art, this application provides a sulfide solid-state battery, a preparation method and application of the sulfide solid-state battery. By using an amorphous flexible sulfide electrolyte and a high ionic conductivity electrolyte in combination with the cathode, the lithium-ion transport efficiency of the cathode can be ensured, and at the same time, the deformation ability of the flexible amorphous electrolyte can buffer the volume change of the cathode; the electrolyte layer uses an amorphous flexible electrolyte, enabling it to adapt to the volume changes of the cathode and anode to a certain extent and maintain a good contact with the cathode and anode interfaces. Using a pre-lithiated double-layer anode at the anode can improve the initial efficiency of the battery. In addition, the Young's modulus of the pre-lithiated homogeneous silicon carbon becomes smaller, resulting in a decrease in the porosity of the anode after isostatic pressing, which is beneficial to the long-term stable cycling of the battery.

[0005] The specific technical solutions provided by the embodiments of this application are as follows:

[0006] In the first aspect, a sulfide solid-state battery is provided. The sulfide solid-state battery includes a cathode, an electrolyte membrane, and an anode. The cathode includes a cathode active material, a sulfide electrolyte, a conductive agent, and a first binder; the electrolyte membrane includes an amorphous sulfide electrolyte and a second binder, and the anode includes a current collector, a first anode layer and a second anode layer sequentially arranged on the surface of the current collector.

[0007] In a specific embodiment, the weight ratio of the cathode active material, the sulfide electrolyte, the conductive agent, and the first binder in the cathode is (75 - 88):(10 - 20):(0.5 - 2):(1.5 - 4).

[0008] Specifically, the weight fraction ratios of the positive electrode active material, the sulfide electrolyte, the conductive agent, and the first binder are set to one of 75:20:0.5:1.5, 75:20:0.5:2, 75:20:0.5:3, 75:20:0.5:4, 75:20:1:2, 75:20:1:3, 75:20:1:4, 75:20:1.5:2, 75:20:1.5:3, 75:20:1.5:4, 75:20:2:2, 75:20:2:3, 75:20:2:4, 82:18:0.5:2, 82:18:0.5:3, 82:18:0.5:4, 82:18:1:2, 82:18:1:3, 82:18:1:4, 85:15:0.5:2, 85:15:1:2, 85:15:1:3, 85:15:1.5:3, 85:15:1:4, 85:15:2:4, 86:14:0.5:2, 86:14:1:2, 86:14:1:3, 86:14:1.5:3, 86:14:1:4, 86:14:2:4, 88:10:0.5:2, 88:12:1:2, 88:14:1:3, 88:12:1.5:3, 88:10:1:4, 88:10:2:4.

[0009] In a specific embodiment, the sulfide electrolyte includes a positive electrode crystalline sulfide electrolyte and a positive electrode amorphous sulfide electrolyte;

[0010] Among them, the weight fraction ratio of the positive electrode crystalline sulfide electrolyte and the positive electrode amorphous sulfide electrolyte is (2:8) to (8:2).

[0011] Specifically, the mass fraction ratio of the positive electrode crystalline sulfide electrolyte and the positive electrode amorphous sulfide electrolyte is one of 2:8, 2:7, 2:6, 2:5, 2:4, 2:3, 2:2, 2:1, 3:1, 3:2, 3:3, 4:2, 4:3, 4:4, 5:2, 5:3, 5:4, 5:5, 6:2, 6:3, 6:4, 6:5, 6:6, 7:2, 7:3, 7:4, 7:5, 7:6, 7:7, 8:2, 8:3, 8:4, 8:5, 8:6, 8:7, or 8:8.

[0012] Specifically, the positive electrode crystalline sulfide electrolyte includes one or more of Li6PS5X or LiSiPSX; among them, X in the Li6PS5X and / or the LiSiPSX is selected from Cl or Br.

[0013] Specifically, the positive electrode amorphous sulfide electrolyte includes one or more of Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, or Li7P2S8I.

[0014] In a specific embodiment, the ionic conductivity of the positive electrode crystalline sulfide electrolyte is set to 6 ms / cm to 12 ms / cm.

[0015] Specifically, the ionic conductivity of the positive electrode crystalline sulfide electrolyte is set to one of 6 ms / cm, 6.1 ms / cm, 6.2 ms / cm, 6.3 ms / cm, 6.4 ms / cm, 6.5 ms / cm, 6.6 ms / cm, 6.7 ms / cm, 6.8 ms / cm, 6.9 ms / cm, 7 ms / cm, 7.1 ms / cm, 7.2 ms / cm, 7.3 ms / cm, 7.4 ms / cm, 7.5 ms / cm, 7.6 ms / cm, 7.7 ms / cm, 7.8 ms / cm, 7.9 ms / cm, 8 ms / cm, 8.1 ms / cm, 8.2 ms / cm, 8.3 ms / cm, 8.4 ms / cm, 8.5 ms / cm, 8.6 ms / cm, 8.7 ms / cm, 8.8 ms / cm, 8.9 ms / cm, 9 ms / cm, 9.1 ms / cm, 9.2 ms / cm, 9.3 ms / cm, 9.4 ms / cm, 9.5 ms / cm, 9.6 ms / cm, 9.7 ms / cm, 9.8 ms / cm, 9.9 ms / cm, 10 ms / cm, 10.1 ms / cm, 10.2 ms / cm, 10.3 ms / cm, 10.4 ms / cm, 10.5 ms / cm, 10.6 ms / cm, 10.7 ms / cm, 10.8 ms / cm, 10.9 ms / cm, 11 ms / cm, 11.1 ms / cm, 11.2 ms / cm, 11.3 ms / cm, 11.4 ms / cm, 11.5 ms / cm, 11.6 ms / cm, 11.7 ms / cm, 11.8 ms / cm, 11.9 ms / cm, or 12 ms / cm.

[0016] In a specific embodiment, the ionic conductivity of the positive electrode amorphous sulfide electrolyte is set to 1 ms / cm to 4 ms / cm.

[0017] Specifically, the ionic conductivity of the positive electrode amorphous sulfide electrolyte is set to one of 1 mS / cm, 1.1 mS / cm, 1.2 mS / cm, 1.3 mS / cm, 1.4 mS / cm, 1.5 mS / cm, 1.6 mS / cm, 1.7 mS / cm, 1.8 mS / cm, 1.9 mS / cm, 2 mS / cm, 2.1 mS / cm, 2.2 mS / cm, 2.3 mS / cm, 2.4 mS / cm, 2.5 mS / cm, 2.6 mS / cm, 2.7 mS / cm, 2.8 mS / cm, 2.9 mS / cm, 3 mS / cm, 3.1 mS / cm, 3.2 mS / cm, 3.3 mS / cm, 3.4 mS / cm, 3.5 mS / cm, 3.6 mS / cm, 3.7 mS / cm, 3.8 mS / cm, 3.9 mS / cm, or 4 mS / cm.

[0018] In a specific embodiment, the positive electrode active material includes one or more of lithium niobate, a ternary positive electrode material of nickel cobalt manganese lithium oxide coated with alumina, or lithium iron phosphate; wherein, the ternary positive electrode material of nickel cobalt manganese lithium oxide coated with alumina includes one or more of NCM9 series ternary positive electrode materials and NCM8 series ternary positive electrode materials.

[0019] In a specific embodiment, the conductive agent includes one or more of carbon black, carbon nanotubes, graphene, or carbon fiber materials.

[0020] By setting the positive electrode material of the battery to be formed by compounding an amorphous flexible sulfide electrolyte and a high ionic conductivity electrolyte, the transport efficiency of lithium ions in the positive electrode of the battery is ensured. At the same time, the flexible deformation ability of the amorphous sulfide electrolyte can buffer the volume change of the positive electrode material during use, which is beneficial to the long-term stable cycling of the sulfide solid-state battery.

[0021] In a specific embodiment, the weight ratio of the amorphous sulfide electrolyte to the second binder in the electrolyte is (94-98):(2-6).

[0022] Specifically, the weight ratio of the amorphous sulfide electrolyte to the second binder is one of 94:2, 94:3, 94:4, 94:5, 94:6, 95:2, 95:3, 95:4, 95:5, 96:6, 96:2, 96:3, 96:4, 96:5, 96:6, 97:2, 97:3, 97:4, 97:5, 97:6, 98:2, 98:3, 98:4, 98:5, or 98:6.

[0023] In a specific embodiment, the amorphous sulfide electrolyte is the same as or different from the positive amorphous sulfide electrolyte, and the amorphous sulfide electrolyte includes one or more of Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, or Li7P2S8I.

[0024] Since the materials in the positive electrode, negative electrode, and electrolyte of the sulfide solid-state battery are in contact through particles with each other, and the contact between particles is a hard contact, during the charge and discharge process of the battery, the particles expand or contract, resulting in obvious volume change behaviors of the positive and negative electrode materials and the electrolyte. In this application, by setting the electrolyte to include an amorphous sulfide electrolyte, the electrolyte can adapt to the volume changes from the positive and negative electrodes to a certain extent during the use of the battery, so that the interfaces between the electrolyte and the positive and negative electrodes always maintain good contact, thereby ensuring the reliability of the battery performance.

[0025] In a specific embodiment, the current collector is a copper-lithium composite tape, wherein the thickness of lithium in the copper-lithium composite tape is 3 μm to 7 μm, and the thickness of copper in the copper-lithium composite tape is 6 μm to 10 μm.

[0026] Specifically, the thickness of lithium in the copper-lithium composite tape is set to be one of 3 μm, 4 μm, 5 μm, 6 μm, or 7 μm; the thickness of copper in the copper-lithium composite tape is set to be one of 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

[0027] In a specific embodiment, the first negative electrode layer includes a homogeneous silicon-carbon material and a third binder, wherein the weight ratio of the homogeneous silicon-carbon material to the third binder is (94 to 98):(2 to 6).

[0028] Specifically, the weight ratio of the homogeneous silicon-carbon material to the third binder is set to be one of 92:2, 94:3, 94:4, 94:5, 94:6, 95:2, 95:3, 95:4, 95:5, 95:6, 96:2, 96:3, 96:4, 96:5, 96:6, 97:2, 97:3, 97:4, 97:5, 97:6, 98:2, 98:3, 98:4, 98:5, or 98:6.

[0029] In a specific embodiment, the second negative electrode layer includes a negative crystalline sulfide electrolyte, a hard carbon material, and a fourth binder; wherein the weight ratio of the negative crystalline sulfide electrolyte, the hard carbon material, and the fourth binder is (15 to 37):(60 to 80):(3 to 5).

[0030] In a specific embodiment, the negative crystalline sulfide electrolyte is the same as or different from the positive crystalline sulfide electrolyte, and the negative crystalline sulfide electrolyte includes one or more of Li6PS5X or LiSiPSX; wherein X in the Li6PS5X and / or the LiSiPSX is selected from Cl or Br.

[0031] Specifically, the weight ratio of the negative crystalline sulfide electrolyte, the hard carbon material, and the fourth binder is set to one of 15:60:3, 15:60:4, 15:60:5, 15:61:3, 15:62:3, 15:63:3, 15:64:3, 15:65:3, 15:70:3, 15:75:3, 15:80:3, 15:61:4, 15:62:4, 15:63:4, 15:64:4, 15:65:4, 15:70:4, 15:75:4, 15:80:4, 15:61:5, 15:62:5, 15:63:5, 15:64:5, 15:65:5, 15:70:5, 15:75:5, 15:80:5, 20:61:3, 20:62:3, 20:63:3, 20:64:3, 20:65:3, 20:70:3, 20:75:3, 20:80:3, 20:61:4, 20:62:4, 20:63:4, 20:64:4, 20:65:4, 20:70:4, 20:75:4, 20:80:4, 20:61:5, 20:62:5, 20:63:5, 20:64:5, 20:65:5, 20:70:5, 20:75:5, 20:80:5, 30:61:3, 30:62:3, 30:63:3, 30:64:3, 30:65:3, 30:70:3, 30:75:3, 30:80:3, 30:61:4, 30:62:4, 30:63:4, 30:64:4, 30:65:4, 30:70:4, 30:75:4, 30:80:4, 30:61:5, 30:62:5, 30:63:5, 30:64:5, 30:65:5, 30:70:5, 30:75:5, 30:80:5, 37:61:3, 37:62:3, 37:63:3, 37:64:3, 37:65:3, 37:70:3, 37:75:3, 37:80:3, 37:61:4, 37:62:4, 37:63:4, 37:64:4, 37:65:4, 37:70:4, 37:75:4, 37:80:4, 37:61:5, 37:62:5, 37:63:5, 37:64:5, 37:65:5, 37:70:5, 37:75:5 or 37:80:5.

[0032] In a specific embodiment, the mass percentage of silicon in the homogeneous silicon carbide material is 40% to 60%, and / or the particle size D50 of the homogeneous silicon carbide material is 1 μm to 8 μm.

[0033] Specifically, the mass percentage of silicon in the homogeneous silicon carbide material is set to one of 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% or 60%.

[0034] Specifically, the particle size D50 of the homogeneous silicon carbide material is set to one or more of 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.7 μm, 7.8 μm, 7.9 μm or 8 μm.

[0035] In a specific embodiment, the thickness of the first negative electrode layer is 60 μm to 100 μm, and the thickness of the second negative electrode layer is 10 μm to 50 μm.

[0036] Specifically, the thickness of the first negative electrode layer is set to one of 60 μm, 61 μm, 62 μm, 63 μm, 64 μm, 65 μm, 66 μm, 67 μm, 68 μm, 69 μm, 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm, 81 μm, 82 μm, 83 μm, 84 μm, 85 μm, 86 μm, 87 μm, 88 μm, 89 μm, 90 μm, 91 μm, 92 μm, 93 μm, 94 μm, 95 μm, 96 μm, 97 μm, 98 μm, 99 μm or 100 μm.

[0037] Specifically, the thickness of the second negative electrode layer is set to be one of 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm or 50μm.

[0038] In a specific embodiment, the particle size D50 of the negative electrode crystalline sulfide electrolyte is 800nm to 5μm.

[0039] Specifically, the particle size D50 of the negative electrode crystalline sulfide electrolyte is one of 800nm, 810nm, 820nm, 830nm, 840nm, 850nm, 860nm, 870nm, 880nm, 890nm, 900nm, 910nm, 920nm, 930nm, 940nm, 950nm, 960nm, 970nm, 980nm, 990nm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.1μm, 3.2μm, 3.3μm, 3.4μm, 3.5μm, 3.6μm, 3.7μm, 3.8μm, 3.9μm, 4μm, 4.1μm, 4.2μm, 4.3μm, 4.4μm, 4.5μm, 4.6μm, 4.7μm, 4.8μm, 4.9μm or 5μm.

[0040] In a specific embodiment, the particle size D50 of the hard carbon material is 7μm to 11μm.

[0041] Specifically, the particle size D50 of the hard carbon material is set to one of 7μm, 7.1μm, 7.2μm, 7.3μm, 7.4μm, 7.5μm, 7.6μm, 7.7μm, 7.8μm, 7.9μm, 8μm, 8.1μm, 8.2μm, 8.3μm, 8.4μm, 8.5μm, 8.6μm, 8.7μm, 8.8μm, 8.9μm, 9μm, 9.1μm, 9.2μm, 9.3μm, 9.4μm, 9.5μm, 9.6μm, 9.7μm, 9.8μm, 9.9μm, 10μm, 10.1μm, 10.2μm, 10.3μm, 10.4μm, 10.5μm, 10.6μm, 10.7μm, 10.8μm, 10.9μm or 11μm.

[0042] In a specific embodiment, the first binder, the second binder, the third binder and the fourth binder are the same or different, wherein the first binder includes one or more of fluororubber, styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, polymethyl methacrylate or polyethylene oxide.

[0043] By setting the anode material in the present application to form a pre-lithiated bilayer structure through the composite of the first anode layer and the second anode layer, the homogeneous silicon carbon in the first anode layer of the bilayer structure has a smaller volume change compared with the pure silicon anode, and has a higher specific capacity (1700 mAh / g) than the graphite anode. By pre-lithiating the homogeneous silicon carbon, the structural stability of the silicon carbon anode and the ion migration rate of the silicon carbon anode can be further improved, thereby improving the electrode reaction kinetics. Silicon carbon pre-lithiation can promote the fusion of the silicon carbon boundary, improve the denseness of the electrode, and enhance the battery rate performance. The hard carbon in the second anode layer of the bilayer structure has a high ion diffusion coefficient, does not hinder ion transfer, plays a role in buffering the volume change of the first anode layer, maintains the stability of the interface, and the hard carbon material can also intercalate lithium to prevent lithium deposition short circuit on the anode surface, so that the porosity of the anode material can be reduced after hydrostatic pressure, which is beneficial to the long-term stable cycle of the battery.

[0044] Second, a method for preparing a sulfide solid-state battery according to the above is provided, and the method includes:

[0045] Dissolve and mix the positive electrode active material, sulfide electrolyte, conductive agent, first binder and first solvent to obtain a positive electrode paste, and coat the positive electrode paste on the positive electrode current collector to form a positive electrode sheet;

[0046] Dissolve and mix an amorphous sulfide electrolyte, a second binder, and a second solvent to obtain an electrolyte slurry, coat the electrolyte slurry onto a release film, dry it, and peel it off from the release film to obtain an electrolyte membrane;

[0047] Dissolve and mix a negative crystalline sulfide electrolyte, a hard carbon material, a fourth binder, and a third solvent to obtain an outer layer mixture, coat the outer layer mixture onto a metal substrate, dry it to obtain a second negative electrode layer, dissolve and mix a homogeneous silicon-carbon material, a third binder, and a fourth solvent to obtain an inner layer mixture, and coat the inner layer mixture onto the surface of the second negative electrode layer, dry it to obtain a first negative electrode layer;

[0048] Roll and transfer the first negative electrode layer and the second negative electrode layer onto a current collector to form a negative electrode tab;

[0049] Assemble the positive electrode tab, the electrolyte membrane, and the negative electrode tab, and after welding the electrode ears, encapsulating, and isostatic pressing, a sulfide solid-state battery is formed.

[0050] In a specific embodiment, the solid content in the positive electrode slurry is 50% - 60%. Specifically, the solid content in the positive electrode slurry is set to one of 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%.

[0051] In a specific embodiment, the substrate film is configured as a PET release film.

[0052] In a specific embodiment, the solid content in the electrolyte slurry is 45% - 60%. Specifically, the solid content in the electrolyte slurry is set to one of 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%.

[0053] In a specific embodiment, the drying temperature for drying to obtain the electrolyte is set to 60°C - 90°C. Specifically, the drying temperature is set to one of 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, or 90°C.

[0054] In a specific embodiment, the metal substrate is configured as a nickel-plated copper foil.

[0055] In a specific embodiment, the drying temperatures of the second negative electrode layer and the first negative electrode layer are both set to 60°C to 90°C. Specifically, the drying temperature is set to one of 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C.

[0056] In a specific embodiment, the first negative electrode layer and the second negative electrode layer coated on the nickel-plated copper foil and the lithium copper composite tape are pressed into a whole by means of roll pressing or isostatic pressing, and then the nickel-plated copper foil is peeled off. The first negative electrode layer contacts the lithium layer of the lithium copper composite tape to complete prelithiation. At the same time, the double-layer structure negative electrode is transferred from the nickel-plated copper foil to the lithium copper composite tape, and a prelithiated double-layer structure negative electrode sheet is obtained. Among them, the bonding force of the nickel-plated copper foil to the second negative electrode layer is less than the bonding force of the lithium copper composite tape to the first negative electrode layer. Therefore, the double-layer structure negative electrode can be transferred from the nickel-plated copper foil to the lithium copper composite tape.

[0057] In a specific embodiment, the isostatic pressing conditions are set to a pressure of 300 MPa to 500 MPa and a time of 3 min to 10 min.

[0058] Specifically, the isostatic pressing condition pressure is set to one of 300 MPa, 310 MPa, 320 MPa, 330 MPa, 340 MPa, 350 MPa, 360 MPa, 370 MPa, 380 MPa, 390 MPa, 400 MPa, 410 MPa, 420 MPa, 430 MPa, 440 MPa, 450 MPa, 460 MPa, 470 MPa, 480 MPa, 490 MPa or 500 MPa.

[0059] Specifically, the isostatic pressing time is set to one of 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0060] In a specific embodiment, the first solvent, the second solvent, the third solvent and the fourth solvent are the same or different. The first solvent is set to an organic solvent. Specifically, the organic solvent includes one or more of toluene, xylene, anisole, isobutyl isobutyrate, butyl butyrate or hexyl butyrate.

[0061] In a third aspect, there is provided an application of a sulfide solid-state battery according to the sulfide solid-state battery described above or a sulfide solid-state battery prepared by the preparation method of the sulfide solid-state battery described above in a vehicle.

[0062] The embodiments of the present application have the following beneficial effects:

[0063] 1. The solution provided by the embodiments of the present application, by setting a sulfide electrolyte in the positive electrode and using an amorphous flexible electrolyte in the electrolyte layer, through the synergistic cooperation of the materials in the positive electrode and the electrolyte layer, realizes the self-adaptive volume change of the electrolyte to the positive and negative electrodes during the charge and discharge process of the battery, so as to maintain a good contact with the positive and negative electrode interfaces; at the same time, by setting a pre-lithiated double-layer structure negative electrode at the negative electrode, the initial efficiency of the battery can be improved. In addition, the Young's modulus of the pre-lithiated homogeneous silicon-carbon becomes smaller, so that the porosity of the negative electrode decreases after isostatic pressing, further strengthening the synergistic effect with the positive electrode and the electrolyte, and realizing the long-term stable cycle of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0065] Figure 1 FIG. shows a schematic diagram of a preparation method of a sulfide solid-state battery according to the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0066] To make the objectives, technical solutions, and advantages of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0068] In one embodiment, a sulfide solid-state battery is provided. The sulfide solid-state battery includes a positive electrode, an electrolyte, and a negative electrode material. The positive electrode includes a positive electrode active material, a sulfide electrolyte, a conductive agent, and a first binder; the electrolyte includes an amorphous sulfide electrolyte and a second binder, and the negative electrode material includes a current collector, a first negative electrode layer and a second negative electrode layer sequentially arranged on the surface of the current collector.

[0069] Specifically, the weight ratio of the cathode active material, sulfide electrolyte, conductive agent, and first binder in the cathode is (75-88):(10-20):(0.5-2):(1.5-4).

[0070] Specifically, the weight ratio of the cathode active material, sulfide electrolyte, conductive agent, and first binder includes but is not limited to 75:20:0.5:1.5, 75:20:0.5:2, 75:20:0.5:3, 75:20:0.5:4, 75:20:1:2, 75:20:1:3, 75:20:1:4, 75:20:1.5:2, 75:20:1.5:3, 75:20:1.5:4, 75:20:2:2, 75:20:2:3, 75:20:2:4, 82:18:0.5:2, 82:18:0.5:3, 82:18:0.5:4, 82:18:1:2, 82:18:1:3, 82:18:1:4, 85:15:0.5:2, 85:15:1:2, 85:15:1:3, 85:15:1.5:3, 85:15:1:4, 85:15:2:4, 86:14:0.5:2, 86:14:1:2, 86:14:1:3, 86:14:1.5:3, 86:14:1:4, 86:14:2:4, 88:10:0.5:2, 88:12:1:2, 88:14:1:3, 88:12:1.5:3, 88:10:1:4 or 88:10:2:4.

[0071] In a specific embodiment, the sulfide electrolyte includes a cathode crystalline sulfide electrolyte and a cathode amorphous sulfide electrolyte; wherein, the weight ratio of the cathode crystalline sulfide electrolyte to the cathode amorphous sulfide electrolyte is (2:8)-(8:2).

[0072] Specifically, the mass fraction ratio of the cathode crystalline sulfide electrolyte to the cathode amorphous sulfide electrolyte includes but is not limited to 2:8, 2:7, 2:6, 2:5, 2:4, 2:3, 2:2, 2:1, 3:1, 3:2, 3:3, 4:2, 4:3, 4:4, 5:2, 5:3, 5:4, 5:5, 6:2, 6:3, 6:4, 6:5, 6:6, 7:2, 7:3, 7:4, 7:5, 7:6, 7:7, 8:2, 8:3, 8:4, 8:5, 8:6, 8:7 or 8:8.

[0073] Specifically, the cathode crystalline sulfide electrolyte includes but is not limited to Li6PS5X or LiSiPSX; wherein, X in Li6PS5X and LiSiPSX is selected from Cl or Br.

[0074] Specifically, the positive electrode amorphous sulfide electrolyte includes but is not limited to Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, or Li7P2S8I.

[0075] In a specific embodiment, the ionic conductivity of the positive electrode crystalline sulfide electrolyte is set to 6 mS / cm to 12 mS / cm.

[0076] Specifically, the ionic conductivity of the positive electrode crystalline sulfide electrolyte includes but is not limited to 6 mS / cm, 6.1 mS / cm, 6.2 mS / cm, 6.3 mS / cm, 6.4 mS / cm, 6.5 mS / cm, 6.6 mS / cm, 6.7 mS / cm, 6.8 mS / cm, 6.9 mS / cm, 7 mS / cm, 7.1 mS / cm, 7.2 mS / cm, 7.3 mS / cm, 7.4 mS / cm, 7.5 mS / cm, 7.6 mS / cm, 7.7 mS / cm, 7.8 mS / cm, 7.9 mS / cm, 8 mS / cm, 8.1 mS / cm, 8.2 mS / cm, 8.3 mS / cm, 8.4 mS / cm, 8.5 mS / cm, 8.6 mS / cm, 8.7 mS / cm, 8.8 mS / cm, 8.9 mS / cm, 9 mS / cm, 9.1 mS / cm, 9.2 mS / cm, 9.3 mS / cm, 9.4 mS / cm, 9.5 mS / cm, 9.6 mS / cm, 9.7 mS / cm, 9.8 mS / cm, 9.9 mS / cm, 10 mS / cm, 10.1 mS / cm, 10.2 mS / cm, 10.3 mS / cm, 10.4 mS / cm, 10.5 mS / cm, 10.6 mS / cm, 10.7 mS / cm, 10.8 mS / cm, 10.9 mS / cm, 11 mS / cm, 11.1 mS / cm, 11.2 mS / cm, 11.3 mS / cm, 11.4 mS / cm, 11.5 mS / cm, 11.6 mS / cm, 11.7 mS / cm, 11.8 mS / cm, 11.9 mS / cm, or 12 mS / cm.

[0077] In a specific embodiment, the ionic conductivity of the positive electrode amorphous sulfide electrolyte is set to 1 mS / cm to 4 mS / cm.

[0078] Specifically, the ionic conductivity of the positive electrode amorphous sulfide electrolyte includes, but is not limited to, 1 mS / cm, 1.1 mS / cm, 1.2 mS / cm, 1.3 mS / cm, 1.4 mS / cm, 1.5 mS / cm, 1.6 mS / cm, 1.7 mS / cm, 1.8 mS / cm, 1.9 mS / cm, 2 mS / cm, 2.1 mS / cm, 2.2 mS / cm, 2.3 mS / cm, 2.4 mS / cm, 2.5 mS / cm, 2.6 mS / cm, 2.7 mS / cm, 2.8 mS / cm, 2.9 mS / cm, 3 mS / cm, 3.1 mS / cm, 3.2 mS / cm, 3.3 mS / cm, 3.4 mS / cm, 3.5 mS / cm, 3.6 mS / cm, 3.7 mS / cm, 3.8 mS / cm, 3.9 mS / cm or 4 mS / cm.

[0079] In a specific embodiment, the positive electrode active material includes, but is not limited to, lithium niobate, a ternary positive electrode material of nickel cobalt manganese lithium oxide coated with alumina, or lithium iron phosphate; wherein, the ternary positive electrode material of nickel cobalt manganese lithium oxide coated with alumina includes, but is not limited to, NCM9 series ternary positive electrode materials and NCM8 series ternary positive electrode materials.

[0080] In a specific embodiment, the conductive agent includes, but is not limited to, carbon black, carbon nanotubes, graphene or carbon fiber materials.

[0081] By setting the positive electrode formed by compounding an amorphous flexible sulfide electrolyte and a high ionic conductivity electrolyte, the transport efficiency of lithium ions in the battery positive electrode is ensured, and at the same time, the flexible deformation ability of the amorphous sulfide electrolyte can buffer the volume change during the use of the positive electrode, which is beneficial to the long-term stable cycling of the sulfide solid-state battery.

[0082] In a specific embodiment, the weight ratio of the amorphous sulfide electrolyte to the second binder in the electrolyte is (94 - 98):(2 - 6).

[0083] Specifically, the weight ratio of the amorphous sulfide electrolyte to the second binder includes, but is not limited to, 94:2, 94:3, 94:4, 94:5, 94:6, 95:2, 95:3, 95:4, 95:5, 96:6, 96:2, 96:3, 96:4, 96:5, 96:6, 97:2, 97:3, 97:4, 97:5, 97:6, 98:2, 98:3, 98:4, 98:5 or 98:6.

[0084] In a specific embodiment, the amorphous sulfide electrolyte is the same as or different from the positive electrode amorphous sulfide electrolyte. The amorphous sulfide electrolyte includes, but is not limited to, Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, or Li7P2S8I.

[0085] Since the materials in the positive electrode, negative electrode, and electrolyte of the sulfide solid-state battery are in contact through particles with each other, and the contact between particles is a hard contact, during the charge and discharge process of the battery, the particles expand or contract, resulting in obvious volume change behaviors of the positive and negative electrode materials and the electrolyte. In this application, by setting the electrolyte to include an amorphous sulfide electrolyte, the electrolyte can adapt to the volume changes from the positive electrode and the negative electrode to a certain extent during the use of the battery, keeping the interfaces between the electrolyte and the positive electrode and the negative electrode in good contact all the time, thereby ensuring the reliability of the battery performance.

[0086] In a specific embodiment, the current collector is a copper-lithium composite tape, wherein the thickness of lithium in the copper-lithium composite tape is 3 μm to 7 μm, and the thickness of copper in the copper-lithium composite tape is 6 μm to 10 μm. Using the lithium-copper composite tape as the current collector can pre-lithiate the homogeneous silicon-carbon material.

[0087] Specifically, the thickness of lithium in the copper-lithium composite tape is set to one of 3 μm, 4 μm, 5 μm, 6 μm, or 7 μm; the thickness of copper in the copper-lithium composite tape is set to one of 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

[0088] In a specific embodiment, the first negative electrode layer includes a homogeneous silicon-carbon material and a third binder, wherein the weight ratio of the homogeneous silicon-carbon material to the third binder is (94 - 98):(2 - 6).

[0089] Specifically, the weight ratio settings of the homogeneous silicon-carbon material to the third binder include, but are not limited to, 92:2, 94:3, 94:4, 94:5, 94:6, 95:2, 95:3, 95:4, 95:5, 95:6, 96:2, 96:3, 96:4, 96:5, 96:6, 97:2, 97:3, 97:4, 97:5, 97:6, 98:2, 98:3, 98:4, 98:5, or 98:6.

[0090] In a specific embodiment, the second negative electrode layer includes a negative electrode crystalline sulfide electrolyte, a hard carbon material, and a fourth binder; wherein the weight ratio of the negative electrode crystalline sulfide electrolyte, the hard carbon material, and the fourth binder is (15 - 37):(60 - 80):(3 - 5).

[0091] In a specific embodiment, the negative crystalline sulfide electrolyte is the same as or different from the positive crystalline sulfide electrolyte. The negative crystalline sulfide electrolyte includes, but is not limited to, Li6PS5X or LiSiPSX; wherein, X in Li6PS5X and LiSiPSX is selected from Cl or Br.

[0092] Specifically, the weight ratio of the negative crystalline sulfide electrolyte, the hard carbon material, and the fourth binder includes, but is not limited to, 15:60:3, 15:60:4, 15:60:5, 15:61:3, 15:62:3, 15:63:3, 15:64:3, 15:65:3, 15:70:3, 15:75:3, 15:80:3, 15:61:4, 15:62:4, 15:63:4, 15:64:4, 15:65:4, 15:70:4, 15:75:4, 15:80:4, 15:61:5, 15:62:5, 15:63:5, 15:64:5, 15:65:5, 15:70:5, 15:75:5, 15:80:5, 20:61:3, 20:62:3, 20:63:3, 20:64:3, 20:65:3, 20:70:3, 20:75:3, 20:80:3, 20:61:4, 20:62:4, 20:63:4, 20:64:4, 20:65:4, 20:70:4, 20:75:4, 20:80:4, 20:61:5, 20:62:5, 20:63:5, 20:64:5, 20:65:5, 20:70:5, 20:75:5, 20:80:5, 30:61:3, 30:62:3, 30:63:3, 30:64:3, 30:65:3, 30:70:3, 30:75:3, 30:80:3, 30:61:4, 30:62:4, 30:63:4, 30:64:4, 30:65:4, 30:70:4, 30:75:4, 30:80:4, 30:61:5, 30:62:5, 30:63:5, 30:64:5, 30:65:5, 30:70:5, 30:75:5, 30:80:5, 37:61:3, 37:62:3, 37:63:3, 37:64:3, 37:65:3, 37:70:3, 37:75:3, 37:80:3, 37:61:4, 37:62:4, 37:63:4, 37:64:4, 37:65:4, 37:70:4, 37:75:4, 37:80:4, 37:61:5, 37:62:5, 37:63:5, 37:64:5, 37:65:5, 37:70:5, 37:75:5 or 37:80:5.

[0093] In a specific embodiment, the mass percentage of silicon in the homogeneous silicon-carbon material is 40% to 60%, and / or the particle size D50 of the homogeneous silicon-carbon material is 1 μm to 8 μm.

[0094] Specifically, the mass percentage of silicon in the homogeneous silicon-carbon material includes, but is not limited to, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% or 60%.

[0095] Specifically, the particle size D50 of the homogeneous silicon-carbon material includes, but is not limited to, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.7 μm, 7.8 μm, 7.9 μm or 8 μm.

[0096] In a specific embodiment, the thickness of the first negative electrode layer is 60 μm to 100 μm, and the thickness of the second negative electrode layer is 10 μm to 50 μm.

[0097] Specifically, the thickness of the first negative electrode layer includes, but is not limited to, 60 μm, 61 μm, 62 μm, 63 μm, 64 μm, 65 μm, 66 μm, 67 μm, 68 μm, 69 μm, 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm, 81 μm, 82 μm, 83 μm, 84 μm, 85 μm, 86 μm, 87 μm, 88 μm, 89 μm, 90 μm, 91 μm, 92 μm, 93 μm, 94 μm, 95 μm, 96 μm, 97 μm, 98 μm, 99 μm or 100 μm.

[0098] Specifically, the thickness of the second negative electrode layer includes, but is not limited to, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm or 50 μm.

[0099] In a specific embodiment, the particle size D50 of the negative electrode crystalline sulfide electrolyte is 800 nm to 5 μm.

[0100] Specifically, the particle size D50 of the negative electrode crystalline sulfide electrolyte includes, but is not limited to, 800 nm, 810 nm, 820 nm, 830 nm, 840 nm, 850 nm, 860 nm, 870 nm, 880 nm, 890 nm, 900 nm, 910 nm, 920 nm, 930 nm, 940 nm, 950 nm, 960 nm, 970 nm, 980 nm, 990 nm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm, 4 μm, 4.1 μm, 4.2 μm, 4.3 μm, 4.4 μm, 4.5 μm, 4.6 μm, 4.7 μm, 4.8 μm, 4.9 μm or 5 μm.

[0101] In a specific embodiment, the particle size D50 of the hard carbon material is 7 μm to 11 μm.

[0102] Specifically, the particle size D50 of the hard carbon material includes, but is not limited to, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.7 μm, 7.8 μm, 7.9 μm, 8 μm, 8.1 μm, 8.2 μm, 8.3 μm, 8.4 μm, 8.5 μm, 8.6 μm, 8.7 μm, 8.8 μm, 8.9 μm, 9 μm, 9.1 μm, 9.2 μm, 9.3 μm, 9.4 μm, 9.5 μm, 9.6 μm, 9.7 μm, 9.8 μm, 9.9 μm, 10 μm, 10.1 μm, 10.2 μm, 10.3 μm, 10.4 μm, 10.5 μm, 10.6 μm, 10.7 μm, 10.8 μm, 10.9 μm or 11 μm.

[0103] In a specific embodiment, the first binder, the second binder, the third binder, and the fourth binder are the same or different, wherein the first binder includes, but is not limited to, fluororubber, styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated nitrile rubber, nitrile rubber, SEBS, polymethyl methacrylate, or polyethylene oxide.

[0104] In this embodiment, by setting the anode material in the present application to form a pre-lithiated double-layer structure through the first anode layer and the second anode layer, the homogeneous silicon-carbon in the first anode layer of the double-layer structure has a smaller volume change compared to a pure silicon anode and a higher specific capacity (1700 mAh / g) than a graphite anode. By pre-lithiating the homogeneous silicon-carbon, the structural stability of the silicon-carbon anode and the ion migration rate of the silicon-carbon anode can be further improved, thereby enhancing the electrode reaction kinetics. Silicon-carbon pre-lithiation can promote the fusion of the silicon-carbon boundaries, improve the denseness of the electrode, and enhance the battery rate performance. The hard carbon in the second anode layer of the double-layer structure has a high ion diffusion coefficient, does not hinder ion transfer, plays a role in buffering the volume change of the first anode layer, and maintains the stability of the interface. The hard carbon material can also intercalate lithium to prevent lithium plating short circuit on the anode surface, so that the porosity of the anode material decreases after static pressure, which is beneficial to the long-term stable cycling of the battery.

[0105] Corresponding to the above embodiment, this embodiment provides a method for preparing a sulfide solid-state battery, the method comprising:

[0106] Step 1: Dissolve and mix a cathode active material, a sulfide electrolyte, a conductive agent, a first binder, and a first solvent to obtain a cathode slurry, ball-mill the cathode slurry, and coat the ball-milled cathode slurry onto a cathode current collector to form a cathode electrode sheet.

[0107] Specifically, weigh each component according to a preset ratio of the cathode active material, the sulfide electrolyte, the conductive agent, and the first binder. Then, first dissolve the first binder in the first solvent, then add the remaining components, and obtain the cathode slurry after ball-milling at a ball-milling speed of 200 rpm to 400 rpm for a ball-milling time of 40 min to 80 min. Coat the cathode slurry onto an aluminum foil current collector and dry to obtain the cathode electrode sheet.

[0108] Wherein, the solid content in the cathode slurry is 50% to 60%. Specifically, the solid content in the cathode slurry includes but is not limited to 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%.

[0109] Step 2: Dissolve and mix an amorphous sulfide electrolyte, a second binder, and a second solvent to obtain an electrolyte slurry, coat the electrolyte slurry onto a release film, dry it, and peel it off from the release film to obtain an electrolyte membrane.

[0110] Specifically, weigh each component according to a preset ratio of the amorphous sulfide electrolyte and the second binder. Then, dissolve the second binder in the second solvent, then add the remaining components, and obtain the electrolyte slurry after ball-milling at a speed of 200 rpm to 400 rpm for 40 min to 80 min. Coat the electrolyte slurry onto a PET release film, dry it, and peel it off from the release film to obtain the electrolyte membrane.

[0111] In a specific embodiment, the solid content in the electrolyte slurry is 45% to 60%. Specifically, the solid content in the electrolyte slurry includes but is not limited to 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% or 60%.

[0112] In a specific embodiment, the drying temperature for drying the electrolyte is set to 60°C to 90°C. Specifically, the drying temperature includes but is not limited to 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C.

[0113] Step 3: Dissolve and mix the negative electrode crystalline sulfide electrolyte, hard carbon material, fourth binder, and third solvent to obtain an outer layer mixture, coat the outer layer mixture on a metal substrate, and dry it to obtain a second negative electrode layer. Dissolve and mix the homogeneous silicon-carbon material, third binder, and fourth solvent to obtain an inner layer mixture, and coat the inner layer mixture on the surface of the second negative electrode layer and dry it to obtain a first negative electrode layer.

[0114] Specifically, weigh each component according to the preset ratio of the negative electrode crystalline sulfide electrolyte, hard carbon material, and fourth binder in the second negative electrode layer. First, dissolve the fourth binder in the third solvent, then add other components, and ball mill at a rotation speed of 200 rpm to 400 rpm for 40 min to 80 min to obtain a negative electrode slurry. Coat the negative electrode slurry on a nickel-plated copper foil and dry it to obtain a second negative electrode layer. Weigh each component in the first negative electrode layer according to the preset ratio, dissolve the third binder in the fourth solvent, then add other components, ball mill at a rotation speed of 200 rpm to 400 rpm for 40 min to 80 min, and then coat it on the surface of the second negative electrode layer and dry it to form a negative electrode material.

[0115] In a specific embodiment, the metal substrate is configured as a nickel-plated copper foil.

[0116] In a specific embodiment, the drying temperature for both the second negative electrode layer and the first negative electrode layer is set to 60°C to 90°C. Specifically, the drying temperature includes but is not limited to 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C.

[0117] Step 4: Roll-transfer the first negative electrode layer and the second negative electrode layer onto the current collector to form a negative electrode sheet.

[0118] In a specific embodiment, the current collector is selected as a copper-lithium composite tape. The first negative electrode layer and the second negative electrode layer coated on the nickel-plated copper foil and the copper-lithium composite tape are pressed into a whole by means of rolling or isostatic pressing, and then the nickel-plated copper foil is peeled off. The first negative electrode layer contacts the lithium layer of the copper-lithium composite tape to complete prelithiation. At the same time, the double-layer structure negative electrode is transferred from the nickel-plated copper foil to the copper-lithium composite tape, and the prelithiated double-layer structure negative electrode material is obtained. Among them, the bonding force of the nickel-plated copper foil to the second negative electrode layer is less than the bonding force of the copper-lithium composite tape to the first negative electrode layer. Therefore, the double-layer structure negative electrode can be transferred from the nickel-plated copper foil to the copper-lithium composite tape.

[0119] Step 5: Assemble the positive electrode sheet, the electrolyte membrane and the negative electrode sheet, and form a sulfide solid-state battery after welding the electrode tabs, encapsulating and isostatic pressing.

[0120] In a specific embodiment, the isostatic pressing conditions are set as a pressure of 300 MPa to 500 MPa and a time of 3 min to 10 min.

[0121] Specifically, the isostatic pressing condition pressure includes but is not limited to 300 MPa, 310 MPa, 320 MPa, 330 MPa, 340 MPa, 350 MPa, 360 MPa, 370 MPa, 380 MPa, 390 MPa, 400 MPa, 410 MPa, 420 MPa, 430 MPa, 440 MPa, 450 MPa, 460 MPa, 470 MPa, 480 MPa, 490 MPa or 500 MPa.

[0122] Specifically, the isostatic pressing time includes but is not limited to 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0123] In a specific embodiment, the first solvent, the second solvent, the third solvent and the fourth solvent are the same or different. The first solvent is set as an organic solvent. Specific organic solvents include but are not limited to toluene, xylene, anisole, isobutyl isobutyrate, butyl butyrate or hexyl butyrate.

[0124] Corresponding to the above embodiments, this embodiment provides an application of a sulfide solid-state battery prepared according to the sulfide solid-state battery described above or according to the preparation method of the sulfide solid-state battery described above in a vehicle.

[0125] Example 1

[0126] Combined with the above embodiments, a sulfide solid-state battery and a preparation method are provided, which specifically include the following steps:

[0127] S1. According to the weight ratio of NCM83, sulfide electrolyte, VGCF (carbon nanotube), and fluororubber being 85:15:1.5:3, where fluororubber is used as the first binder, select the crystalline sulfide electrolyte for the positive electrode as LPSCl, and the amorphous sulfide electrolyte for the positive electrode as amorphous Li7P2S8I. Set the weight ratio of LPSCl to amorphous Li7P2S8I as 2:8 and weigh each component. Select isobutyl isobutyrate as the first solvent. First, dissolve the binder carbon nanotube in isobutyl isobutyrate, then add the remaining components, and ball-mill at a speed of 300 rpm for 60 min to obtain the positive electrode slurry. Coating the positive electrode slurry on an aluminum foil current collector and drying at 80 °C to obtain the positive electrode sheet. Among them, the solid content of the positive electrode slurry is 55%. The particle size D50 of the sulfide electrolyte is 800 nm.

[0128] S2. Weigh each component according to the weight ratio of Li7P2S8I and fluororubber being 96:4. Select isobutyl isobutyrate as the second solvent. First, dissolve the binder EY in isobutyl isobutyrate, then add the remaining components, and ball-mill at 300 rpm for 60 min to obtain the electrolyte slurry; coat the electrolyte slurry on a PET film and dry at 80 °C, and then peel it off from the pet film to obtain the electrolyte membrane. Among them, the solid content of the electrolyte slurry is 50%, and the particle size D50 of the sulfide electrolyte is 2 um.

[0129] S3. Weigh each component according to the weight ratio of hard carbon material, LPSCl, and fluororubber being 60:37:3. Then dissolve the fluororubber, which is used as the fourth binder, in isobutyl isobutyrate, and then add the remaining components and ball-mill at 300 rpm for 60 min to obtain the outer layer mixture. Coating it on a nickel-plated copper foil and drying at 80 °C to obtain the second negative electrode layer, and the thickness of the second negative electrode layer is 10 um; weigh each component according to the weight ratio of homogeneous silicon-carbon material and the third binder being 96:4. First, dissolve the third binder in isobutyl isobutyrate, then add the remaining components and ball-mill at 300 rpm for 60 min to obtain the outer layer mixture. Coating it on the surface of the second negative electrode layer and drying at 80 °C to obtain the first negative electrode layer, and the thickness of the first negative electrode layer is 90 um, and the particle size D50 of the sulfide electrolyte is 1 um.

[0130] S4. Press the double-layer negative electrode material coated on the nickel-plated copper foil and the lithium-copper composite tape (the thickness of the lithium layer is 5 um) into a whole by isostatic pressing (200 MPa, 1 min), remove the nickel-plated copper foil, and make the first negative electrode layer contact with the lithium layer of the lithium-copper composite tape. While completing prelithiation, the double-layer structure negative electrode is transferred from the nickel-plated copper foil to the lithium-copper composite tape, obtaining a prelithiated double-layer structure negative electrode.

[0131] S5. Assemble the positive electrode layer, the solid electrolyte layer, and the pre-lithiated double-layer structure negative electrode together, weld the electrode tabs, encapsulate, and perform isostatic pressing. The isostatic pressing pressure is 300 MPa for 10 min to form a sulfide solid-state battery.

[0132] Example 2

[0133] Corresponding to the above example, a sulfide solid-state battery and a preparation method are provided. The difference between Example 2 and Example 1 is that the weight ratio of the crystalline sulfide electrolyte to the amorphous sulfide electrolyte in the positive electrode is 8:2.

[0134] Example 3

[0135] Corresponding to the above example, a sulfide solid-state battery and a preparation method are provided. The difference between Example 3 and Example 2 is that the weight ratio of the crystalline sulfide electrolyte to the amorphous sulfide electrolyte in the positive electrode is 5:5.

[0136] Example 4

[0137] Corresponding to the above example, a sulfide solid-state battery and a preparation method are provided. The difference between Example 4 and Example 1 is that the thickness of the second negative electrode layer is set to 50 μm.

[0138] Comparative Example 1

[0139] Corresponding to the above example, a sulfide solid-state battery and a preparation method are provided. The difference between Comparative Example 1 and Example 1 is that the sulfide electrolyte in the positive electrode only includes the amorphous sulfide electrolyte in the positive electrode.

[0140] Comparative Example 2

[0141] Corresponding to the above example, a sulfide solid-state battery and a preparation method are provided. The difference between Comparative Example 2 and Example 1 is that the sulfide electrolyte in the positive electrode only includes the crystalline sulfide electrolyte in the positive electrode.

[0142] Comparative Example 3

[0143] Corresponding to the above example, a sulfide solid-state battery and a preparation method are provided. The difference between Comparative Example 3 and Example 1 is that the electrolyte only includes the crystalline sulfide electrolyte.

[0144] Comparative Example 4

[0145] Corresponding to the above example, a sulfide solid-state battery and a preparation method are provided. The difference between Comparative Example 4 and Example 1 is that the second negative electrode layer is not provided.

[0146] Comparative Example 5

[0147] Corresponding to the above embodiments, a sulfide solid-state battery and a preparation method are provided. The difference between Comparative Example 5 and Embodiment 1 is that the first negative electrode layer is not pre-lithiated.

[0148] According to the above Embodiments 1 to 4, and Comparative Examples 1 to 5, the corresponding sulfide solid-state batteries were prepared, and all the prepared sulfide solid-state batteries were set to be tested in the same environment and under the same conditions. The test results are shown in Table 1.

[0149] Table 1 Test Results of Sulfide Solid-State Batteries in Each Group

[0150]

[0151]

[0152] Combined with the test results in Table 1, it can be concluded that in Embodiments 1 to 3, a mixed crystalline and amorphous electrolyte is used in the positive electrode. The crystalline electrolyte has a higher ionic conductivity, which can improve the rate performance of the battery. Among them, the content of the crystalline electrolyte in Embodiment 2 is the highest, so the capacity at 0.5C is the highest. The content of the amorphous sulfide electrolyte in the positive electrode of Embodiment 1 is the highest, which can alleviate the volume change of the positive electrode and improve the cycle stability of the battery. The second negative electrode layer plays a role in stabilizing the interface of the first negative electrode layer. The thickness of the second negative electrode layer in Embodiment 1 is 10 μm and that in Embodiment 4 is 50 μm, and there is no obvious difference in battery performance, indicating that the second negative electrode layer has good ion transport and will not increase the internal resistance of the battery. In Comparative Example 1, the positive electrode uses all amorphous electrolytes, which reduces the rate performance of the positive electrode and results in a low capacity of the battery at 0.5C. In Comparative Example 2, the positive electrode is all crystalline electrolyte, and the battery has good rate performance, but the cycle stability is worse than that of the positive electrode using a composite electrolyte. In Comparative Example 3, the electrolyte layer uses a crystalline electrolyte and cannot adapt to the volume changes of the positive and negative electrodes, so the battery performance decays significantly. In Comparative Example 4, there is no second negative electrode layer, and the cycle performance stability of the battery is also inferior to that of the battery with a buffer layer. In Comparative Example 5, the first negative electrode layer is not pre-lithiated, and the first efficiency and cycle stability of the battery are the worst.

[0153] Although the preferred embodiments in the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be interpreted to include the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0154] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A sulfide solid-state battery, comprising a positive electrode, an electrolyte membrane and a negative electrode, characterized in that: The positive electrode includes a positive electrode active material, a sulfide electrolyte, a conductive agent and a first binder; the electrolyte membrane includes an amorphous sulfide electrolyte and a second binder, and the negative electrode includes a current collector, a first negative electrode layer and a second negative electrode layer sequentially arranged on the surface of the current collector.

2. The sulfide solid-state battery according to claim 1, characterized in that: The weight ratio of the positive electrode active material, the sulfide electrolyte, the conductive agent and the first binder in the positive electrode is (75-88):(10-20):(0.5-2):(1.5-4).

3. The sulfide solid-state battery according to claim 2, characterized in that: The sulfide electrolyte includes a positive electrode crystalline sulfide electrolyte and a positive electrode amorphous sulfide electrolyte; Wherein, the weight ratio of the positive electrode crystalline sulfide electrolyte to the positive electrode amorphous sulfide electrolyte is (2:8) to (8:2).

4. The sulfide solid-state battery according to any one of claims 1 to 3, characterized in that: The weight ratio of the amorphous sulfide electrolyte and the second binder in the electrolyte is (94-98):(2-6).

5. The sulfide solid-state battery according to any one of claims 1 to 3, characterized in that: The current collector is a copper-lithium composite tape, the thickness of lithium in the copper-lithium composite tape is 3 μm to 7 μm, and the thickness of copper in the copper-lithium composite tape is 6 μm to 10 μm; The first negative electrode layer includes a homogeneous silicon-carbon material and a third binder; Wherein, the weight ratio of the homogeneous silicon-carbon material and the third binder is (94-98):(2-6); The second negative electrode layer comprises a negative electrode crystalline sulfide electrolyte, a hard carbon material and a fourth binder; Wherein, the weight ratio of the negative electrode crystalline sulfide electrolyte, the hard carbon material and the fourth binder is (15-37):(60-80):(3-5).

6. The sulfide solid-state battery according to claim 5, characterized in that: The mass percentage of silicon in the homogeneous silicon-carbon material is 40% to 60%; And / or, the particle size D50 of the homogeneous silicon-carbon material is 1 μm to 8 μm.

7. The sulfide solid-state battery according to claim 5, characterized in that: The thickness of the first negative electrode layer is 60 μm to 100 μm, and the thickness of the second negative electrode layer is 10 μm to 50 μm.

8. The sulfide solid-state battery according to claim 5, characterized in that: The particle size D50 of the negative electrode crystalline sulfide electrolyte is 800nm ​​to 5μm; The particle size D50 of the hard carbon material is 7 μm to 11 μm.

9. A method for preparing a sulfide solid-state battery according to any one of claims 1 to 8, characterized in that: The method comprises: Dissolving and mixing a positive electrode active material, a sulfide electrolyte, a conductive agent, a first binder and a first solvent to obtain a positive electrode slurry, and coating the positive electrode slurry on a positive electrode current collector to form a positive electrode sheet; Dissolving and mixing an amorphous sulfide electrolyte, a second binder, and a second solvent to obtain an electrolyte slurry, coating the electrolyte slurry on a release film, drying, and peeling the electrolyte slurry from the release film to obtain an electrolyte membrane; Dissolving and mixing the negative electrode crystalline sulfide electrolyte, the hard carbon material, the fourth binder and the third solvent to obtain an outer layer mixture, coating the outer layer mixture on the metal substrate, and drying to obtain a second negative electrode layer, dissolving and mixing the homogeneous silicon-carbon material, the third binder and the fourth solvent to obtain an inner layer mixture, coating the inner layer mixture on the surface of the second negative electrode layer, and drying to obtain a first negative electrode layer; Rolling and transferring the first negative electrode layer and the second negative electrode layer onto a current collector to form a negative electrode sheet; The positive electrode sheet, the electrolyte membrane and the negative electrode sheet are assembled, and the tabs are welded, packaged and isostatically pressed to form a sulfide solid-state battery.

10. Use of the sulfide solid-state battery according to any one of claims 1 to 8 or the sulfide solid-state battery prepared according to the preparation method of the sulfide solid-state battery according to claim 9 in a vehicle.

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