Sulfide solid-state battery containing liquid crystal elastomer and preparation method of sulfide solid-state battery

Abstract

The invention belongs to the technical field of all-solid-state batteries, and particularly relates to a liquid crystal elastomer-containing sulfide solid-state battery and a preparation method thereof. The sulfide solid-state battery comprises an electrode membrane and an electrolyte membrane, and the electrode membrane is prepared by mixing a liquid crystal elastomer serving as a binder with an electrode material through a dry method; and / or the electrolyte membrane is prepared by mixing a liquid crystal elastomer serving as a binder with a sulfide solid electrolyte through a dry method; the liquid crystal elastomers are the same or different and are prepared from liquid crystal functional monomers containing at least one unsaturated bond and polymeric monomers containing unsaturated double bonds through free radical polymerization; or the liquid crystal functional monomer containing at least one unsaturated bond and a polymeric monomer containing sulfydryl or amido are subjected to sulfur-alkene reaction or Michael addition reaction. In the preparation process of the sulfide solid-state battery, a solvent is not needed, and the sulfide solid-state battery has important significance of energy conservation, emission reduction and environmental protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of all-solid-state batteries, and specifically relates to a sulfide solid-state battery containing a liquid crystal elastomer and a preparation method thereof. Background Art

[0002] With the widespread adoption of personal electronic devices and electric vehicles, lithium-ion batteries have become an integral part of our lives. However, the fire risks associated with the flammable organic electrolytes used in these batteries have a significant impact on human society. Furthermore, the energy density of liquid lithium-ion batteries has reached a critical point, severely limiting their development. Therefore, replacing traditional organic electrolytes with non-flammable solid electrolytes can not only reduce fire risks but also significantly increase battery energy density, and is considered a promising direction for future battery technology development.

[0003] Excellent solid electrolytes should have high ionic conductivity and a wide electrochemical window. Sulfide solid electrolytes are highly favored for their excellent ionic conductivity and easy processability. Sulfide solid electrolytes have broad application prospects in solid-state lithium batteries. At present, sulfide solid-state lithium batteries prepared based on the stacking or winding process of sulfide solid electrolyte membranes and electrode membranes have received great attention from industry and academia. The mainstream production process of sulfide solid electrolyte membranes and electrode membranes currently reported is wet preparation. For example, Professor Zhu Hongli of Northeastern University in the United States used a new etherified cellulose-toluene binder-solvent system to prepare an ultra-thin sulfide solid electrolyte film with a thickness as low as 47μm and an ultra-low surface resistance (4.32Ωcm -2 ) and ultra-high ionic conductivity (1.67 mS cm -1 ) (Adv.Mater.2021,33,2105505). Chinese patent (CN202211604948.9) discloses a self-healing binder made of methyl methacrylate and ester monomers for preparing sulfide solid electrolyte film. Lv Zhongwei et al. used xylene as solvent and styrene-ethylene-butylene-styrene block copolymer as binder to prepare a sulfide solid electrolyte film with high ionic conductivity (4.7×10 -4 S cm -1 ) self-supporting sulfide solid electrolyte membrane and composite sulfur positive electrode sheet with high sulfur content and high sulfur loading (Power Technology, 2024, 48, 4).

[0004] Professor Dong-Won Kim of Hanyang University in South Korea used acrylonitrile-butadiene rubber (NBR) as a polymer binder in a composite cathode, demonstrating good elasticity and excellent adhesion, and preventing severe contact failure at the cathode / sulfide interface during cycling (J.Ind.Eng.Chem.2023,122,341). Professor Song Jiangxuan's team at Xi'an Jiaotong University used a wet coating technique to prepare a silicon anode using an ion-electron hybrid conductive binder, providing a new strategy for rapid three-dimensional carrier transport within the electrode (Adv.Mater.2024,36,2405025). However, the wet-film formation process for sulfide solid electrolyte membranes and electrode membranes has significant drawbacks, such as the use of toxic organic solvents that cause environmental pollution, relatively high costs, and compromised ionic conductivity of the electrolyte membrane. Therefore, to promote the further development of sulfide solid-state lithium batteries, dry-film formation processes have greater application potential. However, the polytetrafluoroethylene binder commonly used in the dry-process production of electrolyte and electrode membranes currently suffers from high environmental toxicity, insufficient mechanical properties, and poor reduction stability in the resulting sulfide solid electrolyte membranes. This has led to numerous difficulties in developing a dry-process production process suitable for large-scale applications. Therefore, the development of non-fluoropolymer binders suitable for dry-process production has become a top priority in the development of sulfide solid-state lithium batteries. Summary of the Invention

[0005] The object of the present invention is to provide a sulfide solid-state battery containing a liquid crystal elastomer and a preparation method thereof.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A sulfide solid-state battery, comprising an electrode membrane and an electrolyte membrane, wherein the electrode membrane is prepared by dry-processing a mixture of a liquid crystal elastomer as a binder and an electrode material; and / or the electrolyte membrane is prepared by dry-processing a mixture of a liquid crystal elastomer as a binder and a sulfide solid electrolyte;

[0008] Preferably, the electrode membrane is prepared by dry-forming a liquid crystal elastomer as a binder mixed with an electrode material, and the electrolyte membrane is prepared by dry-forming a liquid crystal elastomer as a binder mixed with a sulfide solid electrolyte;

[0009] The liquid crystal elastomers are the same or different and are prepared by free radical polymerization of a liquid crystal functional monomer containing at least one unsaturated bond and a polymeric monomer containing an unsaturated double bond, or by sulfhydryl-ene reaction or Michael addition reaction of a liquid crystal functional monomer containing at least one unsaturated bond and a polymeric monomer containing a thiol group or an amine group.

[0010] Liquid crystal elastomer is used as a binder and is mixed with electrode materials or sulfide solid electrolytes under solvent-free conditions. The liquid crystal elastomer is fibrillated by grinding and evenly filled between the electrode materials or sulfide solid electrolytes. The electrode membrane or electrolyte membrane is further prepared by extrusion.

[0011] The liquid crystal elastomer accounts for 0.2 wt% to 30 wt% of the electrode film, the sulfide solid electrolyte accounts for 0 to 10 wt%, the conductive agent accounts for 0 to 5 wt%, and the electrode material accounts for 70 wt% to 99.8 wt%;

[0012] The liquid crystal elastomer accounts for 0.2 wt% to 30 wt% of the electrolyte membrane, and the sulfide solid electrolyte accounts for 70 wt% to 99.8 wt%.

[0013] Preferably, the liquid crystal elastomer in the electrode film accounts for 0.2 wt% to 10 wt%, the sulfide solid electrolyte accounts for 0 to 10 wt%, the conductive agent accounts for 0 to 5 wt%, and the electrode material accounts for 80 wt% to 99.8 wt%;

[0014] Preferably, the liquid crystal elastomer accounts for 0.2 wt% to 10 wt% of the electrolyte membrane, and the sulfide solid electrolyte accounts for 90 wt% to 99.8 wt%.

[0015] When the liquid crystal elastomer is prepared by free radical polymerization of a liquid crystal functional monomer containing at least one unsaturated bond and a polymerizable monomer containing an unsaturated double bond, the liquid crystal functional monomer containing at least one unsaturated bond accounts for 5 to 99% by weight of the liquid crystal elastomer; and the polymerizable monomer containing an unsaturated double bond accounts for 1 to 95% by weight of the liquid crystal elastomer;

[0016] Preferably, the liquid crystal functional monomer containing at least one unsaturated bond accounts for 20 to 60% of the mass of the liquid crystal elastomer; the polymerized monomer containing an unsaturated double bond accounts for 40 to 80% of the mass of the liquid crystal elastomer;

[0017] When the liquid crystal elastomer is prepared by a sulfene-ene reaction or a Michael addition reaction of a liquid crystal functional monomer containing at least one unsaturated bond and a polymeric monomer containing a thiol group or an amine group, the liquid crystal functional monomer containing at least one unsaturated bond accounts for 5 to 99% of the mass of the liquid crystal elastomer, and the polymeric monomer containing a thiol group or an amine group accounts for 1 to 95% of the mass of the liquid crystal elastomer;

[0018] Preferably, the liquid crystal functional monomer containing at least one unsaturated bond accounts for 20-60% of the mass of the liquid crystal elastomer, and the polymerizable monomer containing a mercapto group or an amino group accounts for 40-80% of the mass of the liquid crystal elastomer.

[0019] The liquid crystal functional monomer containing at least one unsaturated bond is methyl benzoate and azobenzene structural units, and has a molecular weight of 300-10000Da;

[0020] The polymerizable monomer containing an unsaturated double bond is one or more of ether-containing acrylic acid esters, ether-containing vinyl ethers, ether-containing allyl ethers, aminoethyl acrylate, allylamine, acrylonitrile, sodium acrylate, lithium acrylate, acrylic acid esters containing lithium carboxylate or lithium sulfonate structures, cyanoethyl acrylate, acrylic acid esters, styrene, and butadiene;

[0021] The polymer monomer containing thiol groups is a compound containing 1 to 6 thiol groups and has a molecular weight of 200-10000 Da.

[0022] The sulfide solid electrolyte material is Li6PS5X (X is Cl, Br and I), Li2S-P2S5 glass ceramic type, thio-LISICON type, anion doped Li2S-P2S5, Na3XS4 (X is P, Sb), Na 10 N x P 3-x S 12 (0≤x≤2, N=Si, Ge or Sn), Na2S:(1-x)P2S5 (wherein x=0.7~0.8).

[0023] The electrode material includes a positive electrode material and a negative electrode material; wherein the positive electrode material is selected from lithium nickel cobalt manganese oxide, lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese oxide, lithium-rich manganese-based materials, nickel manganese spinel, Na x One or more of PR(CN)6 (P, R is Fe, Co, Ni, Mn), sodium vanadium phosphate, sodium ferric sulfate, elemental sulfur, elemental selenium, sodium manganese oxide, sodium ion fluorophosphate, sodium vanadium fluorophosphate, and sodium cobalt oxide;

[0024] The negative electrode material is selected from one or more of metallic lithium alloys, graphite, hard carbon, molybdenum disulfide, lithium titanate, silicon-based materials, carbon-germanium composite materials, carbon-tin composite materials, antimony oxide, antimony-carbon composite materials, tin-antimony composite materials, lithium titanium oxide and lithium metal nitride.

[0025] The conductive agent is selected from one or more of graphite, Super P, KS6 graphite, Ketjen black, and acetylene black.

[0026] The sulfide solid-state battery is a sulfide all-solid-state lithium or sodium battery.

[0027] A method for preparing a sulfide solid-state battery comprises: using a liquid crystal elastomer as a binder, mixing it with an electrode material or a sulfide solid electrolyte in the absence of a solvent; fibrillating the liquid crystal elastomer through grinding and uniformly filling it between the electrode material or the sulfide solid electrolyte; further extruding the liquid crystal elastomer to prepare an electrode membrane or electrolyte membrane; and directly stacking or winding the electrolyte membrane and the electrode membrane to form a sulfide solid-state battery.

[0028] The advantages of the present invention are:

[0029] 1. The present invention utilizes the liquid crystal properties of liquid crystal elastomers to form nano-scale fibers during grinding. These fibers are evenly dispersed in the gaps between electrode particles or sulfide solid electrolyte particles, coated on the surface of the electrode particles or sulfide solid electrolyte particles to act as a binder, and can be formed into a film by extrusion. The thickness of the sulfide composite solid electrolyte film can be as low as 15 μm, and it has high ionic conductivity (2 to 6×10 -3 S cm -1 ), high mechanical strength (tensile strength 10-60MPa) and excellent flexibility. The prepared electrode film also has high mechanical strength (tensile strength 10-60MPa) and excellent flexibility. The process is not restricted by solvents, and also avoids the structural damage of the solvent to the sulfide solid electrolyte. Moreover, the preparation process is simple and easy to achieve large-scale production.

[0030] 2. The liquid crystal elastomer content in the electrode membrane and sulfide electrolyte of the present invention can be reduced to 0.2wt%, which helps to reduce the interference of non-ionic conductors on the ion transport inside the electrode membrane or sulfide electrolyte membrane, thereby improving the ion transport performance and enhancing the rate performance of the sulfide solid-state battery. At the same time, it can adapt to the stacking or winding process to prepare sulfide solid-state batteries, realize the integrated binder preparation, and reduce the difficulty of battery assembly.

[0031] 3. No solvent is required in the preparation process of the sulfide solid-state battery of the present invention, which is of great significance for energy conservation, emission reduction and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 1 is a cross-sectional morphology diagram and elemental analysis diagram of the sulfide electrolyte film in Example 1 of the present invention.

[0033] Figure 2 This is a physical photo of the negative electrode film in Example 2 of the present invention.

[0034] Figure 3 This is a physical picture of the composite positive electrode film in Example 3 of the present invention.

[0035] Figure 4 Long-cycle charge and discharge diagram of the batteries assembled in Application Example 1 of the present invention and Comparative Application Example 1.

[0036] Figure 5 This is a physical photo of the sulfide electrolyte membrane in Example 4 of the present invention.

[0037] Figure 6 This is a long-cycle diagram of charge and discharge of batteries assembled in Application Example 2 of the present invention and Comparative Application Example 2.

[0038] Figure 7 This is a rate performance diagram of the batteries assembled in Application Example 3 of the present invention and Comparative Application Example 3. DETAILED DESCRIPTION

[0039] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0040] Preparation Example 1: Preparation of Liquid Crystal Elastomer A1

[0041] Components containing unsaturated double bonds Liquid crystal functional monomers containing unsaturated bonds, accounting for 40% of the mass of liquid crystal elastomers Accounting for 60% of the mass of liquid crystal elastomer, and Add to anhydrous toluene, use AIBN as an initiator, reflux at 160°C under argon protection, and react for 4 hours. The reacted sample is precipitated in anhydrous ethanol and dried in a vacuum oven at 120°C to obtain liquid crystal elastomer A1:

[0042]

[0043] Preparation Example 2: Preparation of Liquid Crystal Elastomer A2

[0044] Liquid crystal functional monomers containing unsaturated bonds Accounts for 40% of the mass of liquid crystal elastomer, containing mercapto components Accounting for 60% of the mass of liquid crystal elastomer, and Added into anhydrous toluene, DPA was used as an initiator under argon protection, and the reaction time was 4 h at room temperature. The two components underwent Michael addition reaction to obtain liquid crystal elastomer A2.

[0045]

[0046] Preparation Example 3: Preparation of Liquid Crystal Elastomer A3

[0047] Liquid crystal functional monomers containing unsaturated bonds Components containing unsaturated double bonds account for 40% of the mass of liquid crystal elastomers Accounting for 40% of the mass of liquid crystal elastomer, and The reaction mixture was added to anhydrous toluene and refluxed at 160°C under argon protection for 4 hours. The sample after the reaction was precipitated in anhydrous ethanol and dried in a vacuum oven at 120°C to obtain liquid crystal elastomer A3.

[0048]

[0049] Preparation Example 4: Preparation of Liquid Crystal Elastomer A4

[0050] Liquid crystal functional monomers containing unsaturated bonds Components containing unsaturated double bonds account for 40% of the mass of liquid crystal elastomers Accounting for 40% of the mass of liquid crystal elastomer, and The reaction mixture was added to anhydrous toluene and refluxed at 50°C under argon protection with AIBN as an initiator for 6 hours. The sample after the reaction was precipitated in anhydrous ether and dried in a vacuum oven at 70°C to obtain liquid crystal elastomer A4.

[0051]

[0052] Preparation Example 5: Preparation of Liquid Crystal Elastomer A5

[0053] Liquid crystal functional monomers containing unsaturated bonds Components containing unsaturated double bonds account for 45% of the mass of liquid crystal elastomers Accounting for 45% of the mass of liquid crystal elastomer, and The reaction mixture was added to anhydrous toluene and refluxed at 60°C under argon protection. AIBME was used as an initiator and the reaction time was 7 hours. The sample after the reaction was precipitated in anhydrous acetone and dried in a vacuum oven at 80°C to obtain liquid crystal elastomer A5.

[0054]

[0055] Preparation Example 6: Preparation of Liquid Crystal Elastomer A6

[0056] Liquid crystal functional monomers containing unsaturated bonds Accounting for 50% of the mass of liquid crystal elastomer, containing amino components Accounting for 50% of the mass of the liquid crystal elastomer, and The mixture was added to anhydrous toluene and refluxed at 80°C under argon protection for 5 h. The two components underwent Michael addition reaction to obtain liquid crystal elastomer A6.

[0057]

[0058] The polymerizable monomer containing an unsaturated double bond in the above preparation examples can be arbitrarily replaced with ether-containing acrylates, ether-containing vinyl ethers, ether-containing allyl ethers, aminoethyl acrylate, allylamine, acrylonitrile, sodium acrylate, lithium acrylate, acrylates containing lithium carboxylates or lithium sulfonates, cyanoethyl acrylate, acrylic acid esters, styrene, or butadiene. Because these substances share the same unsaturated bond characteristics, they can achieve the goal of functionalizing the polymer structure and optimizing its performance, and thus can achieve the same technical effects as the preparation examples.

[0059] Example 1

[0060] The sulfide solid electrolyte powder Li6PS5Cl and the liquid crystal elastomer A1 were mixed in a mass percentage of 99%:1% and ground in a ball mill at 200r / min for 15min to obtain a mixed powder. The mixed powder was then directly spread on a heating plate at 80℃ and manually rolled with an iron rod to a film thickness of 15μm ( Figure 1 ), after cooling to room temperature, a self-sustaining sulfide electrolyte film was obtained. The ionic conductivity of the sulfide electrolyte film at room temperature was 1.2 mSc -1 .

[0061] Example 2

[0062] Nano-silicon and liquid crystal elastomer A1 were mixed in a mass percentage of 90%:10% and then hand-ground in a mortar for 45 minutes. The mixed powder was fully rolled on a 140°C hot roller machine until the film thickness was 50 μm to obtain a silicon negative electrode film. Figure 2 shown.

[0063] Example 3

[0064] The positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), sulfide solid electrolyte powder Li6PS5Cl, liquid crystal elastomer A1, and Ketjen black were mixed in a mass percentage of 90%:8%:1%:1% and hand-ground in a mortar for 30 minutes. The mixed powder was placed between two smooth stainless steel plates and directly hot-pressed on a flat-plate hot press at 140°C for 15 minutes (about 250MPa) to obtain a flexible and bendable composite positive electrode film. Figure 3 .

[0065] Application Example 1

[0066] The sulfide electrolyte film of Example 1, the silicon negative electrode film of Example 2, and the composite positive electrode film of Example 3 were cut into appropriate sizes, stacked and assembled into a battery. The long-term charge and discharge cycle performance of the battery was shown in FIG. Figure 4 .

[0067] Example 4

[0068] The sulfide solid electrolyte powder Li6PS5Cl and the liquid crystal elastomer A2 were mixed in a mass percentage of 90%:10% and then hand-ground in a mortar for 45 minutes. The mixed powder was fully rolled to 20 μm by a 100°C hot roller machine to obtain a sulfide electrolyte film. Figure 5 .

[0069] Example 5

[0070] The positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), sulfide solid electrolyte powder Li6PS5Cl, liquid crystal elastomer A2, and Super P were mixed in a mass percentage of 89%:5%:5%:1% and hand-ground in a mortar for 30 minutes. The mixed powder was then placed between two smooth stainless steel plates and directly hot-pressed at 120°C for 2 minutes (about 150MPa) on a flat hot press to obtain a composite positive electrode film.

[0071] Example 6

[0072] The negative electrode materials Si and A2 were mixed in a mass percentage of 90%:10% and hand-ground in a mortar for 30 minutes. The mixed powder was fully rolled on a 140° C. hot roller to a film thickness of 60 μm to obtain a negative electrode film.

[0073] Application Example 2: After the negative electrode film prepared in Example 6 is cut into a suitable size, it is assembled into a battery with the sulfide electrolyte film prepared in Example 4 and the composite positive electrode film laminate prepared in Example 5. The battery's long charge and discharge cycle performance is shown in FIG. Figure 6 .

[0074] Example 7

[0075] Sulfide solid electrolyte powder Li2S-P2S5 and liquid crystal elastomer A3 were mixed in a mass percentage of 98%:2% and hand-ground in a mortar for 25 minutes. The mixed powder was then fully rolled on a 110°C hot roller machine to a film thickness of 30 μm to obtain a sulfide electrolyte film.

[0076] Example 8

[0077] Sulfide solid electrolyte powder Na3PS4 and liquid crystal elastomer A4 were mixed in a mass percentage of 95%:5% and hand-ground in a mortar for 25 minutes. The mixed powder was then fully rolled on a 110°C hot roller machine to a film thickness of 40 μm to obtain a sulfide electrolyte film.

[0078] Example 9

[0079] Sulfide solid electrolyte powder Na 10SiP2S 12 After being mixed with liquid crystal elastomer A4 in a mass percentage of 94%:6% and hand-ground in a mortar for 25 minutes, the mixed powder was fully rolled on a 110°C hot roller machine to a film thickness of 25 μm to obtain a sulfide electrolyte film.

[0080] Example 10

[0081] Sulfide solid electrolyte powder Li2S-P2S5 and liquid crystal elastomer A5 were mixed in a mass percentage of 95%:5% and hand-ground in a mortar for 25 minutes. The mixed powder was then fully rolled on a 120°C hot roller machine to a film thickness of 10 μm to obtain a sulfide electrolyte film.

[0082] Example 11

[0083] The positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), sulfide solid electrolyte powder Li2S-P2S5, liquid crystal elastomer A5, and acetylene black were mixed in a mass percentage of 88%:9%:2%:1% and hand-ground in a mortar for 30 minutes. The mixed powder was then placed between two smooth stainless steel plates and directly hot-pressed at 60°C for 5 minutes (about 100 MPa) on a flat hot press to obtain a composite positive electrode film.

[0084] Application Example 3

[0085] The composite cathode film prepared in Example 11 was cut into a suitable size and assembled into a battery with the sulfide electrolyte film prepared in Example 10 and the lithium-indium alloy negative electrode laminate of the prior art. The charge and discharge rate performance of the battery was shown in FIG. Figure 7 .

[0086] Example 12

[0087] The negative electrode material hard carbon and A6 were mixed in a mass percentage of 98%:2% and hand-ground in a mortar for 30 minutes. The mixed powder was fully rolled on a 140° C. hot roller to a film thickness of 50 μm to obtain a negative electrode film.

[0088] Example 13

[0089] The sulfide solid electrolyte powder Li2S-P2S5 and the liquid crystal elastomer A5 were mixed and ground at a mass percentage of 99%:1 under mechanical stirring, and then the mixed powder was fully rolled on a 150°C hot roller machine to a film thickness of 10 μm to obtain a sulfide electrolyte film.

[0090] Example 14

[0091] The positive electrode material S, Li6PS5Cl, liquid crystal elastomer A6 and Super P were mixed in a mass percentage of 92%:4%:3%:1, and then hand-ground in a mortar for 30 minutes. The mixed powder was fully rolled on a 140°C hot roller machine to a film thickness of 20 μm to obtain a sulfide composite positive electrode film.

[0092] The sulfide solid electrolyte suitable for the liquid crystal elastomer prepared above is not only the one shown in the embodiment, but can also be one of Li6PS5X (X is Br and I), thio-LISICON type, Na2S: (1-x) P2S5 (wherein x = 0.7 to 0.8); the equipped positive electrode material can also be selected from lithium nickel cobalt manganese oxide, lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese oxide, lithium-rich manganese-based materials, nickel manganese spinel, NaxPR (CN) 6 (P, R is Fe, Co, Ni, Mn), sodium vanadium phosphate, sodium iron sulfate, elemental sulfur, elemental selenium, sodium manganese oxide, sodium ion fluorophosphate, sodium vanadium fluorophosphate, sodium cobalt oxide; the equipped negative electrode material can also be selected from one or more of metal lithium alloy, molybdenum disulfide, lithium titanate, silicon-based material, carbon germanium composite material, carbon tin composite material, antimony oxide, antimony carbon composite material, tin antimony composite material, lithium titanium oxide and lithium metal nitride.

[0093] Comparative Application Example 1

[0094] The sulfide solid electrolyte powder Li6PS5Cl and the polytetrafluoroethylene binder PTFE (commercially available) were mixed in a mass percentage of 99%:1% and ground in a ball mill at 200 rpm for 15 min to obtain a mixed powder. The mixed powder was then directly spread on a heating plate at 80°C and manually rolled with an iron rod to a film thickness of 15 μm.

[0095] The positive electrode materials NCM811 and Li6PS5Cl were mixed with polytetrafluoroethylene binder PTFE and Super P in a mass percentage of 90%:8%:1%:1% and hand-ground in a mortar for 30 minutes. The mixed powder was then placed between two smooth stainless steel plates and directly hot-pressed on a flat-plate hot press at 120°C for 15 minutes (about 250MPa) to obtain a composite positive electrode film.

[0096] The negative electrode material Si and the polytetrafluoroethylene binder PTFE were mixed in a mass percentage of 90%:10% and hand-ground in a mortar for 30 minutes. The mixed powder was fully rolled on a hot roller at 140° C. to obtain a negative electrode film.

[0097] The sulfide film, composite positive electrode film and negative electrode film stack prepared above were assembled into a battery, and its charge and discharge long cycle performance was shown in FIG. Figure 4 .

[0098] Depend on Figure 4It can be seen that the mechanical properties of the membrane prepared by using PTFE as a binder in Comparative Application Example 1 are poor. In addition, by comparing the long-cycle performance of solid-state batteries prepared with PTFE as a binder and liquid crystal elastomer A1 as a binder, it is found that the solid-state battery cycle performance of the application example of the present invention using liquid crystal elastomer A1 as a binder is better, demonstrating the excellence of liquid crystal elastomers.

[0099] Comparative Application Example 2

[0100] Sulfide solid electrolyte powder Li6PS5Cl and liquid crystal elastomer A2 were mixed in a mass ratio of 60%:40% and hand-ground in a mortar for 45 minutes. The mixed powder was then fully rolled on a 140°C hot roller machine to a film thickness of 20 μm to obtain a sulfide electrolyte film.

[0101] The positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), sulfide solid electrolyte powder Li6PS5Cl, liquid crystal elastomer A2, and Super P were mixed in a mass percentage of 89%:5%:5%:1% and hand-ground in a mortar for 30 minutes. The mixed powder was then placed between two smooth stainless steel plates and directly hot-pressed at 120°C for 2 minutes (about 150MPa) on a flat hot press to obtain a composite positive electrode film.

[0102] The negative electrode materials Si and A2 were mixed in a mass percentage of 90%:10% and hand-ground in a mortar for 30 minutes. The mixed powder was fully rolled on a 140° C. hot roller to a film thickness of 60 μm to obtain a negative electrode film.

[0103] The sulfide electrolyte membrane prepared above was cut into a suitable size and assembled into a battery with the prepared composite positive electrode film and negative electrode film laminate. The battery's charge and discharge long cycle performance was shown in FIG. Figure 6 .

[0104] Depend on Figure 6 It can be seen from the cycle performance that a too high content of liquid crystal elastomer will lead to a decrease in the conductivity of the sulfide film, and a too high content of liquid crystal elastomer will lead to a decrease in battery capacity. At the same time, the cycle performance and rate performance will also decrease, proving that the effect can only be achieved under the specific conditions of the embodiment of the present invention.

[0105] Comparative Application Example 3

[0106] Sulfide solid electrolyte powder Li2S-P2S5 and liquid crystal elastomer A5 were mixed in a mass ratio of 50%:50% and hand-ground in a mortar for 25 minutes. The mixed powder was then fully rolled on a 120°C hot roller machine to a film thickness of 10 μm to obtain a sulfide electrolyte film.

[0107] The positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), sulfide solid electrolyte powder Li2S-P2S5, liquid crystal elastomer A5, and acetylene black were mixed in a mass percentage of 88%:9%:2%:1% and hand-ground in a mortar for 30 minutes. The mixed powder was then placed between two smooth stainless steel plates and directly hot-pressed at 60°C for 5 minutes (about 100 MPa) on a flat hot press to obtain a composite positive electrode film.

[0108] After the prepared sulfide film is cut to a suitable size, it is assembled into a battery with the prepared composite positive electrode film and lithium-indium alloy negative electrode stack. The charge and discharge rate performance is shown in Figure 7 .

[0109] Depend on Figure 7 It can be seen that the use of excessive binder in Comparative Application Example 3 results in insufficient lithium ion transmission capacity of the electrolyte membrane and poor rate performance.

[0110] Comparative Application Example 4

[0111] Without adding liquid crystal elastomer A6, the positive electrode material S was mixed with Li6PS5Cl and Super P in a mass percentage of 92%:5%:3%, and then hand-grinded in a mortar for 30 minutes. The mixed powder was then fully rolled on a hot roller at 140°C for 20 minutes. Ultimately, no sulfide composite positive electrode film was obtained.

[0112] As can be seen from the above, it is impossible to prepare the electrolyte membrane and the negative electrode membrane by roller pressing without adding liquid crystal elastomer. It can be seen that when liquid crystal elastomer is not used as a binder, the electrolyte membrane, positive electrode membrane and negative electrode membrane cannot be prepared. The embodiments of the present invention utilize the liquid crystal properties of liquid crystal elastomer to form nano-scale fibers during grinding, which are evenly dispersed in the gaps between electrode particles or sulfide solid electrolyte particles, and coated on the surface of electrode particles or sulfide solid electrolyte particles to act as a binder. This process is not limited by solvents and also avoids the structural damage of sulfide solid electrolytes by solvents. In addition, the preparation process is simple and easy to achieve large-scale production.

[0113] As can be seen from the above examples and comparative examples, the present invention uses liquid crystal elastomer as a binder for the preparation of solvent-free sulfide solid-state battery electrode membranes and electrolyte membranes, avoiding the use of solvents, preventing the potential damage of solvents to the sulfide solid electrolyte structure, and significantly reducing the emission of volatile organic compounds. In the method of the present application, the liquid crystal elastomer is formed into fibers by grinding and coated on the surface of sulfide particles or electrode particles to play a bonding role. The fibers exhibit excellent mechanical properties, which improve the mechanical properties of the prepared electrode membrane / electrolyte membrane. At the same time, the chemical composition of the liquid crystal elastomer does not contain the fluorine element in the commonly used dry binder PTFE, thereby avoiding potential harm to the environment from the source. In addition, the content of liquid crystal elastomer in the electrode membrane and sulfide electrolyte of the present invention can be reduced to 0.2wt%, which helps to reduce the interference of non-ionic conductors on the internal ion transport of the electrode membrane or sulfide electrolyte membrane, thereby improving the ion transport performance and the rate performance of the sulfide solid-state battery. At the same time, it can adapt to the lamination or winding process to prepare sulfide solid-state batteries, realize integrated binder preparation, reduce the difficulty of battery assembly, and the assembled battery exhibits high discharge capacity, excellent cycle stability and excellent rate performance.

[0114] The above description is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principles of the present invention. These improvements and changes are also considered to be within the scope of protection of the present invention.

Claims

1. A sulfide solid-state battery comprising an electrode membrane and an electrolyte membrane, characterized in that: The electrode membrane is prepared by dry-processing a mixture of a liquid crystal elastomer as a binder and an electrode material; and / or the electrolyte membrane is prepared by dry-processing a mixture of a liquid crystal elastomer as a binder and a sulfide solid electrolyte; The liquid crystal elastomers are the same or different and are prepared by free radical polymerization of a liquid crystal functional monomer containing at least one unsaturated bond and a polymeric monomer containing an unsaturated double bond, or by sulfhydryl-ene reaction or Michael addition reaction of a liquid crystal functional monomer containing at least one unsaturated bond and a polymeric monomer containing a thiol group or an amine group.

2. The sulfide solid-state battery according to claim 1, characterized in that: Liquid crystal elastomer is used as a binder and is mixed with electrode materials or sulfide solid electrolytes in the absence of solvents. The liquid crystal elastomer is fibrillated by grinding and evenly filled between the electrode materials or sulfide solid electrolytes. The electrode membrane or electrolyte membrane is further prepared by extrusion.

3. The sulfide solid-state battery according to claim 1, characterized in that: The liquid crystal elastomer accounts for 0.2 wt% to 30 wt% of the electrode film, the sulfide solid electrolyte accounts for 0 to 10 wt%, the conductive agent accounts for 0 to 5 wt%, and the electrode material accounts for 70 wt% to 99.8 wt%; The liquid crystal elastomer accounts for 0.2 wt% to 30 wt% of the electrolyte membrane, and the sulfide solid electrolyte accounts for 70 wt% to 99.8 wt%.

4. The sulfide solid-state battery according to claim 1, characterized in that: When the liquid crystal elastomer is prepared by free radical polymerization of a liquid crystal functional monomer containing at least one unsaturated bond and a polymerizable monomer containing an unsaturated double bond, the liquid crystal functional monomer containing at least one unsaturated bond accounts for 5 to 99% of the mass of the liquid crystal elastomer; and the polymerizable monomer containing an unsaturated double bond accounts for 1 to 95% of the mass of the liquid crystal elastomer; When a liquid crystal elastomer is prepared by a liquid crystal functional monomer containing at least one unsaturated bond and a polymeric monomer containing a thiol group or an amine group through a sulfur-ene reaction or a Michael addition reaction, the liquid crystal functional monomer containing at least one unsaturated bond accounts for 5 to 99% of the mass of the liquid crystal elastomer, and the polymeric monomer containing a thiol group or an amine group accounts for 1 to 95% of the mass of the liquid crystal elastomer.

5. The sulfide solid-state battery according to claim 4, characterized in that: The liquid crystal functional monomer containing at least one unsaturated bond is methyl benzoate and azobenzene structural units, and has a molecular weight of 300-10000Da; The polymerizable monomer containing an unsaturated double bond is one or more of ether-containing acrylic acid esters, ether-containing vinyl ethers, ether-containing allyl ethers, aminoethyl acrylate, allylamine, acrylonitrile, sodium acrylate, lithium acrylate, acrylic acid esters containing lithium carboxylate or lithium sulfonate structures, cyanoethyl acrylate, acrylic acid esters, styrene, and butadiene; The polymer monomer containing thiol groups is a compound containing 1 to 6 thiol groups and has a molecular weight of 200-10000 Da.

6. The sulfide solid-state battery according to claim 3, characterized in that: The sulfide solid electrolyte is Li6PS5X (X is Cl, Br and I), Li2S-P2S5 glass ceramic type, thio-LISICON type, anion doped Li2S-P2S5, Na3XS4 (X is P, Sb), Na 10 N x P 3-x S 12 (0≤x≤2, N=Si, Ge or Sn), Na2S:(1-x)P2S5 (wherein x=0.7~0.8).

7. The sulfide solid-state battery according to claim 3, characterized in that: The electrode material includes a positive electrode material and a negative electrode material; wherein the positive electrode material is selected from lithium nickel cobalt manganese oxide, lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese oxide, lithium-rich manganese-based materials, nickel manganese spinel, Na x One or more of PR(CN)6 (P, R is Fe, Co, Ni, Mn), sodium vanadium phosphate, sodium ferric sulfate, elemental sulfur, elemental selenium, sodium manganese oxide, sodium ion fluorophosphate, sodium vanadium fluorophosphate, and sodium cobalt oxide; The negative electrode material is selected from one or more of metallic lithium alloys, graphite, hard carbon, molybdenum disulfide, lithium titanate, silicon-based materials, carbon-germanium composite materials, carbon-tin composite materials, antimony oxide, antimony-carbon composite materials, tin-antimony composite materials, lithium titanium oxide and lithium metal nitride.

8. The sulfide solid-state battery according to claim 3, characterized in that: The conductive agent is selected from one or more of graphite, Super P, KS6 graphite, Ketjen black, and acetylene black.

9. The sulfide solid-state battery according to claim 1, characterized in that: The sulfide solid-state battery is a sulfide all-solid-state lithium or sodium battery.

10. A method for preparing a sulfide solid-state battery according to claim 1, characterized in that: Liquid crystal elastomer is used as a binder and is mixed with electrode materials or sulfide solid electrolytes under solvent-free conditions. The liquid crystal elastomer is fibrillated by grinding and evenly filled between the electrode materials or sulfide solid electrolytes. The electrode membrane or electrolyte membrane is further prepared by extrusion. The electrolyte membrane and the electrode membrane are directly stacked or wound to assemble into a sulfide solid-state battery.

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