An electrochemical device

Abstract

The present invention belongs to the field of electrochemical energy storage technology, and specifically relates to an electrochemical device. The present invention separates the positive electrode electrolyte from the negative electrode electrolyte via a solid electrolyte membrane, adds a high content of a nitrile compound to the positive electrode electrolyte, and adds a high content of an ether compound to the negative electrode electrolyte. The nitrile compound can effectively improve the stability of the positive electrode interface, and the ether compound can effectively improve the stability of the negative electrode interface. The nitrile compound will not penetrate into the negative electrode to cause adverse side reactions with the negative electrode, and the ether compound will not penetrate into the positive electrode to cause adverse oxidation reactions with the positive electrode, thereby improving the cycle life of the electrochemical device, especially improving the cycle life of an electrochemical device containing metallic lithium in the negative electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage, and in particular relates to an electrochemical device. Background Art

[0002] Lithium-ion batteries, as one of the most widely used electrochemical devices, are secondary batteries. The electrolyte in lithium-ion batteries has a significant impact on battery performance, but the electrolyte composition is complex, with some components incompatible with the negative electrode of lithium-ion batteries and others with the positive electrode, significantly shortening the battery's cycle life. Summary of the Invention

[0003] In order to solve the problem of incompatibility between the electrolyte and the electrodes of the electrochemical device, the present invention provides an electrochemical device in which the positive electrode electrolyte and the negative electrode electrolyte are separated by a solid electrolyte membrane, so that a high content of nitrile compounds can be added to the positive electrode electrolyte and a high content of ether compounds can be added to the negative electrode electrolyte. The electrochemical device designed in this way has a significantly improved cycle life.

[0004] The object of the present invention is achieved through the following technical solutions:

[0005] An electrochemical device comprising a positive electrode sheet, a negative electrode sheet, a solid electrolyte membrane, a positive electrode electrolyte, a negative electrode electrolyte and a packaging shell;

[0006] The positive electrode sheet and the negative electrode sheet are located on both sides of the solid electrolyte membrane, the positive electrode electrolyte is located on one side of the positive electrode sheet, and the negative electrode electrolyte is located on one side of the negative electrode sheet. The positive electrode electrolyte and the negative electrode electrolyte are separated by the solid electrolyte membrane.

[0007] According to the present invention, the solid electrolyte membrane has a dense structure, specifically, a dense non-porous structure or a dense non-through-pore structure.

[0008] According to the present invention, the positive electrode electrolyte includes a nitrile compound, and the mass fraction of the nitrile compound is not less than 5%; the negative electrode electrolyte includes an ether compound, and the mass fraction of the ether compound is not less than 4%.

[0009] According to the present invention, the positive electrode electrolyte further includes lithium salt A, solvent A and additive A; the negative electrode electrolyte further includes lithium salt B, solvent B and additive B.

[0010] According to the present invention, the ratio of the retention amount m1 (unit: g) of the positive electrode electrolyte to the design capacity Q (unit: Ah) of the electrochemical device satisfies 0.5 g / Ah≤m1 / Q≤2.0 g / Ah.

[0011] According to the present invention, the ratio of the retained amount m2 (unit: g) of the negative electrode electrolyte to the designed capacity Q (unit: Ah) of the electrochemical device satisfies 0.5g / Ah≤m2 / Q≤2.0g / Ah.

[0012] According to the present invention, the amount m1 of the positive electrode electrolyte is less than or equal to the amount m2 of the negative electrode electrolyte.

[0013] According to the present invention, the lithium salt A contains at least 60 wt % of lithium hexafluorophosphate.

[0014] According to the present invention, the lithium salt B contains at least 50 wt% of lithium difluorooxalatoborate.

[0015] According to the present invention, the lithium salt B contains at least 1 wt % of lithium nitrate.

[0016] According to the present invention, the solid electrolyte membrane is an inorganic solid electrolyte membrane with a dense non-porous structure, or the solid electrolyte membrane is an inorganic solid electrolyte membrane with a dense non-through-pore structure.

[0017] According to the present invention, the ionic conductivity of the solid electrolyte membrane is ≥0.1 ms / cm.

[0018] According to the present invention, the material forming the solid electrolyte membrane is at least one of a Garnet-type oxide electrolyte, a NASICON-type oxide electrolyte, a perovskite-type oxide electrolyte and a sulfide electrolyte.

[0019] According to the present invention, a positive electrode sealing ring is provided between the positive electrode sheet and the solid electrolyte membrane to prevent the positive electrode electrolyte from leaking from the edge of the positive electrode sheet.

[0020] According to the present invention, a negative electrode sealing ring is provided between the negative electrode sheet and the solid electrolyte membrane to prevent the negative electrode electrolyte from leaking from the edge of the negative electrode sheet.

[0021] According to the present invention, the positive electrode sealing ring and the negative electrode sealing ring are arranged to ensure that the electrolyte cannot penetrate, and the material forming the positive electrode sealing ring (or defined as a sealant) and the material forming the negative electrode sealing ring (or defined as a sealant) are the same or different, and are independently selected from at least one of maleic anhydride grafted polypropylene, polyurethane, nitrile rubber, butyl rubber, chloroprene rubber, epoxy resin and silicone rubber.

[0022] According to the present invention, the positive electrode sheet includes a positive electrode current collector, a positive electrode coating area arranged on at least one side surface of the positive electrode current collector, and a positive electrode sealing area connected to the positive electrode coating area and located outside the positive electrode coating area; a positive electrode paste is arranged in the positive electrode coating area, and a positive electrode sealing ring is arranged in the positive electrode sealing area.

[0023] According to the present invention, the negative electrode sheet includes a negative electrode current collector, a negative electrode coating area arranged on at least one side surface of the negative electrode current collector, and a negative electrode sealing area connected to the negative electrode coating area and located outside the negative electrode coating area; a negative electrode paste is arranged in the negative electrode coating area, and a negative electrode sealing ring is arranged in the negative electrode sealing area.

[0024] According to the present invention, the electrochemical device may be a battery or a supercapacitor.

[0025] Beneficial effects of the present invention:

[0026] The present invention separates the positive electrode electrolyte from the negative electrode electrolyte through a solid electrolyte membrane, adds a high content of nitrile compounds to the positive electrode electrolyte, and adds a high content of ether compounds to the negative electrode electrolyte. The nitrile compounds can effectively improve the stability of the positive electrode interface, and the ether compounds can effectively improve the stability of the negative electrode interface. The nitrile compounds will not penetrate into the negative electrode to cause adverse side reactions with the negative electrode, and the ether compounds will not penetrate into the positive electrode to cause adverse oxidation reactions with the positive electrode. The electrochemical device based on this design has a significantly improved cycle life, especially the cycle life of the electrochemical device containing metallic lithium in the negative electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 4 is a cross-sectional view of the structure of the lithium-ion battery of the present invention.

[0028] Figure 2 This is an expanded view of a stacked unit of the lithium-ion battery of the present invention. DETAILED DESCRIPTION

[0029] Typically, the composition of the electrolyte in an electrochemical device is relatively complex. Some components are incompatible with the negative electrode of the electrochemical device, and some components are incompatible with the positive electrode of the electrochemical device, which limits the application of the electrochemical device. Nitrile compounds can effectively stabilize transition metal elements, thereby improving the stability of the positive electrode interface, but they can cause adverse side reactions at the negative electrode. Therefore, to improve the cycle life, the addition of nitrile compounds in electrochemical devices is strictly controlled within 5%. Ether compounds can effectively improve the stability of the negative electrode interface, but they can cause adverse side reactions at the high-voltage positive electrode. Therefore, to improve the cycle life, the addition of ether compounds in electrochemical devices is strictly controlled within 4%, and in actual applications, no ether compounds are even added.

[0030] The inventors of the present application unexpectedly discovered that if the positive electrode electrolyte and the negative electrode electrolyte are separated by a solid electrolyte membrane, and a high content of nitrile compounds is added to the positive electrode electrolyte and a high content of ether compounds is added to the negative electrode electrolyte, the cycle life of the electrochemical device can be effectively improved.

[0031] <Electrochemical Device>

[0032] The present invention provides an electrochemical device, which includes a positive electrode sheet, a negative electrode sheet, a solid electrolyte membrane, a positive electrode electrolyte, a negative electrode electrolyte and a packaging shell;

[0033] The positive electrode sheet and the negative electrode sheet are located on both sides of the solid electrolyte membrane, the positive electrode electrolyte is located on one side of the positive electrode sheet, and the negative electrode electrolyte is located on one side of the negative electrode sheet. The positive electrode electrolyte and the negative electrode electrolyte are separated by the solid electrolyte membrane.

[0034] According to the present invention, the solid electrolyte membrane has a dense structure, specifically, a dense non-porous structure or a dense non-through-pore structure.

[0035] In the present invention, the positive electrode electrolyte and the negative electrode electrolyte have different compositions.

[0036] In the present invention, the positive electrode electrolyte and the negative electrode electrolyte are separated by a solid electrolyte membrane, which means that the positive electrode electrolyte and the negative electrode electrolyte are separated by the solid electrolyte membrane and do not contact each other, but ions can move through the solid electrolyte membrane.

[0037] <Positive Electrolyte and Negative Electrolyte>

[0038] In some embodiments, the positive electrode electrolyte includes a nitrile compound, and the mass fraction of the nitrile compound is not less than 5%.

[0039] In some embodiments, the mass fraction of the nitrile compound is not less than 5%, which means that the mass of the nitrile compound accounts for not less than 5% of the total mass of the positive electrode electrolyte, that is, greater than or equal to 5%. In this case, the nitrile compound can fully form a protective layer on the surface of the positive electrode active material, effectively stabilizing the transition metal elements in the positive electrode active material and preventing the transition metal elements from being destroyed under high voltage, thereby improving the stability of the positive electrode interface and improving the cycle performance. If the mass fraction is less than 5%, although the nitrile compound can also form a protective layer on the surface of the positive electrode active material and improve the stability of the positive electrode interface, the improvement effect is not significant.

[0040] In some embodiments, the mass fraction of the nitrile compound is 5% to 80%, and illustratively can be 5%, 6%, 7%, 8%, 9%, 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80%.

[0041] In some embodiments, the nitrile compound is selected from at least one of acetonitrile, propionitrile, butyronitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, 1,3,6-hexanetrinitrile, 1,3,5-pentanetriconitrile, ethylene glycol bispropionitrile ether, hexafluorocyclotriphosphazene, pentafluoroethoxycyclotriphosphazene, pentafluorophenoxycyclotriphosphazene, 1,4-dicyano-2-butene, p-fluorobenzonitrile, p-methylbenzonitrile, 2-fluoroadiponitrile, 2,2-difluorosuccinonitrile, tricyanobenzene, acrylonitrile, crotononitrile, trans-butenedicononitrile, and trans-hexenedicononitrile. More preferably, acetonitrile and succinonitrile are selected.

[0042] In some embodiments, the negative electrode electrolyte includes an ether compound, and the mass fraction of the ether compound is not less than 4%.

[0043] In some embodiments, the mass fraction of the ether compound being no less than 4% means that the mass of the ether compound accounts for no less than 4% of the total mass of the negative electrode electrolyte, i.e., greater than or equal to 4%. In this case, the ether compound has excellent anti-reduction stability, especially the high stability of the ether compound with metallic lithium, which can effectively inhibit the interfacial side reactions between the negative electrode electrolyte and the negative electrode material, thereby significantly improving the negative electrode interfacial stability and improving the cycle performance. If the mass fraction is less than 4%, although the ether compound can also improve the negative electrode interfacial stability, the improvement effect is not significant.

[0044] In some embodiments, the mass fraction of the ether compound is 4% to 80%, illustratively 4%, 5%, 6%, 7%, 8%, 9%, 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80%.

[0045] In some embodiments, the ether compound is selected from at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, 1,3-dioxolane, dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 3-ethyltetrahydrofuran, and dimethyltetrahydrofuran. More preferably, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, 1,3-dioxolane, dioxane, and tetrahydrofuran are selected.

[0046] In some embodiments, the positive electrode electrolyte further includes lithium salt A, solvent A and additive A.

[0047] In some embodiments, the negative electrode electrolyte further includes lithium salt B, solvent B and additive B.

[0048] In some embodiments, the ratio of the retained amount m1 (unit: g) of the positive electrode electrolyte to the designed capacity Q (unit: Ah) of the electrochemical device satisfies 0.5 g / Ah≤m1 / Q≤2.0 g / Ah.

[0049] In some embodiments, the ratio of the amount m2 (unit: g) of the negative electrode electrolyte to the design capacity Q (unit: Ah) of the electrochemical device satisfies 0.5 g / Ah≤m2 / Q≤2.0 g / Ah.

[0050] In some embodiments, the positive electrode electrolyte retention amount m1 is less than the negative electrode electrolyte retention amount m2. Due to the rapid growth rate of the negative electrode SEI film in the electrochemical device, the negative electrode electrolyte is generally consumed faster than the positive electrode electrolyte in the electrochemical device. This configuration can further improve the cycling performance of the entire electrochemical device.

[0051] In some embodiments, the lithium salt A and the lithium salt B are the same or different and are independently selected from lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF6), lithium difluorophosphate (LiPF2O2), 4,5-dicyano-2-trifluoromethylimidazolium lithium (LiDTI), lithium bis(oxalato)borate (LiBOB), lithium bis(malonate)borate (LiBMB), lithium difluorooxalatoborate (LiDFOB), lithium bis(difluoromalonate)borate (LiBDFMB), Lithium (malonate oxalate) borate (LiMOB), lithium (difluoromalonate oxalate) borate (LiDFMOB), lithium tris(oxalato) phosphate (LiTOP), lithium tris(difluoromalonate) phosphate (LiTDFMP), lithium tetrafluorooxalatophosphate (LiTFOP), lithium difluorobis(oxalato)phosphate (LiDFOP), lithium bis(trifluoromethanesulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (LiN(SO2F)(SO2CF3)), lithium nitrate (LiNO3), lithium fluoride (LiF), LiN(SO2C n F 2n+1 )2、LiN(SO2F)(SO2C n F 2n+1 ) (n is an integer from 2 to 10).

[0052] In some embodiments, the solvent A and solvent B are the same or different and are independently selected from ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), fluorodimethyl carbonate, fluoroethyl methyl carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, One or more of ethyl acetate (EA), propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, methyl difluoroacetate, ethyl difluoroacetate, γ-butyrolactone (GBL), γ-valerolactone, δ-valerolactone, fluoroether F-EPE, fluoroether D2, fluoroether HFPM, fluoroether MFE, fluoroether EME, sulfolane, dimethyl sulfoxide (DMSO), dichloromethane, and dichloroethane.

[0053] In some embodiments, the additive A and the additive B are the same or different and are independently selected from vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propane sultone (PS), trifluoromethyl ethylene carbonate, dimethyl sulfate, vinyl sulfate (DTD), methyl vinyl sulfate, propylene sulfate, vinyl sulfite, succinic anhydride, biphenyl, diphenyl ether, toluene, xylene, cyclohexylbenzene, fluorobenzene, p-fluorotoluene, p-fluoroanisole, tert-butylbenzene, tert-amylbenzene, propylene One or more of sultone, butane sultone, methylene methanedisulfonate, ethylene glycol bis(propionitrile) ether, hexamethyldisilazane, heptamethyldisilazane, dimethyl methylphosphonate, diethyl ethylphosphonate, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, triphenyl phosphite, tris(trimethylsilyl)borate, tris(trimethylsilyl)phosphate, 1,2-bis(cyanoethoxy)ethane, 1,2,3-tris(cyanoethoxy)propane, bis(cyanoethyl)sulfone, and 3-(trimethylsilyloxy)propionitrile.

[0054] In some embodiments, the lithium salt A contains at least 60 wt % of lithium hexafluorophosphate. Adding more than 60 wt % of lithium hexafluorophosphate can significantly reduce the preparation cost of the electrochemical device while ensuring its performance.

[0055] In some embodiments, the lithium salt B contains at least 50 wt% of lithium difluorooxalatoborate. Adding more than 50 wt% of lithium difluorooxalatoborate can improve the stability of the negative electrode SEI film and further increase the cycle life, especially when using metallic lithium as the negative electrode.

[0056] In some embodiments, the lithium salt B contains at least 1 wt % lithium nitrate. Adding lithium nitrate at a content of 1 wt % or more can increase the proportion of inorganic components in the negative electrode SEI film, improve the stability of the negative electrode SEI film, and further increase the cycle life, especially when using metallic lithium as the negative electrode.

[0057] <Solid electrolyte membrane>

[0058] As described above, the solid electrolyte membrane has a dense structure, specifically, a dense non-porous structure or a dense non-through-pore structure.

[0059] In some embodiments, the solid electrolyte membrane is an inorganic solid electrolyte membrane having a dense structure without through-holes.

[0060] In some embodiments, the solid electrolyte membrane is an inorganic solid electrolyte membrane having a dense non-porous structure.

[0061] In some embodiments, the density of the solid electrolyte membrane is greater than or equal to 99%, for example, 99% to 100%.

[0062] In some embodiments, the solid electrolyte membrane is different from conventional diaphragms. The solid electrolyte membrane of the present invention has a dense structure, specifically a dense non-porous structure or a dense non-through-pore structure. The setting of the solid electrolyte membrane with such a structure prevents the electrolyte from passing through, but the lithium ions in the electrolyte can migrate and pass through the solid electrolyte membrane. Therefore, the setting of the solid electrolyte membrane can ensure that the positive electrode electrolyte and the negative electrode electrolyte on both sides of the solid electrolyte membrane are separated by the solid electrolyte membrane and do not contact each other.

[0063] In some embodiments, the solid electrolyte membrane preferably has a thickness of 5 μm to 100 μm. Solid electrolyte membranes with a thickness less than 5 μm are difficult to produce using existing manufacturing techniques. Furthermore, when the thickness is less than 5 μm, the solid electrolyte membrane is too weak, easily cracked, and difficult to assemble into an electrochemical device. While solid electrolyte membranes with a thickness greater than 100 μm have high mechanical strength and are easier to assemble into electrochemical devices, excessively thick solid electrolyte membranes can reduce the energy density of the electrochemical device.

[0064] In some embodiments, the ionic conductivity of the solid electrolyte membrane is ≥ 0.1 ms / cm. Preferably, the ionic conductivity of the solid electrolyte membrane is ≥ 1 ms / cm.

[0065] In some embodiments, the material forming the solid electrolyte membrane is at least one of a Garnet-type oxide electrolyte, a NASICON-type oxide electrolyte, a perovskite-type oxide electrolyte, and a sulfide electrolyte.

[0066] In some embodiments, the Garnet-type oxide electrolyte is preferably at least one of lithium lanthanum zirconium oxide (LLZO), tantalum-doped lithium lanthanum zirconium oxide (LLZTO), and niobium-doped lithium lanthanum zirconium oxide (LLZNO).

[0067] In some embodiments, the NASICON-type oxide electrolyte is selected from Li 1+2x’ Zr 2-x’ Ca x’ (PO4)3, where 0.1≤x'≤0.4; Li 1+x+y Al x (Ti m Zr n Ge r ) 2-x Si y P 3-y O 12 , where 0≤x≤2, 0≤y≤3, 0≤m≤1, 0≤n≤1, 0≤r≤1, m+n+r=1. Preferred are lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), lithium aluminum titanium germanium phosphate and lithium silicon germanium phosphate (Li3Zr2Si2PO 12 ) at least one of .

[0068] In some embodiments, the perovskite oxide electrolyte is preferably lithium lanthanum titanate (LLTO).

[0069] In some embodiments, the sulfide electrolyte is preferably Li3PS4, Li7P3S 11 、Li 4-x ”Ge 1-x ”P x "S4 (X" = 0.4 or X" = 0.6) and Li6PS5X (X is selected from at least one of F, Cl, Br, and I).

[0070] In some embodiments, the thickness of the solid electrolyte membrane is 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm. More preferably, in some embodiments, the thickness of the solid electrolyte membrane is 15 μm, 20 μm, 25 μm, or 30 μm.

[0071] In some embodiments, the solid electrolyte membrane is prepared as follows:

[0072] The material forming the solid electrolyte membrane is ball-milled into a solid electrolyte powder with a particle size of less than 2 μm; the solid electrolyte powder, a binder, and a solvent are then mixed and dispersed uniformly to obtain a solid electrolyte slurry; the solid electrolyte slurry is coated on a polymer base film, and the solvent is dried to obtain a composite film; the composite film is removed from the polymer base film and cut to the desired specifications, and then subjected to pressure, high-temperature debinding, and sintering in an inert gas atmosphere to obtain the solid electrolyte membrane. The solid electrolyte membrane prepared using this method is an all-inorganic solid electrolyte membrane. Due to the high-temperature sintering, the solid electrolyte membrane is an inorganic membrane with a dense, non-porous structure or a dense, non-through-pore structure, making it impossible for liquids to directly pass through.

[0073] The debinding temperature is 200-1400°C, which is set according to the type of adhesive.

[0074] The sintering temperature is 200 to 1400° C., and is specifically set according to the type of material forming the solid electrolyte membrane.

[0075] The pressure range is 10 to 300 MPa.

[0076] The binder and the solvent are not particularly limited, and can be preferably selected according to the type of material forming the solid electrolyte membrane.

[0077] Among them, the binder is preferably one or more of polyvinylidene fluoride (PVDF), polyethylene oxide, polyvinyl alcohol, polyvinyl butyral (PVB), ethyl cellulose (EC), and acrylic resin.

[0078] Among them, the solvent is preferably one or more of NMP, water, acetonitrile and toluene.

[0079] <Positive and negative electrode sealing rings>

[0080] In some embodiments, a positive electrode sealing ring is provided between the positive electrode sheet and the solid electrolyte membrane to prevent the positive electrode electrolyte from leaking from the edge of the positive electrode sheet.

[0081] In some embodiments, a negative electrode sealing ring is provided between the negative electrode sheet and the solid electrolyte membrane to prevent the negative electrode electrolyte from leaking from the edge of the negative electrode sheet.

[0082] In some embodiments, the positive electrode sealing ring and the negative electrode sealing ring are arranged to ensure that the electrolyte cannot penetrate, and the material forming the positive electrode sealing ring (or defined as a sealant) and the material forming the negative electrode sealing ring (or defined as a sealant) are the same or different, preferably at least one of maleic anhydride grafted polypropylene, polyurethane, nitrile rubber, butyl rubber, chloroprene rubber, epoxy resin and silicone rubber.

[0083] In some embodiments, the positive electrode sealing ring may be formed by melting or solidifying the material forming the positive electrode sealing ring.

[0084] In some embodiments, the negative electrode sealing ring may be formed by melting or solidifying the material forming the negative electrode sealing ring.

[0085] <Positive and negative electrodes>

[0086] In some embodiments, the positive electrode sheet includes a positive electrode current collector, a positive electrode coating area arranged on at least one side surface of the positive electrode current collector, and a positive electrode sealing area connected to the positive electrode coating area and located outside the positive electrode coating area; a positive electrode paste is arranged in the positive electrode coating area, and a positive electrode sealing ring is arranged in the positive electrode sealing area.

[0087] In some embodiments, the negative electrode sheet includes a negative electrode current collector, a negative electrode coating area arranged on at least one side surface of the negative electrode current collector, and a negative electrode sealing area connected to the negative electrode coating area and located outside the negative electrode coating area; a negative electrode paste is arranged in the negative electrode coating area, and a negative electrode sealing ring is arranged in the negative electrode sealing area.

[0088] In some embodiments, the positive electrode active material in the positive electrode sheet can be a positive electrode active material known in the art, which can perform reversible insertion / deinsertion of ions. For example, it can be a lithium transition metal composite oxide, wherein the transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce and Mg. The lithium transition metal composite oxide can also be doped with elements with high electronegativity, such as one or more of S, F, Cl and I, which can make the positive electrode active material have higher structural stability and electrochemical performance. As an example, the lithium transition metal composite oxide is such as LiMn2O4, LiNiO2, LiCoO2, LiNi 1-y Co y O2(0 <y<1)、LiNi a Co b Al 1-a-b O2(0 <a<1,0<b<1,0<a+b<1)、LiMn 1-m-n Ni m Co nOne or more of O2(0 < m < 1, 0 < n < 1, 0 < m + n < 1), LiMPO4 (M can be one or more of Fe, Mn, Co), and Li3V2(PO4)3. Optionally, the positive electrode sheet may further include a conductive agent. Optionally, the positive electrode sheet may further include a binder. As an example, the binder is polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), nitrile rubber (NBR), aqueous acrylic resin, polyvinyl alcohol, polyvinyl butyral, polyurethane, fluorinated rubber, carboxymethyl cellulose (CMC), polyacrylic acid (PAA). The positive electrode sheet can be prepared according to conventional methods in the art. Generally, the positive electrode active material and the optional conductive agent and binder are dispersed in a solvent (such as N-methylpyrrolidone, abbreviated as NMP) to form a uniform positive electrode slurry. The positive electrode slurry is coated in the positive electrode coating area of the positive electrode current collector. After processes such as drying, a positive electrode coating paste is formed, and the positive electrode sheet is obtained.

[0089] In some embodiments, the negative electrode active material in the negative electrode sheet can be a negative electrode active material known in the art. For example, it can be one or more of metallic lithium, natural graphite, artificial graphite, mesocarbon microbeads (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, spinel-structured lithium titanate, and Li-Al alloy. Optionally, the negative electrode sheet may further include a conductive agent. Optionally, the negative electrode sheet may further include a binder. As an example, the binder includes but is not limited to polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), nitrile rubber (NBR), aqueous acrylic resin, polyvinyl alcohol, polyvinyl butyral, polyurethane, fluorinated rubber, carboxymethyl cellulose (CMC), polyacrylic acid (PAA), epoxy resin, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinylpyrrolidone, nylon. The negative electrode sheet can be prepared according to conventional methods in the art. Generally, the negative electrode active material and the optional conductive agent and binder are dispersed in a solvent (such as water) to form a uniform negative electrode slurry. The negative electrode slurry is coated in the negative electrode coating area of the negative electrode current collector. After processes such as drying, a negative electrode coating paste is formed, and the negative electrode sheet is obtained.

[0090] In order to obtain a higher energy density, the negative electrode sheet preferably uses a metallic lithium negative electrode sheet or a negative electrode sheet containing metallic lithium, and its preparation method is as follows: In a low-humidity environment (usually carried out in a drying room with a dew point temperature below -30°C), a commercial metallic lithium strip (foil) and / or lithium alloy strip (foil) and a copper foil (mesh) are mechanically pressed using a roll press or other pressing equipment, so that the metallic lithium strip (foil) and / or lithium alloy strip (foil) are tightly attached to the copper foil (mesh), and a certain blank area is left at the edge of the copper foil (mesh) for subsequent tab welding.

[0091] In some embodiments, the conductive agent in the positive electrode sheet includes, but is not limited to, a carbon-based material, a metal-based material, a conductive polymer, or a mixture thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, and silver. In some embodiments, the conductive polymer is a polyphenylene derivative.

[0092] In some embodiments, the conductive agent in the negative electrode sheet includes, but is not limited to, a carbon-based material, a metal-based material, a conductive polymer, or a mixture thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, and silver. In some embodiments, the conductive polymer is a polyphenylene derivative.

[0093] In some embodiments, the positive electrode current collector in the positive electrode sheet includes, but is not limited to: aluminum foil, carbon-coated aluminum foil, perforated aluminum foil, stainless steel foil, a polymer substrate coated with a conductive metal, and any combination thereof.

[0094] In some embodiments, the negative current collector in the negative electrode sheet includes, but is not limited to: copper foil, carbon-coated copper foil, perforated copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and any combination thereof.

[0095] <Battery or supercapacitor>

[0096] In some embodiments, the electrochemical device may be a battery (eg, a lithium-ion battery) or a supercapacitor.

[0097] In some embodiments, the battery assembly method is as follows: in a low humidity environment (usually in a dry room with a dew point temperature below -30°C), the positive electrode electrolyte is evenly dripped onto the positive electrode paste in the positive electrode sheet, and then a sealant (i.e., a material forming a positive electrode sealing ring) is applied to the positive electrode sealing area located outside the positive electrode coating area, and then the solid electrolyte membrane is stacked on the positive electrode sheet and the positive electrode sheet and the solid electrolyte membrane are bonded together by the sealant; the negative electrode electrolyte is evenly dripped onto the negative electrode paste in the negative electrode sheet, and then a sealant (i.e., a material forming a negative electrode sealing ring) is applied to the negative electrode sealing area located outside the negative electrode coating area, and then the negative electrode sheet is stacked on the solid electrolyte membrane and the negative electrode sheet and the solid electrolyte membrane are bonded together by the sealant, wherein the solid electrolyte membrane is located between the positive electrode sheet and the negative electrode sheet to serve as an isolation; after multi-layer stacking, a stacked battery cell can be obtained, the battery cell is welded with positive and negative electrode ears, placed in a packaging shell and sealed, and after aging, formation, and sorting, a battery can be obtained.

[0098] Figure 1 It is a cross-sectional view of the lithium-ion battery structure (a cross-sectional view in the vertical stacking direction), which includes a positive electrode collector, a positive electrode paste (fully soaked in the positive electrode electrolyte), a solid electrolyte membrane, a negative electrode paste (fully soaked in the negative electrode electrolyte), a negative electrode collector, a negative electrode paste (fully soaked in the negative electrode electrolyte), a solid electrolyte membrane, a positive electrode paste (fully soaked in the positive electrode electrolyte), a positive electrode collector, a positive electrode paste (fully soaked in the positive electrode electrolyte), a solid electrolyte membrane, a negative electrode paste (fully soaked in the negative electrode electrolyte), a negative electrode collector, a negative electrode paste (fully soaked in the negative electrode electrolyte)... stacked in sequence, the sealing areas at the edges of the positive electrode paste and the negative electrode paste are covered with sealant, and the positive and negative electrode sheets are bonded to the solid electrolyte membrane to constitute the battery.

[0099] In the stacked structure here, the number of negative electrode sheets is n, and the number of positive electrode sheets is n+1, meaning that both ends of the stacked structure have positive electrode sheets. Alternatively, the stacking arrangement can be changed so that the number of positive electrode sheets is n and the number of negative electrode sheets is n+1, meaning that both ends of the stacked structure have negative electrode sheets. Alternatively, the stacking arrangement can be changed so that the number of positive electrode sheets is n and the number of negative electrode sheets is n, meaning that one end of the stacked structure has a negative electrode sheet and the other end has a positive electrode sheet, where n is an integer greater than or equal to 1.

[0100] As can be seen from the stacked structure, only one side of the electrode plates at either end of the stack can be used and participate in the battery's charge and discharge reactions. Usually, for ease of manufacturing, the electrode plates at both ends are double-sided with the same paste as the internal ones. To further save space and increase energy density, the electrode plates at both ends are single-sided with the paste facing inward.

[0101] Figure 2 is an expanded view of a stacked unit of a lithium-ion battery (top view along the stacking direction), Figure 2 In the figure, a is a schematic diagram of the positive electrode sheet. The positive electrode paste is located in the central area of the electrode sheet. The blank positive electrode current collector around the edge of the positive electrode paste is the sealing area, and its surface is coated with sealant. Figure 2 b in the figure is a schematic diagram of a solid electrolyte; Figure 2 The negative electrode sheet (c) is a schematic diagram. The negative electrode paste is located in the center of the sheet. The blank area around the negative electrode paste is the negative current collector sealing area, which is coated with sealant. The positive electrode paste area ≤ the negative electrode paste area (here ≤ means that the positive electrode paste area can be completely covered by the negative electrode paste area after stacking). The negative electrode sheet ≤ the solid electrolyte (here ≤ means that the negative electrode sheet can be completely covered by the solid electrolyte after stacking).

[0102] <Applications of Electrochemical Devices>

[0103] The present invention also provides uses of the electrochemical device. The uses of the electrochemical device of the present invention are not particularly limited and can be used in various known applications. Examples include mobile computers, laptop computers, mobile phones, e-book players, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD televisions, portable cleaners, calculators, memory cards, portable recorders, radios, backup power supplies, automobiles, motorcycles, electric boats, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, cameras, large household batteries, and energy storage power stations.

[0104] <Examples and Comparative Examples>

[0105] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value can serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0106] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number themselves, and “a variety” in “one or more” means more than two.

[0107] The present invention summary is not intended to describe every disclosed embodiment or every implementation of the present invention. The following description more specifically illustrates exemplary embodiments. Throughout this application, guidance is provided in many places through a series of examples, which can be used in various combinations. In each example, the enumeration is intended only as a representative group and should not be construed as exhaustive.

[0108] The present disclosure is further illustrated by the following examples and comparative examples, which are intended for illustrative purposes only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and all instruments used in the examples are commercially available.

[0109] Preparation Example 1

[0110] (1) Preparation of positive electrode sheet

[0111] Weigh 972 g, 14 g, and 14 g of the positive electrode active material lithium cobalt oxide, carbon black conductive agent, and binder polyvinylidene fluoride (PVDF) respectively, disperse them in 400 g of N-methylpyrrolidone (NMP), stir them thoroughly to form a uniform positive electrode slurry, coat the positive electrode slurry on the positive electrode current collector aluminum foil, and then dry, roll-press, and cut to obtain the positive electrode sheet.

[0112] (2) Preparation of negative electrode sheet

[0113] Preparation of conventional negative electrode sheets: Weigh 970 g, 10 g, 10 g (in terms of solid weight) of the negative electrode active material (graphite and / or silicon oxide and / or silicon-carbon composite material), carbon black conductive agent, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC), respectively, disperse them in 1100 g of deionized water, stir them thoroughly to form a uniform negative electrode slurry, coat the negative electrode slurry on the negative electrode current collector copper foil, and then dry, roll-press, and cut to obtain the negative electrode sheet.

[0114] Preparation of metal lithium negative electrode sheet: In a low humidity environment (this experiment was carried out in a dry room with a dew point temperature of -40°C), a roller press or other pressing equipment is used to mechanically press commercial metal lithium strips (foils), lithium alloy strips (foils) and copper foil (mesh) so that the metal lithium strips (foils), lithium alloy strips (foils) and copper foil (mesh) are tightly attached together. A certain blank area is left at the edge of the copper foil (mesh) for subsequent tab welding, and the negative electrode sheet is obtained after cutting.

[0115] (3) Preparation of solid electrolyte membrane

[0116] a. Preparation of lithium lanthanum zirconium tantalum oxide (LLZTO) solid electrolyte membrane

[0117] ① Take 200 grams of lithium lanthanum zirconium tantalum oxide solid electrolyte, place it in a nitrogen-filled ball mill, put it into a ball milling equipment, set the speed to 800 rpm, and fully ball mill for 12 hours to obtain lithium lanthanum zirconium tantalum oxide solid electrolyte powder with an average particle size of 600 nm; ② Weigh 96 grams of the lithium lanthanum zirconium tantalum oxide solid electrolyte powder obtained in step ①, 4 grams of polyethylene oxide with a molecular weight of 5 million, and 200 grams of acetonitrile, mix and disperse them evenly to obtain a solid electrolyte slurry; ③ The electrolyte slurry obtained in step ② is coated on a PET base film, and the solvent is dried to obtain a composite film; The composite film is removed from the PET base film and cut into the required specifications, and first debinding (to fully decompose the binder) under argon atmosphere at 300°C and 20 MPa pressure for 6 hours, and then sintered at 1200°C and 300 MPa to obtain a solid electrolyte film with a thickness of 30 μm and a room temperature ionic conductivity of 1.3 ms / cm.

[0118] b. Preparation of Li6PS5Cl solid electrolyte membrane

[0119] ① Take 200 grams of Li6PS5Cl solid electrolyte, place it in a ball milling jar filled with argon, put it into a ball milling equipment, set the speed to 800 rpm, and fully ball mill for 24 hours to obtain Li6PS5Cl solid electrolyte powder with an average particle size of 800 nm; ② Weigh 97 grams of Li6PS5Cl solid electrolyte powder obtained in step ①, 3 grams of molecular weight nitrile rubber, and 150 grams of toluene to mix and disperse them evenly to obtain a solid electrolyte slurry; ③ The electrolyte slurry obtained in step ② is coated on a PTFE base film, and the solvent is dried to obtain a composite film; The composite film is removed from the PTFE base film and cut into the required specifications. Under an argon atmosphere, the binder is first debonded (to fully decompose the binder) at 350°C and 25 MPa pressure for 10 hours, and then sintered at 550°C and 300 MPa to obtain a solid electrolyte film with a thickness of 30 μm and a room temperature ionic conductivity of 4.6 ms / cm.

[0120] c. Test method for ionic conductivity

[0121] The ionic conductivity test method is as follows: the solid electrolyte membrane is punched into discs with a radius of r = 8mm using a punching machine, and then both sides of the solid electrolyte membrane disc are gold-sprayed using an ion sputtering device. Then, stainless steel discs (SS) with a radius of r = 8mm are placed closely on both sides of the gold-sprayed solid electrolyte membrane original sheet, and the two are sealed and assembled into an SS / solid electrolyte membrane / SS symmetrical blocking cell. The above symmetrical blocking cell is subjected to an alternating current impedance (EIS) test using an electrochemical workstation under the following test conditions: amplitude of 10mV, frequency of 10~10 6 Hz, temperature 25℃, before testing, the battery needs to be left at the test temperature for 1 hour to stabilize the battery, and the impedance spectrum is obtained and the data is fitted to obtain the body resistance R b The conductivity of the solid electrolyte membrane can be calculated according to the following equation: δ = d / (R b S)

[0122] Where, δ is the conductivity of the solid electrolyte membrane, R b is the bulk resistance obtained by fitting the impedance spectrum data, d is the thickness of the solid electrolyte membrane, S is the electrode area, S = πr 2 .

[0123] (4) Preparation of electrolyte

[0124] a. Preparation of positive electrode electrolyte

[0125] In an argon-filled glove box with a water content of <1 ppm, lithium salt A, solvent A, additive A, and nitrile compound are uniformly mixed in a certain mass ratio.

[0126] b. Preparation of negative electrode electrolyte

[0127] In an argon-filled glove box with a water content of <1 ppm, lithium salt B, solvent B, additive B, and ether compound are uniformly mixed in a certain mass ratio.

[0128] c. Preparation of electrolyte for control group

[0129] The positive electrode electrolyte and the negative electrode electrolyte were respectively mixed in a mass ratio of 1:1 to obtain the control group electrolyte.

[0130] Table 1 Electrolyte ratio

[0131]

[0132] In Table 1, Z1-Z14 are the positive electrolytes, and F1-F14 are the negative electrolytes. Weigh 50% Z1 and 50% F1 and mix them to obtain electrolyte H1. Weigh 50% Z2 and 50% F2 and mix them to obtain electrolyte H2. Similarly, we obtain electrolytes H3-H14. Weigh 50% Z1 and 50% F9 and mix them to obtain electrolyte H15. Weigh 50% Z2 and 50% F10 and mix them to obtain electrolyte H16. Weigh 50% Z3 and 50% F11 and mix them to obtain electrolyte H17. Weigh 50% Z4 and 50% F12 and mix them to obtain electrolyte H18.

[0133] (5) Preparation of lithium-ion batteries

[0134] In a low humidity environment (this experiment was conducted in a dry room with a dew point temperature of -40°C), the positive electrode electrolyte was evenly dripped onto the positive electrode paste in the positive electrode sheet, and then a sealant (i.e., a material forming a positive electrode sealing ring) was applied to the positive electrode sealing area located outside the positive electrode coating area. The solid electrolyte membrane was then stacked on the positive electrode sheet and the positive electrode sheet and the solid electrolyte membrane were bonded together by the sealant. The negative electrode electrolyte was evenly dripped onto the negative electrode paste in the negative electrode sheet, and then a sealant (i.e., a material forming a negative electrode sealing ring) was applied to the negative electrode sealing area located outside the negative electrode coating area. The negative electrode sheet was then stacked on the solid electrolyte membrane and the negative electrode sheet and the solid electrolyte membrane were bonded together by the sealant. The solid electrolyte membrane is located between the positive and negative electrode sheets and acts as an insulator. After 11 layers of positive electrode sheets, 20 layers of solid electrolyte membrane, and 10 layers of negative electrode sheets are alternately stacked to obtain a stacked cell. The cell was welded to the positive and negative tabs, placed in a packaging shell and sealed. After aging, formation, and sorting, the battery was obtained.

[0135] (6) Preparation of conventional lithium-ion batteries

[0136] The positive electrode sheet, negative electrode sheet and PP separator (thickness 20μm) are stacked by a stacking machine to prepare a conventional lithium battery cell. The positive and negative electrode ears of the battery cell are welded, placed in a packaging shell and sealed, and then the electrolyte is injected, aged, formed and sorted to obtain a conventional lithium-ion battery.

[0137] 2. Battery performance test

[0138] Normal temperature cycle life: Place the lithium-ion battery at 25°C, discharge at a constant current of 0.5C to the lower voltage limit (3.0V), let it stand for 5 minutes; then charge at a constant current of 0.5C to the upper voltage limit (4.5V), then charge at a constant voltage of 4.5V to a current of 0.05C, let it stand for 5 minutes; then discharge at a constant current of 0.5C to 3.0V, let it stand for 5 minutes. This is one charge and discharge cycle. Repeat this charge / discharge cycle until the ratio of the discharge capacity to the initial discharge capacity in a certain cycle is ≤80%. The number of cycles experienced is the cycle life.

[0139] Table 2 Battery information and performance test

[0140]

[0141]

[0142] Table 3 General battery information and performance test

[0143]

[0144] From the cycle life test results of the embodiment and comparative example batteries in Table 2, it can be seen that the battery of the present invention, using electrolytes with different components in the positive electrode and the negative electrode, can significantly improve the battery cycle life.

[0145] From the cycle life test results of the embodiment in Table 2 and the conventional batteries in Table 3, it can be seen that the cycle life of the battery of the present invention is significantly higher than that of the conventional lithium battery.

[0146] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. An electrochemical device, characterized in that The electrochemical device comprises a positive electrode sheet, a negative electrode sheet, a solid electrolyte membrane, a positive electrode electrolyte, a negative electrode electrolyte and a packaging shell; The positive electrode sheet and the negative electrode sheet are located on both sides of the solid electrolyte membrane, the positive electrode electrolyte is located on one side of the positive electrode sheet, and the negative electrode electrolyte is located on one side of the negative electrode sheet, and the positive electrode electrolyte and the negative electrode electrolyte are separated by the solid electrolyte membrane; The positive electrode electrolyte includes a nitrile compound, and the mass fraction of the nitrile compound is not less than 5%; the negative electrode electrolyte includes an ether compound, and the mass fraction of the ether compound is not less than 4%; The electrochemical device is a lithium-ion battery or a supercapacitor; The solid electrolyte membrane has a dense non-porous structure or a dense non-through-pore structure; the material forming the solid electrolyte membrane is at least one of a Garnet-type oxide electrolyte, a NASICON-type oxide electrolyte, a perovskite-type oxide electrolyte and a sulfide electrolyte.

2. The electrochemical device according to claim 1, characterized in that The positive electrode electrolyte further includes lithium salt A, solvent A and additive A; the negative electrode electrolyte further includes lithium salt B, solvent B and additive B; And / or, the lithium salt A contains at least 60 wt % of lithium hexafluorophosphate; And / or, the lithium salt B contains at least 50 wt% of lithium difluorooxalatoborate; And / or, the lithium salt B contains at least 1 wt % of lithium nitrate.

3. The electrochemical device according to claim 1, characterized in that The ratio of the amount m1 of the positive electrode electrolyte to the design capacity Q of the electrochemical device satisfies 0.5g / Ah≤m1 / Q≤2.0g / Ah; And / or, the ratio of the retained amount m2 of the negative electrode electrolyte to the designed capacity Q of the electrochemical device satisfies 0.5g / Ah≤m2 / Q≤2.0g / Ah; And / or, the amount m1 of the positive electrode electrolyte retained is ≤ the amount m2 of the negative electrode electrolyte retained.

4. The electrochemical device according to claim 1, characterized in that The ionic conductivity of the solid electrolyte membrane is ≥0.1 ms / cm.

5. The electrochemical device according to claim 1, characterized in that: A positive electrode sealing ring is provided between the positive electrode sheet and the solid electrolyte membrane to prevent the positive electrode electrolyte from leaking from the edge of the positive electrode sheet; And / or, a negative electrode sealing ring is provided between the negative electrode sheet and the solid electrolyte membrane to prevent the negative electrode electrolyte from leaking from the edge of the negative electrode sheet.

6. The electrochemical device according to claim 5, characterized in that: The material forming the positive electrode sealing ring and the material forming the negative electrode sealing ring are the same or different, and are independently selected from at least one of maleic anhydride grafted polypropylene, polyurethane, nitrile rubber, butyl rubber, chloroprene rubber, epoxy resin and silicone rubber.

7. The electrochemical device according to claim 5, characterized in that: The positive electrode sheet includes a positive electrode current collector, a positive electrode coating region disposed on at least one side of the positive electrode current collector, and a positive electrode sealing region connected to the positive electrode coating region and located outside the positive electrode coating region; a positive electrode paste is disposed in the positive electrode coating region, and a positive electrode sealing ring is disposed in the positive electrode sealing region; And / or, the negative electrode sheet includes a negative electrode current collector, a negative electrode coating area arranged on at least one side surface of the negative electrode current collector, and a negative electrode sealing area connected to the negative electrode coating area and located outside the negative electrode coating area; a negative electrode paste is arranged in the negative electrode coating area, and a negative electrode sealing ring is arranged in the negative electrode sealing area.

Images