CN115986210B - Electrochemical device and electronic device - Google Patents
Electrochemical device and electronic device Download PDFInfo
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- CN115986210B CN115986210B CN202310143123.XA CN202310143123A CN115986210B CN 115986210 B CN115986210 B CN 115986210B CN 202310143123 A CN202310143123 A CN 202310143123A CN 115986210 B CN115986210 B CN 115986210B
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Abstract
The application provides an electrochemical device and an electronic device, wherein the electrochemical device comprises a negative electrode plate and electrolyte, the electrolyte comprises a compound shown in a formula (I) and a compound shown in a formula (II), the mass percentage of the compound shown in the formula (I) is a%, a is more than or equal to 0.05 and less than or equal to 5, the mass percentage of the compound shown in the formula (II) is b%, and b is more than or equal to 0.05 and less than or equal to 5 based on the mass of the electrolyte. The high-temperature cycle performance and the high-temperature storage performance of the electrochemical device can be improved by simultaneously adding the compound shown in the formula (I) and the compound shown in the formula (II) into the electrolyte and regulating and controlling the mass percentage of the compound shown in the formula (I) and the compound shown in the formula (II) in the electrolyte within the range of the application.
Description
Technical Field
The present disclosure relates to the field of electrochemical technology, and in particular, to an electrochemical device and an electronic device.
Background
The lithium ion battery has the advantages of high specific energy, light weight, long cycle life and the like, and is widely applied to consumer batteries. With the development of the electronic products toward light weight and portability, people put forward higher demands on the charging speed, cruising ability, safety and the like of lithium ion batteries. Increasing the cut-off voltage of charging is one of the mainstream ways to increase its energy density, but increasing the charging voltage tends to reduce the high temperature cycle performance and the high temperature storage performance.
In the prior art, ethylene carbonate (VC), fluoroethylene carbonate (FEC), bis (fluoroethylene carbonate) (DFEC), bis (lithium oxalato) borate (LiBOB) and bis (lithium oxalato) borate (LiDFOB) type positive and negative electrode interface film forming additives are added into electrolyte to inhibit the consumption of the electrolyte in the cycle process of the lithium ion battery so as to improve the stability of the positive and negative electrode interfaces and reduce the possibility of side reactions of the electrolyte and an exposed fresh interface, thereby improving the cycle performance of the lithium ion battery. However, the method makes the interface component generated by the first reaction between the electrolyte and the anode interface and the cathode interface have larger impedance, and meanwhile, decomposes part of other products, thereby deteriorating the high-temperature storage performance of the lithium ion battery. Therefore, how to improve the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
An object of the present application is to provide an electrochemical device and an electronic device to improve high temperature cycle performance and high temperature storage performance of the electrochemical device.
In the context of the present application, the present application is explained using a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to a lithium ion battery. The specific technical scheme is as follows:
The first aspect of the present application provides an electrochemical device comprising a negative electrode tab and an electrolyte; the electrolyte comprises a compound shown in a formula (I) and a compound shown in a formula (II):
R 7 selected from substituted or unsubstituted C 1 To C 10 Alkylene, substituted or unsubstituted C 3 To C 10 Cycloalkylene, substituted or unsubstituted C 1 To C 10 Oxy subunit, substituted or unsubstituted C 2 To C 10 Alkenylene, substituted or unsubstituted C 2 To C 10 Alkynylene, substituted or unsubstituted C 6 To C 10 Arylene, substituted or unsubstituted C 1 To C 10 Alkyloxy, substituted or unsubstituted C 2 To C 10 Alkenylene oxy, substituted or unsubstituted C 2 To C 10 Alkynyloxy;
when substituted, the substituent is selected from at least one of a halogen atom or a cyano group; preferably, the substituents are selected from halogen atoms or cyano groups, and the substituents of the respective groups may be the same or different;
based on the mass of the electrolyte, the mass percentage of the compound shown in the formula (I) is a percent, a is more than or equal to 0.05 and less than or equal to 5, and the mass percentage of the compound shown in the formula (II) is b percent, b is more than or equal to 0.05 and less than or equal to 5. For example, the value of a may be 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or any value in the range between any two of the foregoing values. The value of b may be 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or any value between any two of the foregoing.
The inventor has found through a great deal of research that the compound shown in the formula (I) can neutralize the alkalinity of the surface of the positive electrode active material particles on the surface of the positive electrode plate, inhibit the reaction of the solvent in the electrolyte on the surface of the positive electrode plate, and the compound shown in the formula (I) contains unsaturated double bonds, can be reduced preferentially on the surface of the negative electrode active material particles, and inhibit the reduction reaction of the solvent in the electrolyte. The compound shown in the formula (II) can be oxidized on the surface of the positive electrode plate preferentially to generate an interface component containing phosphate, which is beneficial to lithium ions (Li) + ) The resistance of the lithium ion battery is reduced, thereby improving the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device. However, the product of the reaction of the compound shown in the formula (II) on the surface of the negative electrode plate can damage an electrolyte solid interface (SEI) film, so that the consumption of electrolyte is easy to accelerate, and the cycle performance of an electrochemical device is influenced. The compound shown in the formula (I) and the compound shown in the formula (II) are added into the electrolyte simultaneously, the compound shown in the formula (I) can react on the surface of the negative electrode plate in preference to the compound shown in the formula (II), the compound shown in the formula (II) is oxidized on the surface of the positive electrode plate to generate an interface component containing phosphate, and Li is improved + The transmission rate of the electrochemical device is reduced. According to the electrolyte, the compound shown in the formula (I) and the compound shown in the formula (II) are added simultaneously, and the mass percentage of the compound shown in the formula (I) and the compound shown in the formula (II) in the electrolyte is regulated and controlled within the scope of the application, so that the compound shown in the formula (I) and the compound shown in the formula (II) are synergistic, and the high-temperature cycle performance and the high-temperature storage performance of an electrochemical device are improved.
Preferably, a is 0.1.ltoreq.3 and b is 0.1.ltoreq.2. For example, the value of a may be, for example, 0.1, 0.5, 1, 1.5, 2, 2.5, 3 or any value between any two of the foregoing. The value of b may be 0.1, 0.5, 1, 1.5, 2 or any value between any two of the above ranges. More preferably, 0.5.ltoreq.a.ltoreq.1, 0.1.ltoreq.b.ltoreq.0.8. For example, the value of a may be 0.5, 0.6, 0.7, 0.8, 0.9, 1 or any value between any two of the above ranges. The value of b may be 0.1, 0.2, 0.4, 0.6, 0.8 or any value between any two of the above ranges. The mass percentage of the compound represented by the formula (I) and the compound represented by the formula (II) in the electrolyte is controlled within the above-described preferred range, and the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device can be further improved.
In some embodiments of the present application, 0.1.ltoreq.a/b.ltoreq.10. Preferably, 1.ltoreq.a/b.ltoreq.8. More preferably, 1.ltoreq.a/b.ltoreq.5. For example, the value of a/b may be 0.1, 1, 2,3, 4, 5, 6, 7, 8, 9, 10 or any value between any two of the foregoing ranges. The ratio a/b of the mass percent a% of the compound shown in the formula (I) to the mass percent b% of the compound shown in the formula (II) is regulated within the range, so that the synergistic effect of the compound shown in the formula (I) and the compound shown in the formula (II) is facilitated, and the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device are further improved.
In some embodiments of the present application, the compound of formula (I) is selected from at least one of norbornene dianhydride (CAS number: 129-64-6), methylnadic anhydride (CAS number: 25134-21-8), chlorobridge anhydride (CAS number: 115-27-5), cis-5-norbornene-exo-2, 3-dicarboxylic anhydride (CAS number: 2746-19-2), nadic anhydride (CAS number: 826-62-0), 7-allylbicyclo [2.2.1] hept-5-ene-2, 3-dicarboxylic anhydride (CAS number: 10193-26-7), or methyl-5-norbornene-2, 3-dicarboxylic anhydride (CAS number: 14806-35-0). Preferably, the compound represented by formula (I) is at least one selected from norbornene dianhydride (CAS number: 129-64-6), methyl nadic anhydride (CAS number: 25134-21-8), 7-allylbicyclo [2.2.1] hept-5-ene-2, 3-dicarboxylic anhydride (CAS number: 10193-26-7), methyl-5-norbornene-2, 3-dicarboxylic anhydride (CAS number: 14806-35-0) and nadic anhydride (CAS number: 826-62-0). The compound shown in the formula (I) is selected to be beneficial to improving the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device.
In some embodiments of the present application, the compound of formula (II) is selected from at least one of the following compounds of formula (II-1) to formula (II-10):
preferably, the compound represented by formula (II) is selected from at least one of the following compounds:
the compound shown in the formula (II) is selected to be beneficial to improving the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device.
In some embodiments of the present application, the electrolyte further comprises a dinitrile compound comprising at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, suberonitrile, terephthalonitrile, tetradecanedinitrile, azomalononitrile, methyleneglutaronitrile, or glutaronitrile. Based on the mass of the electrolyte, the mass percentage of the dinitrile compound is d.0.1-8. For example, d may have a value of 0.1, 1,2,3, 4, 5, 6, 7, 8 or any value between any two of the foregoing ranges.
In some embodiments of the present application, the electrolyte further comprises a tri-nitrile compound comprising at least one of 1,3, 5-benzene tri-nitrile, 2,4, 6-trifluorobenzene-1, 3, 5-tri-nitrile, 2-bromobenzene-1, 3, 5-tri-nitrile, 1,3, 6-hexane tri-nitrile, 1,2, 3-propane tri-nitrile, 1,3, 5-pentane tri-nitrile, or 1,2, 6-hexane tri-nitrile. Based on the mass of the electrolyte, the mass percentage of the tri-nitrile compound is e.1-8. For example, the value of e may be 0.1, 1,2,3, 4, 5, 6, 7, 8 or any value between any two of the above ranges.
In some embodiments of the present application, the electrolyte further includes a dinitrile compound including at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, suberonitrile, terephthalonitrile, tetradecanedinitrile, azomalononitrile, methyleneglutaronitrile or glutaronitrile, and a tri-nitrile compound including at least one of 1,3, 5-benzenetrinitrile, 2,4, 6-trifluorobenzene-1, 3, 5-tri-nitrile, 2-bromobenzene-1, 3, 5-tri-nitrile, 1,3, 6-hexanetrinitrile, 1,2, 3-propanetrinitrile, 1,3, 5-valerotril or 1,2, 6-hexanetrinitrile. Based on the mass of the electrolyte, the mass percentage of the dinitrile compound is d.ltoreq.d.ltoreq.8, and the mass percentage of the dinitrile compound is e.ltoreq.e.ltoreq.0.1.ltoreq.8. For example, d may have a value of 0.1, 1,2,3, 4, 5, 6, 7, 8 or any value between any two of the above ranges, and e may have a value of 0.1, 1,2,3, 4, 5, 6, 7, 8 or any value between any two of the above ranges. In some embodiments of the present application, 1.ltoreq.d+e.ltoreq.8. For example, d+e may have a value of 1,2,3, 4, 5, 6, 7, 8 or any value between any two of the above ranges.
The inventor finds that the dinitrile compound and/or the trinitrile compound are further added into the electrolyte, and the values of the dinitrile compound mass percent d, the trinitrile compound mass percent e and d+e are regulated and controlled within the range of the application, so that the dissolution of transition metal elements in the positive electrode active material can be inhibited, the risk of damaging an SEI film is reduced, and the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device are improved.
In some embodiments of the present application, the electrolyte further includes an ester additive including at least one of 1, 3-Propane Sultone (PS), vinyl sulfate (DTD), fluoroethylene carbonate (FEC), or ethylene carbonate (VC). Based on the mass of the electrolyte, the mass percentage of the ester additive is f%, and f is more than or equal to 0 and less than or equal to 15, preferably, f is more than or equal to 0.5 and less than or equal to 5. For example, the value of f may be 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or any value between any two of the above ranges.
In some embodiments of the present application, the electrolyte further comprises a lithium salt additive comprising lithium bis (fluorosulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), lithium tetrafluoroborate (LiBF) 4 ) Lithium bisoxalato borate (LiBOB), lithium difluorooxalato borate (LIDOB) or lithium difluorophosphate (LiPO) 2 F 2 ) At least one of them. Based on the mass of the electrolyte, the mass percent of the lithium salt additive is g%, and the g is more than or equal to 0 and less than or equal to 5, preferably, the g is more than or equal to 0.2 and less than or equal to 1. For example, g may have a value of 0, 0.2, 1, 2, 3, 4, 5 or any value between any two of the above ranges.
In some embodiments of the present application, the electrolyte may further incorporate an ester additive comprising at least one of 1, 3-propane sultone, vinyl sulfate, fluoroethylene carbonate, or ethylene carbonate, and a lithium salt additive comprising at least one of lithium bis (fluorosulfonyl) imide, lithium tetrafluoroborate, lithium bis (oxalato) borate, lithium difluorooxalato borate, or lithium difluorophosphate.
And the electrolyte is further added with an ester additive and/or a lithium salt additive, and the mass percentage content of the ester additive and the lithium salt additive is regulated and controlled within the range of the application, so that a protective interface can be formed on the surface of the positive electrode plate and/or the surface of the negative electrode plate, and the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device are improved.
In some embodiments of the present application, the electrolyte further comprises at least one of a cyclic carbonate, a chain carbonate, or a chain carboxylate, the cyclic carbonate comprising at least one of propylene carbonate (also known as propylene carbonate, abbreviated as PC) or ethylene carbonate (VEC), the chain carbonate comprising at least one of dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), methyl Propyl Carbonate (MPC), dioctyl carbonate, dipentyl carbonate, ethylisobutyl carbonate, isopropyl carbonate, di-n-butyl carbonate, diisopropyl carbonate, or propyl carbonate, the chain carboxylate comprising at least one of methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, propyl Propionate (PP), butyl propionate, pentyl propionate, methyl haloacetate, ethyl haloacetate, propyl haloacetate, ethyl halopropionate, propyl halopropionate, butyl halopropionate, or pentyl halopropionate. Based on the mass of the electrolyte, the mass percentage of the cyclic carbonate is h% which is more than or equal to 20 and less than or equal to 50, the mass percentage of the chain carbonate is i% which is more than or equal to 0 and less than or equal to 70, the mass percentage of the chain carboxylate is c% which is more than or equal to 0 and less than or equal to 55, and preferably, the mass percentage of the chain carbonate is more than or equal to 20 and less than or equal to 40. For example, the value of h may be 20, 25, 30, 35, 40, 45, 50 or any value between any two of the above ranges. The value of i may be 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or any value between any two of the foregoing ranges of values. The value of c may be 0, 4, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or any value between any two of the foregoing. The cyclic carbonate is stable, has high dielectric constant and high viscosity; the stability and viscosity of the chain carbonate are moderate; the chain carboxylic acid esters have low viscosity, good flowability, but poor stability. The cyclic carboxylic acid ester, the chain carbonic acid ester and the chain carboxylic acid ester are combined and used, and the mass percentage of the cyclic carboxylic acid ester, the chain carbonic acid ester and the chain carboxylic acid ester in the electrolyte is regulated and controlled within the range, so that the electrolyte has good wettability to the positive electrode active material and the negative electrode active material, the transmission speed of lithium ions is improved, the electrolyte has good stability, the risks of decomposition and gas production of the electrolyte are reduced, and the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device are improved.
The electrolyte of the present application further includes a lithium salt, and the present application is not particularly limited as long as the object of the present application can be achieved.For example, the lithium salt may include lithium hexafluorophosphate (LiPF) 6 ）、LiAsF 6 、LiClO 4 、LiB(C 6 H 5 ) 4 、LiCH 3 SO 3 、LiCF 3 SO 3 、LiN(SO 2 CF 3 ) 2 、LiC(SO 2 CF 3 ) 3 Or Li (lithium) 2 SiF 6 At least one of them. The content of the lithium salt in the electrolyte is not particularly limited as long as the object of the present application can be achieved. For example, the mass percentage of lithium salt may be 8% to 20% based on the mass of the electrolyte.
In some embodiments of the present application, the negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, it being understood that the negative electrode active material layer may be disposed on one surface of the negative electrode current collector or on both surfaces of the negative electrode current collector, and the "surface" is the entire area or a partial area of the surface of the negative electrode current collector. The anode active material layer includes an anode active material.
In some embodiments of the present application, the anode active material includes various substances capable of reversibly intercalating and deintercalating active ions, which are known in the art as anode active materials for electrochemical devices. For example, the anode active material includes natural graphite, artificial graphite, intermediate phase micro carbon spheres (MCMB), hard carbon, soft carbon, li-Sn alloy, li-Sn-O alloy, sn, snO, snO 2 Spinel-structured lithium titanate Li 4 Ti 5 O 12 At least one of Li-Al alloy or metallic lithium.
In some embodiments of the present application, the negative electrode active material includes silicon element, and the mass percentage of the silicon element in the negative electrode active material is y.0.5.ltoreq.y.ltoreq.10. For example, the value of Y may be 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or any value between any two of the foregoing ranges. The silicon-based material is introduced to enable the negative electrode active material to contain silicon element, and the mass percentage content Y% of the silicon element in the negative electrode active material can be regulated and controlled by the content of the introduced silicon-based material. Further, the method comprises the steps of,the negative electrode active material comprises silicon-based material, natural graphite, artificial graphite, intermediate phase micro carbon spheres (MCMB), hard carbon, soft carbon, li-Sn alloy, li-Sn-O alloy, sn, snO, snO 2 Spinel-structured lithium titanate Li 4 Ti 5 O 12 At least one of Li-Al alloy or metallic lithium. The kind of the silicon-based material is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, silicon-based materials may include, but are not limited to, silicon oxygen composites, silicon carbon composites, elemental silicon.
When the silicon-based material is included in the anode active material, the energy density of the electrochemical device can be improved due to the high gram capacity advantage of the silicon-based material, but the anode active material has higher volume expansion rate, the mass percent content of silicon element in the anode active material is regulated and controlled within the range, and the impedance of the electrochemical device can be regulated and controlled within a reasonable range on the basis of improving the energy density of the electrochemical device, so that the high-temperature cycle performance and the high-temperature storage performance of the electrochemical device are improved.
The negative electrode current collector is not particularly limited as long as the object of the present application can be achieved. For example, the negative electrode current collector may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper, or the like. The anode active material layer of the present application contains an anode active material. In the present application, the thickness of the negative electrode current collector and the negative electrode active material layer is not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the anode current collector is 6 μm to 10 μm, and the thickness of the anode active material layer is 30 μm to 130 μm. Optionally, the anode active material layer may further include at least one of a conductive agent, a stabilizer, and a binder. The kind of the conductive agent, the stabilizer, and the binder in the anode active material layer is not particularly limited as long as the object of the present application can be achieved. The mass ratio of the anode active material, the conductive agent, the stabilizer, and the binder in the anode active material layer is not particularly limited as long as the object of the present application can be achieved. For example, the mass ratio of the anode active material, the conductive agent, the stabilizer and the binder in the anode active material layer is (95-98): 0-1.5): 0.5-3): 1.0-2.
In some embodiments of the present application, an electrochemical device includes an electrode assembly, a package pouch, and an electrolyte as described in any of the preceding embodiments, the electrode assembly and the electrolyte being contained in the package pouch. The structure of the electrode assembly is not particularly limited in the present application as long as the object of the present application can be achieved. For example, the electrode assembly is constructed in a lamination structure or a winding structure. The electrode assembly comprises a positive electrode plate, a diaphragm and the negative electrode plate according to any of the previous embodiments, wherein the diaphragm is arranged between the positive electrode plate and the negative electrode plate.
The positive electrode sheet is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The present application is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode current collector may include an aluminum foil, an aluminum alloy foil, a composite current collector, or the like. The positive electrode active material layer of the present application contains a positive electrode active material. The kind of the positive electrode active material is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode active material may include lithium nickel cobalt manganese oxide (811, 622, 523, 111), lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide (LiCoO) 2 ) At least one of lithium manganate, lithium iron manganese phosphate, lithium titanate, and the like. In the present application, the positive electrode active material may further contain a non-metal element, for example, a non-metal element including at least one of fluorine, phosphorus, boron, chlorine, silicon, or sulfur, which can further improve the stability of the positive electrode active material. In the present application, the thicknesses of the positive electrode current collector and the positive electrode active material layer are not particularly limited as long as the objects of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm, preferably 6 μm to 18 μm. The thickness of the single-sided positive electrode active material layer is 30 μm to 120 μm. In the present application, the positive electrode active material layer may be provided on one surface in the thickness direction of the positive electrode current collector, or may be provided on both surfaces in the thickness direction of the positive electrode current collector. Optionally, the positive electrode active material layer may further include a conductive agent and a binder. The application relates to the conduction in the positive electrode active material layerThe types of the electric agent and the binder are not particularly limited as long as the object of the present application can be achieved. The mass ratio of the positive electrode active material, the conductive agent, and the binder in the positive electrode active material layer is not particularly limited in this application, and those skilled in the art can select according to actual needs as long as the object of this application can be achieved. For example, the mass ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode active material layer is (97.5-97.9): (0.9-1.7): (1.0-2.0).
The separator is not particularly limited as long as the object of the present application can be achieved. For example, the material of the separator may include, but is not limited to, at least one of Polyethylene (PE), polypropylene (PP) -based Polyolefin (PO), polyester (e.g., polyethylene terephthalate (PET)), cellulose, polyimide (PI), polyamide (PA), spandex, or aramid; the type of separator may include, but is not limited to, at least one of a woven film, a nonwoven film (nonwoven), a microporous film, a composite film, separator paper, a laminate film, or a spun film. For example, the separator may include a substrate layer and a surface treatment layer. The substrate layer may be a nonwoven fabric, a film, or a composite film having a porous structure, and the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate, polyimide, or the like. Optionally, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane may be used. Optionally, a surface treatment layer is disposed on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or may be a layer formed by mixing a polymer and an inorganic material. For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, and may be selected from at least one of alumina, silica, magnesia, titania, hafnia, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconia, yttria, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium sulfate, or the like, for example. The binder is not particularly limited, and may be at least one selected from polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene, for example. The polymer layer contains a polymer, and the material of the polymer comprises at least one of polyamide, polyacrylonitrile, acrylic polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene) and the like.
The packaging bag is not particularly limited, and may be a packaging bag known in the art as long as the object of the present application can be achieved. Such as an aluminum plastic film or a steel shell.
The kind of the electrochemical device is not particularly limited in the present application, and may include any device in which an electrochemical reaction occurs. For example, electrochemical devices may include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries (lithium ion batteries), sodium ion secondary batteries (sodium ion batteries), lithium polymer secondary batteries, and lithium ion polymer secondary batteries.
The method for producing the electrochemical device is not particularly limited, and any method known in the art may be used as long as the object of the present application can be achieved. For example, the method of manufacturing an electrochemical device includes, but is not limited to, the steps of: sequentially stacking the positive electrode plate, the diaphragm and the negative electrode plate, winding and folding the positive electrode plate, the diaphragm and the negative electrode plate according to the need to obtain an electrode assembly with a winding structure, placing the electrode assembly into a packaging bag, injecting electrolyte into the packaging bag, and sealing to obtain an electrochemical device; or sequentially stacking the positive electrode plate, the diaphragm and the negative electrode plate, fixing four corners of the whole lamination structure to obtain an electrode assembly of the lamination structure, placing the electrode assembly into a packaging bag, injecting electrolyte into the packaging bag, and sealing to obtain the electrochemical device.
A second aspect of the present application provides an electronic device comprising an electrochemical device according to any one of the embodiments described above. Therefore, the electronic device has good high-temperature cycle performance and high-temperature storage performance.
The electronic device of the present application is not particularly limited, and may include, but is not limited to: notebook computers, pen-input computers, mobile computers, electronic book players, portable telephones, portable facsimile machines, portable copiers, portable printers, headsets, video recorders, liquid crystal televisions, hand-held cleaners, portable CD-players, mini-compact discs, transceivers, electronic notebooks, calculators, memory cards, portable audio recorders, radios, standby power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game machines, watches, electric tools, flash lamps, cameras, household large-sized batteries, lithium ion capacitors, and the like.
The beneficial effects of this application:
the application provides an electrochemical device and an electronic device, wherein the electrochemical device comprises a negative electrode plate and electrolyte, the electrolyte comprises a compound shown in a formula (I) and a compound shown in a formula (II), the mass percentage of the compound shown in the formula (I) is a%, a is more than or equal to 0.05 and less than or equal to 5, the mass percentage of the compound shown in the formula (II) is b%, and b is more than or equal to 0.05 and less than or equal to 5 based on the mass of the electrolyte. The high-temperature cycle performance and the high-temperature storage performance of the electrochemical device can be improved by simultaneously adding the compound shown in the formula (I) and the compound shown in the formula (II) into the electrolyte and regulating and controlling the mass percentage of the compound shown in the formula (I) and the compound shown in the formula (II) in the electrolyte within the range of the application.
Of course, not all of the above-described advantages need be achieved simultaneously in practicing any one of the products or methods of the present application.
Detailed Description
The following description of the technical solutions in the embodiments of the present application will be made clearly and completely in connection with the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments herein, a person of ordinary skill in the art would be able to obtain all other embodiments based on the disclosure herein, which are within the scope of the disclosure herein.
In the specific embodiment of the present application, the present application is explained using a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to a lithium ion battery.
Hereinafter, embodiments of the present application will be described in more detail with reference to examples and comparative examples. The various tests and evaluations were carried out according to the following methods.
Test method and apparatus:
test of impedance (Rss):
the lithium ion battery was charged to 4.5V at a constant current of 0.7C, and then charged to a constant voltage of 0.05C. Standing for 10min, discharging at 0.1C constant current for 8h, and recording voltage V1; standing for 15min, and recording the retested voltage as V2, rss= (V2-V1)/0.1C, wherein the retested voltage is used as an index for evaluating the impedance of the lithium ion battery.
Test of storage properties at 85 ℃):
the thickness of the lithium ion battery in the half-charged state was measured at 25C and designated as C1. And then charging the lithium ion battery to 4.5V at a constant current of 0.7C, then charging the lithium ion battery to a constant voltage until the current is 0.05C, standing for 10min to obtain a fully charged lithium ion battery, standing the fully charged lithium ion battery at 85 ℃ for 8h, and then recording the test thickness of the fully charged lithium ion battery at 25 ℃ as C2, wherein the thickness expansion rate= (C2-C1)/C1×100% and the thickness expansion rate is used as an index for evaluating the high-temperature storage performance.
Testing of capacity retention:
at 45 ℃, the lithium ion battery is charged to 4.5V at a constant current of 0.7C, then charged to 0.05C at a constant voltage of 4.5V, and then discharged to 3.0V at a constant current of 1C, and the first cycle is the first cycle, and the discharge capacity of the first cycle is recorded. The lithium ion battery was charged and discharged for 500 cycles according to the above conditions, and the discharge capacity for 500 cycles was recorded. 45 ℃ capacity retention (%) = (500 th cycle discharge capacity/first cycle discharge capacity) ×100%, 45 ℃ capacity retention was used as an index for evaluating high temperature cycle performance of lithium ion batteries.
Example 1-1
Preparation of electrolyte:
in an argon atmosphere glove box with the water content being less than 10ppm, the cyclic carbonate Ethylene Carbonate (EC) and the chain carbonate diethyl carbonate (DEC) are mixed according to the mass ratio of 30:70 After homogenization, lithium hexafluorophosphate (LiPF) was added 6 ) Dissolving and uniformly mixing to obtain the basic electrolyte. And adding the norbornene dianhydride shown in the formula (I) and the compound shown in the formula (II-2) into the basic electrolyte, and uniformly mixing to obtain the electrolyte.
LiPF based on electrolyte mass 6 The mass percentage of the compound shown in the formula (I) is 15%, the mass percentage of the compound shown in the formula (I) is a% = 0.05%, the mass percentage of the compound shown in the formula (II) is b% = 0.5%, and the balance is cyclic carbonate and chain carbonate, wherein the sum of the mass percentages of the cyclic carbonate, the chain carbonate, the lithium salt, the compound shown in the formula (I) and the compound shown in the formula (II) is 100%.
Preparing a negative electrode plate:
mixing negative electrode active material artificial graphite, binder styrene-butadiene rubber (SBR for short) and stabilizer sodium carboxymethylcellulose (CMC-Na) according to a mass ratio of 95:2:3, adding deionized water as a solvent, and stirring under the action of a vacuum stirrer to obtain negative electrode slurry with the solid content of 70wt% and uniform system. And uniformly coating the negative electrode slurry on one surface of a negative electrode current collector copper foil with the thickness of 8mm, and drying at 90 ℃ to obtain the negative electrode plate with the single-side coated negative electrode active material layer (with the thickness of 130 mm). And repeating the steps on the other surface of the copper foil to obtain the negative electrode plate with the double-sided coating negative electrode active material layer. Drying at 90 ℃, cold pressing, cutting, and drying for 4 hours under the vacuum condition at 90 ℃ to obtain the negative electrode plate with the specification of 76mm multiplied by 851mm for standby.
Preparing a positive electrode plate:
LiCoO as positive electrode active material 2 Mixing the conductive agent Carbon Nano Tube (CNT) and the binder polyvinylidene fluoride according to the mass ratio of 95:2:3, adding N-methyl pyrrolidone (NMP) as a solvent, and stirring under the action of a vacuum stirrer to obtain anode slurry with the solid content of 75wt% and uniform system. The positive electrode slurry is uniformly coated on one surface of a positive electrode current collector aluminum foil with the thickness of 10 mu m, and is dried at the temperature of 85 ℃ to obtain a positive electrode plate with a single-side coated positive electrode active material layer (with the thickness of 110 mm). Thereafter, another aluminum foil is arrangedRepeating the steps on the surface to obtain the positive electrode plate with the double-sided coating positive electrode active material layer. Drying at 85 ℃, cold pressing, cutting, and drying for 4 hours at 85 ℃ under vacuum to obtain the positive pole piece with the specification of 74mm multiplied by 867mm for later use.
A diaphragm:
polyethylene film with a thickness of 7 μm was used.
Preparation of a lithium ion battery:
and stacking and winding the prepared negative electrode plate, the prepared diaphragm and the prepared positive electrode plate in sequence to obtain the electrode assembly with a winding structure. And placing the electrode assembly in an aluminum plastic film packaging bag, drying, injecting electrolyte, and performing vacuum packaging, standing, formation, degassing, trimming and other procedures to obtain the lithium ion battery. The upper limit voltage of the formation is 4.15V, the formation temperature is 70 ℃, and the formation standing time is 2h.
Examples 1-2 to 1-25
The procedure of example 1-1 was repeated except that the relevant production parameters were adjusted as shown in Table 1.
Examples 1 to 2 to 1 to 25, liPF was used when the mass percentage of the compound represented by the formula (I) and/or the mass percentage of the compound represented by the formula (II) was changed 6 The mass percentage of the compound shown in the formula (I) and the mass percentage of the compound shown in the formula (II) are 100 percent.
Example 2-1
Preparing a negative electrode plate:
mixing the negative electrode active material artificial graphite with the silicon-based material SiO, the binder SBR and the stabilizer CMC-Na according to the mass ratio of 94.84:0.16:2:3, then adding deionized water as a solvent, and stirring under the action of a vacuum stirrer to obtain negative electrode slurry with the solid content of 70wt% and uniform system. And uniformly coating the negative electrode slurry on one surface of a negative electrode current collector copper foil with the thickness of 8mm, and drying at 90 ℃ to obtain the negative electrode plate with the single-side coated negative electrode active material layer (with the thickness of 130 mm). And repeating the steps on the other surface of the copper foil to obtain the negative electrode plate with the double-sided coating negative electrode active material layer. Drying at 90 ℃, cold pressing, cutting, and drying for 4 hours under the vacuum condition at 90 ℃ to obtain the negative electrode plate with the specification of 76mm multiplied by 851mm for standby.
The remainder was the same as in examples 1-4.
Examples 2-2 to 2-5
The procedure of example 2-1 was repeated except that the relevant production parameters were adjusted as shown in Table 2.
Examples 2 to 6
Examples 2 to 3 were repeated except that in the "preparation of electrolyte", the cyclic carbonate Ethylene Carbonate (EC) and the chain carbonate diethyl carbonate (DEC) were replaced with the chain carboxylate Propyl Propionate (PP), the chain carbonate diethyl carbonate (DEC) and the cyclic carbonate Ethylene Carbonate (EC) in a mass ratio of 30:70 to a mass ratio of 50:20:30.
Example 3-1
The procedure of examples 2 to 6 was repeated, except that in the "preparation of an electrolyte solution", adiponitrile, a dinitrile compound having a mass percentage d% =0.1% was further added to the base electrolyte solution, and the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate and the chain carbonate was reduced, with the exception that the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound represented by the formula (I), the compound represented by the formula (II) and the dinitrile compound was 100%.
Examples 3-2 to 3-3
The procedure of example 3-1 was repeated except that the relevant production parameters were adjusted as shown in Table 3.
Examples 3-2 to 3, when the mass percentage of dinitrile compound was changed, liPF 6 The mass percentage of the compound shown in the formula (I) and the compound shown in the formula (II) is unchanged, the sum of the mass percentages of the chain carboxylic ester, the cyclic carbonate and the chain carbonate is changed, and the sum of the mass percentages of the chain carboxylic ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound shown in the formula (I), the compound shown in the formula (II) and the dinitrile compound is 100%.
Examples 3 to 4
The procedure of example 3-1 was repeated except that in the "preparation of electrolyte", adiponitrile as a dinitrile compound was replaced with 1,3, 6-hexanetrinitrile as a dinitrile compound.
Examples 3 to 5 to 3 to 6
The procedure was as in examples 3-4, except that the relevant preparation parameters were adjusted as in Table 3.
Examples 3 to 5 to 3 to 6, liPF was used when the mass percentage of the dinitrile compound was changed 6 The mass percentage of the compound shown in the formula (I) and the compound shown in the formula (II) is unchanged, the sum of the mass percentages of the chain carboxylic ester, the cyclic carbonate and the chain carbonate is changed, and the sum of the mass percentages of the chain carboxylic ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound shown in the formula (I), the compound shown in the formula (II) and the tri-nitrile compound is 100%.
Examples 3 to 7
The procedure of examples 3 to 4 was repeated except that in the "preparation of an electrolyte solution", dinitrile compound adiponitrile was further added to the base electrolyte solution in a mass percentage d% = 0.5%, and the mass percentage e% of the tri-nitrile compound 1,3, 6-hexanetrinitrile was adjusted to 0.5%, so that the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate and the chain carbonate was reduced, and the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound represented by the formula (I), the compound represented by the formula (II), the dinitrile compound and the tri-nitrile compound was 100%.
Examples 3 to 8 to 3 to 11
The procedure was as in examples 3-7, except that the relevant preparation parameters were adjusted as in Table 3.
Examples 3 to 8 to 3 to 11, liPF was used when the mass percentage of the dinitrile compound and the tri-nitrile compound was changed 6 The mass percentage of the compound shown in the formula (I) and the compound shown in the formula (II) is unchanged, the sum of the mass percentages of the chain carboxylic ester, the cyclic carbonate and the chain carbonate is changed, and the chain carboxylic ester, the cyclic carbonate, the chain carbonate, the lithium salt and the formulaI) The sum of the mass percentages of the compound shown in the formula (II), the dinitrile compound and the tri-nitrile compound is 100%.
Examples 3 to 12
The procedure of examples 3 to 8 was repeated, except that in the "preparation of an electrolyte solution", a lithium salt additive LiBOB was further added to the base electrolyte solution in a mass percentage of g% = 0.2%, and the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound represented by formula (I), the compound represented by formula (II), the dinitrile compound, the trinitrile compound, and the lithium salt additive was 100%.
Examples 3 to 13 to 3 to 14
The procedure was as in examples 3-12, except that the relevant preparation parameters were adjusted as in Table 3.
In examples 3 to 13 to 3 to 14, when the mass percentage of the lithium salt additive is changed, the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate and the chain carbonate is changed, and the mass percentages of the other components are not changed, and the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound represented by the formula (I), the compound represented by the formula (II), the dinitrile compound and the lithium salt additive is 100%.
Examples 3 to 15
The procedure of examples 3 to 8 was repeated, except that in the "preparation of an electrolyte solution", an ester additive PS was further added to the base electrolyte solution in a mass percentage of f% = 0.5%, and the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound represented by formula (I), the compound represented by formula (II), the dinitrile compound and the ester additive was 100%.
Examples 3 to 16 to 3 to 17
The procedure was as in examples 3-15, except that the relevant preparation parameters were adjusted as in Table 3.
In examples 3 to 16 to 3 to 17, when the mass percentage of the ester additive is changed, the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate and the chain carbonate is changed, and the mass percentages of the other components are not changed, and the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound represented by the formula (I), the compound represented by the formula (II), the dinitrile compound and the ester additive is 100%.
Examples 3 to 18
The procedure of examples 3 to 13 was repeated except that in the "preparation of an electrolyte solution", liDFOB was adjusted to LiBOB, and the base electrolyte solution was further added with an ester additive PS having a mass percentage of f% = 4%, and the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound represented by the formula (I), the compound represented by the formula (II), the dinitrile compound, the trinitrile compound, the lithium salt additive and the ester additive was 100%.
Examples 3 to 19
The procedure of examples 3 to 18 was repeated except that in "preparation of electrolyte", the ester additive PS was adjusted to the mass percentage f% =4% and the mass percentage of the ester additive FEC was adjusted to the mass percentage f% =15%, and the sum of the mass percentages of the chain carboxylic acid ester, the cyclic carbonate, the chain carbonate, the lithium salt, the compound represented by formula (I), the compound represented by formula (II), the dinitrile compound, the lithium salt additive and the ester additive was 100%.
Comparative examples 1-1 to 1-7
The procedure of example 1-1 was repeated except that the relevant production parameters were adjusted as shown in Table 1.
Comparative examples 1-1 to 1-7, liPF was used when the mass percentage of the compound represented by the formula (I) and/or the mass percentage of the compound represented by the formula (II) was changed 6 Is unchanged in mass percent, cyclic carbonic acidThe sum of the mass percentages of the ester and the chain carbonate is changed, and the sum of the mass percentages of the cyclic carbonate, the chain carbonate, the lithium salt, the compound shown in the formula (I) and the compound shown in the formula (II) is 100%.
Comparative example 2-1
The procedure was as in comparative example 1-1, except that the relevant preparation parameters were adjusted according to Table 2.
Comparative examples 2 to 2
The procedure was as in comparative examples 1-2, except that the relevant preparation parameters were adjusted according to Table 2.
Comparative examples 2 to 3
The procedure was as in comparative examples 1-3, except that the relevant preparation parameters were adjusted as in Table 2.
The preparation parameters and performance parameters of each example and comparative example are shown in tables 1 to 3.
TABLE 1
Note that: the "\" in Table 1 indicates that there are no relevant preparation parameters.
As can be seen from examples 1-1 to 1-25 and comparative examples 1-1 to 1-7, the lithium ion battery in which the compound represented by formula (I) and the compound represented by formula (II) were simultaneously added to the electrolyte, and the mass percentages of the compound represented by formula (I) and the compound represented by formula (II) were within the range of the present application, has a higher capacity retention rate at 45 ℃ and a lower thickness expansion rate at 85 ℃, indicating that the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery were improved. In comparative examples 1-1, the compound represented by the formula (I) and the compound represented by the formula (II) were not added to the electrolyte, and in comparative examples 1-2 and 1-3, the compound represented by the formula (I) and the compound represented by the formula (II) were not added to the electrolyte at the same time, and in comparative examples 1-4 to 1-7, at least one of the mass percentages of the compound represented by the formula (I) or the compound represented by the formula (II) in the electrolyte was not within the scope of the present application, and the lithium ion batteries of comparative examples 1-1 to 1-7 were low in capacity retention at 45℃and high in thickness expansion at 85℃showed that the high-temperature cycle performance and the high-temperature storage performance of the lithium ion batteries could not be improved.
As can be seen from examples 1-1 to 1-8 and comparative examples 1-6, the mass percentage a% of the compound shown in formula (I) generally affects the high temperature cycle performance and the high temperature storage performance of the lithium ion battery, and the lithium ion battery with the mass percentage a% of the compound shown in formula (I) within the scope of the application has a higher capacity retention rate at 45 ℃ and a lower thickness expansion rate at 85 ℃, which indicates that the lithium ion battery has good high temperature cycle performance and high temperature storage performance.
As can be seen from examples 1-4, examples 1-9 to examples 1-13 and comparative examples 1-7, the mass percentage b% of the compound shown in formula (II) generally affects the high temperature cycle performance and the high temperature storage performance of the lithium ion battery, and the lithium ion battery with the mass percentage b% of the compound shown in formula (II) within the scope of the application has a higher capacity retention rate at 45 ℃ and a lower thickness expansion rate at 85 ℃ and shows that the lithium ion battery has good high temperature cycle performance and high temperature storage performance.
The ratio of the mass percent a% of the compound shown in the formula (I) to the mass percent b% of the compound shown in the formula (II) generally affects the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery, and as can be seen from examples 1-1 to 1-17, the lithium ion battery with the value of a/b in the range of the application has higher capacity retention rate at 45 ℃ and lower thickness expansion rate at 85 ℃, and shows that the lithium ion battery has good high-temperature cycle performance and high-temperature storage performance.
The type of the compound shown in the formula (I) generally affects the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery, and as can be seen from examples 1-4 and examples 1-18 to examples 1-21, the lithium ion battery with the type of the compound shown in the formula (I) within the scope of the application has higher capacity retention rate at 45 ℃ and lower thickness expansion rate at 85 ℃, which indicates that the lithium ion battery has good high-temperature cycle performance and high-temperature storage performance.
The type of the compound shown in the formula (II) generally affects the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery, and as can be seen from examples 1-4 and examples 1-22 to examples 1-25, the lithium ion battery with the type of the compound shown in the formula (II) within the scope of the application has higher capacity retention rate at 45 ℃ and lower thickness expansion rate at 85 ℃, which indicates that the lithium ion battery has good high-temperature cycle performance and high-temperature storage performance.
TABLE 2
Note that: the "\" in Table 2 indicates that there are no relevant preparation parameters.
When the negative electrode active material comprises a silicon-based material containing silicon element, the silicon-based material can further improve the high-temperature cycle performance of the lithium ion battery. However, as the silicon-based material has a larger volume expansion rate, the high-temperature storage performance of the lithium ion battery can be influenced, and the high-temperature storage performance of the lithium ion battery is obviously improved by selecting the electrolyte with the mass percentage of the compound shown in the formula (I) and the compound shown in the formula (II) in the application range and simultaneously adding the compound shown in the formula (I) and the compound shown in the formula (II). As can be seen from examples 1-4, examples 2-1 to 2-5, and comparative examples 2-1 to 2-3, when the electrolyte of the present application is selected and the mass percentage content Y% of the silicon element in the negative electrode active material is regulated within the scope of the present application, the lithium ion battery has a higher capacity retention rate at 45 ℃ and a lower thickness expansion rate at 85 ℃, which indicates that the lithium ion battery has good high-temperature cycle performance and high-temperature storage performance. In the lithium ion batteries of comparative examples 2-1 to 2-3, the compound represented by the formula (I) and the compound represented by the formula (II) were not simultaneously added to the electrolyte, and the capacity retention rate at 45℃was low and the thickness expansion rate at 85℃was high, indicating that the lithium ion batteries did not have good high-temperature cycle performance and high-temperature storage performance.
The contents of the chain carboxylic ester, the chain carbonate and the cyclic carbonate in the electrolyte generally affect the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery, and as can be seen from examples 2-3 and examples 2-6, the lithium ion battery with the contents of the chain carboxylic ester, the chain carbonate and the cyclic carbonate in the application range is selected, and has higher 45 ℃ capacity retention rate and lower 85 ℃ thickness expansion rate, which indicates that the lithium ion battery has good high-temperature cycle performance and high-temperature storage performance. And, the addition of the chain carboxylic ester in examples 2-6 enables the lithium ion battery to have higher capacity retention rate at 45 ℃, which indicates that the addition of the chain carboxylic ester in the electrolyte is beneficial to further improving the wettability of the electrolyte in the positive electrode active material and the negative electrode active material and the transmission speed of lithium ions, thereby further improving the high-temperature cycle performance of the lithium ion battery.
TABLE 3 Table 3
Note that: the "\" in Table 3 indicates that there are no relevant preparation parameters.
Further addition of dinitrile and/or tri-nitrile compounds to the electrolyte generally also affects the high temperature cycle performance and high temperature storage performance of the lithium ion battery, and as can be seen from examples 2-6, 3-1 to 3-9, the electrolyte containing dinitrile and/or tri-nitrile compounds is selected, and the mass percent of dinitrile and/or tri-nitrile compounds is in the range of the application, which has lower impedance, higher 45 ℃ capacity retention rate and lower 85 ℃ thickness expansion rate, indicating that the lithium ion battery has good high temperature cycle performance and high temperature storage performance.
The kinds of dinitrile compounds and/or tri-nitrile compounds generally affect the high-temperature cycle performance and the high-temperature storage performance of the lithium ion battery, and as can be seen from examples 3-8, examples 3-10 and examples 3-11, the lithium ion battery with the kinds of dinitrile compounds and/or tri-nitrile compounds within the scope of the application has lower impedance, higher 45 ℃ capacity retention rate and lower 85 ℃ thickness expansion rate, which indicates that the lithium ion battery has good high-temperature cycle performance and high-temperature storage performance.
As can be seen from examples 3-1 to 3-9, the lithium ion battery with d+e value within the scope of the application has lower impedance, higher capacity retention rate at 45 ℃ and lower thickness expansion rate at 85 ℃, which indicates that the lithium ion battery has good high-temperature cycle performance and high-temperature storage performance.
Further addition of lithium salt additives and/or ester additives to the electrolyte generally also affects the high temperature cycle performance and high temperature storage performance of the lithium ion battery, and as can be seen from examples 3-8, 3-12 to 3-19, the electrolyte containing the lithium salt additives and/or ester additives is selected, and the mass percent of the lithium salt additives and/or ester additives is in the range of the application, and the lithium ion battery has lower impedance, higher 45 ℃ capacity retention rate and lower 85 ℃ thickness expansion rate, which indicates that the lithium ion battery has good high temperature cycle performance and high temperature storage performance.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments.
The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the scope of the present application. Any modifications, equivalent substitutions, improvements, etc. that are within the spirit and principles of the present application are intended to be included within the scope of the present application.
Claims (12)
1. An electrochemical device comprises a negative electrode plate and electrolyte;
the electrolyte comprises a compound shown in a formula (I) and a compound shown in a formula (II):
wherein R is 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 8 、R 9 And R is 10 Each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1 To C 10 Alkyl, substituted or unsubstituted C 2 To C 10 Alkenyl, substituted or unsubstituted C 2 To C 10 Alkynyl, substituted or unsubstituted C 6 To C 10 Aryl, substituted or unsubstituted C 1 To C 10 Alkoxy, substituted or unsubstituted C 2 To C 10 Alkenyloxy, substituted or unsubstituted C 2 To C 10 Alkynyloxy, substituted or unsubstituted C 6 To C 10 Aryloxy, substituted or unsubstituted C 1 To C 10 Alkoxyalkyl, substituted or unsubstituted C 1 To C 10 Carboxyl, substituted or unsubstituted C 2 To C 10 Carboxylate group, substituted or unsubstituted C 2 To C 10 Carbonate group, cyano group, amino group, substituted or unsubstituted C 1 To C 10 Sulfate group, substituted or unsubstituted C 1 To C 10 Sulfite group, substituted or unsubstituted C 1 To C 10 Borate group, substituted or unsubstituted C 1 To C 10 Silyl, substituted or unsubstituted C 1 To C 10 Siloxane group, substituted or unsubstituted C 1 To C 10 A phosphate group;
R 7 selected from substituted or unsubstituted C 1 To C 10 Alkylene, substituted or unsubstituted C 3 To C 10 Cycloalkylene, substituted or unsubstituted C 1 To C 10 Oxy subunit, substituted or unsubstituted C 2 To C 10 Alkenylene, substituted or unsubstituted C 2 To C 10 Alkynylene, substituted or unsubstituted C 6 To C 10 Arylene, substituted or unsubstituted C 1 To C 10 Alkyloxy, substituted or unsubstituted C 2 To C 10 Alkenylene oxy, substituted or unsubstituted C 2 To C 10 Alkynyloxy;
when substituted, the substituent is selected from at least one of a halogen atom or a cyano group;
based on the mass of the electrolyte, the mass percentage of the compound shown in the formula (I) is a percent, a is more than or equal to 0.05 and less than or equal to 5, and the mass percentage of the compound shown in the formula (II) is b percent, b is more than or equal to 0.05 and less than or equal to 5; a/b is more than or equal to 0.1 and less than or equal to 10.
2. The electrochemical device according to claim 1, wherein 0.1.ltoreq.a.ltoreq.3, and 0.1.ltoreq.b.ltoreq.2.
3. The electrochemical device according to claim 1, wherein 0.5.ltoreq.a.ltoreq.1, and 0.1.ltoreq.b.ltoreq.0.8.
4. The electrochemical device according to claim 1, wherein 1.ltoreq.a/b.ltoreq.8.
5. The electrochemical device according to claim 1, wherein 1.ltoreq.a/b.ltoreq.5.
6. The electrochemical device according to claim 1, wherein the compound represented by the formula (I) is selected from at least one of norbornene dianhydride, methyl nadic anhydride, chlorobridge anhydride, cis-5-norbornene-exo-2, 3-dicarboxylic anhydride, nadic anhydride, 7-allylbicyclo [2.2.1] hept-5-ene-2, 3-dicarboxylic anhydride or methyl-5-norbornene-2, 3-dicarboxylic anhydride.
7. The electrochemical device according to claim 1, wherein the compound represented by the formula (II) is selected from at least one of the following compounds of the formula (II-1) to (II-10):
8. the electrochemical device of claim 1, wherein the electrolyte further comprises a dinitrile compound and/or a tri-nitrile compound, the electrolyte satisfying at least one of the following conditions (a) or (b):
(a) The dinitrile compound comprises at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, suberonitrile, terephthalonitrile, tetradecanedinitrile, azomalononitrile, methyleneglutaronitrile or glutaronitrile, and the mass percentage of the dinitrile compound is d% or less, 0.1-8, based on the mass of the electrolyte;
(b) The dinitrile compound comprises at least one of 1,3, 5-benzene dinitrile, 2,4, 6-trifluorobenzene-1, 3, 5-dinitrile, 2-bromobenzene-1, 3, 5-dinitrile, 1,3, 6-hexane dinitrile, 1,2, 3-propane trimethyl nitrile, 1,3, 5-valertrimethyl nitrile or 1,2, 6-hexane trimethyl nitrile,
based on the mass of the electrolyte, the mass percentage of the tri-nitrile compound is e.0.1-8.
9. The electrochemical device according to claim 8, wherein 1.ltoreq.d+e.ltoreq.8.
10. The electrochemical device of claim 1, wherein the electrolyte satisfies at least one of the following conditions (c) or (d):
(c) The electrolyte also comprises an ester additive, wherein the ester additive comprises at least one of 1, 3-propane sultone, vinyl sulfate, fluoroethylene carbonate or ethylene carbonate, and the mass percentage of the ester additive is f percent, and f is more than or equal to 0 and less than or equal to 15 based on the mass of the electrolyte;
(d) The electrolyte also comprises a lithium salt additive, wherein the lithium salt additive comprises at least one of lithium bis (fluorosulfonyl) imide, lithium tetrafluoroborate, lithium bis (oxalato) borate, lithium difluorooxalato borate or lithium difluorophosphate, and the mass percentage of the lithium salt additive is g% or less and 0.ltoreq.5 based on the mass of the electrolyte.
11. The electrochemical device according to claim 1, wherein the anode tab comprises an anode current collector and an anode active material layer disposed on at least one surface of the anode current collector, the anode active material layer comprising an anode active material comprising elemental silicon;
the mass percentage of silicon element in the anode active material is Y, and Y is more than or equal to 0.5 and less than or equal to 10.
12. An electronic device comprising the electrochemical device of any one of claims 1 to 11.
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| WO2022116170A1 (en) * | 2020-12-04 | 2022-06-09 | 宁德新能源科技有限公司 | Electrolyte, and electrochemical device and electronic device comprising electrolyte |
| CN112701349B (en) * | 2020-12-28 | 2022-07-12 | 宁德新能源科技有限公司 | Electrolyte solution, electrochemical device and electronic apparatus including the same |
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| CN111342135A (en) * | 2020-03-13 | 2020-06-26 | 宁德新能源科技有限公司 | Electrochemical device and electronic device comprising same |
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