CN115966770A - Electrolyte, electrochemical device containing electrolyte and electronic device - Google Patents
Electrolyte, electrochemical device containing electrolyte and electronic device Download PDFInfo
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Abstract
An electrolyte, an electrochemical device and an electronic device including the same are provided, wherein the electrolyte includes a compound of formula (I). The electrolyte containing the compound of the formula (I) is applied to an electrochemical device, and a stable anode solid interface film with good ion diffusion performance can be formed on the surface of an anode of the electrochemical device, so that the problem that an anode active material is damaged under high voltage is solved, the oxygen release of an anode active material layer is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature can be improved, and the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device are improved.
Description
Technical Field
The present disclosure relates to the field of electrochemical technologies, and more particularly, to an electrolyte, an electrochemical device including the electrolyte, and an electronic device including the electrolyte.
Background
Electrochemical devices (lithium ion batteries) are widely used in the fields of smart phones, wearable devices, consumer-grade unmanned aerial vehicles, electric vehicles and the like due to the advantages of high energy density, long cycle life, no memory effect and the like. With the wide application of lithium ion batteries in the above fields, the energy density of lithium ion batteries is increasingly demanded by the market.
As the energy density increases, the voltage of the lithium ion battery also increases. The increase of the voltage of the lithium ion battery can aggravate the damage to the anode active material layer, thereby aggravating the oxygen release of the anode active material layer and catalyzing the oxidation decomposition of the electrolyte at high temperature to generate gas.
Disclosure of Invention
The present application is directed to an electrolyte, an electrochemical device and an electronic device including the same, for improving high temperature gassing of the electrolyte. The specific technical scheme is as follows:
in a first aspect, the present application provides an electrolyte comprising a compound of formula (I):
Preferably, R 1 、R 2 And R 3 Each independently selected from a hydrogen atom, halogen, carboxaldehyde, methyl, ethyl, propyl, butyl, ethenyl, propenyl, butenyl, ethynyl, propynyl, butynyl, pyrrolyl or pyridyl; r 4 、R 5 And R 6 Each independently selected from a hydrogen atom, a methylthio group, a dimethylsulfide group, a methyl group, an ethyl group, a propyl group, a butyl group, an ethenyl group, a propenyl group, a butenyl group, an ethynyl group, a propynyl group, a butynyl group, a pyrrolyl group or a pyridyl group. The application of the electrolyte comprising the compound of formula (I) having a group within the above range to an electrochemical device can improve the oxidative decomposition gas evolution of the electrolyte at high temperature, thereby improving the high-temperature storage performance and high-temperature intermittent cycle performance of the electrochemical device.
More preferably, the compound of formula (I) comprises at least one of the following compounds:
when the electrolyte containing the compound of the formula (I) in the range is applied to an electrochemical device, a stable anode solid interface film with better ion diffusion performance can be formed on the surface of an anode, the problem that an anode active material is damaged under high voltage can be solved, the oxygen release of an anode active material layer is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature is further improved, and the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device are further improved.
In some embodiments of the present application, 0.1. Ltoreq. A. Ltoreq.3. By regulating the mass percentage of the compound of the formula (I) within the range, a positive solid interface film with proper thickness can be formed on the surface of the positive electrode, the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device can be further improved, and the electrochemical device has good normal-temperature cycle performance.
In some embodiments herein, the electrolyte further comprises a carboxylic acid ester comprising at least one of ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, or butyl propionate; based on the mass of the electrolyte, the mass percentage of the carboxylic ester is B percent, and B is more than or equal to 10 and less than or equal to 70. The electrolyte comprises the compound shown in the formula (I) and the carboxylic ester in the range, and the content of the carboxylic ester is regulated and controlled to be in the range, so that the ion transmission capability of the electrolyte can be ensured, the solid interface film of the anode can be more stable and is not easy to decompose in the charge-discharge cycle process, the oxygen release of the active material layer of the anode is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature can be improved, and the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device are further improved.
In some embodiments of the present application, 0.0005. Ltoreq.A/B. Ltoreq.0.4. By regulating the A/B value within the range, the synergistic effect between the compound shown in the formula (I) and the carboxylic ester can be fully exerted, and the electrode solid interface film is further more stable and is not easy to decompose in the charge-discharge cycle process, so that the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device are further improved.
In some embodiments of the present application, 0.0075. Ltoreq.A/B. Ltoreq.0.2. By regulating the value of A/B within the range, the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device can be better.
In some embodiments of the present application, the electrolyte further comprises an ester additive comprising at least one of vinylene carbonate, ethylene carbonate, 1,3-propane sultone, or fluoroethylene carbonate; based on the mass of the electrolyte, the mass percentage content of the ester additive is D percent, and D is more than or equal to 0.5 and less than or equal to 18. The electrolyte comprises the ester additive in the range and the content of the ester additive is regulated and controlled to be in the range, so that the solid interface film of the electrode is more stable, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device are improved, and the electrochemical device has good high-temperature storage performance. In the present application, the electrode solid interface film refers to a positive electrode solid interface film and a negative electrode solid interface film.
In some embodiments of the present application, the electrolyte further comprises a nitrile compound, the nitrile compound comprising at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, sebaconitrile, 3,3 '-oxydipropanitrile, hex-2-enedinitrile, fumarodinitrile, 2-pentenenitrile, methylglutaronitrile, 4-cyanoheptanedinitrile, (Z) -but-2-enedinitrile, 2,2,3,3-tetrafluorosuccinonitrile, ethylene glycol bis (propionitrile) ether, 1,3,5-glutaronitrile, 1,3,6-adiponitrile, 1,2,6-adiponitrile, 1,2,3-tris (2-cyanato) propane, 3264 zxft 3864-malononitrile, 2,2' - (1,4-phenylenedinitrile), 3825-glutaronitrile, 3638 zxft 3224-3724-4924-hexamethylenenitrile, or 4924-adiponitrile; based on the mass of the electrolyte, the mass percentage content of the nitrile compounds is E percent, and E is more than or equal to 1 and less than or equal to 8. The electrolyte comprises the nitrile compound within the range and the content of the nitrile compound is regulated and controlled within the range, so that the solid interface film of the anode is more stable and is not easy to decompose in the charge-discharge cycle process, the oxygen release of the active material layer of the anode is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature can be improved, the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device can be improved, and meanwhile, the electrochemical device has good normal-temperature cycle performance.
In some embodiments of the present application, the electrolyte includes a lithium salt additive including at least one of lithium difluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium bisoxalato borate, or lithium difluorooxalato borate; based on the mass of the electrolyte, the mass percentage content of the lithium salt additive is C%, and C is more than or equal to 0.01 and less than or equal to 4. The electrolyte comprises the lithium salt additive in the range and the content of the lithium salt additive is regulated and controlled to be in the range, so that the solid interface film of the electrode is more stable and is not easy to decompose in the charge-discharge cycle process, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device are improved, and the electrochemical device has good high-temperature storage performance.
In some embodiments of the present application, 0.1. Ltoreq. A/C. Ltoreq.30. By regulating the A/C value in the range, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device can be better.
In a second aspect, the present application provides an electrochemical device, which includes the electrolyte provided in the first aspect, and thus the electrochemical device provided in the present application has good high-temperature storage performance, high-temperature intermittent cycle performance, and normal-temperature cycle performance.
In a third aspect, an electronic device is provided that includes an electrochemical device provided in the second aspect of the present application. The electrochemical device provided by the application has good high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance. Therefore, the electronic device has a long service life.
The beneficial effect of this application:
an electrolyte, an electrochemical device and an electronic device including the same are provided, wherein the electrolyte includes a compound of formula (I). The electrolyte containing the compound of the formula (I) is applied to an electrochemical device, and a stable anode solid interface film with good ion diffusion performance can be formed on the surface of an anode of the electrochemical device, so that the problem that an anode active material is damaged under high voltage is solved, the oxygen release of an anode active material layer is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature can be improved, and the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device are improved.
Of course, not all of the above advantages need be achieved in the practice of any one product or method of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be described clearly and completely below, and it should be understood that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the description herein are intended to be within the scope of the present disclosure.
In the embodiments of the present application, the present application is explained by taking 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.
In a first aspect, the present application provides an electrolyte comprising a compound of formula (I):
The electrolyte containing the compound of the formula (I) is applied to an electrochemical device, a stable anode solid interface film with proper thickness and good ion diffusion performance can be formed on the surface of an anode, the problem that an anode active material is damaged at high voltage can be solved, the oxygen release of an anode active material layer is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature can be improved, and the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device are improved. When A is too small, the thickness of the anode solid interface film formed on the surface of the anode is too small, even a complete anode solid interface film cannot be formed on the surface of the anode, the oxidative decomposition gas generation of the electrolyte at high temperature cannot be improved, and the improvement of the high-temperature storage performance of the electrochemical device is not facilitated. The mass percentage of the compound of the formula (I) is regulated and controlled within the range, so that a positive solid interface film with proper thickness can be formed on the surface of a positive electrode, and the high-temperature storage performance and the high-temperature intermittent cycle performance of an electrochemical device can be improved. In the present application, "high temperature" means a temperature of 45 ℃ or higher, and normal temperature means a temperature of 25 ℃. + -. 5 ℃.
Preferably, R 1 、R 2 And R 3 Each independently selected from the group consisting of atoms, halogens, carboxaldehyde groups, carbolpropylcarbonyl groups, methyl groups, ethyl groups, propyl groups, butyl groups, ethenyl groups, propenyl groups, butenyl groups, ethynyl groups, propyne groupsAlkyl, butynyl, pyrrolyl or pyridyl; r is 4 、R 5 And R 6 Each independently selected from a hydrogen atom, a methylthio group, a dimethylsulfide group, a methyl group, an ethyl group, a propyl group, a butyl group, an ethenyl group, a propenyl group, a butenyl group, an ethynyl group, a propynyl group, a butynyl group, a pyrrolyl group or a pyridyl group. When the electrolyte containing the compound of the formula (I) with the group in the range is applied to an electrochemical device, a stable anode solid interface film with better ion diffusion performance can be formed on the surface of an anode, the problem that an anode active material is damaged under high voltage can be solved, the oxygen release of an anode active material layer is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature is further improved, and the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device are further improved.
More preferably, the compound of formula (I) comprises at least one of the following compounds:
when the electrolyte containing the compound of the formula (I) in the range is applied to an electrochemical device, a stable anode solid interface film with better ion diffusion performance can be formed on the surface of an anode, the problem that an anode active material is damaged under high voltage can be solved, the oxygen release of an anode active material layer is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature is further improved, and the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device are further improved.
In some embodiments of the present application, the electrolyte further includes a carboxylic acid ester including at least one of ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, or butyl propionate; based on the mass of the electrolyte, the mass percentage of the carboxylic ester is B percent, and B is more than or equal to 10 and less than or equal to 70. For example, B may be 10, 20, 30, 40, 50, 60, 70 or a range of any two of these values. The electrolyte comprises the compound shown in the formula (I) and the carboxylic ester within the range, and the content of the carboxylic ester is regulated and controlled within the range, so that the ion transmission capability of the electrolyte can be ensured, the solid interface film of the anode can be more stable and is not easy to decompose in the charge-discharge cycle process, the oxygen release of the active material layer of the anode is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature can be improved, and the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device can be improved.
In some embodiments of the present application, 0.0005. Ltoreq. A/B. Ltoreq.0.4, preferably 0.0075. Ltoreq.A/B. Ltoreq.0.2. For example, A/B can be 0.0005, 0.0008, 0.001, 0.005, 0.01, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, or a range consisting of any two of these values. By regulating the A/B value within the range, the synergistic effect between the compound shown in the formula (I) and the carboxylic ester can be fully exerted, the ion transport capability of the electrolyte can be ensured, the solid interface film of the anode can be further more stable and is not easy to decompose in the charge-discharge cycle process, the oxygen release of the active material layer of the anode is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature can be improved, and the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device are further improved.
In some embodiments of the present application, the electrolyte further includes an ester additive including at least one of Vinylene Carbonate (VC), ethylene carbonate (VEC), 1,3-propane sultone, or fluoroethylene carbonate (FEC); based on the mass of the electrolyte, the mass percentage content of the ester additive is D percent, and D is more than or equal to 0.5 and less than or equal to 18. For example, D can be 0.5, 1, 1.5, 3, 4.5, 6, 7.5, 9, 10, 11, 12, 15, 16, 18, or a range consisting of any two of these values. The electrolyte comprises the ester additive in the range and the content of the ester additive is regulated and controlled to be in the range, so that the electrode solid interface film is more stable and is not easy to decompose in the charge-discharge cycle process, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device are improved, and the electrochemical device has good high-temperature storage performance.
In some embodiments of the present application, the electrolyte further comprises a nitrile compound, the nitrile compound comprising at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, sebaconitrile, 3,3 '-oxydipropanitrile, hex-2-enedinitrile, fumarodinitrile, 2-pentenenitrile, methylglutaronitrile, 4-cyanoheptanedinitrile, (Z) -but-2-enedinitrile, 2,2,3,3-tetrafluorosuccinonitrile, ethylene glycol bis (propionitrile) ether, 1,3,5-glutaronitrile, 1,3,6-adiponitrile, 1,2,6-adiponitrile, 1,2,3-tris (2-cyanato) propane, 3264 zxft 3864-malononitrile, 2,2' - (1,4-phenylenedinitrile), 3825-glutaronitrile, 3638 zxft 3224-3724-4924-hexamethylenenitrile, or 4924-adiponitrile; the nitrile compound is E percent, E is more than or equal to 1 and less than or equal to 8, and E can be 1,2,3, 4, 5, 6, 7 and 8 or a range formed by any two of the values. The electrolyte comprises the nitrile compound in the range and the content of the nitrile compound is regulated and controlled to be in the range, so that the solid interface film of the anode is more stable and is not easy to decompose in the charge-discharge cycle process, the oxygen release of the active material layer of the anode is reduced, the oxidative decomposition gas generation of the electrolyte at high temperature can be improved, the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device are favorably improved, and meanwhile, the electrochemical device has good normal-temperature cycle performance.
In some embodiments of the present application, the electrolyte includes a lithium salt additive including at least one of lithium difluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium bisoxalato borate, or lithium difluorooxalato borate; the lithium salt additive is C% in a mass percentage of 0.01 ≦ C ≦ 4, for example, C may be 0.01, 0.05, 0.1, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 3.5, 4 or any two of these ranges. The electrolyte comprises the lithium salt additive in the range and the content of the lithium salt additive is regulated and controlled to be in the range, so that the solid interface film of the electrode is more stable and is not easy to decompose in the charge-discharge cycle process, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device are improved, and the electrochemical device has good high-temperature storage performance.
In some embodiments of the present application, 0.1. Ltoreq. A/C. Ltoreq.30. For example, A/C can be 0.1, 0.2, 0.5, 1,2, 3.5, 5, 7, 10, 15, 18, 21, 27, 30, or a range consisting of any two of these values. By regulating the A/C value in the range, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device can be better.
In some embodiments of the present application, an electrolyte includes a compound of formula (I), a carbonate-based solvent, and a lithium salt, wherein the carbonate-based solvent includes at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), butylene Carbonate (BC), dimethyl carbonate (DMC), ethyl Methyl Carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl Propyl Carbonate (MPC), ethyl Propyl Carbonate (EPC), dioctyl carbonate, dipentyl carbonate, ethyl isobutyl carbonate, isopropyl methyl carbonate, di-n-butyl carbonate, diisopropyl carbonate, or propyl carbonate; the lithium salt includes lithium hexafluorophosphate. Based on the mass of the electrolyte, the mass percentage of the carbonate solvent is 80-88%, and the mass percentage of the lithium salt is 8-15%. For example, the carbonate-based solvent may be contained in an amount of 80%, 82%, 84%, 86%, 88% by mass or in a range of any two values, and the lithium salt may be contained in an amount of 8%, 9%, 10%, 11%, 13%, 15% by mass or in a range of any two values. The electrolyte comprises the carbonate solvent and the lithium salt within the range, and the content of the carbonate solvent and the content of the lithium salt are regulated and controlled within the range, so that the electrolyte environment which enables the electrode solid interface film to be more stable can be obtained, and the high-temperature storage performance and the high-temperature intermittent cycle performance of the electrochemical device can be improved.
In some embodiments of the present application, the electrolyte includes a compound of formula (I), a carbonate-based solvent, a lithium salt, and a carboxylate, and the electrolyte may further include at least one of an ester additive, a nitrile compound, or a lithium salt additive. Wherein the carbonate solvent comprises at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dioctyl carbonate, dipentyl carbonate, ethyl isobutyl carbonate, isopropyl methyl carbonate, di-n-butyl carbonate, diisopropyl carbonate or propyl carbonate; the lithium salt includes lithium hexafluorophosphate. Based on the mass of the electrolyte, the mass percentage content of the carbonate solvent is 10-80%, and the mass percentage content of the lithium salt is 8-15%. For example, the carbonate-based solvent may be present in an amount of 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80% by mass or in a range of any two values, and the lithium salt may be present in an amount of 8%, 9%, 10%, 11%, 13%, 15% by mass or in a range of any two values. The mass percentage of the carboxylate is 10-70%, the mass percentage of the ester additive is 0.5-18%, the mass percentage of the nitrile compound is 1-8%, and the mass percentage of the lithium salt additive is 0.01-4%. The electrolyte comprises a carbonate solvent, a lithium salt and a carboxylate in the above range, optionally the electrolyte further comprises at least one of an ester additive, a nitrile compound or a lithium salt additive, and the content of the above components is regulated and controlled in the above range, so that the electrode solid interface film is more stable, and the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the electrochemical device are improved.
In a second aspect, the present application provides an electrochemical device comprising the electrolyte provided in the first aspect, and the electrochemical device provided in the present application has good high-temperature storage performance, high-temperature intermittent cycle performance, and normal-temperature cycle performance.
The electrochemical device of the present application further comprises an electrode assembly comprising a positive electrode tab, a negative electrode tab, and a separator.
The application has no particular limitation on the positive electrode piece as long as the purpose of the application can be achieved. For example, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode current collector is not particularly limited as long as the object of the present invention can be achieved. For example, the positive electrode collector may include an aluminum foil or an aluminum alloy foil, etc. The positive electrode active material layer of the present application contains a positive electrode active material. This application is alignedThe kind of the 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 ) And 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 include a non-metal element, for example, the non-metal element includes at least one of fluorine, phosphorus, boron, chlorine, silicon, sulfur, and the like, which can further improve the stability of the positive electrode active material. In the present application, the thickness of the positive electrode current collector and the positive 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 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, and may also be provided on both surfaces in the thickness direction of the positive electrode current collector. The "surface" herein may be the entire region of the positive electrode current collector or a partial region of the positive electrode current collector, and the present application is not particularly limited as long as the object of the present application can be achieved. The positive electrode active material layer of the present application may further include a conductive agent and a binder.
This application does not have special restriction to the negative pole piece, as long as can realize this application purpose. For example, 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. The present application 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 a copper foil, a copper alloy foil, a nickel foil, a titanium foil, a nickel foam, a copper foam, or the like. The anode active material layer of the present application contains an anode active material. The present application does not particularly limit the kind of the anode active material as long as the object of the present application can be achieved. For example, the negative active material may include natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB), hard carbon, soft carbon, silicon-carbon composite, siO x （0<x is less than or equal to 2), or metallic lithium, and the like. In thatIn the present application, the thickness of the anode current collector and the anode 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 negative electrode current collector is 4 to 12 μm, and the thickness of the single-sided negative electrode active material layer is 30 to 130 μm. In the present application, the negative electrode active material layer may be provided on one surface in the thickness direction of the negative electrode current collector, and may also be provided on both surfaces in the thickness direction of the negative electrode current collector. The "surface" herein may be the entire region of the negative electrode current collector or a partial region of the negative electrode current collector, and the present application is not particularly limited as long as the object of the present application can be achieved. The negative electrode active material layer of the present application may further include a conductive agent and a binder.
The above-mentioned conductive agent and binder are not particularly limited as long as the object of the present application can be achieved. For example, the conductive agent may include at least one of conductive carbon black (Super P), carbon Nanotubes (CNTs), carbon nanofibers, flake graphite, carbon dots, graphene, or the like. The binder may include at least one of polyvinyl alcohol, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyamideimide, styrene Butadiene Rubber (SBR), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), aqueous acrylic resin, carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Na), or the like.
The separator is not particularly limited as long as the object of the present application can be achieved. For example, the release film may include a base material layer and a surface treatment layer. The substrate layer may be a non-woven 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 film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film 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 a layer formed by mixing a polymer and an inorganic substance. For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited and may be, for example, at least one selected from 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. The binder is not particularly limited, and may be, for example, at least one selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyvinylpyrrolidone, polyvinyl ether, and polymethyl methacrylate. The polymer layer contains a polymer, and the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride-hexafluoropropylene, or the like. In the present application, the thickness of the separation film is not particularly limited as long as the object of the present application can be achieved, and for example, the thickness of the separation film may be 5 μm to 500 μm.
The electrochemical device of the present application is not particularly limited, and may include any device in which electrochemical reactions occur. In one embodiment of the present application, an electrochemical device may include, but is not limited to: a lithium ion secondary battery (lithium ion battery), a lithium metal secondary battery, a sodium ion secondary battery (sodium ion battery), a sodium metal secondary battery, a lithium polymer secondary battery, a lithium ion polymer secondary battery, or the like.
The preparation process of the electrochemical device is well known to those skilled in the art, and the present application is not particularly limited, and for example, may include, but is not limited to, the following steps: stacking the positive pole piece, the isolating membrane and the negative pole piece in sequence, winding, folding and the like according to needs to obtain an electrode assembly with a winding structure, putting the electrode assembly into a packaging bag, injecting electrolyte into the packaging bag and sealing the packaging bag to obtain the electrochemical device; or, stacking the positive pole piece, the isolating membrane and the negative pole piece in sequence, fixing four corners of the whole lamination structure by using an adhesive tape 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 the packaging bag to obtain the electrochemical device. In addition, an overcurrent prevention element, a guide plate, or the like may be placed in the packaging bag as necessary to prevent a pressure rise or overcharge/discharge inside the electrochemical device. The application has no limitation to the packaging bag, and the person skilled in the art can select the packaging bag according to actual needs as long as the purpose of the application can be achieved. For example, a plastic-aluminum film package can be used.
In a third aspect, an electronic device is provided that includes an electrochemical device provided in the second aspect of the present application. The electrochemical device provided by the application has good high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance. Therefore, the electronic device has a long service life.
The electronic device of the present application is not particularly limited, and may be any electronic device known in the art. In some embodiments, the electronic device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a handheld cleaner, a portable CD player, a mini-disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power source, an electric motor, an automobile, a motorcycle, a power-assisted bicycle, a lighting fixture, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a large household battery or lithium ion capacitor, and the like.
Examples
Hereinafter, embodiments of the present application will be described in more detail with reference to examples and comparative examples. Various tests and evaluations were carried out according to the following methods. Unless otherwise specified, "part" and "%" are based on mass.
Test method and apparatus
And (3) testing the high-temperature storage performance:
the high-temperature storage performance of the lithium ion battery was evaluated by storing the lithium ion battery at 60 ℃ for a storage time of a thickness expansion rate of 10%. The specific test flow is as follows: testing the initial thickness D1 of the lithium ion battery at 25 ℃; charging the lithium ion battery to 4.5V at a constant current of 0.5C at 25 ℃, then charging the lithium ion battery at a constant voltage of 4.5V until the current is 0.05C, then standing the lithium ion battery in a high-temperature furnace at 60 ℃, testing the thickness of the lithium ion battery every day, recording the thickness D2 of the lithium ion battery, and recording the thickness expansion rate = (D2-D1)/D1 multiplied by 100 percent, and recording the days when the thickness expansion rate is 10 percent according to the calculation method of the thickness expansion rate, wherein the days are used as indexes for evaluating the high-temperature storage performance of the lithium ion battery.
Testing the high-temperature intermittent cycle performance:
the specific test flow is as follows: the lithium ion battery is placed in a high-temperature furnace at 45 ℃, the lithium ion battery is charged to 4.5V at a constant current of 0.5C, then is charged at a constant voltage until the current is 0.05C, the initial full charge thickness of the lithium ion battery is measured, the lithium ion battery is kept stand for 1170min at 45 ℃, and then is discharged to 3.0V at a constant current of 0.5C, and the first cycle is carried out. And (4) circulating the lithium ion battery for multiple times according to the conditions, and measuring the full charge thickness of the lithium ion battery in each circulation. And (3) repeatedly carrying out charge and discharge cycles with the capacity of the first discharge as 100 percent until the retention rate of the discharge capacity decays to 70 percent of the first discharge capacity, stopping the test, and recording the number of cycles as an index for evaluating the retention rate of the intermittent cycle capacity of the lithium ion battery.
Capacity retention ratio = (capacity after the end of each discharge cycle/first discharge capacity) × 100%.
Testing the normal-temperature cycle performance:
charging the lithium ion battery to 4.25V at a constant current of 1.2C, charging the lithium ion battery to 0.7C at a constant voltage of 4.25V at a current of 0.7C, then charging the lithium ion battery to 4.5V at a constant current of 0.7C, charging the lithium ion battery to 0.05C at a constant voltage of 4.5V, standing for 5min, then discharging the lithium ion battery to 3.0V at a constant current of 0.5C, and recording the discharge capacity at the first circulation. And (4) circulating the lithium ion battery for multiple times according to the conditions, and measuring the discharge capacity of the lithium ion battery in each circulation. And (3) repeatedly carrying out charge and discharge cycles with the capacity of the first discharge as 100 percent until the discharge capacity retention rate is attenuated to 80 percent of the first discharge capacity, stopping the test, and recording the number of cycles as an index for evaluating the normal-temperature cycle capacity retention rate of the lithium ion battery. Capacity retention ratio = (capacity after completion of each discharge cycle/first discharge capacity) × 100%.
Example 1-1
< preparation of electrolyte solution >
In an argon atmosphere glove box having a water content of < 10ppm, EC, PC and DEC were mixed at a mass ratio of 10 6 And a compound of formula (I), formula (I-1), and uniformly stirring to obtain the electrolyte. Wherein, based on the mass of the electrolyte, liPF 6 Is 12 percent, and the compound of the formula (I) is 0.3 percent.
< preparation of Positive electrode sheet >
LiCoO as positive electrode active material 2 And mixing the conductive carbon black serving as a conductive agent and the PVDF serving as a binder according to the mass ratio of 95. And uniformly coating the positive electrode slurry on one surface of an aluminum foil of a positive electrode current collector with the thickness of 12 mu m, and drying the aluminum foil at 85 ℃ for 4 hours to obtain a positive electrode plate with the coating thickness of 110 mu m and the width of 74mm, wherein the single surface of the positive electrode plate is coated with a positive electrode active material layer. And repeating the steps on the other surface of the aluminum foil to obtain the positive pole piece with the positive active material layer coated on the two surfaces. And then drying for 4 hours under the vacuum condition of 85 ℃, and obtaining the positive pole piece with the specification of 74mm multiplied by 867mm through cold pressing, slitting and cutting.
< preparation of negative electrode sheet >
Mixing a negative electrode active material graphite, a binder styrene butadiene rubber and a negative electrode thickener sodium carboxymethyl cellulose according to a mass ratio of 95. And uniformly coating the negative electrode slurry on one surface of a copper foil of a negative electrode current collector with the thickness of 12 mu m, and drying the copper foil at 85 ℃ for 4 hours to obtain a negative electrode pole piece with the coating thickness of 130 mu m and the width of 76.6mm, wherein the single surface of the negative electrode pole piece is coated with a negative electrode active material layer. And repeating the steps on the other surface of the copper foil to obtain the negative pole piece with the negative active material layer coated on the two surfaces. And then drying for 4 hours at 85 ℃ under vacuum condition, and obtaining the negative pole piece with the specification of 76.6mm multiplied by 875mm through cold pressing, cutting into pieces and slitting.
< preparation of separator >
Mixing PVDF and alumina ceramic according to the mass ratio of 1:2, adding NMP as a solvent, preparing ceramic layer slurry with the solid content of 12wt%, uniformly stirring, uniformly coating the slurry on one surface of a polyethylene base material with the thickness of 5 mu m, and drying to obtain the isolating membrane with the single surface coated with the alumina ceramic layer with the thickness of 2 mu m. Adding PVDF into NMP solvent, stirring uniformly, preparing PVDF slurry with solid content of 25wt%, and coating 0.15mg/cm on the surface of an alumina ceramic layer 2 Is dried at 85 ℃ for 4 hours, and finally, the other surface of the polyethylene substrate is coated with 0.15mg/cm 2 The PVDF was dried at 85 ℃ for 4 hours to obtain an isolation membrane.
< preparation of lithium ion Battery >
And (3) stacking the prepared positive pole piece, the isolating membrane and the negative pole piece in sequence, so that one surface of the isolating membrane coated with the aluminum oxide ceramic layer and the PVDF faces the positive pole piece, one surface of the isolating membrane coated with the PVDF faces the negative pole piece, the isolating membrane is positioned between the positive pole piece and the negative pole piece to play an isolating role, and then winding to obtain the electrode assembly. And (3) after welding the tabs, putting the electrode assembly into an aluminum-plastic film packaging bag, placing the aluminum-plastic film packaging bag in a vacuum oven at 85 ℃ for drying for 12 hours to remove moisture, injecting the prepared electrolyte, and performing vacuum packaging, standing, formation, shaping and other processes to obtain the lithium ion battery.
Examples 1-2 to examples 1-15
The procedure of example 1-1 was repeated, except that the kind and mass% of the compound of formula (I) in < preparation of electrolyte solution > were changed according to Table 1, the mass% of the base solvent was changed, and the mass% of the lithium salt was not changed.
Example 2-1 to example 2-21
Examples 1 to 12 were repeated except that in < preparation of electrolyte > a carboxylic acid ester was further added as shown in Table 2, and the kind and mass percentage of the compound of formula (I), the kind and mass percentage of the carboxylic acid ester were adjusted as shown in Table 2, the mass percentage of the base solvent was changed, and the mass percentage of the lithium salt was not changed.
Example 3-1 to example 3-10
The examples were conducted in the same manner as in examples 2 to 16 except that in < preparation of electrolyte > ester additives and/or nitrile compounds were further added as shown in Table 3, and the types and mass percentages of the ester additives and the types and mass percentages of the nitrile compounds were adjusted as shown in Table 3, and the mass percentages of the base solvents were changed without changing the mass percentages of the lithium salts.
Example 4-1 to example 4-14
Examples 3 to 7 were conducted in the same manner as in example 3, except that in < preparation of electrolyte > a lithium salt additive was further added as shown in Table 4, and the kind and mass percentage of the compound of formula (I), the kind and mass percentage of the lithium salt additive, and the mass percentage of the base solvent were changed as shown in Table 4, and the mass percentage of the lithium salt was not changed.
Comparative examples 1 to 1
The same procedure as in example 1-1 was repeated, except that the compound of formula (I) was not added in < preparation of electrolyte solution >, the mass percentage of the base solvent was changed, and the mass percentage of the lithium salt was not changed.
Comparative examples 1 to 2
The same as in example 1-1 was repeated, except that diethyl (thien-2-ylmethyl) phosphate was used as an additive in place of the compound of formula (I) in < preparation of electrolyte >.
Comparative examples 1-3 to comparative examples 1-4
The same procedures as in example 1-1 were repeated, except that the mass percentage of the compound of formula (I) was changed and the mass percentage of the base solvent was changed in accordance with Table 1 in < preparation of electrolyte solution >, and the mass percentage of the lithium salt was not changed.
Comparative example 2-1
Examples 2 to 9 were conducted except that the compound of the formula (I) was not added as shown in Table 2 in < preparation of electrolyte solution >, the mass% of the base solvent was changed, and the mass% of the lithium salt was not changed.
Comparative example 3-1
The procedure was repeated as in examples 3 to 4 except that the compound of the formula (I) was not added in < preparation of electrolyte solution >, the mass% of the base solvent was changed, and the mass% of the lithium salt was not changed.
Comparative examples 3 to 2
The examples were conducted in the same manner as in examples 3 to 5 except that the compound of formula (I) was not added in < preparation of electrolyte solution >, the mass% of the base solvent was changed, and the mass% of the lithium salt was not changed.
Comparative examples 3 to 3
Examples 3 to 7 were conducted in the same manner as in examples 3 to 7 except that the compound of the formula (I) was not added in < preparation of electrolyte solution >, the mass percentage of the base solvent was changed, and the mass percentage of the lithium salt was not changed.
Comparative example 4-1
The examples were conducted in the same manner as in examples 4 to 5 except that the compound of formula (I) was not added in < preparation of electrolyte solution >, the mass% of the base solvent was changed, and the mass% of the lithium salt was not changed.
The preparation parameters and performance parameters of each example and comparative example are shown in tables 1 to 4.
TABLE 1
Note: the "/" in table 1 indicates no relevant preparation parameters.
As can be seen from examples 1-1 to 1-9, comparative examples 1-1 and 1-2, the application of the electrolyte including the compound of formula (I) to the lithium ion battery can extend the storage time of the lithium ion battery at 60 ℃ and increase the number of high-temperature intermittent cycles of the lithium ion battery, thereby enabling the lithium ion battery to have better high-temperature storage performance and high-temperature intermittent cycle performance.
The mass percent A% of the compound of formula (I) generally affects the high-temperature storage performance and the high-temperature intermittent cycle performance of the lithium ion battery. As can be seen from examples 1 to 5, examples 1 to 10 to examples 1 to 15, comparative examples 1 to 3 and comparative examples 1 to 4, when the a value is too small, the storage time of the lithium ion battery at 60 ℃ is short. When the value of a is too large, the lithium ion battery has a short storage time at 60 ℃ and a small number of high-temperature intermittent cycles. When A is more than or equal to 0.01 and less than or equal to 5, the lithium ion battery has better high-temperature storage performance and more high-temperature intermittent cycle turns. When A is more than or equal to 0.1 and less than or equal to 3, the lithium ion battery has longer storage time at 60 ℃ and more high-temperature intermittent cycle cycles. Therefore, the storage time of the lithium ion battery at 60 ℃ is longer and the high-temperature intermittent cycle number is more by regulating and controlling the A in the range of the application, namely the lithium ion battery has better high-temperature storage performance and high-temperature intermittent cycle performance.
TABLE 2
Note: the "/" in table 2 indicates no relevant parameters.
The kind of carboxylate generally affects the high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance of the lithium ion battery. From examples 1-12, 2-1 to 2-6, it can be seen that the lithium ion battery with the carboxylate type within the scope of the present application has longer storage time at 60 ℃ and more cycles at normal temperature, and can keep more high-temperature intermittent cycles, so that the electrolyte further introduces the carboxylate under the condition of containing the compound of formula (I), so that the lithium ion battery has better high-temperature storage performance and normal-temperature cycle performance while having good high-temperature intermittent cycle performance.
The mass percentage content B% of the carboxylic ester generally affects the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the lithium ion battery, and as can be seen from examples 2-2, 2-7 to 2-12, when the value B is within the range of the application, the lithium ion battery has longer storage time at 60 ℃ and more high-temperature intermittent cycle turns and normal-temperature cycle turns, that is, the lithium ion battery has better high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance.
The ratio A/B of the mass percent of the compound of formula (I) to the mass percent of the carboxylic ester generally affects the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the lithium ion battery, and it can be seen from examples 2-2, 2-13 to 2-21 that when A/B is within the range of the present application, the storage time of the lithium ion battery at 60 ℃ is longer, and the number of high-temperature intermittent cycles and the number of normal-temperature cycles are more. Namely, the lithium ion battery has better high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance.
As can be seen from examples 2-9, examples 1-12 and comparative example 2-1, when the electrolyte of the lithium ion battery only comprises the compound of formula (I) or only comprises carboxylic ester, the lithium ion battery has short storage time at 60 ℃, and fewer high-temperature intermittent cycle circles and normal-temperature cycle circles; when the electrolyte of the lithium ion battery simultaneously comprises the compound shown in the formula (I) and the carboxylic ester, the lithium ion battery has longer storage time at 60 ℃, more high-temperature intermittent cycle circles and more normal-temperature cycle circles, namely the lithium ion battery has better high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance.
TABLE 3
Note: the "/" in table 3 indicates no relevant preparation parameters.
The types and the mass percentage content D% of the ester additives generally affect the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the lithium ion battery. It can be seen from examples 2-16 and 3-1 to 3-4 that the lithium ion battery with the type and D value of the ester additive within the range of the present application has a longer storage time at 60 ℃, a larger number of high-temperature intermittent cycles and a larger number of normal-temperature cycles, so that the electrolyte further introduces the ester additive when containing the compound of formula (I), and the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the lithium ion battery can be simultaneously improved.
The type and mass percentage content E% of nitrile compounds generally affect the high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance of the lithium ion battery. From examples 2 to 16, examples 3 to 5 and examples 3 to 6, it can be seen that the lithium ion battery having the kind of nitrile compound and the E value within the range of the present application has a longer storage time at 60 ℃, a larger number of high-temperature intermittent cycles and a larger number of normal-temperature cycles, and thus it was demonstrated that the high-temperature storage performance and the high-temperature intermittent cycle performance of the lithium ion battery can be further improved by further introducing the nitrile compound into the electrolyte solution containing the compound of formula (I).
It can be seen from examples 2-16, 3-7 to 3-8 that when the electrolyte of the lithium ion battery includes both the ester additive and the nitrile compound, the lithium ion battery has longer storage time at 60 ℃, and more high-temperature intermittent cycle cycles and normal-temperature cycle cycles. Therefore, under the condition that the electrolyte contains the compound shown in the formula (I), the ester additive and the nitrile compound are introduced simultaneously, so that the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the lithium ion battery can be further improved.
As can be seen from examples 3-4, examples 2-16 and comparative example 3-1, when the electrolyte of the lithium ion battery only comprises the compound of formula (I) or only comprises the ester additive, the lithium ion battery has short storage time at 60 ℃ and fewer high-temperature intermittent cycle circles and normal-temperature cycle circles; when the electrolyte of the lithium ion battery simultaneously comprises the compound shown in the formula (I) and the ester additive, the lithium ion battery has longer storage time at 60 ℃, more high-temperature intermittent cycle circles and more normal-temperature cycle circles, namely the lithium ion battery has better high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance.
As can be seen from examples 3 to 5, examples 2 to 16 and comparative examples 3 to 2, when the electrolyte of the lithium ion battery only includes the compound of formula (I) or only includes the nitrile compound, the lithium ion battery has short storage time at 60 ℃, and fewer high-temperature intermittent cycle cycles and normal-temperature cycle cycles; when the electrolyte of the lithium ion battery simultaneously comprises the compound shown in the formula (I) and the nitrile compound, the lithium ion battery has longer storage time at 60 ℃, more high-temperature intermittent cycle circles and more normal-temperature cycle circles, namely the lithium ion battery has better high-temperature storage performance and high-temperature intermittent cycle performance and has good normal-temperature cycle performance.
As can be seen from examples 3 to 7, examples 2 to 16 and comparative examples 3 to 3, when the electrolyte of the lithium ion battery includes only the compound of formula (I) or only the nitrile compound and the nitrile compound, the lithium ion battery has a short storage time at 60 ℃, and a small number of high-temperature intermittent cycles and normal-temperature cycles; when the electrolyte of the lithium ion battery simultaneously comprises the compound shown in the formula (I), the ester additive and the nitrile compound, the lithium ion battery has longer storage time at 60 ℃ and more high-temperature intermittent cycle circles and normal-temperature cycle circles, namely the lithium ion battery has better high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance.
TABLE 4
Note: the "/" in Table 4 indicates no relevant preparation parameters.
The type and mass percentage content C% of the lithium salt additive generally affect the high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance of the lithium ion battery. It can be seen from examples 3-7 and 4-1 to 4-9 that the lithium ion battery having the types of lithium salt additives and the C value within the range of the present application has a longer storage time at 60 ℃ and more high-temperature intermittent cycle cycles and normal-temperature cycle cycles, so that the lithium ion battery can improve the high-temperature intermittent cycle performance and normal-temperature cycle performance of the lithium ion battery by further introducing the lithium salt additive into the electrolyte under the condition that the electrolyte contains the compound of formula (I), and the lithium ion battery has better high-temperature storage performance.
The ratio A/C of the mass percentage of the compound of formula (I) to the mass percentage of the lithium salt additive generally affects the high-temperature storage performance, the high-temperature intermittent cycle performance and the normal-temperature cycle performance of the lithium ion battery, and it can be seen from examples 4-5 to examples 4-14 that when the A/C is within the range of the application, the storage time of the lithium ion battery at 60 ℃ is longer, the number of high-temperature intermittent cycle cycles and the number of normal-temperature cycle cycles are more, that is, the lithium ion battery has better high-temperature storage performance, high-temperature intermittent cycle performance and normal-temperature cycle performance.
As can be seen from examples 4-5, examples 3-7 and comparative example 4-1, when the electrolyte of the lithium ion battery only comprises the compound of formula (I) or only comprises the lithium salt additive, the high-temperature intermittent cycle number and the normal-temperature cycle number of the lithium ion battery are fewer; when the electrolyte of the lithium ion battery simultaneously comprises the compound shown in the formula (I) and the lithium salt additive, the lithium ion battery has longer storage time at 60 ℃, more high-temperature intermittent cycle circles and more normal-temperature cycle circles, namely the lithium ion battery has better high-temperature intermittent cycle performance and normal-temperature cycle performance, and simultaneously has good high-temperature storage performance.
It is to be noted that 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.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments.
The above are merely preferred embodiments of the present application, and are not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application are included in the protection scope of the present application.
Claims (13)
1. An electrolyte comprising a compound of formula (I):
R 1 、R 2 and R 3 Each independently selected from hydrogen atom, halogen, C 2 -C 5 Carbonyl group of (C) 1 -C 5 Aldehyde group of (A), C unsubstituted or substituted by Ra 1 -C 5 Alkyl, C unsubstituted or substituted by Ra 2 -C 5 Alkenyl of (3), C unsubstituted or substituted by Ra 2 -C 5 Alkynyl of (2), unsubstituted or substituted by Ra C 3 -C 5 N-heterocycloalkyl of (A), C 3 -C 5 The N heteroaryl group of (1); r 4 、R 5 And R 6 Each independently selected from hydrogen atom, C 1 -C 5 Alkylthio of, C 2 -C 5 Thioether of (C) 3 -C 5 N-heterocycloalkyl of (A), C 3 -C 5 N heteroaryl, unsubstituted or substituted by Ra C 1 -C 5 Alkyl, C unsubstituted or substituted by Ra 2 -C 5 Alkenyl of (3), C unsubstituted or substituted by Ra 2 -C 5 Alkynyl of (a); the substituents Ra of each group are independently selected from halogen and C 1 -C 5 Aldehyde group of (A), C 2 -C 5 Carbonyl group of (C) 2 -C 5 Ester group, sulfonic acid group, amino group, C 2 -C 5 Amide, cyano or anhydride of (a);
based on the mass of the electrolyte, the mass percentage content of the compound of the formula (I) is A%, and A is more than or equal to 0.01 and less than or equal to 5.
2. The electrolyte of claim 1, wherein R 1 、R 2 And R 3 Each independently selected from a hydrogen atom, halogen, carboxaldehyde, methyl, ethyl, propyl, butyl, ethenyl, propenyl, butenyl, ethynyl, propynyl, butynyl, pyrrolyl or pyridyl; r 4 、R 5 And R 6 Each independently selected from hydrogen atom, methylthio group, dimethyl sulfide group, methyl group, ethyl group, propyl group, butyl group, ethenyl group, propenyl group, butenyl group, ethynyl group, propynyl group, butyl groupAlkynyl, pyrrolyl or pyridyl.
3. The electrolyte of claim 1, wherein the compound of formula (I) comprises at least one of:
4. the electrolyte of claim 1, wherein 0.1 ≦ A ≦ 3.
5. The electrolyte of claim 1, wherein the electrolyte further comprises a carboxylic acid ester comprising at least one of ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, or butyl propionate; based on the mass of the electrolyte, the mass percentage of the carboxylic ester is B percent, and B is more than or equal to 10 and less than or equal to 70.
6. The electrolyte of claim 5, wherein 0.0005. Ltoreq. A/B. Ltoreq.0.4.
7. The electrolyte solution according to claim 5, wherein 0.0075. Ltoreq.A/B. Ltoreq.0.2.
8. The electrolyte of claim 5, wherein the electrolyte further comprises an ester additive comprising at least one of vinylene carbonate, ethylene carbonate, 1,3-propane sultone, or fluoroethylene carbonate; based on the mass of the electrolyte, the mass percentage content of the ester additive is D percent, and D is more than or equal to 0.5 and less than or equal to 18.
9. The electrolyte of claim 5 or 8, wherein the electrolyte further comprises a nitrile compound comprising at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, sebaconitrile, 3,3 '-oxydipropynitrile, hex-2-enedinitrile, fumarodinitrile, 2-pentenenitrile, methylglutaronitrile, 4-cyanoheptanedinitrile, (Z) -but-2-enedinitrile, 2,2,3,3-tetrafluorosuccinonitrile, ethylene glycol bis (propionitrile) ether, 1,3,5-glutaronitrile, 1,3,6-adiponitrile, 34 1,2,6-adiponitrile, 1,2,3-tris (2-cyanato) propane, 1,1,3,3-propanetetracarbonitrile, 2,2' - (34 zxft 3234-phenylene) dipropionitrile, 3825-pentanedinitrile, 3638 zxft 3224-4924-tetracyclocarbonitrile, or 3724-adiponitrile; based on the mass of the electrolyte, the mass percentage content of the nitrile compounds is E percent, and E is more than or equal to 1 and less than or equal to 8.
10. The electrolyte of claim 9, wherein the electrolyte includes a lithium salt additive including at least one of lithium difluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium bisoxalato borate, or lithium difluorooxalato borate; based on the mass of the electrolyte, the mass percentage content of the lithium salt additive is C%, and C is more than or equal to 0.01 and less than or equal to 4.
11. The electrolyte of claim 10, wherein 0.1. Ltoreq.A/C.ltoreq.30.
12. An electrochemical device comprising the electrolyte of any one of claims 1 to 11.
13. An electronic device comprising the electrochemical device of claim 12.
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| CN115332638A (en) * | 2022-10-14 | 2022-11-11 | 宁德新能源科技有限公司 | Electrolyte, electrochemical device and electronic device |
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