Electrolyte, battery containing electrolyte, energy storage device and electric equipment

Abstract

The invention provides an electrolyte, a battery containing the electrolyte, an energy storage device and electric equipment, the electrolyte comprises a non-aqueous organic solvent and a first additive, the non-aqueous organic solvent comprises a carbonic ester compound, the first additive comprises a compound shown in a formula (I), in the formula (I), R1-R10 are independently selected from hydrogen, nitryl and substituted or unsubstituted alkyl, and in the formula (I), R1-R10 are independently selected from hydrogen, nitryl and substituted or unsubstituted alkyl. At least one of R1-R10 is a nitro group; based on the mass of the electrolyte, the mass percentage content of the compound shown in the formula (I) is a, and a is larger than or equal to 0.01% and smaller than or equal to 10%. # imgabs0 #

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an electrolyte, a battery containing the electrolyte, an energy storage device, and an electrical equipment. Background Art

[0002] Secondary batteries (such as lithium-ion batteries) have the advantages of high energy density, low self-discharge, and light weight, and are therefore widely used in fields such as energy storage devices.

[0003] As people's requirements for the performance of secondary batteries increase, for example, the requirements for the performance of secondary batteries in energy storage scenarios increase, secondary batteries are not only required to have high energy density, but also required to have good room temperature cycle performance and high temperature cycle performance to ensure the long-term service life of secondary batteries in energy storage application scenarios. Summary of the invention

[0004] In order to solve the above technical problems, the present application discloses an electrolyte, a battery containing the electrolyte, an energy storage device and an electrical equipment to improve the room temperature cycle performance and high temperature cycle performance of a secondary battery.

[0005] In a first aspect, the present application provides an electrolyte, comprising a non-aqueous organic solvent and a first additive, wherein the non-aqueous organic solvent comprises a carbonate compound, and the first additive comprises a compound represented by formula (I):

[0006]

[0007] In formula (I), R 1 ~R 10 are independently selected from hydrogen, nitro, substituted or unsubstituted alkyl, and R 1 ~R 10 At least one of them is nitro;

[0008] Based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is a, 0.01%≤a≤10%.

[0009] In some embodiments of the present application, 0.1%≤a≤1%.

[0010] In some embodiments of the present application, the compound represented by formula (I) is selected from at least one of the following compounds:

[0011]

[0012]

[0013]

[0014] In some embodiments of the present application, the carbonate compound includes at least one of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate.

[0015] In some embodiments of the present application, the electrolyte further includes a second additive, wherein the second additive includes at least one of vinylene carbonate and fluoroethylene carbonate.

[0016] In some embodiments of the present application, based on the mass of the electrolyte, the mass percentage of the vinylene carbonate is b, the mass percentage of the fluoroethylene carbonate is c, 0.01%≤b≤10%, and / or, 0.01%≤c≤10%.

[0017] In some embodiments of the present application, based on the mass of the electrolyte, 0.1%≤b≤3%, and / or, 0.1%≤c≤3%.

[0018] In a second aspect, the present application provides a battery, comprising the electrolyte described in the first aspect.

[0019] In a third aspect, the present application provides an energy storage device, comprising a housing and at least one battery as described in the second aspect, wherein the battery is accommodated in the housing.

[0020] In a fourth aspect, the present application provides an electrical device, comprising the energy storage device described in the third aspect, wherein the energy storage device supplies power to the electrical device.

[0021] Compared with the prior art, this application has at least the following beneficial effects:

[0022] The present application provides an electrolyte, a battery containing the electrolyte, an energy storage device and an electrical device, wherein the electrolyte includes a non-aqueous organic solvent and a first additive, the non-aqueous organic solvent includes a carbonate compound, the first additive includes a compound shown in formula (I), and based on the mass of the electrolyte, the mass percentage of the compound shown in formula (I) is a, 0.01%≤a≤10%, so that it is conducive to forming a SEI (Solid Electrolyte Interphase) membrane with an inner layer of inorganic components and an outer layer of organic components. This SEI membrane has the advantages of high ionic conductivity and good mechanical stability, thereby improving the room temperature cycle performance and high temperature cycle performance of the secondary battery and extending the cycle life of the secondary battery. When the secondary battery of the present application is applied to an energy storage device, the service life of the energy storage device at room temperature and high temperature is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of the structure of a household energy storage system according to an implementation scheme of the present application;

[0025] Figure 2 A schematic diagram of the structure of an energy storage system according to an implementation scheme of the present application;

[0026] Figure 3 The photos of samples with different electrolytes.

[0027] Explanation of the reference numerals: 1 - energy storage device, 2 - electric energy conversion device, 3 - first user load, 4 - second user load, 400 - energy storage system, 410 - high voltage cable, 420 - first electric energy conversion device, 430 - second electric energy conversion device. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0030] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0031] In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0033] It should be noted that, in the content of the present application, lithium-ion batteries are used as an example of secondary batteries to explain the present application, but the secondary batteries of the present application are not limited to lithium-ion batteries, and can also be sodium-ion batteries.

[0034] In view of this, the present application provides an electrolyte, which includes a non-aqueous organic solvent and a first additive, the non-aqueous organic solvent includes a carbonate compound, and the first additive includes a compound represented by formula (I):

[0035]

[0036] In formula (I), R 1 ~R 10 are independently selected from hydrogen, nitro, substituted or unsubstituted alkyl, and R 1 ~R 10 At least one of them is a nitro group; based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is a, 0.01%≤a≤10%; in another optional embodiment, 0.1%≤a≤1%. For example, a is 0.01%, 0.05%, 0.1%, 0.5%, 1%, 5% or 10%.

[0037] The compound represented by formula (I) of the present application is conducive to forming a SEI film with an inner layer of inorganic components and an outer layer of organic components. This SEI film has the advantages of high ionic conductivity and good mechanical stability, thereby improving the room temperature cycle performance and high temperature cycle performance of lithium-ion batteries and extending the cycle life of lithium-ion batteries. This may be because the compound represented by formula (I) of the present application is easily soluble in carbonate system electrolytes, and is therefore easier to reduce and decompose into a film, thereby improving the stability of the SEI film; and the compound represented by formula (I) of the present application contains three functional groups, benzoic anhydride, benzene ring and nitro, in the molecule, wherein the nitro group can be preferentially reduced to generate nitrogen-containing inorganic SEI components (such as lithium nitride (Li3 N), lithium oxynitride (LiN x O y ), wherein the benzoic anhydride plays a role in stabilizing the nitro group and improving the solubility of the compound represented by formula (I), and the benzoic anhydride structure can be reduced to generate O - and C· free radicals, and initiates the ring-opening polymerization of ethylene carbonate (EC) to generate polycarbonate organic SEI components; the benzene rings therein are rich in π electrons, which can interact with the surface of the negative electrode active material (such as graphite), enhance the adsorption capacity of the compound represented by formula (I) on the surface of the negative electrode active material, and are more conducive to the reduction and decomposition of the compound represented by formula (I) on the surface of the negative electrode active material to form a SEI film. Under the joint action of the above three functional groups, they can participate in the construction of the SEI interface film step by step, thereby forming a SEI film with an inner layer of inorganic components and an outer layer of organic components, improving the lithium ion interface transmission capacity while reducing the occurrence of side reactions, thereby stabilizing the negative electrode interface. And the inventors further discovered that the content of the compound shown in formula (I) should not be too low or too high. When the content of the compound shown in formula (I) is too low (for example, less than 0.01%), it is difficult for the compound shown in formula (I) to effectively form an SEI film, which is not conducive to improving the stability of the negative electrode interface; when the content of the compound shown in formula (I) is too high (for example, higher than 10%), the formed SEI film is thicker, resulting in a larger interface impedance, which affects the cycle performance of the lithium-ion battery. By regulating the content of the compound shown in formula (I) within the above range, a dense and moderately thick SEI film can be formed. The SEI film has the advantages of high ionic conductivity and good mechanical stability, and the SEI film can effectively passivate the negative electrode interface, thereby improving the stability of the negative electrode interface. When the lithium-ion battery of the present application is applied to an energy storage device, the service life of the energy storage device at room temperature and high temperature is improved.

[0038] In the present application, high temperature refers to a temperature greater than or equal to 45°C.

[0039] In some embodiments of the present application, the compound represented by formula (I) is selected from at least one of the following compounds:

[0040]

[0041]

[0042]

[0043] In some embodiments of the present application, the carbonate compound includes at least one of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC). The compound represented by formula (I) of the present application is easily soluble in an electrolyte containing the above carbonate compound, and is more easily reduced and decomposed into a film, which is beneficial to improving the stability of the SEI film.

[0044] In some embodiments of the present application, the electrolyte further comprises a second additive, the second additive comprising at least one of vinylene carbonate (VC) and fluoroethylene carbonate (FEC). By combining the compound represented by formula (I) with VC and / or FEC, the room temperature cycle performance and high temperature cycle performance of the lithium ion battery can be further improved.

[0045] In some embodiments of the present application, based on the mass of the electrolyte, the mass percentage of VC is b, the mass percentage of FEC is c, 0.01%≤b≤10%, and / or, 0.01%≤c≤10%; in other embodiments, 0.1%≤b≤3%, and / or, 0.1%≤c≤3%. For example, b is 0.01%, 0.05%, 0.1%, 0.5%, 0.8%, 1%, 3%, 5% or 10%, and c is 0.01%, 0.05%, 0.1%, 0.5%, 0.8%, 1%, 3%, 5% or 10%. By regulating the content of VC and / or FEC within the above range, it is beneficial to further improve the room temperature cycle performance and high temperature cycle performance of lithium-ion batteries.

[0046] The present application has no particular limitation on the content of the non-aqueous organic solvent in the electrolyte, as long as the purpose of the present application can be achieved. For example, the mass percentage of the non-aqueous organic solvent in the electrolyte is 60% to 90%.

[0047] In an optional embodiment, it is understood that the non-aqueous organic solvent may also include other organic solvents besides carbonate compounds, which is not particularly limited in the present application.

[0048] The present application has no particular restrictions on the preparation process of the electrolyte. For example, at least one carbonate compound (such as EC, EMC, DMC, etc.) can be mixed in a certain mass ratio, and then a lithium salt is added to dissolve and mix evenly, and then an electrolyte additive such as the compound represented by formula (I) is added and dissolved.

[0049] The present application has no particular limitation on lithium salts. For example, lithium salts include LiPF 6 , LiBF 4 , LiFSI, LiTFSI, LiBOB, LiODFP, LiODFB, LiPO 2 F 2 or CF 3 SO 3 At least one of Li.

[0050] The present application has no particular limitation on the concentration of lithium salt in the electrolyte, as long as the purpose of the present application can be achieved. 6 For example, LiPF 6The concentration in the electrolyte is 5wt% to 25wt%, for example, LiPF 6 The concentration of is 5wt%, 10wt%, 11wt%, 12wt%, 15wt%, 20wt% or 25wt%.

[0051] The present application also provides a battery, comprising the electrolyte described in any embodiment of the present application.

[0052] The lithium-ion battery of the present application also includes a positive electrode plate and a separator, wherein the separator is located between the positive electrode plate and the negative electrode plate to play an isolating role.

[0053] The present application has no special restrictions on the positive electrode sheet, as long as the purpose of the present application can be achieved. For example, the positive electrode sheet usually includes a positive current collector and a positive active material layer. The positive active material layer can be arranged on one surface in the thickness direction of the positive current collector, or on two surfaces in the thickness direction of the positive current collector. In the present application, the positive active material layer is arranged on the surface of the positive current collector, that is, the positive active material layer can be arranged in a partial area of ​​one surface of the positive current collector, or in the entire area of ​​one surface of the positive current collector. The present application has no special restrictions on the positive current collector, as long as the purpose of the present application can be achieved, for example, it can include but is not limited to aluminum foil, aluminum alloy foil or composite current collector. In the present application, there is no special restriction on the thickness of the positive current collector, as long as the purpose of the present application can be achieved, for example, the thickness is 8μm to 13μm. The single-sided thickness of the positive active material layer of the present application can be 100μm to 200μm.

[0054] In the present application, the positive electrode active material layer includes a positive electrode active material. The present application has no particular limitation on the positive electrode active material as long as the purpose of the present application can be achieved. For example, it may include at least one of lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganese oxide and lithium iron manganese phosphate.

[0055] In the present application, the positive electrode active material layer may also include a positive electrode conductive agent. The present application has no particular restrictions on the positive electrode conductive agent, as long as the purpose of the present application can be achieved. For example, it may include but is not limited to at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fibers, acetylene black and graphene. The above-mentioned carbon nanotubes may include but are not limited to single-walled carbon nanotubes and / or multi-walled carbon nanotubes. In the present application, the positive electrode active material layer may also include a positive electrode binder. The present application has no particular restrictions on the positive electrode binder, as long as the purpose of the present application can be achieved. For example, it may include but is not limited to at least one of fluorine-containing resins, polypropylene resins, fiber-type binders, rubber-type binders or polyimide-type binders.

[0056] The present application has no special restrictions on the negative electrode sheet, as long as the purpose of the present application can be achieved. For example, the negative electrode sheet usually includes a negative electrode collector and a negative electrode active material layer. The negative electrode active material layer can be arranged on one surface or two surfaces in the thickness direction of the negative electrode collector. In the present application, the negative electrode active material layer is arranged on the surface of the negative electrode collector, that is, the negative electrode active material layer can be arranged in a partial area of ​​one surface of the negative electrode collector, or in the entire area of ​​one surface of the negative electrode collector. The present application has no special restrictions on the negative electrode collector, as long as the purpose of the present application can be achieved. For example, it can include but is not limited to copper foil, copper alloy foil, nickel foil or composite current collector. In the present application, there is no special restriction on the thickness of the negative electrode collector, as long as the purpose of the present application can be achieved, for example, the thickness is 4μm to 12μm. The single-sided thickness of the negative electrode active material layer of the present application can be 70μm to 200μm.

[0057] In the present application, the negative electrode active material layer includes a negative electrode active material, wherein the negative electrode active material is not particularly limited as long as the purpose of the present application can be achieved. For example, it may include at least one of artificial graphite, natural graphite soft carbon, hard carbon, lithium metal, sodium metal, silicon, silicon carbon and silicon oxygen negative electrode.

[0058] In the present application, the negative electrode active material layer may further include a negative electrode binder. The present application has no particular restrictions on the negative electrode binder, as long as the purpose of the present application can be achieved, for example, it may include at least one of acrylate, polyamide, polyimide, polyamideimide, polyvinylidene fluoride (PVDF), styrene-butadiene rubber, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, and sodium carboxymethyl cellulose.

[0059] The present application has no particular restrictions on the diaphragm, and those skilled in the art can select according to actual needs, as long as the purpose of the present application can be achieved. For example, the diaphragm may include a substrate layer and a surface treatment layer. The substrate layer is a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide. Specifically, polypropylene porous film, polyethylene porous film, polypropylene non-woven fabric, polyethylene non-woven fabric or polypropylene-polyethylene-polypropylene porous composite film can be selected.

[0060] The battery of the present application also includes a shell, and the present application has no particular limitation on the shell, and those skilled in the art can select it according to actual needs, as long as the purpose of the present application can be achieved. For example, the shell may include an aluminum-plastic film.

[0061] The present application does not particularly limit the preparation method of the battery, and a preparation method known in the art can be selected as long as the purpose of the present application can be achieved. For example, the preparation method of the battery includes but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and other operations as needed to obtain a bare cell with a wound structure, placing the bare cell in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain a battery.

[0062] The present application also provides an energy storage device, including a housing and at least one battery in any of the above embodiments, wherein the battery is contained in the housing. The energy storage device having the battery has excellent performance, which is beneficial to the use of the energy storage device. By containing the battery in the housing, the fixation and protection of the battery can be increased, thereby improving the service life of the energy storage device. It is understandable that the energy storage device may have one or more batteries, and when the energy storage device contains multiple batteries, the multiple batteries may be connected in at least one of parallel and series connection.

[0063] The present application also provides an electrical device, including the energy storage device in the above-mentioned implementation scheme, which is conducive to improving the product competitiveness and performance of the electrical device. In an optional implementation scheme, the electrical device includes an electrical device body, and the energy storage device is used to supply power to the electrical device body. In an optional implementation scheme, the electrical device body includes a positive electrode of the device and a negative electrode of the device, the positive electrode plate of the battery in the energy storage device is used to electrically connect to the positive electrode of the device body of the electrical device, and the negative electrode plate of the battery in the energy storage device is used to electrically connect to the negative electrode of the device body of the electrical device, so as to supply power to the electrical device.

[0064] The electrical equipment of the present application may include but is not limited to: containers, household energy storage systems, battery vehicles, electric vehicles, ships, spacecraft, electric toys and electric tools, etc., wherein spacecrafts include airplanes, rockets, space shuttles and spacecrafts, etc., electric toys include fixed or mobile electric toys, such as electric car toys, electric ship toys and electric airplane toys, etc., and electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers.

[0065] See also Figure 1 , Figure 1 This is a schematic diagram of the structure of a household energy storage system according to an implementation scheme of the present application, and the present application Figure 1 The implementation plan is described using a household energy storage scenario in user-side energy storage as an example, but the energy storage device of the present application is not limited to the household energy storage scenario.

[0066] The present application provides a household energy storage system, which includes an energy conversion device 2 (photovoltaic panel), a first user load 3 (street lamp), a second user load 4 (such as air conditioner and other household appliances), and an energy storage device 1. The energy storage device 1 is a small energy storage box that can be mounted on an outdoor wall by wall hanging. Specifically, the photovoltaic panel can convert solar energy into electrical energy during the period of low electricity prices. The energy storage device 1 is used to store the electrical energy and supply it to street lamps and household appliances for use during the peak electricity prices, or to supply power when the power grid is out of power / power outage.

[0067] See also Figure 2 , Figure 2 This is a schematic diagram of the structure of an energy storage system 400 according to an implementation scheme of the present application, and the present application Figure 2 The implementation plan is described using the shared energy storage scenario on the generation / distribution side as an example, and the energy storage device 1 of the present application is not limited to the energy storage scenario on the generation / distribution side.

[0068] The present application provides an energy storage system 400, which includes: a high-voltage cable 410, a first electric energy conversion device 420, a second electric energy conversion device 430 and an energy storage device 1 provided in the present application. In the case of power generation, the first electric energy conversion device 420 and the second electric energy conversion device 430 are used to convert other forms of energy into electric energy, which are connected to the high-voltage cable 410 and supplied to the power distribution network for use. When the power load is low and the first electric energy conversion device 420 and the second electric energy conversion device 430 generate excess power, the excess power is stored in the energy storage device 1, thereby reducing the wind and solar power abandonment rates and improving the problem of new energy power generation and consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 1 in conjunction with the high-voltage cable 410 in a grid-connected mode to the power consumption side, thereby providing peak shaving, frequency regulation, standby and other services for the power grid operation, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling of the power grid, and alleviating the power supply pressure of the power grid.

[0069] Optionally, the first electric energy conversion device 420 and the second electric energy conversion device 430 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy and mechanical energy into electric energy.

[0070] The number of energy storage devices 1 can be multiple, and multiple energy storage devices 1 are connected in series or in parallel. Multiple energy storage devices 1 are supported and electrically connected by isolation plates (not shown). In this embodiment, "multiple" refers to two or more. An energy storage box can also be provided outside the energy storage device 1 to accommodate the energy storage device 1.

[0071] Optionally, the energy storage device 1 may include but is not limited to a battery module, a battery pack, a battery system, etc. Among them, the battery module may be a battery module formed by connecting multiple batteries of the present application in series / parallel, the battery pack may include multiple batteries of the present application, and the battery system may be a charging and discharging system including the battery or battery pack of the present application.

[0072] The actual application form of the energy storage device 1 provided in the embodiment of the present application may be, but is not limited to, the listed products, and may also be other application forms. The embodiment of the present application does not strictly limit the application form of the energy storage device 1. The embodiment of the present application only takes the energy storage device 1 as a multi-core battery as an example for explanation. When the energy storage device 1 is a single battery, the energy storage device 1 may be at least one of a cylindrical battery, a square battery, and the like.

[0073] Example

[0074] Hereinafter, the embodiments of the present application will be described in more detail with reference to preparation examples, examples and comparative examples. Various tests and evaluations were performed according to the following methods.

[0075] Example 1-1

[0076] <Preparation of positive electrode sheet>

[0077] The positive electrode active material lithium iron phosphate (LiFePO 4 ), conductive carbon black (Super-P), and binder PVDF are mixed in a mass ratio of 97:0.7:2.3; then N-methylpyrrolidone (NMP) is added as a solvent to prepare a positive electrode slurry with a solid content of 60wt%, and stirred evenly, and then the positive electrode slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10μm, and dried at 85℃; then, the above steps are repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided positive electrode active material layer. After drying, cold pressing, slitting, and cutting, a positive electrode sheet is obtained. The single-sided thickness of the positive electrode active material layer is 100μm.

[0078] <Preparation of negative electrode sheet>

[0079] The negative electrode active material artificial graphite, conductive carbon black (Super-P), thickener carboxymethyl cellulose (CMC), and binder styrene butadiene rubber (SBR) are mixed in a mass ratio of 96.5:0.5:1:2, and deionized water is added to prepare a negative electrode slurry with a solid content of 50wt%, and stirred evenly. The negative electrode slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 6μm, and dried at 85℃; then, the above steps are repeated on the other surface of the copper foil to obtain a negative electrode sheet with a negative electrode active material layer coated on both sides. After drying, cold pressing, striping, and cutting, a negative electrode sheet is obtained. The single-sided thickness of the negative electrode active material layer is 70μm.

[0080] <Preparation of Electrolyte>

[0081] In an argon atmosphere glove box with a moisture content of ≤1ppm, EC, EMC, and DMC were mixed in a mass ratio of 1:1:2, and then lithium salt LiPF was added. 6 and dissolved in the above non-aqueous organic solvent, stirred until dissolved uniformly to obtain a basic electrolyte, and then added to the basic electrolyte a first additive (i.e., the compound represented by formula (I)), stirred until dissolved uniformly to obtain an electrolyte containing the first additive. 6 The concentration in the electrolyte is 13 wt %. The type and content of the first additive are shown in Table 1.

[0082] <Preparation of Separator>

[0083] A polyethylene (PE) porous polymer film with a thickness of 16 μm was used as the separator.

[0084] <Preparation of lithium-ion batteries>

[0085] The positive electrode sheet, separator and negative electrode sheet prepared above are stacked in order, with the separator placed between the positive and negative electrodes to play an isolating role, and wound to obtain a bare battery cell. After welding the pole ears, the bare battery cell is placed in an aluminum-plastic film packaging bag, and the electrolyte is injected after vacuum drying. After vacuum packaging, standing, formation, shaping, capacity testing and other processes, a lithium-ion battery is obtained.

[0086] Example 1-2 to Example 1-40

[0087] Except that the type and / or content of the first additive is adjusted according to Table 1 in <Preparation of Electrolyte>, the rest is the same as Example 1-1.

[0088] Example 2-1

[0089] Except that in <Preparation of Electrolyte>, a second additive is further added to the electrolyte, the rest is the same as Example 1-27. The type and content of the second additive are shown in Table 2.

[0090] Example 2-2 to Example 2-6

[0091] Except that the type and content of the second additive were adjusted as shown in Table 2 in <Preparation of Electrolyte>, the rest was the same as Example 2-1.

[0092] Example 3-1

[0093] Except that a second additive is further added to the electrolyte in <Preparation of electrolyte>, the rest is the same as Example 1-32. The type and content of the second additive are shown in Table 3.

[0094] Example 3-2 to Example 3-6

[0095] Except that the type and content of the second additive were adjusted as shown in Table 3 in <Preparation of Electrolyte>, the rest was the same as Example 3-1.

[0096] Comparative Example 1

[0097] Except that only the second additive VC is added to the basic electrolyte without adding the first additive in <Preparation of Electrolyte>, the rest is the same as Example 1-1. The mass percentage of the second additive in the electrolyte is 0.5%.

[0098] Comparative Example 2

[0099] The method is the same as Example 1-1 except that only the second additive FEC is added to the basic electrolyte without adding the first additive in <Preparation of Electrolyte> The mass percentage of the second additive in the electrolyte is 0.5%.

[0100] Comparative Example 3 to Comparative Example 4

[0101] Except that the content of the first additive is adjusted according to Table 1 in <Preparation of Electrolyte>, the rest is the same as Example 1-27.

[0102] Comparative Example 5 to Comparative Example 6

[0103] Except that the content of the first additive is adjusted according to Table 1 in <Preparation of Electrolyte>, the rest is the same as Example 1-32.

[0104] Table 1 Preparation parameters of Example 1-1 to Example 1-40 and Comparative Example 1 to Comparative Example 6

[0105]

[0106]

[0107]

[0108] Table 2 Preparation parameters of Examples 1-27, 2-1 to 2-6

[0109] Type of Second Additive Content of the second additive (wt%) Examples 1-27 / / Example 2-1 VC 0.1 Example 2-2 VC 0.5 Example 2-3 VC 3.0 Embodiment 2-4 FEC 0.1 Embodiment 2-5 FEC 0.5 Embodiment 2-6 FEC 3.0

[0110] Note: In Table 2, “ / ” indicates that there is no relevant preparation parameter.

[0111] Table 3 Preparation parameters of Examples 1-32, 3-1 to 3-6

[0112] Type of Second Additive Content of the second additive (wt%) Example 1-32 / / Example 3-1 VC 0.1 Example 3-2 VC 0.5 Example 3-3 VC 3.0 Embodiment 3-4 FEC 0.1 Embodiment 3-5 FEC 0.5 Embodiment 3-6 FEC 3.0

[0113] Note: In Table 3, “ / ” indicates that there is no relevant preparation parameter.

[0114] Test methods and equipment:

[0115] 25℃ 0.5P cycle performance test:

[0116] Use the Blue Power charge and discharge test equipment (model: CT3002N) to perform 0.5P constant power charge and discharge cycles on the lithium-ion battery at 25°C until it reaches 70% SOH (healthy state, i.e., discharge capacity divided by initial capacity), and record the number of cycles corresponding to 70% SOH at 25°C and 0.5P.

[0117] 45℃ 1P cycle performance test:

[0118] Use the Blue Electric charge and discharge test equipment (same model) to perform 1P constant power charge and discharge cycles on the lithium-ion battery at 45°C until the SOH is 70%, and record the number of cycles corresponding to 70% SOH at 45°C 1P.

[0119] Table 4 Performance data of each embodiment and comparative example

[0120]

[0121]

[0122]

[0123] It can be seen from Examples 1-1 to 1-40 and Comparative Examples 1 to 2 that when the electrolyte contains only the second additive but not the first additive, the number of cycles from room temperature (25°C) to 70% SOH of Comparative Examples 1 and 2 is small, and the number of cycles from high temperature (45°C) to 70% SOH is also small; while the number of cycles from room temperature (25°C) to 70% SOH and the number of cycles from high temperature (45°C) to 70% SOH of the lithium ion battery of the present application are both improved, indicating that the electrolyte of the present application can effectively improve the room temperature cycle performance and high temperature cycle performance of the lithium ion battery and extend the cycle life of the lithium ion battery.

[0124] From Examples 1-25 to 1-29 and Comparative Examples 3 to 4, it can be seen that when the content of the first additive in the electrolyte is too little (e.g., Comparative Example 3), the number of cycles of the lithium-ion battery from normal temperature (25°C) to 70% SOH and the number of cycles of the lithium-ion battery from high temperature (45°C) to 70% SOH are both less, which may be due to the limited effect of the first additive with too low content on the improvement of the normal and high temperature cycle performance of the lithium-ion battery; when the content of the first additive in the electrolyte is too much (e.g., Comparative Example 4), the number of cycles of the lithium-ion battery from normal temperature (25°C) to 70% SOH and the number of cycles of the lithium-ion battery from high temperature (45°C) to 70% SOH are also less, which may be due to the fact that the first additive with too high content leads to a thicker SEI film, which in turn leads to a larger interface impedance, inhibiting the improvement of the normal and high temperature cycle performance of the lithium-ion battery. The above conclusion can also be drawn from the performance data of Examples 1-30 to 1-34 and Comparative Examples 5 to 6.

[0125] From Examples 1-27 and 2-1 to 2-6, it can be seen that by further adding the second additive to the electrolyte, the number of cycles of the lithium-ion battery from room temperature (25°C) to 70% SOH and the number of cycles from high temperature (45°C) to 70% SOH are further increased. This may be due to the synergistic effect of the second additive and the first additive, thereby further improving the room temperature cycle performance and high temperature cycle performance of the lithium-ion battery and further extending the cycle life of the lithium-ion battery. The above conclusion can also be drawn from the performance data of Examples 1-32 and 3-1 to 3-6.

[0126] Figure 3 The photos of electrolyte sample No. 1, electrolyte sample No. 2, electrolyte sample No. 3 and electrolyte sample No. 4 are shown in FIG. 1 , wherein electrolyte sample No. 1 is the basic electrolyte prepared in Example 1-1, and electrolyte sample No. 2 is the basic electrolyte with 0.5 wt% LiNO added thereto. 3 The electrolyte obtained after the reaction was: electrolyte sample No. 3 was the electrolyte obtained in Example 1-32, and electrolyte sample No. 4 was the electrolyte obtained in Example 1-33. Figure 1 It can be seen that the No. 1 electrolyte sample is colorless, clear and transparent, while the No. 2 electrolyte sample has LiNO 3 It is difficult to dissolve and forms a white suspension. Electrolyte samples No. 3 and No. 4 are also colorless, clear and transparent, indicating that the first additive of the present application is easily soluble in the carbonate system electrolyte and has good potential for large-scale industrial application.

[0127] The above is a detailed introduction to an electrolyte, a battery containing the electrolyte, an energy storage device and an electrical equipment disclosed in the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core inventions of the embodiments of the present application. At the same time, for general technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An electrolyte, characterized in that: It includes a non-aqueous organic solvent and a first additive, wherein the non-aqueous organic solvent includes a carbonate compound, and the first additive includes a compound represented by formula (I): In formula (I), R1 to R 10 Each is independently selected from hydrogen, nitro, substituted or unsubstituted alkyl, and R1 to R 10 At least one of them is nitro; Based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is a, 0.01%≤a≤10%.

2. The electrolyte according to claim 1, characterized in that 0.1％≤a≤1％。 3. The electrolyte according to claim 1, characterized in that The compound represented by formula (I) is selected from at least one of the following compounds:

4. The electrolyte according to claim 1, characterized in that The carbonate compound includes at least one of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate.

5. The electrolyte according to any one of claims 1 to 3, characterized in that The electrolyte further includes a second additive including at least one of vinylene carbonate and fluoroethylene carbonate.

6. The electrolyte according to claim 5, characterized in that Based on the mass of the electrolyte, the mass percentage of the vinylene carbonate is b, the mass percentage of the fluoroethylene carbonate is c, 0.01%≤b≤10%, and / or, 0.01%≤c≤10%.

7. The electrolyte according to claim 5, characterized in that Based on the mass of the electrolyte, 0.1%≤b≤3%, and / or, 0.1%≤c≤3%.

8. A battery, characterized in that: The electrolyte comprises the electrolyte according to any one of claims 1 to 7.

9. An energy storage device, characterized in that: The invention comprises a casing and at least one battery according to claim 8, wherein the battery is accommodated in the casing.

10. An electrical device, characterized in that: It includes the energy storage device as described in claim 9, and the energy storage device supplies power to the electrical equipment.

Images