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 first additive, the first additive comprises a compound shown in a formula (I), in the formula (I), R1, R2, R3, R4 and R5 are independently selected from hydrogen and alkynyl of C2-C10, and at least two of R1 to R5 are alkynyl; based on the mass of the electrolyte, the mass percentage content of the compound shown in the formula (I) is A, and 0.1% < = A < = 5%. # 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 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 cycle performance of the secondary battery, thereby increasing the long-term service life of the secondary battery in energy storage application scenarios.

[0005] In a first aspect, the present application provides an electrolyte, comprising a first additive, wherein the first additive comprises a compound represented by formula (I):

[0006]

[0007] In formula (I), R1, R2, R3, R4, and R5 are each independently selected from hydrogen, C2 to C 10 alkynyl, and at least two of R1 to R5 are alkynyl; based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is A, 0.1%≤A≤5%.

[0008] In some embodiments of the present application, 0.3%≤A≤3%.

[0009] In some embodiments of the present application, the compound represented by formula (I) is selected from at least one of the following compounds:

[0010]

[0011] In some embodiments of the present application, the electrolyte further includes a second additive, the second additive including at least one of fluoroethylene carbonate, vinylene carbonate, tris(trimethylsilyl)phosphate and vinyl sulfate, and based on the mass of the electrolyte, the mass percentage of the second additive is B, 0.1%≤B≤10%.

[0012] In some embodiments of the present application, 0.1%≤B≤4%.

[0013] In some embodiments of the present application, the electrolyte further includes a non-aqueous organic solvent, and the non-aqueous organic solvent includes at least one of a cyclic carbonate, a chain carbonate, and a carboxylate.

[0014] In some embodiments of the present application, the cyclic carbonate includes at least one of ethylene carbonate and propylene carbonate; the chain carbonate includes at least one of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; the carboxylic acid ester includes at least one of propyl acetate, ethyl acetate and propyl propionate.

[0015] In a second aspect, the present application provides a battery, comprising the electrolyte described in the first aspect.

[0016] In some embodiments of the present application, the battery further comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material comprises LiFePO4, LiFe 1-a M a PO4, LiCoO2, LiMn2O4, LiMnO2, Li2MnO4, Li 1+b Mn 1-a M a O2、LiCo 1-a M a O2、Li2Mn 1-a Any one of O4, wherein M is selected from at least one of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B and F, 0≤a<1, 0≤b<0.2.

[0017] 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.

[0018] 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.

[0019] Compared with the prior art, this application has at least the following beneficial effects:

[0020] The present application provides an electrolyte, a battery containing the electrolyte, an energy storage device and an electrical device, wherein the electrolyte includes a first additive, 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, 0.1%≤A≤5%, so that the ionic conductivity of the SEI (Solid Electrolyte Interphase) membrane can be improved while improving the stability of the SEI membrane. This SEI membrane has the advantages of high ionic conductivity and good stability, thereby improving the cycle performance 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 is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 A schematic diagram of the structure of a household energy storage system according to an implementation scheme of the present application;

[0023] Figure 2 A schematic diagram of the structure of an energy storage system according to an implementation scheme of the present application.

[0024] 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

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] It should be noted that, in the present application, a lithium-ion battery is used as an example of a secondary battery to explain the present application, but the secondary battery of the present application is not limited to a lithium-ion battery.

[0031] In view of this, the present application provides an electrolyte, which includes a first additive, and the first additive includes a compound represented by formula (I):

[0032]

[0033] In formula (I), R1, R2, R3, R4, and R5 are each independently selected from hydrogen, C2 to C 10 alkynyl, and at least two of R1 to R5 are alkynyl; based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is A, 0.1%≤A≤5%; in another optional embodiment, 0.3%≤A≤3%. For example, A is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1%, 3% or 5%.

[0034] The inventors have found that the compound represented by formula (I) of the present application (hereinafter referred to as the compound of formula (I)) helps to improve the stability and ionic conductivity of the SEI film. This may be because the molecular structure of the compound of formula (I) contains two acetylene groups, which can enable multiple molecules of the compound of formula (I) to polymerize through the unsaturated bonds in the two acetylene groups, thereby forming a "hand-in-hand" structure between multiple molecules of the compound of formula (I), which is conducive to the formation of a dense and uniform SEI film layer, thereby facilitating the improvement of the stability of the SEI film. If the molecular structure contains only one acetylene group, it is difficult to form the above-mentioned "hand-in-hand" structure; and the compound of formula (I) contains a pyridine ring, which can generate a nitrogen-containing inorganic SEI component (such as Li3N) during the reduction process. This inorganic SEI component has high ionic conductivity characteristics, can effectively accelerate the diffusion of lithium ions, and reduce interfacial side reactions. Under the action of the above multiple factors, the stability and ionic conductivity of the SEI film are simultaneously improved. The inventors further discovered that the content of the compound of formula (I) should not be too low or too high. When the content of the compound of formula (I) is too low (for example, less than 0.1%), the SEI film is less, and it is difficult to form effective protection for the negative electrode interface. In addition, the generated nitrogen-containing inorganic SEI component is small, and the ionic conductivity of the SEI film is low; when the content of the compound of formula (I) is too high (for example, higher than 5%), the SEI film is thicker, which affects the diffusion of lithium ions, resulting in the ionic conductivity of the SEI film being also low. By regulating the content of the compound of formula (I) within the above range, it is beneficial to obtain a SEI film with high ionic conductivity and good interface stability. When the lithium-ion battery of the present application is applied to an energy storage device, the service life of the energy storage device is increased, thereby reducing the operating cost of the energy storage device.

[0035] In some embodiments of the present application, the compound represented by formula (I) is selected from at least one of the following compounds:

[0036]

[0037] In some embodiments of the present application, the electrolyte further includes a second additive, the second additive includes at least one of fluoroethylene carbonate (FEC), vinylene carbonate (VC), tris(trimethylsilyl) phosphate and vinyl sulfate, and the mass percentage of the second additive is B based on the mass of the electrolyte, 0.1%≤B≤10%; in another optional embodiment, 0.1%≤B≤4%. For example, B is 0.1%, 0.5%, 1%, 4%, 5% or 10%. Including the above-mentioned second additive in the electrolyte and regulating the content of the second additive within the above range is conducive to the formation of alkyl lithium carbonate, lithium fluoride (LiF), Li x PO y F zAnd Li2S SEI film, thereby further improving the stability of the SEI film, and has little effect on the ionic conductivity of the SEI film, which is beneficial to further improve the cycle performance of lithium-ion batteries.

[0038] In some embodiments of the present application, the electrolyte further includes a non-aqueous organic solvent, and the non-aqueous organic solvent includes at least one of a cyclic carbonate, a chain carbonate, and a carboxylic acid ester.

[0039] In some embodiments of the present application, the cyclic carbonate includes at least one of ethylene carbonate (EC) and propylene carbonate (PC); the chain carbonate includes at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC); the carboxylic acid ester includes at least one of propyl acetate, ethyl acetate and propyl propionate.

[0040] 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%.

[0041] The present application has no particular restrictions on the preparation process of the electrolyte. For example, at least one of the above-mentioned cyclic carbonates, chain carbonates and carboxylates can be mixed in a certain mass ratio, and then lithium salt is added to dissolve and mix evenly, and then electrolyte additives such as the compound of formula (I) are added and dissolved.

[0042] The present application has no particular limitation on the lithium salt. For example, the lithium salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium dioxalatoborate (LiBOB), lithium difluorooxalatophosphate (LiODFP), lithium difluorooxalatoborate (LiODFB), lithium difluorophosphate (LiPO2F2) and lithium trifluoromethanesulfonate (CF3SO3Li).

[0043] The present application also provides a battery, comprising the electrolyte described in any embodiment of the present application.

[0044] 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.

[0045] In some embodiments of the present application, the battery further comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material comprises LiFePO4, LiFe 1-a M a PO4, LiCoO2, LiMn2O4, LiMnO2, Li2MnO4, Li 1+bMn 1-a M a O2、LiCo 1-a M a O2、Li2Mn 1-a Any one of O4, wherein M is selected from at least one of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B and F, 0≤a<1, 0≤b<0.2.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 can include at least one of artificial graphite, natural graphite soft carbon, hard carbon, silicon, silicon carbon and silicon oxygen negative electrode.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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 the 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] Example

[0066] 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.

[0067] Example 1-1

[0068] <Preparation of positive electrode sheet>

[0069] The positive electrode active material lithium iron phosphate (LiFePO4), 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 cold pressing, striping, and cutting, a positive electrode sheet is obtained. The single-sided thickness of the positive electrode active material layer is 100μm.

[0070] <Preparation of negative electrode sheet>

[0071] 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 cold pressing, striping, and cutting, a negative electrode sheet is obtained. The single-sided thickness of the negative electrode active material layer is 70μm.

[0072] <Preparation of Electrolyte>

[0073] In an argon atmosphere glove box with a moisture content of ≤1ppm, ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 1:2:1, and then lithium salt LiPF6 is added and dissolved in the above-mentioned non-aqueous organic solvent, and stirred until it is uniformly dissolved to obtain a basic electrolyte, and then the first additive (i.e., the compound of formula (I)) is added to the basic electrolyte, and stirred until it is uniformly dissolved to obtain an electrolyte containing the first additive. Among them, the concentration of LiPF6 in the electrolyte is 12.5wt%, and the type and content of the first additive are shown in Table 1.

[0074] <Preparation of Separator>

[0075] A 16 μm thick polypropylene (PP) porous polymer film was used as the separator.

[0076] <Preparation of lithium-ion batteries>

[0077] 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.

[0078] Example 1-2 to Example 1-9

[0079] Except that the content of the first additive was adjusted according to Table 1 in <Preparation of Electrolyte>, the rest was the same as Example 1-1.

[0080] Example 1-10 to Example 1-14

[0081] Except that the type of the first additive was adjusted according to Table 1 in <Preparation of Electrolyte>, the rest was the same as Example 1-3.

[0082] Example 1-15 to Example 1-19

[0083] Except that the type of the first additive was adjusted according to Table 1 in <Preparation of Electrolyte>, the rest was the same as Example 1-8.

[0084] Example 2-1

[0085] Except that a second additive is further added to the electrolyte in <Preparation of Electrolyte>, the rest is the same as Example 1-3. The type and content of the second additive are shown in Table 2.

[0086] Example 2-2 to Example 2-5

[0087] Except that the content of the second additive was adjusted according to Table 2 in <Preparation of Electrolyte>, the rest was the same as Example 2-1.

[0088] Example 2-6 to Example 2-8

[0089] Except that the type of the second additive was adjusted according to Table 2 in <Preparation of Electrolyte>, the rest was the same as Example 2-4.

[0090] Comparative Example 1 to Comparative Example 2

[0091] Except that the content of the first additive was adjusted according to Table 1 in <Preparation of Electrolyte>, the rest was the same as Example 1-1.

[0092] Comparative Example 3

[0093] 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%.

[0094] Table 1: Preparation parameters of Examples 1-1 to 1-19 and Comparative Examples 1 to 3

[0095]

[0096]

[0097] Note: In Table 1, “ / ” indicates that there is no relevant preparation parameter.

[0098] Table 2: Preparation parameters of Examples 1-3, 2-1 to 2-8

[0099] Type of Second Additive Content of the second additive (wt%) Examples 1-3 / / Example 2-1 VC 0.1 Example 2-2 VC 0.5 Example 2-3 VC 1.0 Embodiment 2-4 VC 4.0 Embodiment 2-5 VC 10.0 Embodiment 2-6 FEC 4.0 Embodiment 2-7 Tris(trimethylsilyl)phosphate 4.0 Embodiment 2-8 Vinyl Sulfate 4.0

[0100] Note: In Table 2, “ / ” indicates that there is no relevant preparation parameter.

[0101] Test methods and equipment:

[0102] DC resistance (DCR) test:

[0103] The test temperature is 25℃. The lithium-ion battery is charged to 3.65V at a constant current of 0.5 times (C), then charged to a current of 0.05C at a constant voltage of 3.65V, and then left to stand for 30 minutes. Then, it is cycled 9 times according to the following process: discharge at a constant current of 0.1C for 60 minutes, stand for 60 minutes, record the voltage V1 after standing for 60 minutes, then discharge at a constant current of 1.07C for 30 seconds, record the voltage V2 at the end of discharge; then stand for 40 seconds, then charge at a constant current of 1.07C for 30 seconds, and stand for 10 minutes. The state of charge (SOC) after the end of the 5th cycle discharge is taken as the 50% SOC of the lithium-ion battery. According to the V1 and V2 recorded in the 5th cycle, the discharge DCR is calculated according to the following formula: DCR = (V1-V2) / I, where I = 1.07C.

[0104] 45℃ Cyclic Performance Test:

[0105] The lithium-ion batteries prepared in the embodiments and comparative examples were subjected to a charge and discharge cycle test on a charge and discharge instrument (model: Nebula charge and discharge test system BAT-NEEFLCT-05300-V010). The test temperature was 45°C. The lithium-ion batteries were charged to 3.65V at 1P constant current, and then discharged to 2.5V at 1P constant power. This is one charge and discharge cycle. The capacity retention rate of the battery after 500 cycles is calculated by charging / discharging in this way. The capacity retention rate calculation formula is: Capacity retention rate after the 500th cycle = (discharge capacity after the 500th cycle / discharge capacity of the first cycle) × 100%.

[0106] Table 3 Performance data of each embodiment and comparative example

[0107]

[0108]

[0109] It can be seen from Examples 1-1 to 1-9 and Comparative Examples 1 to 2 that when the content of the first additive (i.e., the compound of formula (I)) is too low (e.g., Comparative Example 1), the DCR of the lithium-ion battery is high and the capacity retention rate after 500 cycles at 45°C is low. This may be because when the content of the first additive is too low, less SEI film is formed, it is difficult to form effective protection for the negative electrode interface, and the generated nitrogen-containing inorganic SEI component is small, and the SEI film ion conductivity is low; when the content of the first additive is too high (e.g., Comparative Example 2), the lithium-ion battery has a high DCR and a low capacity retention rate after 500 cycles at 45°C. The DCR of the battery is relatively high and the capacity retention rate after 500 cycles at 45°C is relatively low. This may be because when the content of the first additive is too high, the SEI film is thicker, which affects the diffusion of lithium ions, resulting in the ionic conductivity of the SEI film being also low; while the lithium-ion battery of the present application has a low DCR and a high capacity retention rate after 500 cycles at 45°C, indicating that the electrolyte of the present application can effectively improve the ionic conductivity and stability of the SEI film, thereby reducing the DCR of the lithium-ion battery and improving the cycle performance of the lithium-ion battery, especially the high-temperature cycle performance.

[0110] The type of the first additive (i.e., the compound of formula (I)) will generally also affect the performance of the lithium-ion battery. It can be seen from Examples 1-1 and 1-10 to 1-14 that by regulating the type of the compound of formula (I) within the scope of this application, it is beneficial to obtain a lithium-ion battery with low DCR and excellent cycle performance. The above conclusion can also be drawn from the performance data of Examples 1-8 and 1-15 to 1-19.

[0111] It can be seen from Examples 1-3 and 2-1 to 2-5 that by further adding the second additive to the electrolyte, the capacity retention rate of the lithium-ion battery after 500 cycles at 45°C is further improved, and the DCR increases slightly. This may be due to the synergistic effect of the second additive and the first additive, which further improves the cycle performance of the lithium-ion battery with little effect on the DCR.

[0112] It can be seen from Example 1-1 and Comparative Example 3 that when the electrolyte contains only the second additive but not the first additive, the capacity retention rate of the lithium-ion battery after 500 cycles at 45°C is low and the DCR is high. This may be because the second additive cannot produce a synergistic effect with the first additive, and thus it is difficult to effectively improve the cycle performance of the lithium-ion battery.

[0113] The type of the second additive will usually also affect the performance of the lithium-ion battery. It can be seen from Example 2-1 and Example 2-6 to Example 2-8 that by adjusting the type of the second additive within the scope of this application, it is beneficial to obtain a lithium-ion battery with low DCR and excellent cycle performance.

[0114] 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: The invention comprises a first additive, wherein the first additive comprises a compound represented by formula (I): In formula (I), R1, R2, R3, R4, and R5 are each independently selected from hydrogen, C2 to C 10 alkynyl, and at least two of R1 to R5 are alkynyl; Based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is A, and 0.1%≤A≤5%.

2. The electrolyte according to claim 1, characterized in that 0.3％≤A≤3％。 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 electrolyte also includes a second additive, which includes at least one of fluoroethylene carbonate, vinylene carbonate, tris(trimethylsilyl)phosphate and vinyl sulfate. Based on the mass of the electrolyte, the mass percentage of the second additive is B, 0.1%≤B≤10%.

5. The electrolyte according to claim 4, characterized in that 0.1％≤B≤4％。 6. The electrolyte according to any one of claims 1 to 5, characterized in that The electrolyte solution further includes a non-aqueous organic solvent, and the non-aqueous organic solvent includes at least one of a cyclic carbonate, a chain carbonate, and a carboxylate.

7. The electrolyte according to claim 6, characterized in that The cyclic carbonate includes at least one of ethylene carbonate and propylene carbonate; the chain carbonate includes at least one of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; the carboxylic acid ester includes at least one of propyl acetate, ethyl acetate and propyl propionate.

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

9. The battery according to claim 8, characterized in that The battery also includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes LiFePO4, LiFe 1-a M a PO4, LiCoO2, LiMn2O4, LiMnO2, Li2MnO4, Li 1+b Mn 1-a M a O2、LiCo 1-a M a O2、Li2Mn 1- a Any one of O4, wherein M is selected from at least one of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B and F, 0≤a<1, 0≤b<0.

2.

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

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

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