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 compound shown in a formula (I) and a compound shown in a formula (II), in the formula (I), R1 is selected from hydrogen, substituted or unsubstituted C1-C6 alkylene, and substituted or unsubstituted C2-C6 alkenylene; in the formula (II), R2, R3, R4, R5 and R6 are independently selected from hydrogen or fluorine atoms, and at least one of R2-R6 is a fluorine atom. # 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 overcharge safety performance and cycle performance to ensure the safety and 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 overcharge safety performance and cycle performance of a secondary battery.

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

[0006]

[0007] In formula (I), R1 is selected from hydrogen, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkenylene;

[0008] In formula (II), R2, R3, R4, R5, and R6 are each independently selected from hydrogen or fluorine atoms, and at least one of R2 to R6 is a fluorine atom.

[0009] In some embodiments of the present application, based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is a, the mass percentage of the compound represented by formula (II) is b, 0.1%≤a≤1%, and 0.1%≤b≤1%.

[0010] In some embodiments of the present application, 0.1%≤a≤0.5%.

[0011] In some embodiments of the present application, 0.1≤a / b≤5.

[0012] In some embodiments of the present application, the compound represented by formula (I) is selected from at least one of the following compounds:

[0013]

[0014] In some embodiments of the present application, the compound represented by formula (II) is selected from at least one of the following compounds:

[0015]

[0016] In a second aspect, the present application provides a battery, comprising the electrolyte described in the first aspect.

[0017] In some embodiments of the present application, the battery further comprises a negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode material layer, wherein the negative electrode material layer comprises a negative electrode active material, and in the Raman spectrum of the negative electrode active material, at 1300 cm -1 Up to 1400cm -1 There is a peak intensity of I in the range D The first characteristic peak at 1550cm -1 Up to 1650cm -1 There is a peak intensity of I in the range G The second characteristic peak, 0.1≤I D / I G ≤0.4.

[0018] In some embodiments of the present application, 0.5≤(a+b)×100 / (I D / I G )≤15.

[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 equipment, wherein the electrolyte comprises a compound represented by formula (I) and a compound represented by formula (II), wherein the compound represented by formula (I) contains a triazole group and a carboxylate group, and the compound represented by formula (II) is a fluorine-containing pyridine compound. The electrolyte of the present application comprises the compound represented by formula (I) and the compound represented by formula (II), and under the synergistic effect of the above two compounds, the overcharge safety performance of the secondary battery is improved while the cycle performance of the battery is improved. When the secondary battery of the present application is used in an energy storage device, the safety and service life of the energy storage device are 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] 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

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] At present, the requirements for overcharge safety of wind and solar energy storage equipment are getting higher and higher, and the improvement of overcharge safety performance of energy storage equipment depends on the development of lithium-ion battery materials. During the overcharge test, as the overcharge proceeds, the voltage of the lithium-ion battery continues to rise, the electrolyte oxidizes at the positive electrode, and the heat generation of the lithium-ion battery cell increases rapidly. The heat generation of the cell causes its temperature to rise rapidly. The increase in the temperature of the cell further promotes the reaction of the electrolyte at the positive electrode / electrolyte interface and the negative electrode / electrolyte interface, thereby causing the cell to further accumulate heat. If the cell cannot quickly reach the overcharge cut-off condition at this time, under the condition of continuous charging, the continuous heat accumulation is likely to cause a chain reaction in the chemical system, causing the reaction heat to continue to accumulate, affecting the safety performance of the lithium-ion battery, and thus affecting the safety of the energy storage device. In the related art, by adjusting the closed-pore temperature of the diaphragm base film, that is, the diaphragm base film closes after the cell reaches a certain temperature, so that the voltage rises rapidly, the overcharged cell reaches the voltage cut-off condition, thereby reducing the risk of thermal runaway of the cell. However, although the battery cell reaches the overcharge cut-off condition when the diaphragm base film is closed, if the heat generation in the early stage is rapid at this time, the reaction inside the battery cell may have been unable to stop due to the chain reaction, which can still easily cause thermal runaway of the battery cell.

[0034] In view of this, the present application provides an electrolyte, which includes a compound represented by formula (I) and a compound represented by formula (II):

[0035]

[0036] In formula (I), R1 is selected from hydrogen, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkenylene;

[0037] In formula (II), R2, R3, R4, R5, and R6 are each independently selected from hydrogen or fluorine atoms, and at least one of R2 to R6 is a fluorine atom.

[0038] The electrolyte of the present application contains the compound represented by the above formula (I) and the compound represented by the formula (II), which can improve the overcharge safety performance of the lithium-ion battery. This may be because: the compound represented by the formula (I) contains two functional groups, a triazole group and a carboxylate group, wherein the triazole group can participate in the film formation at the negative electrode interface to form a SEI (Solid Electrolyte The SEI film formed by the above method has the characteristics of high density and good flexibility; the carboxylate group is easier to combine with lithium ions, which can increase the proportion of the compound molecules represented by formula (I) on the Helmholtz layer, so that the compound represented by formula (I) can reach the negative electrode / electrolyte interface more quickly and easily, so that the compound represented by formula (I) has more opportunities to obtain electrons at the negative electrode and undergo reduction reaction, thereby promoting the formation of the SEI film at the negative electrode interface; the compound represented by formula (II) contains a relatively rich fluorine element. During the film formation process at the negative electrode interface, the compound represented by formula (II) can remove fluorine atoms to generate more inorganic components such as LiF in the SEI film. Under the joint action of the organic polymer formed by the compound represented by formula (I), an SEI film with organic components and inorganic components staggered is formed, and this SEI film has excellent thermal stability. Moreover, during the overcharge process, since the organic components of the SEI film account for a high proportion and have good compactness, it can effectively prevent the solvent in the electrolyte from reacting with the lithiated graphite, avoiding the temperature rising too sharply and causing too fast a chain reaction, thereby reducing the heat generated by the reaction; and the inorganic components in the above SEI film can enhance the thermal stability of the SEI film, protecting the organic components in the SEI film from being broken and dissolved in large quantities during overcharge. In summary, under the combined action of the compound represented by formula (I) and the compound represented by formula (II), the overcharge safety performance of the lithium-ion battery is improved, and the cycle performance of the lithium-ion battery is also improved.

[0039] In some embodiments of the present application, based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is a, and the mass percentage of the compound represented by formula (II) is b, 0.1%≤a≤1%, and 0.1%≤b≤1%; in other embodiments, 0.1%≤a≤0.5%. For example, a is 0.1%, 0.5%, 0.6%, 0.8%, 0.9% or 1%; b is 0.1%, 0.5%, 0.6%, 0.8%, 0.9% or 1%. By regulating the content of the compound represented by formula (I) and the compound represented by formula (II) within the above range, it is beneficial to obtain a lithium ion battery with excellent overcharge safety performance and cycle performance.

[0040] In some embodiments of the present application, 0.1≤a / b≤5. For example, a / b=0.1, a / b=0.2, a / b=0.5, a / b=0.8, a / b=1, a / b=1.5, a / b=3 or a / b=5. By regulating a / b within the above range, the lithium-ion battery has good overcharge safety performance and the cycle performance is further improved.

[0041] In some embodiments of the present application, the compound represented by formula (I) is selected from at least one of the following compounds:

[0042]

[0043]

[0044] By selecting at least one of the compounds of formula (I-1) to formula (I-4) above, it is beneficial to exert a synergistic effect with the compound represented by formula (II), so that the lithium-ion battery exhibits excellent overcharge safety performance and cycle performance.

[0045] In some embodiments of the present application, the compound represented by formula (II) is selected from at least one of the following compounds:

[0046]

[0047] By selecting at least one of the compounds represented by the above formulas (II-1) to (II-4), the lithium-ion battery exhibits excellent overcharge safety performance and cycle performance. In addition, the compounds represented by the above formulas (II-1) to (II-4) are rich in fluorine (F) element. During the film formation process at the negative electrode competing with the compound represented by formula (I), the compounds represented by the above formulas (II-1) to (II-4) can remove F to produce more inorganic components such as LiF, thereby forming a SEI film with an organic and inorganic staggered distribution, which is beneficial to further improve the thermal stability of the SEI film.

[0048] The electrolyte of the present application may further include an organic solvent. For example, the electrolyte may further include a cyclic carbonate and a chain carbonate. 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 present application has no particular restrictions on the content of the organic solvent. For example, the mass percentage of the organic solvent in the electrolyte is 65% to 90%.

[0049] The present application has no particular restrictions on the preparation process of the electrolyte. For example, at least one of ethylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, ethyl methyl carbonate, dimethyl carbonate and vinylene carbonate can be mixed in a certain mass ratio or volume ratio to obtain a non-aqueous organic solvent, and then the compound represented by formula (I) and the compound represented by formula (II) are added, and then lithium salt is added to dissolve and mix evenly.

[0050] The present application has no particular limitation on the lithium salt. For example, the lithium salt includes at least one of LiPF6, LiBF4, LiFSI, LiTFSI, LiBOB, LiODFP, LiODFB, LiPO2F2 or CF3SO3Li.

[0051] The present application has no particular restrictions on the concentration of lithium salt in the electrolyte, as long as the purpose of the present application can be achieved. Taking LiPF6 as an example, the concentration of LiPF6 in the electrolyte is 10wt% to 15wt%, for example, the concentration of LiPF6 is 10wt%, 11wt%, 12wt%, 13wt% or 15wt%.

[0052] The present application also provides a battery, comprising the electrolyte described in any embodiment of the present application.

[0053] In some embodiments of the present application, the battery further comprises a negative electrode sheet, the negative electrode sheet comprises a negative electrode material layer, the negative electrode material layer comprises a negative electrode active material, and in the Raman spectrum of the negative electrode active material, at 1300 cm -1 Up to 1400cm -1 There is a peak intensity of I in the range D The first characteristic peak at 1550cm -1 Up to 1650cm -1 There is a peak intensity of I in the range G The second characteristic peak, 0.1≤I D / I G ≤0.4. For example, I D / I G = 0.1, 0.2, 0.3 or 0.4, by adjusting I D / I G Within the above range, ID / I G The value is relatively small, and the kinetic performance of the negative electrode active material is good, which is beneficial to the improvement of the cycle performance of lithium-ion batteries.

[0054] The present application relates to the negative electrode active material I D / I G There is no particular limitation on the way to control the value of as long as the purpose of the present application can be achieved. For example, the graphitization degree of the negative electrode active material can be adjusted to adjust the I of the negative electrode active material. D / I G For example, the graphitization degree of the negative electrode active material increases, I D / I G The value of increases; the graphitization degree of the negative electrode active material decreases, I D / I G The value of decreases.

[0055] In some embodiments of the present application, 0.5≤(a+b)×100 / (I D / I G )≤15. For example, (a+b)×100 / (I D / I G )=0.5, 1, 3, 5, 8, 10 or 15. The inventors have found that I D / I G The amount of surface defects of the negative electrode active material (such as graphite) can be characterized by controlling I D / I G Thus, the amount of defect points is controlled, and the defect positions on the graphite surface are oxidized to generate hydroxyl groups; nitrogen (N) on the compound represented by formula (I) and the compound represented by formula (II) contains lone electron pairs, which are easy to complex with hydrogen (H) on the hydroxyl groups of the graphite defect points. Based on this, by controlling (a+b)×100 / (I D / I G ) Within the above range, during the charging process, the film is formed more accurately at the defective positions of the graphite to generate organic polymers and inorganic substances such as Li3N, thereby improving the thermal stability of the SEI film and enhancing the overcharge safety performance of the lithium-ion battery.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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, mesophase carbon microbeads, silicon, and silicon carbon.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] Example

[0078] 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.

[0079] Example 1-1

[0080] <Preparation of positive electrode sheet>

[0081] 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, and then cold pressed, striped, and cut to obtain a positive electrode sheet. The single-sided thickness of the positive electrode active material layer is 100μm.

[0082] <Preparation of negative electrode sheet>

[0083] 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, and then the negative electrode sheet is obtained after cold pressing, striping, and cutting. The single-sided thickness of the negative electrode active material layer is 70μm.

[0084] <Preparation of Electrolyte>

[0085] 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 1:1:1, and then lithium salt LiPF6 is added and dissolved in the above solvent, stirred until dissolved evenly, and then the compound represented by formula (I) and the compound represented by formula (II) are added. Among them, the types and contents of the compound represented by formula (I) and the compound represented by formula (II) are shown in Table 1, and the concentration of LiPF6 in the electrolyte is 13wt%.

[0086] <Preparation of Separator>

[0087] A polyethylene (PE) porous polymer film with a thickness of 16 μm was used as the separator.

[0088] <Preparation of lithium-ion batteries>

[0089] 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.

[0090] Example 1-2 to Example 1-10

[0091] Except that the contents of the compound represented by formula (I) and the compound represented by formula (II) are adjusted according to Table 1 in <Preparation of electrolyte>, the rest is the same as Example 1-1.

[0092] Example 1-11 to Example 1-14

[0093] Except that the types of the compound represented by formula (I) and the compound represented by formula (II) are adjusted according to Table 1 in <Preparation of electrolyte>, the rest is the same as Example 1-2.

[0094] Example 2-1 to Example 2-3

[0095] In addition to adjusting the graphitization degree of the negative electrode active material to adjust I D / I G , (a+b)×100 / (I D / I G ) are changed accordingly, the rest is the same as Example 1-2.

[0096] Embodiment 2-4

[0097] Except that in <Preparation of Electrolyte>, the content of the compound of formula (Ⅰ-1) in the electrolyte is adjusted to 0.5wt% and the content of the compound of formula (Ⅱ-4) in the electrolyte is adjusted to 1.0wt%, then a+b=1.5%, the rest is the same as Example 2-1.

[0098] Comparative Example 1

[0099] Except that the compound represented by formula (I) and the compound represented by formula (II) are not added in <Preparation of electrolyte>, the rest is the same as Example 1-1.

[0100] Comparative Example 2 to Comparative Example 6

[0101] Except that the contents of the compound represented by formula (I) and the compound represented by formula (II) are adjusted according to Table 1 in <Preparation of electrolyte>, the rest is the same as Example 1-1.

[0102] Table 1: Preparation parameters of Examples 1-1 to 1-14 and Comparative Examples 1 to 6

[0103]

[0104]

[0105] Note: In Table 1, “\” indicates that there are no relevant preparation parameters.

[0106] Table 2: Preparation parameters of Examples 1-1 to 1-15, Examples 2-1 to 2-4, and Comparative Examples 1 to 6

[0107] a+b(wt%) <![CDATA[I D / I G ]]> <![CDATA[(a+b)×100 / (I D / I G )]]> Example 1-1 0.6 0.25 2.4 Example 1-2 0.8 0.25 3.2 Examples 1-3 1.0 0.25 4 Examples 1-4 1.5 0.25 6 Examples 1-5 0.4 0.25 1.6 Examples 1-6 0.6 0.25 2.4 Examples 1-7 1.0 0.25 4 Examples 1-8 1.3 0.25 5.2 Examples 1-9 0.6 0.25 2.4 Examples 1-10 1.1 0.25 4.4 Embodiment 1-11 0.8 0.25 3.2 Examples 1-12 0.8 0.25 3.2 Examples 1-13 0.8 0.25 3.2 Examples 1-14 0.8 0.25 3.2 Example 2-1 0.8 0.1 8 Example 2-2 0.8 0.34 2.35 Example 2-3 0.8 0.4 2 Embodiment 2-4 1.5 0.1 15 Comparative Example 1 \ \ \ Comparative Example 2 0.1 0.25 0.4 Comparative Example 3 0.1 0.25 0.4 Comparative Example 4 4 0.25 16 Comparative Example 5 1.6 0.25 6.4 Comparative Example 6 1.6 0.25 6.4

[0108] Note: In Table 2, “\” indicates that there are no relevant preparation parameters.

[0109] Test methods and equipment:

[0110] Raman spectroscopy test:

[0111] The Raman spectra of the negative electrode active materials were measured using a Raman spectrometer (model: LabRAM HR Evolution). The negative electrode active materials were measured at 1350 cm -1 The peak intensity at I D , at 1580cm -1 The peak intensity at I G , based on which I is calculated D / I G .

[0112] Overcharge performance test:

[0113] The lithium-ion battery was tested on a charge and discharge instrument (Nebula: BAT-NEEFLCT-05600-V012), left at 25°C for 5 hours, then discharged to 2.5V at 1P constant power, and then charged to 3.65V at 1P constant power and left at 10 minutes; the lithium-ion battery was then transferred to an overcharge test instrument (Baite: 2023040702-C) for testing, charged at a constant current of 0.5C until the voltage of the lithium-ion battery reached 5.475V or the charging time reached 1 hour, observed for 1 hour, and recorded whether there was any expansion, leakage, smoking, fire or explosion. The rating standards are as follows: lithium-ion batteries without leakage are rated as level one, and the test results meet the standards; lithium-ion batteries with leakage but no thermal runaway are rated as level two, and the test results meet the standards; lithium-ion batteries with leakage, smoke, and thermal runaway, but no fire or explosion, are rated as level three, and the test results meet the standards; lithium-ion batteries with fire or explosion are rated as level four, and the test results do not meet the standards. The judgment conditions for whether thermal runaway occurs: set up temperature sensors and arrange them on the surface of the test sample, with a temperature monitoring sampling frequency of 1s. If the temperature rise rate at the monitoring point is ≥3℃ / s or fire or explosion occurs for three consecutive times, it is judged as thermal runaway.

[0114] Cycle performance test:

[0115] The lithium-ion battery was subjected to a charge and discharge cycle test on a charge and discharge instrument, the test temperature was 25°C, the cycle rate was 1C (i.e., both the charge rate and the discharge rate were 1C), the charging voltage was 2.5V to 3.65V, and the capacity retention rate after 2000 cycles was calculated. The capacity retention rate calculation formula for the 25°C cycle is: capacity retention rate after the 2000th cycle = (discharge capacity after the 2000th cycle / discharge capacity of the first cycle) * 100%.

[0116] Table 3: Performance data of various embodiments and comparative examples

[0117]

[0118]

[0119] In combination with Table 1 and Table 3, it can be seen from Examples 1-1 to 1-10 and Comparative Examples 1 to 4 that when the electrolyte does not contain the compound represented by formula (I) and the compound represented by formula (II) (for example, Comparative Example 1), the overcharge performance of the lithium ion battery is level 4, the test result is not up to standard, and the cycle capacity retention rate is low; when only the compound represented by formula (I) is added to the electrolyte (for example, Comparative Example 2), the overcharge performance of the lithium ion battery is level 4, the test result is not up to standard, although its cycle capacity retention rate is improved to a certain extent, it is still low; when only the compound represented by formula (II) is added to the electrolyte (for example, Comparative Example 3), although the overcharge performance of the lithium ion battery meets the standard , but the cycle capacity retention rate is low; when the addition amount of the compound represented by formula (I) and the compound represented by formula (II) in the electrolyte is too high (for example, comparative example 4), although the overcharge performance of the lithium ion battery meets the standard, the cycle capacity retention rate is also low; the electrolyte of the present application includes the compound represented by formula (I) and the compound represented by formula (II), and the contents of the above two compounds are regulated within the scope of the present application. The overcharge performance of the lithium ion battery meets the standard and has a high cycle capacity retention rate, indicating that through the synergistic effect of the compound represented by formula (I) and the compound represented by formula (II), while improving the overcharge safety performance of the lithium ion battery, it can also improve the cycle performance of the lithium ion battery.

[0120] It can also be seen from Examples 1-1 to 1-10 that by adjusting a / b within the scope of the present application, it is beneficial to obtain a lithium-ion battery with good overcharge safety performance and long-term cycle performance.

[0121] The types of the compound represented by formula (I) and the compound represented by formula (II) usually also have an impact on the performance of the lithium-ion battery. It can also be seen from Examples 1-2 and 1-11 to 1-14 that by regulating the types of the compound represented by formula (I) and the compound represented by formula (II) within the scope of this application, it is beneficial to obtain a lithium-ion battery with excellent overcharge safety performance and cycle performance.

[0122] Combining Table 2 and Table 3, it can be seen from Examples 1-1 to 1-15, Examples 2-1 to 2-4, and Comparative Examples 2 to 4 that, on the basis of the lithium-ion battery having the electrolyte of the present application, by adjusting (a+b)×100 / (I D / I G ) Within the scope of this application, it is beneficial to obtain a lithium-ion battery with excellent overcharge safety performance and cycle performance.

[0123] 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: Including compounds represented by formula (I) and compounds represented by formula (II): In formula (I), R1 is selected from hydrogen, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkenylene; In formula (II), R2, R3, R4, R5, and R6 are each independently selected from hydrogen or fluorine atoms, and at least one of R2 to R6 is a fluorine atom.

2. The electrolyte according to claim 1, characterized in that Based on the mass of the electrolyte, the mass percentage of the compound represented by formula (I) is a, the mass percentage of the compound represented by formula (II) is b, 0.1%≤a≤1%, and 0.1%≤b≤1%.

3. The electrolyte according to claim 2, characterized in that 0.1％≤a≤0.5％。 4. The electrolyte according to claim 1, characterized in that 0.1≤a / b≤5.

5. 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:

6. The electrolyte according to claim 1, characterized in that The compound represented by formula (II) is selected from at least one of the following compounds:

7. A battery, characterized in that: The electrolyte comprises the electrolyte described in any one of claims 1 to 6.

8. The battery according to claim 7, characterized in that The battery further comprises a negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode material layer, wherein the negative electrode material layer comprises a negative electrode active material, and in the Raman spectrum of the negative electrode active material, at 1300 cm -1 Up to 1400cm -1 There is a peak intensity of I in the range D The first characteristic peak at 1550cm -1 Up to 1650cm -1 There is a peak intensity of I in the range G The second characteristic peak, 0.1≤I D / I G ≤0.

4.

9. The battery according to claim 8, characterized in that 0.5≤(a+b)×100 / (I D / I G )≤15。 10. An energy storage device, characterized in that: The invention comprises a box and at least one battery according to any one of claims 7 to 9, wherein the battery is accommodated in the box.

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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