Electrolyte, battery, energy storage device and energy storage system

Abstract

The invention provides an electrolyte, a battery, an energy storage device and an energy storage system. The electrolyte provided by the embodiment of the invention comprises a pyridine additive and an isothiocyanate additive. When the electrolyte provided by the embodiment of the invention is applied to the battery, the battery can have relatively good high-temperature cycle performance.

Description

Technical Field

[0001] The present application relates to the field of energy storage, and specifically to an electrolyte, a battery, an energy storage device and an energy storage system. Background Art

[0002] With the continuous development of lithium-ion battery technology, lithium-ion batteries have the advantages of large specific capacity, no memory effect, high operating voltage, fast charging speed, wide operating temperature range, long cycle life, small size, light weight, etc. compared with other types of batteries such as lead-acid, cadmium nickel, etc. At present, lithium-ion batteries have been widely used in mobile phones, laptops, electric vehicles, energy storage cabinets and other fields, and their application range is becoming more and more extensive.

[0003] With the development of the energy storage industry, higher requirements are placed on the life attenuation and service life of lithium-ion batteries. However, the high-temperature cycle performance of existing lithium-ion batteries still needs to be improved. Summary of the invention

[0004] The embodiment of the present application provides an electrolyte, which, when applied to a battery, can enable the battery to have better high-temperature cycle performance.

[0005] A first aspect of the present application provides an electrolyte, which includes a pyridine additive and an isothiocyanate additive.

[0006] In some embodiments, in the electrolyte, the mass ratio of the pyridine additive to the isothiocyanate additive is in a range of 0.2 to 5.

[0007] In some embodiments, in the electrolyte, the mass fraction a of the pyridine additive is in the range of 0.01%≤a≤3%.

[0008] In some embodiments, in the electrolyte, the mass fraction b of the isothiocyanate additive is in the range of 0.01%≤b≤3%.

[0009] In some embodiments, the pyridine additive has the structural formula:

[0010]

[0011] wherein R1 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms;

[0012] R2 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms;

[0013] R3 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms;

[0014] R4 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms;

[0015] R5 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms.

[0016] In some embodiments, the pyridine additive comprises at least one of the following structural formulas:

[0017]

[0018] In some embodiments, the chemical formula of the isothiocyanate additive is: R6-(NCS) n , wherein n is 1 to 3, and R6 is at least one of an alkyl or cycloalkyl group having 1 to 10 carbon atoms, an alkenyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, a halogenated alkyl group or a halogenated cycloalkyl group having 1 to 10 carbon atoms, a halogenated alkenyl group having 1 to 10 carbon atoms, and a halogenated aryl group having 1 to 10 carbon atoms.

[0019] In some embodiments, the isothiocyanate additive comprises at least one of the following structural formulas:

[0020]

[0021] The second embodiment of the present application provides a battery, which includes: the electrolyte, positive electrode plate, separator and negative electrode plate described in the first embodiment of the present application.

[0022] A third aspect of the present application provides an energy storage device, comprising:

[0023] The housing; and

[0024] A plurality of batteries according to the second aspect of the present application are contained in the box.

[0025] The fourth aspect of the present application provides an energy storage system, which includes: an electric energy conversion device and the energy storage device described in the third aspect of the present application, the electric energy conversion device is electrically connected to the energy storage device, the electric energy conversion device is used to convert other forms of energy into electric energy, and the energy storage device is used to store the electric energy.

[0026] The electrolyte of the embodiment of the present application includes a pyridine additive and an isothiocyanate additive. When the electrolyte is applied to a battery, the pyridine additive can participate in the formation of a nitride-rich SEI film, thereby improving the thermal stability of the SEI film, which is beneficial to improving the cycle performance of the battery; the isothiocyanate additive is reduced to form a sulfide, which is beneficial to improving the interface kinetic properties of the SEI film, thereby increasing the initial capacity of the battery using the electrolyte and improving the cycle performance of the battery using the electrolyte. When pyridine additives and isothiocyanate additives are added to the electrolyte at the same time, when the electrolyte is applied to the battery, during the formation of the SEI film in the formation stage of the battery, the isothiocyanate additive will take precedence over the pyridine additive to form a film on the surface of the negative electrode of the battery, and inhibit or reduce the participation of other additives in the film formation, thereby reducing the consumption of active lithium by the pyridine additive in the formation stage and the initial stage of the cycle, and increasing the initial capacity of the battery; in addition, the addition of isothiocyanate additives can reduce the consumption of pyridine additives, so that more pyridine additives are retained in the electrolyte, thereby continuing to exert their effects in the subsequent cycle process of the battery, better repairing the SEI film, and improving the thermal stability of the SEI film, thereby improving the high-temperature cycle performance and cycle life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of 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 creative work.

[0028] Figure 1 It is a schematic diagram of the structure of a battery according to an embodiment of the present application.

[0029] Figure 2 The battery of one embodiment of the present application is Figure 1 Schematic diagram of the cross-sectional structure in the AA direction.

[0030] Figure 3 It is a schematic diagram of the cross-sectional structure of a positive electrode plate according to an embodiment of the present application.

[0031] Figure 4 It is a schematic diagram of the cross-sectional structure of a negative electrode plate according to an embodiment of the present application.

[0032] Figure 5 It is a schematic structural diagram of an energy storage device according to an embodiment of the present application.

[0033] Figure 6 It is a structural block diagram of an energy storage system according to an embodiment of the present application.

[0034] Figure 7 This is an application scenario diagram of an energy storage system according to an embodiment of the present application.

[0035] Description of reference numerals:

[0036] 100 -battery, 110 -positive electrode plate, 111 -positive current collector, 112 -positive electrode active layer, 120 -diaphragm, 130 -negative electrode plate, 131 -negative current collector, 132 -negative electrode active layer, 140 -housing, 150 -end cover assembly, 141 -receiving chamber, 200 -energy storage device, 210 -casing, 300 -energy storage system, 310 -electric energy conversion device. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings 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.

[0038] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0039] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0040] It should be noted that, for the convenience of explanation, in the embodiments of the present application, the same figure marks represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0041] With the continuous development of lithium-ion battery technology, lithium-ion batteries have the advantages of large specific capacity, no memory effect, high operating voltage, fast charging speed, wide operating temperature range, long cycle life, small size, light weight, etc. compared with other types of batteries such as lead-acid, cadmium nickel, etc. At present, lithium-ion batteries have been widely used in mobile phones, laptops, electric vehicles, energy storage cabinets and other fields, and their application range is becoming more and more extensive.

[0042] With the development of the energy storage industry, higher requirements are placed on the life attenuation and service life of lithium-ion batteries. However, the long-cycle performance of existing lithium-ion batteries still needs to be improved.

[0043] Building high-temperature and long-life lithium secondary batteries is an effective way to improve product competitiveness. However, the solid electrolyte interface membrane (SEI membrane) of lithium-ion batteries is destroyed in the late stage of cycling, which will cause the solvent and lithium salt in the electrolyte to undergo side reactions and be consumed, thereby deteriorating the cycle performance; especially under high temperature (45°C) application conditions, the cycle capacity retention rate of lithium-ion batteries is greatly reduced, making it difficult to maintain cycle stability.

[0044] An embodiment of the present application provides an electrolyte, which includes a pyridine additive and an isothiocyanate additive.

[0045] The electrolyte of the embodiments of the present application can be applied to, but is not limited to, lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, etc.

[0046] The electrolyte of the embodiment of the present application includes a pyridine additive and an isothiocyanate additive. When the electrolyte is applied to a battery, the pyridine additive can participate in the formation of a nitride-rich SEI film, thereby improving the thermal stability of the SEI film, which is beneficial to improving the cycle performance of the battery; the isothiocyanate additive is reduced to form a sulfide, which is beneficial to improving the interface kinetic properties of the SEI film, thereby increasing the initial capacity of the battery using the electrolyte and improving the cycle performance of the battery using the electrolyte. When pyridine additives and isothiocyanate additives are added to the electrolyte at the same time, when the electrolyte is applied to the battery, during the formation of the SEI film in the formation stage of the battery, the isothiocyanate additive will take precedence over the pyridine additive to form a film on the surface of the negative electrode of the battery, and inhibit or reduce the participation of other additives in the film formation, thereby reducing the consumption of active lithium by the pyridine additive in the formation stage and the initial stage of the cycle, and increasing the initial capacity of the battery; in addition, the addition of isothiocyanate additives can reduce the consumption of pyridine additives, so that more pyridine additives are retained in the electrolyte, thereby continuing to exert their effects in the subsequent cycle process of the battery, better repairing the SEI film, and improving the thermal stability of the SEI film, thereby improving the high-temperature cycle performance and cycle life of the battery.

[0047] In some embodiments, in the electrolyte, the mass ratio of the pyridine additive to the isothiocyanate additive is in a range of 0.2 to 5.

[0048] It can be understood that in the electrolyte, the mass fraction of the pyridine additive is a, and the mass fraction of the isothiocyanate additive is b, then 0.2≤a / b≤5.

[0049] Specifically, in the electrolyte, the mass ratio of the pyridine additive to the isothiocyanate additive may be, but is not limited to, 0.2, 0.3, 0.5, 0.8, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5, etc.

[0050] In this embodiment, in the electrolyte, the mass ratio of the pyridine additive to the isothiocyanate additive is too low, which may be due to the fact that the content of the pyridine additive in the electrolyte is too little or the content of the isothiocyanate additive is too high. If the content of the pyridine additive in the electrolyte is too little, the high-temperature cycle performance of the battery in the later stage will be reduced; if the content of the isothiocyanate additive is too high, it will inhibit other film-forming additives from participating in the formation of the SEI film, reduce the stability of the SEI film of the battery, and worsen the cycle performance of the battery. In the electrolyte, if the mass ratio of the pyridine additive to the isothiocyanate additive is too high, it may be that the content of the pyridine additive in the electrolyte is too much or the content of the isothiocyanate additive is too low. If the content of the pyridine additive in the electrolyte is too high, the initial capacity of the battery will be deteriorated; if the content of the isothiocyanate additive in the electrolyte is too low, the effect of the isothiocyanate additive in inhibiting the film formation of the pyridine additive will be reduced, thereby deteriorating the initial capacity of the battery or deteriorating the later performance of the battery during high-temperature cycling; in addition, when the mass ratio of the pyridine additive to the isothiocyanate additive is too high, the isothiocyanate cannot effectively inhibit the pyridine additive from participating in the formation of the SEI film, resulting in excessive barrier of the SEI film, and the initial discharge capacity and high-temperature cycle capacity retention rate of the battery using the electrolyte will be reduced. When the mass ratio of the pyridine additive to the isothiocyanate additive in the electrolyte is in the range of 0.2 to 5, the pyridine additive and the isothiocyanate additive can play a better synergistic role, so that the battery has a higher initial capacity and higher high-temperature cycle performance.

[0051] Furthermore, in the electrolyte, the mass ratio of the pyridine additive to the isothiocyanate additive is in the range of 0.3 to 3. In this way, the pyridine additive and the isothiocyanate additive in the electrolyte can play a better synergistic role, and when the electrolyte is applied to a battery, the battery can have a higher initial capacity and higher high-temperature cycle performance.

[0052] Furthermore, in the electrolyte, the mass ratio of the pyridine additive to the isothiocyanate additive is in the range of 0.5 to 2. In this way, the pyridine additive and the isothiocyanate additive in the electrolyte can play a better synergistic role, and when the electrolyte is applied to a battery, the battery can have a higher initial capacity and higher high temperature cycle performance.

[0053] In some embodiments, in the electrolyte, the mass fraction a of the pyridine additive is in the range of 0.01%≤a≤3%.

[0054] Specifically, in the electrolyte, the mass fraction a of the pyridine additive may be but is not limited to 0.01%, 0.03%, 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, etc.

[0055] In this embodiment, in the electrolyte, the mass fraction a of the pyridine additive is too low, and it is difficult for the pyridine additive to improve the high temperature cycle performance of the battery, resulting in reduced high temperature cycle performance of the battery in the later stage; in the electrolyte, the mass fraction a of the pyridine additive is too high, which will deteriorate the initial capacity of the battery. When the mass fraction a of the pyridine additive in the electrolyte is in the range of 0.01%≤a≤3%, the battery using the electrolyte can have a higher initial capacity and high temperature cycle performance.

[0056] Furthermore, in the electrolyte, the mass fraction a of the pyridine additive is in the range of 0.1%≤a≤2.5%. This allows the battery using the electrolyte to have a higher initial capacity and high-temperature cycle performance.

[0057] In some embodiments, in the electrolyte, the mass fraction b of the isothiocyanate additive is in the range of 0.01%≤b≤3%.

[0058] Specifically, in the electrolyte, the mass fraction b of the isothiocyanate additive can be but is not limited to 0.01%, 0.03%, 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, etc.

[0059] In this embodiment, in the electrolyte, if the mass fraction b of the isothiocyanate additive is too low, the effect of the isothiocyanate additive in inhibiting the film formation of the pyridine additive is reduced, thereby deteriorating the initial capacity of the battery or the later performance of the battery in high-temperature cycling; in the electrolyte, if the mass fraction b of the isothiocyanate additive is too high, it will inhibit other film-forming additives from participating in the formation of the SEI film, reduce the stability of the SEI film of the battery, and worsen the cycle performance of the battery. When the mass fraction b of the isothiocyanate additive in the electrolyte is in the range of 0.01%≤b≤3%, the battery using the electrolyte can have a higher initial capacity and better high-temperature cycle performance.

[0060] Furthermore, in the electrolyte, the mass fraction b of the isothiocyanate additive is in the range of 0.1%≤b≤2.5%. This allows the battery using the electrolyte to have a higher initial capacity and better high-temperature cycle performance.

[0061] In some embodiments, the pyridine additive has the structural formula:

[0062]

[0063] wherein R1 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms;

[0064] R2 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms;

[0065] R3 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms;

[0066] R4 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms;

[0067] R5 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms.

[0068] Using the compounds of this embodiment as pyridine additives can better participate in the formation of nitride-rich SEI film in the battery, thereby better improving the thermal stability of the SEI film, and further better improving the high-temperature cycle performance of the battery, especially fluorine-containing pyridine additives, which can better improve the high-temperature cycle performance of the battery; in addition, these pyridine additives can have a better synergistic effect with isothiocyanate additives, while improving the high-temperature cycle performance of the battery, the battery still has a higher initial capacity.

[0069] In some embodiments, the pyridine additive comprises at least one of the following structural formulas:

[0070] (pyridine), (2-fluoropyridine), (2,,3,4,5,6-pentafluoropyridine), (3-vinylpyridine), (3-methyl-5-ethynylpyridine), (2-vinyl-5-fluoro-6-trifluoromethylpyridine).

[0071] Using the compounds of this embodiment as pyridine additives can better participate in the formation of nitride-rich SEI film in the battery, thereby better improving the thermal stability of the SEI film, and further better improving the high-temperature cycle performance of the battery, especially fluorine-containing pyridine additives, which can better improve the high-temperature cycle performance of the battery; in addition, these pyridine additives can have a better synergistic effect with isothiocyanate additives, while improving the high-temperature cycle performance of the battery, the battery still has a higher initial capacity.

[0072] In some embodiments, the chemical formula of the isothiocyanate additive is: R6-(NCS) n , wherein n is 1 to 3, and R6 is at least one of an alkyl or cycloalkyl group having 1 to 10 carbon atoms, an alkenyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, a halogenated alkyl group or halogenated cycloalkyl group having 1 to 10 carbon atoms, a halogenated alkenyl group having 1 to 10 carbon atoms, and a halogenated aryl group having 1 to 10 carbon atoms.

[0073] The compound of this embodiment is used as an isothiocyanate additive to reduce and generate sulfide, which is beneficial to improving the SEI film interface kinetics, thereby increasing the initial capacity of the battery using the electrolyte and improving the cycle performance of the battery using the electrolyte.

[0074] In some embodiments, the isothiocyanate additive comprises at least one of the following structural formulas:

[0075] (ethyl isothiocyanate), (allyl isothiocyanate), (cyclohexyl isothiocyanate or cyclohexyl isothiocyanate), (1,4-dithioisocyanate butane or 1,4-butane dithioisocyanate), (p-phenylene diisothiocyanate), (4-trifluoromethylphenyl isothiocyanate).

[0076] The compound of this embodiment is used as an isothiocyanate additive to reduce and generate sulfide, which is beneficial to improving the SEI film interface kinetics, thereby increasing the initial capacity of the battery using the electrolyte and improving the cycle performance of the battery using the electrolyte.

[0077] In some embodiments, the electrolyte further comprises a lithium salt. The lithium salt comprises at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalatoborate) (LiBOB), lithium difluorobis(oxalatophosphate) (LiODFP), lithium difluorobis(oxalatoborate) (LiODFB), lithium difluorophosphate (LiPO2F2), lithium trifluoromethanesulfonate (CF3SO3Li), etc.

[0078] Optionally, in the electrolyte, the total molar concentration M of the lithium salt is in the range of 0.7mol / L≤M≤1.4mol / L. In the electrolyte, the total molar concentration M of the lithium salt may be, but is not limited to, 0.7mol / L, 0.8mol / L, 0.9mol / L, 1.0mol / L, 1.1mol / L, 1.2mol / L, 1.3mol / L, 1.4mol / L, etc. If the total molar concentration M of the lithium salt is too small, the concentration of free ions in the electrolyte is too small, which reduces the conductivity of the electrolyte and thus reduces the kinetic performance of the battery; if the total molar concentration M of the lithium salt is too large, it is easy for a part of the electrolyte salt to be undissociated, and the viscosity of the electrolyte will increase, which will reduce the conductivity of the electrolyte and the kinetic performance of the battery. When the total molar concentration M of the lithium salt in the electrolyte is in the range of 0.7mol / L≤M≤1.4mol / L, the electrolyte can have a higher conductivity, so that the battery has better kinetic performance.

[0079] In some embodiments, the electrolyte further includes a sulfur-containing additive. Optionally, the sulfur-containing additive includes at least one of methylene disulfonate, ethylene sulfate, propylene sultone, butyl sultone, and propylene sulfite. The sulfur-containing additive can form lithium sulfate salt or alkyl lithium sulfate salt on the positive electrode plate, which can further stabilize the cathode electrolyte interface film (Cathode Electrolyte Interphase, referred to as CEI film), and can make the solid electrolyte interface film of the positive electrode plate thinner, better reduce the impedance of the positive electrode plate, thereby reducing the high-temperature heat generation of the positive electrode plate and improving the safety performance of the battery. In addition, these sulfur-containing additives in this embodiment are less likely to decompose and produce acid when the battery is at high temperature, and can better reduce the consumption of electrolyte at high temperature, so that the battery maintains a higher cycle capacity retention rate.

[0080] Optionally, in the electrolyte, the mass fraction w1 of the sulfur-containing additive is in the range of 0.1wt%≤w1≤1wt%. Specifically, in the electrolyte, the mass fraction w1 of the sulfur-containing additive may be, but is not limited to, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, etc. In the electrolyte, if the mass fraction w1 of the sulfur-containing additive is too low, the stability of the interface film of the positive electrode sheet is limited, and the safety performance of the battery cannot be well improved; in the electrolyte, if the mass fraction w1 of the sulfur-containing additive is too high, the sulfur-containing additive is easily decomposed to produce acid at high temperature, destroying the interface film of the positive electrode sheet, so that the positive active layer of the positive electrode sheet is directly in contact with the electrolyte, increasing the side reaction between the positive active layer and the electrolyte, thereby increasing the consumption of the electrolyte and reducing the cycle capacity retention rate of the battery. When the mass fraction of the sulfur-containing additive in the electrolyte is 0.1wt%≤w1≤1wt%, the safety performance of the battery can be better improved while maintaining a higher cycle capacity retention rate of the battery.

[0081] Optionally, the electrolyte further includes a film-forming additive. When the electrolyte is applied to a lithium-ion battery, the film-forming additive can be used to promote the formation of an interface film of at least one of the positive electrode sheet and the negative electrode sheet and maintain the stability of the interface film.

[0082] Optionally, the film-forming additive includes at least one of vinyl sulfate (DTD), vinylene carbonate (VC), vinyl carbonate (VEC), fluoroethylene carbonate (FEC), tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, adiponitrile, succinonitrile, and 1,3,6-hexanetrinitrile.

[0083] Optionally, the mass fraction of the film-forming additive ranges from 1.5% to 3%. Specifically, the mass fraction of the film-forming additive may be, but is not limited to, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, etc.

[0084] Optionally, the electrolyte also includes an organic solvent. The organic solvent includes at least one of a cyclic carbonate and a chain carbonate. Cyclic carbonates have a high dielectric constant and high ionic conductivity, and can form a stable SEI film on the surface of the negative electrode plate, but their viscosity is relatively large. Chain carbonates have lower viscosity than cyclic carbonates, better electrochemical stability, and can improve the low-temperature performance of the electrolyte. Therefore, when a mixed solvent of cyclic carbonate and chain carbonate is used, the electrolyte can have a more suitable viscosity and low-temperature stability, and the battery using the electrolyte can form a better film.

[0085] Optionally, the cyclic carbonate may include but is not limited to at least one of ethylene carbonate (EC for short), propylene carbonate (PC for short), etc. The dielectric constant of ethylene carbonate is much greater than that of propylene carbonate, and ethylene carbonate can better promote the formation of SEI film.

[0086] Optionally, the linear carbonate may include but is not limited to at least one of dimethyl carbonate (DMC for short), diethyl carbonate (DEC for short), ethyl methyl carbonate (EMC for short), and the like.

[0087] Optionally, in the electrolyte, the mass fraction of the organic solvent is 60wt% to 85wt%, specifically, but not limited to, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, etc.

[0088] Optionally, the organic solvent further comprises at least one of ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, γ-butyrolactone, and 2,2-difluoroethyl acetate.

[0089] See also Figure 1 and Figure 2 The embodiment of the present application provides a battery 100, which includes the electrolyte, the positive electrode plate 110, the separator 120 and the negative electrode plate 130 described in the embodiment of the present application, and the separator 120 is located between the positive electrode plate 110 and the negative electrode plate 130.

[0090] It should be noted that the positive electrode sheet 110 and the negative electrode sheet 130 are at least partially immersed in the electrolyte.

[0091] It can be understood that the positive electrode sheet 110, the separator 120 and the negative electrode sheet 130 are stacked in sequence to form an electrode assembly. The electrode assembly can be, but is not limited to, a winding structure, a laminated structure, etc., which is not specifically limited in the present application.

[0092] It should be noted that the positive electrode sheet 110 and the negative electrode sheet 130 may be collectively referred to as electrode sheets. In other words, the electrode sheets include the positive electrode sheet 110 and the negative electrode sheet 130 .

[0093] See also Figure 3 Optionally, the positive electrode sheet 110 includes a positive current collector 111 and a positive active layer 112, and the positive active layer 112 is disposed on the surface of the positive current collector 111. It can be understood that the positive active layer 112 can cover one surface or two opposite surfaces of the positive current collector 111.

[0094] Optionally, the positive electrode current collector 111 may be, but is not limited to, an aluminum sheet.

[0095] Optionally, the positive electrode active layer 112 includes a positive electrode active material, a positive electrode conductor, a positive electrode binder and a positive electrode thickener.

[0096] Optionally, the positive electrode active material may be, but is not limited to, lithium iron phosphate.

[0097] Optionally, the positive electrode conductive agent may be, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, carbon fibers, graphene, and the like.

[0098] Optionally, the positive electrode binder may be, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyvinylether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene butadiene rubber (SBR).

[0099] Optionally, in the positive electrode active layer 112, the mass fraction of the positive electrode binder ranges from 2wt% to 4wt%. Specifically, in the positive electrode active layer 112, the mass fraction of the positive electrode binder may be, but is not limited to, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, etc. If the mass fraction of the positive electrode binder is too small, the positive electrode active layer 112 is prone to pulverization or slag; if the mass fraction of the positive electrode binder is too large, the energy density of the positive electrode sheet 110 is reduced.

[0100] Optionally, the positive electrode thickener may be, but is not limited to, at least one of sodium carboxymethyl cellulose (CMC for short), polyacrylamide (PAM) and polymethacrylate (PMA).

[0101] Optionally, the diaphragm 120 may be, but is not limited to, at least one of a polypropylene film (PP film for short), a polyethylene film (PE film for short), a ceramic diaphragm 120 , and the like.

[0102] Optionally, the thickness of the diaphragm 120 is 14 μm to 18 μm. Specifically, the thickness of the diaphragm 120 may be, but is not limited to, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, etc.

[0103] See also Figure 4 Optionally, the negative electrode sheet 130 includes a negative electrode current collector 131 and a negative electrode active layer 132, and the negative electrode active layer 132 is disposed on the surface of the negative electrode current collector 131. It can be understood that the negative electrode active layer 132 can cover one surface or two opposite surfaces of the negative electrode current collector 131.

[0104] Optionally, the negative electrode current collector 131 may be, but is not limited to, a copper sheet.

[0105] Optionally, the negative electrode active layer 132 includes a negative electrode active material, a negative electrode conductor, a negative electrode binder and a negative electrode thickener.

[0106] Optionally, the negative electrode active material may be, but is not limited to, graphite.

[0107] Optionally, the negative electrode conductive agent may be, but is not limited to, at least one of conductive carbon black (SP for short), acetylene black, carbon nanotubes, carbon fibers, graphene, and the like.

[0108] Optionally, the negative electrode binder may be, but is not limited to, at least one of polyvinylidene fluoride, polyamide, polyacrylonitrile, polyacrylate, polyvinyl ether, polymethyl methacrylate, polyhexafluoropropylene, styrene-butadiene rubber, and the like.

[0109] Optionally, in the negative electrode active layer 132, the mass fraction of the negative electrode binder ranges from 2wt% to 4wt%. Specifically, in the negative electrode active layer 132, the mass fraction of the negative electrode binder may be, but is not limited to, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, etc. If the mass fraction of the negative electrode binder is too small, the negative electrode active layer 132 is prone to pulverization or slag; if the mass fraction of the negative electrode binder is too large, the energy density of the negative electrode plate 130 is reduced.

[0110] Optionally, the negative electrode thickener may be, but is not limited to, at least one of sodium carboxymethyl cellulose (CMC for short), polyacrylamide (PAM) and polymethacrylate (PMA).

[0111] Please see again Figure 1 and Figure 2 Optionally, the battery 100 further includes a shell 140 and an end cover assembly 150 , wherein the shell 140 and the end cover assembly 150 enclose a receiving cavity 141 , and the receiving cavity 141 is used to receive the electrolyte, the positive electrode plate 110 , the diaphragm 120 and the negative electrode plate 130 .

[0112] The electrolyte and the battery 100 of the present application are further described below through specific embodiments.

[0113] Examples 1 to 18, Comparative Examples 1 to 9

[0114] The preparation method of the battery 100 of each embodiment and comparative example includes:

[0115] (1) Preparation of electrolyte: In an argon atmosphere glove box with a moisture content of ≤1 ppm, ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 1:2:1 to obtain a mixed solvent, and then dry electrolyte salt lithium hexafluorophosphate is dissolved in the mixed solvent and stirred until completely dissolved and uniformly dissolved, and additives such as vinylene carbonate (VC), fluoroethylene carbonate (FEC), and vinyl sulfate (DTD) are added and stirred uniformly, and pyridine additives and isothiocyanate additives are added and stirred uniformly to obtain an electrolyte, wherein the molar concentration of lithium hexafluorophosphate in the electrolyte is 1 mol / L, and the types and addition amounts of pyridine additives and isothiocyanate additives in each embodiment and comparative example are shown in Table 1 below.

[0116] (2) Preparation of positive electrode sheet 110: The positive electrode active material lithium iron phosphate (LiFePO4), conductive carbon black (positive electrode conductive agent, Super-P), and adhesive (positive electrode binder, PVDF) are dispersed in N-methylpyrrolidone (NMP) solvent according to a preset mass ratio (for example, 94:3:3), mixed evenly and formulated into a positive electrode slurry with a solid content of 60%; the positive electrode slurry is evenly coated on the surface of the positive electrode current collector 111 aluminum foil with a thickness of 10 μm; after drying, cold pressing, slitting, and cutting, the positive electrode slurry is solidified to form a positive electrode active layer 112, thereby obtaining a positive electrode sheet 110, wherein the thickness of a single side of the positive electrode active layer 112 is 100 μm.

[0117] (3) Preparation of negative electrode sheet 130: Artificial graphite (negative electrode active material), sodium carboxymethyl cellulose (negative electrode thickener, referred to as CMC), conductive carbon black (negative electrode conductive agent, Super-P), and styrene-butadiene rubber latex (negative electrode binder SBR) are dispersed in deionized water at a mass ratio of 96:2:1:1, and prepared into a negative electrode slurry with a solid content of 50%. The negative electrode slurry is evenly coated on a 6 μm thick copper foil of the negative electrode current collector 131. The coating weight of the negative electrode slurry is 144 mg / 1540.25 mm 2 After drying, cold pressing, slitting and cutting, the negative electrode slurry is solidified to form a negative electrode active layer 132, and a negative electrode sheet 130 is obtained, wherein the thickness of a single side of the negative electrode active layer 132 is 70 μm.

[0118] (4) Preparation of the separator 120 : A 16 μm polyethylene film was used as the separator 120 .

[0119] (5) Assembly of battery 100: The positive electrode sheet 110, the separator 120, and the negative electrode sheet 130 are stacked in sequence to form an electrode assembly, and the electrode assembly is wound to obtain a bare cell. After welding the tabs, the cell is assembled into an outer package, and after injecting the above-mentioned electrolyte, vacuum packaging, standing, forming, shaping, capacity testing, etc. are performed to finally prepare battery 100.

[0120] The performance test was performed on the battery 100 of each embodiment and comparative example:

[0121] (1) Initialization discharge: The battery 100 is placed at 25°C for 5 hours; charged to 3.65 V at a constant power rate of 1P, and then placed for 10 minutes; discharged to 2.5 V at a constant power rate of 1P, and then placed for 10 minutes; the discharge capacity of the battery 100 is recorded, and the discharge capacity is used as the initial discharge capacity C0 of the battery 100, where 1P refers to 1 times the rated power.

[0122] The initial discharge capacity percentage of the battery 100 = the initial discharge capacity C0 of the battery 100 / the initial discharge capacity C1 of the reference battery 100 × 100%. The initial discharge capacity C1 of the reference battery 100 is the initial discharge capacity of the battery 100 of Comparative Example 1 of the present application. The larger the initial discharge capacity percentage of the battery 100, the higher the initial discharge capacity of the battery.

[0123] (2) 45℃ cycle performance test: Under 45℃ environment, let the initialized battery 100 stand for 5h; charge to 3.65V at 1P constant power, let stand for 10 minutes; discharge to 2.5V at 1P constant power, let stand for 10 minutes; such a charge-discharge process is called a cycle process or a cycle. 1P constant power charging / 1P constant power discharge is used to perform a small cycle performance test on the battery 100, record the discharge capacity of the battery 100 after 1000 cycles, and calculate the cycle capacity retention rate of the battery 100 after 1000 cycles. Cycle capacity retention rate = (discharge capacity of the 1000th cycle / initial discharge capacity C0) × 100%.

[0124] The initial discharge capacity percentage of the battery 100 of each embodiment and comparative example and the cycle capacity retention rate after 1000 cycles at 45° C. and a charge and discharge rate of 1P are shown in Table 2 below.

[0125] Table 1 Addition amount of pyridine additives and isothiocyanate additives in the electrolyte of each embodiment and comparative example

[0126]

[0127]

[0128] Table 2 Test data of each embodiment and comparative example

[0129]

[0130]

[0131] It can be seen from the test results of Comparative Examples 1, 2 and 4 that adding pyridine to the electrolyte can improve the high-temperature cycle capacity retention rate of the battery, but will reduce the initial discharge capacity of the battery.

[0132] It can be seen from the test results of Comparative Examples 1, 3 and 5 that adding ethyl isothiocyanate to the electrolyte can improve the initial discharge capacity and high temperature cycle capacity retention rate of the battery. However, the improvement effect of ethyl isothiocyanate on the high temperature cycle capacity retention rate of the battery is lower than the improvement effect of pyridine on the high temperature cycle capacity retention rate of the battery.

[0133] It can be seen from the test results of Example 4, Comparative Example 6 and Comparative Example 7 that, when the total amount of pyridine additives and isothiocyanate additives added is constant, compared with the solution of adding only pyridine additives (Comparative Example 6), the battery to which pyridine additives and isothiocyanate additives are added simultaneously can not only make the battery have a higher initial discharge capacity, but also make the battery have a higher high-temperature cycle capacity retention rate; compared with the solution of adding only isothiocyanate additives (Comparative Example 7), although the initial discharge capacity of the battery to which pyridine additives and isothiocyanate additives are added is slightly reduced, it always maintains a higher initial discharge capacity. In addition, the battery has a higher high-temperature cycle capacity retention rate.

[0134] From the test results of Comparative Example 2 and Examples 1 to 3, it can be seen that when the amount of pyridine additives added to the electrolyte remains unchanged, adding isothiocyanate additives to the electrolyte can not only increase the initial discharge capacity of the battery, but also improve the high-temperature cycle capacity retention rate of the battery. In addition, as the content of isothiocyanate additives in the electrolyte increases, the initial cycle performance of the battery gradually increases, and the high-temperature cycle capacity retention of the battery first increases and then decreases, but the change range is relatively small. When the amount of isothiocyanate additives added is increased to a small a / b (such as Example 3), the high-temperature cycle capacity retention rate of the battery decreases instead. This is because the isothiocyanate additives have an excessively large inhibitory effect on the participation of other additives in the formation of the SEI film, resulting in poor stability of the SEI film and a decrease in the capacity retention rate of the battery at 45°C cycle. Therefore, when a / b is too small (for example, a / b < 0.2, such as Comparative Example 9), the synergistic effect of the pyridine additive and the isothiocyanate additive cannot be effectively exerted, but the negative effects of the pyridine additive and the isothiocyanate additive on the battery will be amplified, resulting in a decrease in the initial discharge capacity of the battery and the 45°C high-temperature cycle capacity retention rate.

[0135] From the test results of Comparative Example 5, Example 3 to Example 6, it can be seen that when the content of isothiocyanate additives in the electrolyte is unchanged, the addition of pyridine additives can greatly improve the cycle capacity retention rate of the battery at high temperature. When the amount of pyridine additives added is less (such as Example 3), the initial discharge capacity of the battery can also be improved. As the amount of pyridine additives added increases, the initial discharge capacity of the battery gradually decreases. When the amount of pyridine additives added to the mass ratio a / b of the pyridine additive and the isothiocyanate additive is high (such as Example 6), isothiocyanates cannot effectively inhibit the pyridine additive from participating in the formation of the SEI film, resulting in excessive barrier of the SEI film, and the initial discharge capacity and high temperature cycle capacity retention rate of the battery using the electrolyte are reduced. In Example 6, although the high temperature cycle capacity retention rate of the battery is slightly reduced, it is still maintained at a relatively high cycle capacity retention rate. At the same time, it can be seen from the test results of Comparative Example 8 that when the mass ratio a / b of the pyridine additive to the isothiocyanate additive is too high, the initial discharge capacity and cycle capacity retention rate of the battery are greatly reduced.

[0136] In summary, when the mass ratio a / b of pyridine additives to isothiocyanate additives in the electrolyte is between 0.2 and 5, the battery has a higher initial discharge capacity and cycle capacity retention rate. When the mass ratio a / b of pyridine additives to isothiocyanate additives in the electrolyte is too large or too small, the initial discharge capacity and cycle capacity retention rate of the battery will be reduced.

[0137] It can be seen from the test results of Example 5, Example 7 to Example 11 that when the addition amounts of the pyridine additive and the isothiocyanate additive are the same, the type of the pyridine additive is kept unchanged, and the type of the isothiocyanate additive is changed. Compared with the scheme of not adding two additives in Comparative Example 1, the use of pyridine and different types of isothiocyanate additives can increase the initial discharge capacity and cycle capacity retention rate of the battery. In addition, it can be seen from the test results of Example 5, Example 7 to Example 11 that compared with the scheme of using pyridine with other isothiocyanate additives, the use of pyridine and ethyl isothiocyanate or the use of pyridine and 4-trifluoromethylphenyl isothiocyanate can make the battery have a higher initial discharge capacity and a higher high temperature cycle capacity retention rate.

[0138] It can be seen from the test results of Examples 12 to 16 that the use of different types of pyridine additives and different types of isothiocyanate additives in the embodiments of the present application can enable the battery to have a higher initial discharge capacity and a higher high-temperature cycle capacity retention rate.

[0139] It can be seen from the test results of Example 14, Example 17 and Example 18 that, compared with the scheme of using a pyridine additive and an isothiocyanate additive in combination (such as Example 14), the scheme of using two pyridine additives and / or two isothiocyanate additives can better exert the synergistic effect of the pyridine additive and the isothiocyanate additive, so that the battery has a higher initial discharge capacity and a higher high-temperature cycle capacity retention rate.

[0140] See also Figure 5 The embodiment of the present application further provides an energy storage device 200 , which includes a box 210 and a plurality of batteries 100 described in the embodiment of the present application, wherein the plurality of batteries 100 are stacked and accommodated in the box 210 .

[0141] The term "plurality" means greater than or equal to two.

[0142] It can be understood that the multiple batteries 100 of the energy storage device 200 can be connected in parallel with each other; or in series with each other; or partially in parallel and partially in series (in other words, mixed connection). This application does not make any specific restrictions on the connection method of multiple batteries 100 of the same energy storage device 200.

[0143] Optionally, the energy storage device may be at least one of a small energy storage box, a large energy storage cabinet, an energy storage module, etc. The present application does not specifically limit the form of the energy storage device. The form of the energy storage device of the present application is only one of its many forms and should not be understood as a limitation on the energy storage device of the present application.

[0144] It can be understood that the box body 210 has a receiving cavity, and multiple batteries 100 are received in the receiving cavity. In some embodiments, each receiving cavity receives one battery 100. In other embodiments, each receiving cavity receives multiple batteries 100.

[0145] See also Figure 6 and Figure 7 The embodiment of the present application also provides an energy storage system 300, which includes: an electric energy conversion device 310 and the energy storage device 200 described in the embodiment of the present application, the electric energy conversion device 310 is electrically connected to the energy storage device 200, the electric energy conversion device 310 is used to convert other forms of energy into electric energy, and the energy storage device 200 is used to store the electric energy.

[0146] Optionally, the electric energy conversion device 310 can convert at least one other form of energy such as solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy and mechanical energy into electric energy.

[0147] Optionally, the number of the electric energy conversion devices 310 may be one or more. When there are multiple electric energy conversion devices 310, the multiple electric energy conversion devices 310 may be connected in series, in parallel, or in mixed connection, which is not specifically limited in the present application.

[0148] Optionally, the electric energy conversion device 310 may be, but is not limited to, at least one of a photovoltaic panel, a wind power generation device, a hydropower generation device, and the like.

[0149] Optionally, the number of the energy storage devices 200 may be one or more. When the number of the energy storage devices 200 is multiple, the multiple energy storage devices 200 are connected in series or in parallel, which is not specifically limited in the present application.

[0150] When working, the power conversion device 310 is used to convert other forms of energy into electrical energy and store it in the energy storage device 200. The electrical energy stored in the energy storage device 200 can be supplied to electrical loads such as street lamps and household appliances for use when the electricity price is at a peak, or to supply power when the power grid is out of power. The electrical energy generated by the power conversion device 310 can also be supplied to the power grid through high-voltage cables to alleviate the power supply pressure of the power grid during peak hours.

[0151] Mentioning "embodiment" and "implementation method" in this application means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should also be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, provided that there is no contradiction between them.

[0152] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the above preferred implementation modes, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. An electrolyte, characterized in that: The electrolyte includes a pyridine additive and an isothiocyanate additive.

2. The electrolyte according to claim 1, characterized in that In the electrolyte, the mass ratio of the pyridine additive to the isothiocyanate additive is in a range of 0.2 to 5.

3. The electrolyte according to claim 1, characterized in that In the electrolyte, the mass fraction a of the pyridine additive is in the range of 0.01%≤a≤3%.

4. The electrolyte according to claim 1, characterized in that In the electrolyte, the mass fraction b of the isothiocyanate additive is in the range of 0.01%≤b≤3%.

5. The electrolyte according to claim 1, characterized in that The structural formula of the pyridine additive is: wherein R1 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms; R2 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms; R3 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms; R4 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms; R5 is one of hydrogen, halogen, alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, alkynyl having 1 to 10 carbon atoms, haloalkyl having 1 to 10 carbon atoms, haloalkenyl having 1 to 10 carbon atoms, and haloalkynyl having 1 to 10 carbon atoms.

6. The electrolyte according to claim 1, characterized in that The pyridine additive includes at least one of the following structural formulas:

7. The electrolyte according to claim 1, characterized in that The chemical formula of the isothiocyanate additive is: R6-(NCS) n , wherein n is 1 to 3, and R6 is at least one of an alkyl or cycloalkyl group having 1 to 10 carbon atoms, an alkenyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, a halogenated alkyl group or halogenated cycloalkyl group having 1 to 10 carbon atoms, a halogenated alkenyl group having 1 to 10 carbon atoms, and a halogenated aryl group having 1 to 10 carbon atoms.

8. The electrolyte according to claim 1, characterized in that The isothiocyanate additive includes at least one of the following structural formulas:

9. A battery, characterized in that: include: The electrolyte, positive electrode sheet, separator and negative electrode sheet as described in any one of claims 1 to 8.

10. An energy storage device, characterized in that: include: Box; as well as A plurality of batteries according to claim 9, wherein the plurality of batteries are housed in the casing.

11. An energy storage system, characterized in that: include: An electric energy conversion device and an energy storage device as described in claim 10, wherein the electric energy conversion device is electrically connected to the energy storage device, the electric energy conversion device is used to convert other forms of energy into electric energy, and the energy storage device is used to store the electric energy.

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