Electrolyte, battery, energy storage device and power utilization system

Abstract

The application provides an electrolyte, a battery, an energy storage device and a power utilization system. The electrolyte comprises an electrolyte salt, an organic solvent and a first additive, the first additive is a pyridone, and a structural formula of the pyridone is as follows: wherein R1 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; R2 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; R3 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; R4 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; R5 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; and a mass fraction w1 of the pyridone ranges from 0.1% to 5.0%.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of energy storage, in particular to an electrolyte, a battery, an energy storage device and a power utilization system. BACKGROUND

[0002] With the continuous development of lithium ion battery technology, compared with lead-acid, cadmium-nickel and other types of batteries, lithium ion batteries have the advantages of large specific capacity, no memory effect, high working voltage, fast charging speed, wide working temperature range, long cycle life, small size, light weight and the like. At present, lithium ion batteries have been widely used in mobile phones, notebook computers, 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 put forward for the cycle performance of lithium ions, but the cycle performance of existing lithium ion batteries still needs to be improved, and the service life is relatively short. SUMMARY

[0004] The embodiments of the present application provide a battery with high cycle performance.

[0005] In a first aspect, the embodiments of the present application provide an electrolyte, which comprises an electrolyte salt, an organic solvent and a first additive, the first additive is a pyridone, and the structural formula of the pyridone is:

[0006]

[0007] wherein R1 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; R2 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; R3 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; R4 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group; and R5 is at least one of hydrogen, halogen, an alkyl group with 1-5 carbon atoms, a nitro group, a trifluoromethyl group, a mercapto group and an amino group.

[0008] The mass fraction w1 of the pyridone in the electrolyte ranges from 0.1% to 5.0%.

[0009] Further, the mass fraction w1 of the pyridone in the electrolyte ranges from 0.1% to 1%.

[0010] Further, the pyridone is at least one of

[0011] ​Further, the electrolyte salt comprises at least one of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, lithium difluoro oxalate borate, lithium difluoro oxalate phosphate.

[0012] Further, the electrolyte further comprises a second additive, the second additive is fluoroethylene carbonate, and a mass fraction w2 of the fluoroethylene carbonate in the electrolyte ranges from 1% to 4%.

[0013] Further, the electrolyte further comprises a third additive, the third additive comprises at least one of vinylene carbonate, vinyl sulfate, vinyl ethylene carbonate, 1,3-propane sultone.

[0014] Further, the organic solvent comprises at least one of a cyclic carbonate and a chain carbonate; the cyclic carbonate comprises at least one of ethylene carbonate, propylene carbonate, etc.; and the chain carbonate comprises at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0015] In a second aspect, the embodiments of the present application further provide a battery, comprising:

[0016] The electrolyte, the positive electrode sheet, the separator, and the negative electrode sheet provided in the embodiments of the present application.

[0017] Further, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer, the positive electrode active layer is arranged on the surface of the positive electrode current collector, and the positive electrode active layer comprises a positive electrode active material and a carbon material; the carbon material comprises coated carbon and conductive carbon, the coated carbon is wrapped on the surface of the positive electrode active material, and the conductive carbon is dispersed in the positive electrode active layer; a mass fraction A1 of the coated carbon in the positive electrode active layer ranges from 0.6% to 1.5%; and a mass fraction A2 of the conductive carbon in the positive electrode active layer ranges from 0 to 0.5%.

[0018] In a third aspect, the embodiments of the present application further provide an energy storage device, comprising:

[0019] a box; and

[0020] a plurality of batteries provided in the embodiments of the present application, the plurality of batteries are accommodated in the box.

[0021] In a fourth aspect, the embodiments of the present application further provide a power utilization system, comprising:

[0022] a power utilization device, and

[0023] an energy storage device, the energy storage device supplies power to the power utilization device, and the energy storage device comprises at least one battery provided in the embodiments of the present application.

[0024] In the embodiments of the present application, by adding pyridinone as an additive in the electrolyte, the pyridinone can be reduced and decomposed on the surface of the negative active layer of the negative electrode sheet during formation of the battery, thereby generating a dense solid electrolyte interface film (SEI film), and further improving the electrochemical stability and thermal stability of the SEI film of the negative electrode sheet, and further improving the cycle performance of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0026] Figure 1 is an application scenario of the energy storage system provided by the embodiments of the present application.

[0027] Figure 2 is a structural schematic diagram of the energy storage system of an embodiment of the present application.

[0028] Figure 3 is a block diagram of the energy storage system of an embodiment of the present application.

[0029] Figure 4 is a block diagram of the power utilization system of an embodiment of the present application.

[0030] Figure 5 is a structural schematic diagram of the energy storage device of an embodiment of the present application.

[0031] Figure 6 is a structural schematic diagram of the battery of an embodiment of the present application.

[0032] Figure 7 is a structural schematic diagram of the battery of an embodiment of the present application along the direction of A-A. Figure 6

[0033] Figure 8 is a structural schematic diagram of the positive electrode sheet of an embodiment of the present application.

[0034] Figure 9 is a structural schematic diagram of the negative electrode sheet of an embodiment of the present application.

[0035] Explanation of reference signs:

[0036] ​100 - energy storage system, 110 - power conversion device, 130 - power consumption load, 200 - energy storage device, 210 - box body, 300 - power consumption system, 310 - power consumption equipment, 400 - battery, 410 - positive electrode sheet, 411 - positive electrode current collector, 412 - positive electrode active layer, 420 - separator, 430 - negative electrode sheet, 431 - negative electrode current collector, 432 - negative electrode active layer, 440 - shell. DETAILED DESCRIPTION

[0037] In order for those skilled in the art to better understand the scheme of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0038] The terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. 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 can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.

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

[0040] It should be noted that, for the sake of illustration, in the embodiments of the present application, the same reference signs represent the same parts, and for the sake of brevity, detailed description of the same parts is omitted in different embodiments.

[0041] Current energy storage (i.e. energy storage) application scenarios are relatively wide, including power generation side energy storage, power grid side energy storage, renewable energy grid-connected energy storage, and user side energy storage, etc. The corresponding types of energy storage devices include:

[0042] (1) Large energy storage containers applied in power grid side energy storage scenarios, which can be used as high-quality active and reactive power regulation power sources in the power grid, realize load matching of electric energy in time and space, enhance renewable energy consumption capacity, and are of great significance in power grid system backup, relieving peak load power supply pressure and peak regulation.

[0043] (2) The small and medium-sized energy storage cabinet applied in the commercial energy storage scene of the user side (bank, shopping mall, etc.) and the small household energy storage box applied in the household energy storage scene of the user side, and the main operation mode is "peak load shifting". Due to the large price difference between the electricity price at the peak and the valley positions according to the electricity demand, after the user has the energy storage device, in order to reduce the cost, the energy storage cabinet / box is usually charged during the low electricity price period; the electricity in the energy storage device is discharged for use during the high electricity price period, so as to save the electricity cost. In addition, in remote areas and areas with high incidence of natural disasters such as earthquakes and hurricanes, the existence of household energy storage devices is equivalent to that the user provides a standby power source for himself and the power grid, and avoids the inconvenience caused by frequent power outages due to disasters or other reasons.

[0044] Figure 1 FIG. 1 is an application scenario diagram of an energy storage system 100 provided by an embodiment of the present application. The present application Figure 1 The present application takes the household energy storage scene in the user-side energy storage as an example for illustration, and the energy storage device 200 is not limited to the household energy storage scene. Figure 2 FIG. 2 is a structural schematic diagram of the energy storage system 100 of an embodiment of the present application. Figure 3 FIG. 3 is a block diagram of the energy storage system 100 of an embodiment of the present application.

[0045] Please refer to Figures 1 to 3 The present application provides an energy storage system 100, which is a household energy storage system 100, and the energy storage system 100 comprises an electric energy conversion device 110, an energy storage device 200 and an electric load 130. The electric energy conversion device 110 is used for converting other forms of energy into electric energy; the energy storage device 200 is electrically connected to the electric energy conversion device 110 and is used for storing the electric energy of the electric energy conversion device 110; and the electric load 130 is electrically connected to the electric energy conversion device 110 and the energy storage device 200 respectively and is used for working by using the electric energy of the electric energy conversion device 110 or the energy storage device 200. It can be understood that part of the electric energy converted by the electric energy conversion device 110 is stored in the energy storage device 200, and part of the electric energy is used for supplying power to the electric load 130, and the energy storage device 200 is used for storing electric energy and supplying the electric load 130 with electric energy during the high electricity price peak. The energy storage system 100 can not only convert other forms of energy into electric energy, but also store the electric energy in the energy storage device 200 to supply the electric load 130 with sufficient electric energy.

[0046] Optionally, the electric energy conversion device 110 can convert at least one of solar energy, light energy, wind energy, heat energy, tidal energy, biomass energy and mechanical energy into electric energy to provide a stable power supply for the electric load 130 and the energy storage device 200.

[0047] Optionally, the electric energy conversion device 110 can be, but is not limited to, a photovoltaic panel, which can convert solar energy into electric energy during the low electricity price period and store the electric energy in the energy storage device 200. In other embodiments, the energy conversion device 110 can also be at least one of a wind power generation device, a thermal power generation device, a tidal power generation device, a biomass power generation device, and a mechanical power generation device.

[0048] Optionally, the energy storage device 200 is a small energy storage box, which can be installed on an outdoor wall by a wall hanging manner. In other embodiments, the energy storage device 200 can also be a large energy storage container, a battery applied to an electronic device, etc.

[0049] Optionally, the electric load 130 can be a street lamp or a household appliance, a motor vehicle, etc., and the energy storage device 200 is used to store the electric energy and supply the street lamp and the household appliance for use during the peak electricity price period or during the power grid outage.

[0050] It can be understood that the energy storage device 200 can include, but is not limited to, at least one of a battery module, a battery pack, a battery system, etc.

[0051] It can be understood that the schematic diagram in the embodiment is only one form of the energy storage system 100, and should not be understood as a limitation on the energy storage system 100 provided by the present application, nor should it be understood as a limitation on the energy storage device 200 provided by each embodiment of the present application.

[0052] Please refer to Figure 4 , Figure 4 is a block diagram of an electricity utilization system 300 according to an embodiment of the present application. The embodiment of the present application also provides an electricity utilization system 300, which includes: an electricity utilization device 310 and an energy storage device 200, wherein the energy storage device 200 supplies power to the electricity utilization device 310.

[0053] The electricity utilization device 310 according to the embodiment of the present application can be, but is not limited to, a portable electronic device such as a mobile phone, a tablet computer, a notebook computer, a desktop computer, a smart bracelet, a smart watch, an e-book reader, a game console, etc. The electricity utilization device 310 can also be a vehicle such as a car, a truck, a sedan, a van, a motor car, a high-speed train, an electric automatic car, etc. In addition, the electricity utilization device 310 can also be various household appliances such as a refrigerator, a lamp, an air conditioner, etc. It can be understood that the electricity utilization device 310 in the schematic diagram is only one form of the electricity utilization device 310, and should not be understood as a limitation on the electricity utilization device 310 provided by the present application.

[0054] Please refer to Figure 5 , the embodiment of the present application also provides an energy storage device 200, which includes a box body 210 and a plurality of batteries 400, wherein the plurality of batteries 400 are stacked and accommodated in the box body 210.

[0055] Optionally, the battery 400 can be, but is not limited to, a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, an energy storage battery, etc.

[0056] The term "a plurality of" means greater than or equal to two.

[0057] It can be understood that the plurality of batteries 400 of the energy storage device 200 can be connected in parallel with each other, or connected in series with each other, or partially connected in parallel and partially connected in series (in other words, connected in hybrid mode). The application does not make specific limitations on the connection mode of the plurality of batteries 400 of the same energy storage device 200.

[0058] It can be understood that the box body 210 has a receiving cavity (not shown in the figure), and the plurality of batteries 400 are accommodated in the receiving cavity. In some embodiments, each receiving cavity accommodates one battery 400. In other embodiments, each receiving cavity accommodates a plurality of batteries 400.

[0059] With the continuous development of lithium-ion battery technology, compared with lead-acid, cadmium-nickel and other types of batteries, lithium-ion batteries have the advantages of large specific capacity, no memory effect, high working voltage, fast charging speed, wide working temperature range, long cycle life, small volume, light weight, etc. At present, lithium-ion batteries have been widely used in mobile phones, notebook computers, electric vehicles, energy storage cabinets and other fields, and their application range is becoming more and more extensive. With the development of the energy storage industry, higher requirements are put forward for the cycle performance of lithium-ion batteries, but the cycle performance of existing lithium-ion batteries still needs to be improved.

[0060] Please refer to Figure 6 and Figure 7 The embodiments of the present application also provide a battery 400, which comprises an electrolyte, a positive electrode sheet 410, a separator 420 and a negative electrode sheet 430. The separator 420 is located between the positive electrode sheet 410 and the negative electrode sheet 430.

[0061] It can be understood that the positive electrode sheet 410, the separator 420 and the negative electrode sheet 430 are sequentially stacked to form an electrode assembly. The electrode assembly can be, but is not limited to, a winding type structure, a laminated type structure, etc., and the application does not make specific limitations thereon. It can be understood that the battery 400 of the present application can be a square battery, or a cylindrical battery or other shaped battery. In the drawings of the present application, a square battery is taken as an example for illustration, which should not be understood as a limitation of the battery 400 of the present application.

[0062] It should be noted that the positive electrode sheet 410 and the negative electrode sheet 430 can be collectively referred to as an electrode sheet, in other words, the electrode sheet comprises the positive electrode sheet 410 and the negative electrode sheet 430.

[0063] In some embodiments, the electrolyte comprises an electrolyte salt, an organic solvent, and a first additive, the first additive being a pyridone, the pyridone having a structural formula of:

[0064]

[0065] wherein R1 is at least one of hydrogen, halogen, an alkyl group having a carbon atom number of 1-5, a nitro group, a trifluoromethyl group, a mercapto group, and an amino group; R2 is at least one of hydrogen, halogen, an alkyl group having a carbon atom number of 1-5, a nitro group, a trifluoromethyl group, a mercapto group, and an amino group; R3 is at least one of hydrogen, halogen, an alkyl group having a carbon atom number of 1-5, a nitro group, a trifluoromethyl group, a mercapto group, and an amino group; R4 is at least one of hydrogen, halogen, an alkyl group having a carbon atom number of 1-5, a nitro group, a trifluoromethyl group, a mercapto group, and an amino group; and R5 is at least one of hydrogen, halogen, an alkyl group having a carbon atom number of 1-5, a nitro group, a trifluoromethyl group, a mercapto group, and an amino group.

[0066] The mass fraction w1 of the pyridone in the electrolyte is in a range of 0.1%≤w1≤5.0%.

[0067] It can be understood that the pyridone is a 4-pyridone.

[0068] Specifically, the mass fraction w1 of the pyridone in the electrolyte can be, but is not limited to, 0.1%, 0.2%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3%, 3.3%, 3.5%, 3.8%, 4%, 4.3%, 4.5%, 4.8%, 5.0%, etc. If the mass fraction w1 of the pyridone in the electrolyte is too small, the improvement of the compactness of the SEI film on the surface of the negative electrode tab 430 of the battery 400 is limited, and the improvement of the electrochemical stability and thermal stability of the battery 400 is limited. If the mass fraction w1 of the pyridone in the electrolyte is too large, the SEI film formed on the surface of the negative electrode tab 430 is too thick, which increases the impedance of the lithium intercalation of the negative electrode tab 430, and thus the lithium precipitation phenomenon is prone to occur in the lithium intercalation process of the negative electrode tab, the active lithium in the electrolyte is consumed, and thus the cycle performance of the battery 400 is reduced. When the mass fraction w1 of the pyridone in the electrolyte is in a range of 0.1%≤w1≤5.0%, the SEI film formed on the surface of the negative electrode tab 430 has good compactness, and the negative electrode tab 430 has low impedance in the lithium intercalation process, which reduces the lithium precipitation phenomenon, and thus the battery 400 has good cycle performance.

[0069] Further, the mass fraction w1 of the pyridinone in the electrolyte is in the range of 0.1%≤w1≤4%. In this way, the SEI film formed on the surface of the negative electrode plate 430 has better compactness, and the negative electrode plate 430 has lower impedance during lithium intercalation, reducing lithium precipitation, thereby improving the cycle performance of the battery 400.

[0070] Further, the mass fraction w1 of the pyridinone in the electrolyte is in the range of 0.1%≤w1≤3%. In this way, the SEI film formed on the surface of the negative electrode plate 430 has better compactness, and the negative electrode plate 430 has lower impedance during lithium intercalation, reducing lithium precipitation, thereby improving the cycle performance of the battery 400.

[0071] Further, the mass fraction w1 of the pyridinone in the electrolyte is in the range of 0.1%≤w1≤2%. In this way, the SEI film formed on the surface of the negative electrode plate 430 has better compactness, and the negative electrode plate 430 has lower impedance during lithium intercalation, reducing lithium precipitation, thereby improving the cycle performance of the battery 400.

[0072] Further, the mass fraction w1 of the pyridinone in the electrolyte is in the range of 0.1%≤w1≤1%. In this way, the SEI film formed on the surface of the negative electrode plate 430 has better compactness, and the negative electrode plate 430 has lower impedance during lithium intercalation, reducing lithium precipitation, thereby improving the cycle performance of the battery 400.

[0073] Further, the mass fraction w1 of the pyridinone in the electrolyte is in the range of 0.1%≤w1≤0.5%. In this way, the SEI film formed on the surface of the negative electrode plate 430 has better compactness, and the negative electrode plate 430 has lower impedance during lithium intercalation, reducing lithium precipitation, thereby improving the cycle performance of the battery 400.

[0074] During the charge-discharge cycle of the battery 400, on the one hand, the ester organic solvent in the electrolyte is easily reduced on the surface of the negative electrode plate 430 at low potential, reacts with the lithium salt in the electrolyte, and thus consumes active lithium; on the other hand, after the graphite negative electrode active layer 432 occurs the deintercalation lithium behavior, the graphite layer spacing is continuously expanded and reduced, the SEI film on the surface of the negative electrode plate 430 is continuously pulled, and the new graphite interface is exposed to contact with the electrolyte, thereby continuously reacting and consuming the active lithium ions in the electrolyte, thereby reducing the cycle performance of the battery 400.

[0075] In the embodiments of the present application, by adding pyridinone as an additive in the electrolyte, the pyridinone can be reduced and decomposed on the surface of the negative active layer 432 of the negative electrode sheet 430 when the battery 400 is formed, thereby generating a dense SEI film, and further improving the electrochemical stability and thermal stability of the SEI film of the negative electrode sheet 430, and further improving the cycle performance of the battery 400.

[0076] In some embodiments, the pyridinone is at least one of (4(1H)-pyridinone), (2-fluoro-4-pyridinone), (2-trifluoromethyl-4-pyridinone), (1-methyl-2-trifluoromethyl-4-pyridinone), (1-methyl-2-nitro-4-pyridinone), (1-methyl-2-nitro-6-fluoro-4-pyridinone), (1-mercapto-2,6-dimethyl-4-pyridinone).

[0077] In the embodiments, the fluorine-containing pyridinone can better generate LiF on the surface of the negative active layer 432 of the negative electrode sheet 430, the LiF can be a component of the SEI film of the negative electrode sheet 430, and the LiF has high ion conductivity, thereby reducing the impedance of the SEI film of the negative active layer 432 to a certain extent and improving the cycle performance of the battery 400; the nitro-containing pyridinone can generate LiN on the surface of the negative active layer 432 of the negative electrode sheet 430, the LiN has high ion conductivity, thereby reducing the impedance of the SEI film of the negative active layer 432 to a certain extent and improving the cycle performance of the battery 400; the mercapto-containing pyridinone can generate lithium organic sulfonate, lithium sulfide and lithium sulfate on the surface of the negative active layer 432 of the negative electrode sheet 430, all of which have high ion conductivity, thereby reducing the impedance of the SEI film of the negative active layer 432 to a certain extent and improving the cycle performance of the battery 400.

[0078] In some embodiments, the electrolyte further comprises an electrolyte salt, and the electrolyte salt comprises at least one of lithium hexafluorophosphate (LIPF6), lithium bisfluorosulfonimide, lithium bis(trifluoromethanesulfon)imide, lithium difluorophosphate, lithium difluoroboric oxalate, lithium difluorophosphate oxalate, etc.

[0079] In some embodiments, the total molar concentration M of the electrolyte salt in the electrolyte is in the range of 0.7 mol / L≤M≤1.4 mol / L. The total molar concentration M of the electrolyte salt in the electrolyte can be, but is not limited to, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, etc. If the total molar concentration M of the electrolyte salt is too small, the free ion concentration in the electrolyte is too small, which reduces the conductivity of the electrolyte and thus reduces the kinetic performance of the battery 400. If the total molar concentration M of the electrolyte salt is too large, a part of the electrolyte salt may not dissociate, and the viscosity of the electrolyte will increase, which will reduce the conductivity of the electrolyte and also reduce the kinetic performance of the battery 400. When the total molar concentration M of the electrolyte salt in the electrolyte is in the range of 0.7 mol / L≤M≤1.4 mol / L, the electrolyte can have a higher conductivity, and thus the battery 400 can have better kinetic performance.

[0080] Further, the total molar concentration M of the electrolyte salt in the electrolyte is in the range of 0.8 mol / L≤M≤1.3 mol / L. When the total molar concentration M of the electrolyte salt in the electrolyte is in this range, the electrolyte can have a better conductivity, and thus the battery 400 can have better kinetic performance.

[0081] In some embodiments, the electrolyte further comprises a second additive, which is fluoroethylene carbonate (FEC), and the mass fraction w2 of the fluoroethylene carbonate in the electrolyte ranges from 1% to 4%. Specifically, the mass fraction w2 of the fluoroethylene carbonate in the electrolyte can be, but is not limited to, 1%, 1.2%, 1.4%, 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%, 3.1%, 3.4%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, and the like. Adding fluoroethylene carbonate in the electrolyte can improve the cycle capacity retention rate and storage capacity retention rate of the battery 400; if the mass fraction w2 of the fluoroethylene carbonate in the electrolyte is too low, the improvement of the cycle performance of the battery 400 using the electrolyte is limited; if the mass fraction w2 of the fluoroethylene carbonate in the electrolyte is too high, the SEI film of the positive electrode plate 410 and the negative electrode plate 430 formed has too many inorganic components and too few organic components, which reduces the flexibility of the SEI film, and the SEI cannot well alleviate the expansion-contraction in the lithium intercalation-extraction process during the charge-discharge cycle of the battery 400, so that the SEI film is easily broken, which is not conducive to improving the cycle performance of the battery 400.

[0082] In the present embodiment, by adding fluoroethylene carbonate, the fluoroethylene carbonate can be compatible with the pyridinone of the present application, which can better improve the cycle performance of the battery 400.

[0083] In some embodiments, the electrolyte further comprises a third additive, which is a film-forming additive, and the third additive can be used to promote the formation of an interface film of at least one of the positive electrode plate 410 and the negative electrode plate 430 and maintain the stability of the interface film, thereby improving the cycle life of the battery 400.

[0084] Optionally, the third additive comprises at least one of vinylene carbonate (VC), divinylsulfate (DTD), vinyl ethylene carbonate (VEC), 1,3-propane sultone (PS), and the like.

[0085] Optionally, the mass fraction of the third additive in the electrolyte is 1% to 4%. Specifically, the mass fraction of the third additive can be, but is not limited to, 1%, 1.2%, 1.4%, 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%, 3.1%, 3.4%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, and the like.

[0086] Optionally, the organic solvent includes at least one of a cyclic carbonate and a chain carbonate. The cyclic carbonate has high dielectric constant and high ionic conductivity, and can form a stable SEI film on the surface of the negative electrode tab 430, but has large viscosity. The chain carbonate has lower viscosity than the cyclic carbonate, has better electrochemical stability, and can improve the low-temperature performance of the electrolyte. Therefore, when a mixed solvent of the cyclic carbonate and the chain carbonate is used, the electrolyte can have suitable viscosity and low-temperature stability, and the battery 400 using the electrolyte can form a better film.

[0087] Optionally, the cyclic carbonate can include, but is not limited to, at least one of ethylene carbonate (abbreviated as EC), propylene carbonate (abbreviated as PC), and the like. The dielectric constant of ethylene carbonate is much larger than that of propylene carbonate, and ethylene carbonate can better promote the formation of the SEI film.

[0088] Optionally, the chain carbonate can include, but is not limited to, at least one of dimethyl carbonate (abbreviated as DMC), diethyl carbonate (abbreviated as DEC), methyl ethyl carbonate (abbreviated as EMC), and the like. Dimethyl carbonate (abbreviated as DMC) and diethyl carbonate (abbreviated as DEC) can better improve the conductivity and solubility of the electrolyte.

[0089] Optionally, in the electrolyte, the mass fraction of the organic solvent is 60% to 85%. Specifically, it can be, but is not limited to, 60%, 65%, 70%, 75%, 80%, 85%, and the like.

[0090] Optionally, the organic solvent further includes at least one of ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, gamma-butyrolactone, and 2,2-difluoroethyl acetate.

[0091] Optionally, the battery 400 further includes a shell 440 for accommodating the electrolyte, the positive electrode tab 410, the separator 420, and the negative electrode tab 430.

[0092] Please refer to Figure 8In some embodiments, the positive electrode plate 410 includes a positive electrode current collector 411 and a positive electrode active layer 412 disposed on a surface of the positive electrode current collector 411, the positive electrode active layer 412 including a positive electrode active material and a carbon material; the carbon material includes a coating carbon wrapped on a surface of the positive electrode active material and a conductive carbon dispersed in the positive electrode active layer 412; a mass fraction A1 of the coating carbon in the positive electrode active layer 412 ranges from 0.6% to 1.5%; a mass fraction A2 of the conductive carbon in the positive electrode active layer 412 ranges from 0 to 0.6%.

[0093] It can be understood that the positive electrode active layer 412 can cover one surface of the positive electrode current collector 411 or can also cover two opposite surfaces of the positive electrode current collector 411.

[0094] Specifically, in the positive electrode active layer 412, the mass fraction A1 of the coating carbon can be, but is not limited to, 0.6%, 0.65%, 0.7%, 0.75%, 0.77%, 0.8%, 0.87%, 0.9%, 0.95%, 1.04%, 1.1%, 1.15%, 1.20%, 1.25%, 1.30%, 1.35%, 1.40%, 1.45%, 1.5%, etc. In the present embodiment, if the mass fraction A1 of the coating carbon in the positive electrode active layer 412 is too low, the coating carbon cannot completely wrap the positive electrode active material, so that part of the positive electrode active material directly contacts the electrolyte, increasing the side reaction between the electrolyte and the positive electrode active layer 412, thereby increasing the consumption of the electrolyte and reducing the cycle capacity retention rate of the battery 400; in addition, the coating carbon also affects the construction of the interface conductive network of the positive electrode active layer 412, and too low mass fraction of the coating carbon will also deteriorate the conductive performance and affect the kinetics. If the mass fraction A1 of the coating carbon in the positive electrode active layer 412 is too high, at high voltage, the cyclic carbonate solvent in the electrolyte reacts with the coating carbon on the surface of the positive electrode active material (such as lithium iron phosphate) to release heat, increasing the risk of heat generation of the battery 400 and reducing the safety performance of the battery 400; in addition, although the increase of the content of the coating carbon will increase the electronic conductivity of the positive electrode active layer 412, it will also increase the transmission impedance of ions in the positive electrode active layer 412, thereby reducing the ion transmission rate and also reducing the kinetics performance of the positive electrode plate 410; in addition, if the mass fraction A1 of the coating carbon in the positive electrode active layer 412 is too high, the proportion of non-active materials in the positive electrode active layer 412 is increased, thereby reducing the energy density of the positive electrode active layer 412.

[0095] Further, the mass fraction A1 of the coated carbon in the positive electrode active layer 412 is in the range of 0.8%≤A1≤1.3%. In this way, the battery 400 has better cycle capacity retention, higher kinetic performance and higher safety performance.

[0096] Specifically, in the positive electrode active layer 412, the mass fraction A2 of the conductive carbon can be, but is not limited to, 0, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.6%, etc. If the mass fraction A2 of the conductive carbon in the positive electrode active layer 412 is too small, the conductive network of the positive electrode active material (such as lithium iron phosphate) between the binders is insufficient, which reduces the electronic conductivity of the positive electrode active layer 412, thereby reducing the kinetic performance of the positive electrode active layer 412. If the mass fraction A2 of the conductive carbon in the positive electrode active layer 412 is too large, the viscosity of the positive electrode active layer 412 is too large during the slurry preparation process, which increases the difficulty of coating the positive electrode active layer 412 and affects the performance of the positive electrode active layer 412.

[0097] Further, in the positive electrode active layer 412, the mass fraction A2 of the conductive carbon is in the range of 0.15%≤A2≤0.5%. In this way, the battery 400 has higher kinetic performance and higher gram capacity.

[0098] Optionally, the positive electrode current collector 411 can be, but is not limited to, an aluminum sheet or an aluminum foil.

[0099] Optionally, the positive electrode active material can be, but is not limited to, lithium iron phosphate.

[0100] Optionally, the mass fraction of the positive electrode active material in the positive electrode active layer 412 is in the range of 96% to 99%. Specifically, the mass fraction of the positive electrode active material in the positive electrode active layer 412 can be, but is not limited to, 96%, 97%, 98%, 99%, etc.

[0101] Optionally, the conductive carbon can be, but is not limited to, at least one of conductive carbon black (SP), acetylene black, carbon nanotubes, carbon fibers, graphene, etc.

[0102] Optionally, the coated carbon can be obtained by sintering a carbon source by a carbothermal reduction method. Optionally, the carbon source can be, but is not limited to, at least one of glucose, sucrose, starch, a high molecular carbon source such as PEG, etc.

[0103] Optionally, the positive electrode active layer 412 further comprises a first binder and a first thickening agent.

[0104] Optionally, the first binder can be, but is not limited to, at least one of Polyvinylidene Fluoride (PVDF), Polyamide (PA), Polyacrylonitrile (PAN), Polyacrylate, Polyvinylether, Polymethyl Methacrylate (PMMA), Polyhexafluoropropylene, Polymerized Styrene Butadiene Rubber (SBR), and the like.

[0105] Optionally, in the positive active layer 412, the mass fraction of the first binder ranges from 2% to 4%. Specifically, in the positive active layer 412, the mass fraction of the first binder can be, but is not limited to, 2%, 2.5%, 3%, 3.5%, 4%, and the like. If the mass fraction of the first binder is too small, the positive active layer 412 is prone to powdering or spalling; if the mass fraction of the first binder is too large, the energy density of the positive electrode sheet 410 is reduced.

[0106] Optionally, the first thickening agent can be, but is not limited to, at least one of sodium carboxymethyl cellulose (CMC), polyacrylamide (PAM), and polymethyl acrylate (PMA), and the like.

[0107] Optionally, the separator 420 can be, but is not limited to, at least one of a polypropylene film (PP film), a polyethylene film (PE film), a ceramic separator 420, and the like.

[0108] Optionally, the thickness of the separator 420 ranges from 14 μm to 18 μm. Specifically, the thickness of the separator 420 can 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, and the like.

[0109] Please refer to Figure 9 Optionally, the negative electrode sheet 430 includes a negative current collector 431 and a negative active layer 432 disposed on the surface of the negative current collector 431. Understandably, the negative active layer 432 can cover one surface or opposite two surfaces of the negative current collector 431.

[0110] Optionally, the negative current collector 431 can be, but is not limited to, a copper sheet, a copper foil.

[0111] Optionally, the negative active layer 432 comprises a negative active material, a negative conductive agent, a second binder, and a second thickening agent.

[0112] Optionally, the negative active material can be, but is not limited to, graphite. Optionally, the graphite can be natural graphite or artificial graphite, which is not limited in the present application. Optionally, the mass fraction of the negative active material in the negative active layer 432 ranges from 92% to 98%. Specifically, the mass fraction of the negative active material in the negative active layer 432 can be, but is not limited to, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc.

[0113] Optionally, the negative conductive agent can be, but is not limited to, at least one of conductive carbon black (SP for short), acetylene black, carbon nanotubes, carbon fibers, graphene, etc.

[0114] Optionally, the second binder can be, but is not limited to, at least one of polyvinylidene fluoride (PVDF for short), polyamide (PA for short), polyacrylonitrile (PAN for short), polyacrylate, polyvinyl ether, polymethyl methacrylate (PMMA for short), polyhexafluoropropylene, polymerized styrene butadiene rubber (SBR for short), etc.

[0115] Optionally, in the negative active layer 432, the mass fraction of the second binder ranges from 2% to 4%. Specifically, in the negative active layer 432, the mass fraction of the second binder can be, but is not limited to, 2%, 2.5%, 3%, 3.5%, 4%, etc. If the mass fraction of the second binder is too small, the negative active layer 432 is prone to powdering or dropping; if the mass fraction of the second binder is too large, the energy density of the negative electrode sheet 430 is reduced.

[0116] Optionally, the second thickening agent can be, but is not limited to, at least one of sodium carboxymethyl cellulose (CMC for short), polyacrylamide (PAM for short), and polymethyl acrylate (PMA for short).

[0117] The battery 400 of the present application is further described below through specific examples.

[0118] Examples 1 to 28, Comparative Examples 1 to 4

[0119] The preparation method of the battery 400 of each embodiment and the comparative example includes:

[0120] (1) Preparation of the positive electrode tab 410: add conductive carbon black SP (conductive carbon) and PVDF (first binder) dispersed in N-methyl pyrrolidone (NMP for short) solvent into lithium iron phosphate solid powder (including lithium iron phosphate particles and coated carbon coated on the surface of the lithium iron phosphate) to obtain a positive electrode slurry; coat the positive electrode slurry on an aluminum foil (positive electrode current collector 411), and control the coating weight of the positive electrode slurry to be 300 mg / 1540.25 mm 2 ; then, after drying, cold pressing, slitting, and cutting, the positive electrode tab 410 is prepared.

[0121] (2) Preparation of the negative electrode tab 430: mix and disperse the negative electrode active material hard carbon, conductive carbon black SP (second conductive agent), carboxymethyl cellulose sodium CMC (second thickening agent), styrene-butadiene rubber (SBR, second binder), and asphalt in deionized water to obtain a negative electrode slurry; then, coat the negative electrode slurry on a copper foil (negative electrode current collector 431) so that the coating weight of the negative electrode slurry is 144 mg / 1540.25 mm 2 ; then, after drying, cold pressing, slitting, and cutting, the negative electrode tab 430 is prepared.

[0122] (3) Preparation of the electrolyte: remove water from three solvents, dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), and ethylene carbonate (EC), using a molecular sieve so that the water content of the solvents is less than 10 ppm; in an argon atmosphere glove box with a water content of ≤1 ppm, mix dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), and ethylene carbonate (EC) according to a predetermined ratio to obtain a mixed solvent; then, dissolve the dried electrolyte salt lithium hexafluorophosphate into the mixed solvent, stir until completely dissolved and uniform, and then add fluoroethylene carbonate (second additive), pyridone (first additive), and the like to obtain the electrolyte.

[0123] In the prepared electrolyte, the mass ratio of dimethyl carbonate, methyl ethyl carbonate, and ethylene carbonate is 1:1:1; and the addition amount of the vinylene carbonate is 2%.

[0124] The types and addition amounts of the first additive and the addition amount of the second additive in the electrolyte of each embodiment and the comparative example are shown in Table 1 and Table 2. In the embodiments 1 to 25, the comparative example 2, and the comparative example 3, only pyridone is added, and no fluoroethylene carbonate is added, i.e., the addition amount is 0%. In the embodiments 26 to 28, both pyridone and fluoroethylene carbonate are added. In the comparative example 4, only fluoroethylene carbonate is added, and the addition amount of pyridone is 0%.

[0125] (4) Providing the separator 420: a 16 μm polyethylene film is used as the separator 420.

[0126] (5) Assembly of the battery 400: the positive electrode sheet 410, the separator 420, and the negative electrode sheet 430 are sequentially stacked to form an electrode assembly, the electrode assembly is wound to obtain a bare battery cell, the bare battery cell is assembled into an outer package after the tabs are welded, the prepared electrolyte is injected, and the battery 400 is finally prepared after packaging, standing, formation, shaping, capacity testing, and the like.

[0127] The batteries 400 obtained in each of the examples and the comparative examples are subjected to various performance tests, and the details are as follows.

[0128] (1) Cycle performance test at 25°C: the lithium ion battery 400 is charged at 0.5P constant power to 3.65V, and then discharged at 0.5P constant power to 2.5V after standing for 10 minutes. The capacity obtained in this step is the initial discharge capacity C0, and the cycle test of 0.5P charging / 0.5P discharging is performed for 1000 cycles, and the discharge capacity of the 1000th cycle is recorded. The cycle capacity retention rate after 1000 cycles at 25°C is (discharge capacity of the 1000th cycle / initial discharge capacity C0) x 100%.

[0129] (2) Cycle performance test at 45°C: the lithium ion battery 400 is charged at 1P constant power to 3.65V, and then discharged at 1P constant power to 2.5V after standing for 10 minutes. The capacity at this time is the initial discharge capacity C0, and the cycle test of 1P charging / 1P discharging is performed for 1000 cycles, and the discharge capacity of the 1000th cycle is recorded. The cycle capacity retention rate after 1000 cycles at 45°C is (discharge capacity of the 1000th cycle / initial discharge capacity C0) x 100%.

[0130] (3) Storage performance test: the lithium ion battery 400 is charged at 0.5P constant power to 3.65V, and then discharged at 0.5P to 2.5V after standing for 10 minutes. The capacity obtained in this step is the initial discharge capacity C0, and the lithium ion battery 400 is charged at 0.5P constant power to 3.65V after standing for 10 minutes. After being stored in a 45°C oven for 30 days, the lithium ion battery 400 is discharged at 0.5P constant power to 2.5V after standing at 25°C for 10 minutes, and the remaining capacity is recorded. The capacity retention rate after 30 days of storage at 45°C is (remaining capacity of the lithium ion battery 400 after storage / initial discharge capacity C0) x 100%.

[0131] The performance parameters of the batteries 400 of Examples 1 to 25 and Comparative Examples 1 to 3 measured are shown in Table 1.

[0132] Table 1 Performance parameters of the battery 400 of Examples 1-25 and Comparative Examples 1-3

[0133]

[0134]

[0135] As can be seen from the test data of Examples 1-25 and Comparative Examples 1-3, the battery 400 of Comparative Example 1 without the addition of pyridinone has a low cycle capacity retention rate at room temperature (25°C) and a low cycle capacity retention rate at high temperature (45°C), which may be due to the expansion and contraction of the SEI film during the electrochemical process of charging and discharging of the battery 400 during the cycle process. Therefore, the SEI film is constantly being damaged and repaired, and the process of generating the SEI film is the process of the electrolyte components losing and gaining electrons on the surface of the active material. In this process, active lithium is lost, which is irreversible loss, and the reduction of active lithium content leads to poor charging and discharging cycle capability and storage performance of the battery 400.

[0136] The addition of pyridinone in the electrolyte can improve the cycle capacity retention rate of the battery 400 at room temperature (25°C) and at high temperature (45°C). However, if the amount of addition is too low, for example, Comparative Example 2, the SEI film formed on the surface of the negative electrode sheet 430 cannot effectively protect the negative electrode sheet 430, and therefore the improvement in the cycle capacity retention rate at room temperature (25°C) and at high temperature (45°C) is small. When the amount of addition of pyridinone is greater than 5% (for example, Comparative Example 3), the cycle capacity retention rate of the battery 400 at room temperature and at high temperature decreases, which is due to the fact that when the amount of addition of pyridinone in the electrolyte is too high, the SEI film formed on the surface of the negative electrode sheet 430 is too thick, increasing the impedance of lithium intercalation of the negative electrode sheet 430, and thus the negative electrode sheet is prone to lithium precipitation during lithium intercalation, resulting in the loss of active lithium in the electrolyte. Therefore, when the amount of addition of pyridinone is 0.1% to 5%, the cycle capacity retention rate of the battery 400 at room temperature and at high temperature is greatly improved.

[0137] As can be seen from the test data of Examples 1-25 and Comparative Examples 1-3, the addition of pyridinone in the electrolyte can greatly improve the capacity retention rate of the battery 400 stored at 45°C for 30 days. When the amount of addition of pyridinone is 0.1% to 5%, the capacity retention rate of the battery 400 stored at 45°C for 30 days is greatly improved. However, when the amount of addition of pyridinone is greater than 5% (for example, Comparative Example 3), the capacity retention rate of the battery 400 stored at 45°C for 30 days decreases.

[0138] The performance parameters of the battery 400 of Example 3, Example 26 to Example 28 and Comparative Example 4 measured are shown in Table 2 below.

[0139] Table 2 Performance parameters of the battery 400 of Example 3, Example 26 to Example 28 and Comparative Example 4

[0140]

[0141] From the test data of Example 3, Example 26 to Example 28 and Comparative Example 4, it can be seen that, compared with the battery 400 in which only pyridinone is added to the electrolyte (Example 3) or only fluoroethylene carbonate is added to the electrolyte (Comparative Example 4), the battery 400 in which pyridinone and fluoroethylene carbonate are added to the electrolyte (Example 26 to Example 28) can make the battery 400 have higher room temperature cycle capacity retention rate and high temperature cycle capacity retention rate, and the residual capacity retention rate after 30 days of storage at 45°C is also higher. This shows that pyridinone and fluoroethylene carbonate can have a compatibility effect, so that the battery 400 has higher cycle performance.

[0142] In the present application, the phrase "embodiment" or "embodiments" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily mean that all the embodiments refer to the same embodiment, nor is it independent or alternative to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present application can be combined with other embodiments. In addition, it should also be understood that the features, structures or characteristics described in the embodiments of the present application can be combined with each other without contradiction, to form another embodiment of the present application without departing from the spirit and scope of the present application.

[0143] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application.

Claims

1. An electrolyte, characterized in that, The electrolyte comprises an electrolyte salt, an organic solvent, and a first additive, wherein the first additive is a pyridinone, and the structural formula of the pyridinone is: Wherein, R1 is at least one of hydrogen, halogen, alkyl, nitro, trifluoromethyl, mercapto, and amino groups having 1 to 5 carbon atoms; R2 is at least one of hydrogen, halogen, alkyl, nitro, trifluoromethyl, mercapto, and amino groups having 1 to 5 carbon atoms; R3 is at least one of hydrogen, alkyl, trifluoromethyl, and mercapto groups having 1 to 5 carbon atoms; R4 is at least one of hydrogen, halogen, alkyl, nitro, trifluoromethyl, mercapto, and amino groups having 1 to 5 carbon atoms; and R5 is at least one of hydrogen, halogen, alkyl, nitro, trifluoromethyl, mercapto, and amino groups having 1 to 5 carbon atoms. The mass fraction w1 of the pyridinone in the electrolyte is in the range of 0.1% ≤ w1 ≤ 5.0%.

2. The electrolyte according to claim 1, characterized in that, The mass fraction w1 of the pyridinone in the electrolyte is in the range of 0.1% ≤ w1 ≤ 1%.

3. The electrolyte according to claim 1, characterized in that, The pyridone is At least one of them.

4. The electrolyte according to any one of claims 1-3, characterized in that, The electrolyte salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, lithium difluorooxalate borate, and lithium difluorooxalate phosphate.

5. The electrolyte according to any one of claims 1-3, characterized in that, The electrolyte also includes a second additive, which is fluoroethylene carbonate, and the mass fraction w2 of the fluoroethylene carbonate in the electrolyte is in the range of 1% ≤ w2 ≤ 4%.

6. The electrolyte according to any one of claims 1-3, characterized in that, The organic solvent includes at least one of cyclic carbonates and chain carbonates; the cyclic carbonate includes at least one of ethylene carbonate and propylene carbonate; the chain carbonate includes at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

7. A battery, characterized in that, include: The electrolyte, positive electrode, separator, and negative electrode as described in any one of claims 1-6.

8. The battery according to claim 7, characterized in that, The positive electrode sheet includes a positive current collector and a positive active layer. The positive active layer is disposed on the surface of the positive current collector and includes a positive active material and a carbon material. The carbon material includes coated carbon and conductive carbon. The coated carbon is wrapped around the surface of the positive active material, and the conductive carbon is dispersed in the positive active layer. The mass fraction A1 of the coated carbon in the positive active layer is in the range of 0.6% ≤ A1 ≤ 1.5%. The mass fraction A2 of the conductive carbon in the positive active layer is in the range of 0 < A2 ≤ 0.6%.

9. An energy storage device, characterized in that, include: Box; as well as The batteries of claims 7 or 8, wherein the plurality of batteries are housed within the housing.

10. An electrical system, characterized in that, include: Electrical equipment, and The energy storage device of claim 9, wherein the energy storage device supplies power to the electrical equipment.

Images