Electrolyte and lithium ion battery

Abstract

The application discloses an electrolyte and a lithium ion battery. The electrolyte comprises a lithium salt, an organic solvent and an additive A. In the application, the N atom in the pyrimidine ring of the additive A, which is connected with the carbonyl group, can be combined with the H atom of HF generated by the side reaction of the lithium salt in the electrolyte to form a complex, so that the electrolyte acidity and the gas production are reduced.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrolyte and a lithium-ion battery. Background Technology

[0002] With societal development, higher energy density requirements have been placed on lithium-ion batteries. Conventional anode materials can no longer meet these requirements, necessitating the addition of silicon to improve the specific capacity of anode materials. Silicon boasts a theoretical specific capacity as high as 4200 mAh / g, making it a very promising anode material for lithium-ion batteries. However, silicon expands and contracts by over 300% in its fully lithium-intercalated state, easily causing the solid electrolyte interface (SEI) film to rupture. During battery cycling, the SEI film continuously regenerates and ruptures, accelerating electrolyte consumption, leading to particle pulverization and detachment of the anode material, and deteriorating battery performance. To mitigate this, fluoroethylene carbonate (FEC) is often added to the electrolyte. However, FEC has poor thermal stability and can undergo side reactions with LiPF6, ethylene carbonate (EC), etc., at high temperatures, resulting in increased electrolyte acidity, high gas production, and deterioration of the battery's high-temperature storage performance. Summary of the Invention

[0003] The embodiments of the present invention provide an electrolyte and a lithium-ion battery, which can improve the problems of increased electrolyte acidity and high gas production.

[0004] In a first aspect, embodiments of the present invention provide an electrolyte comprising a lithium salt, an organic solvent, and an additive A, wherein the additive A has the structural formula of [insert structural formula here].

[0005] ,

[0006] Wherein, R1 and R2 independently include hydrogen, deuterium, amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid, aldehyde, mercapto, cyano, isocyanate, sulfonyl, unsubstituted or substituted acyl, unsubstituted or substituted C1-C4 olefin, unsubstituted or substituted C1-C4 alkyl, unsubstituted or substituted C3-C4 cycloalkyl, unsubstituted or substituted C1-C4 alkoxy, unsubstituted or substituted C3-C4 alkoxy, and unsubstituted or substituted C4 alkyl groups. The aryl group having 5 to 18 ring atoms substituted by a substituent, the heteroaryl group having 5 to 18 ring atoms that is unsubstituted or substituted by a second substituent, the aryloxy group having 5 to 18 ring atoms that is unsubstituted or substituted by a second substituent, and the heteroaryloxy group having 5 to 18 ring atoms that is unsubstituted or substituted by a second substituent, wherein the second substituent includes one or more of halogen, hydroxyl, carboxyl, nitro, sulfonic acid, aldehyde, mercapto, cyano, acyl, sulfonyl, C1 to C4 alkyl, and C1 to C4 alkoxy.

[0007] In one embodiment, the additive A in the electrolyte has a mass content of 0.1% to 1.0%; and / or

[0008] The lithium salt includes one or more of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide; and / or

[0009] The concentration of the lithium salt in the electrolyte is 1.0 mol / L to 1.3 mol / L.

[0010] In one embodiment, the electrolyte further includes vinylene carbonate, wherein the mass content of vinylene carbonate in the electrolyte is 0.2%-1.0%.

[0011] In one embodiment, the electrolyte further includes fluoroethylene carbonate, wherein the fluoroethylene carbonate has a mass content of 4%-12% in the electrolyte.

[0012] In one embodiment, the electrolyte further includes a lithium salt additive.

[0013] In one embodiment, the lithium salt additive includes one or more of lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium bis(oxalato)borate, and lithium difluorobis(oxalato)phosphate; and / or

[0014] The lithium salt additive has a mass content of 0.5% to 1.0% in the electrolyte.

[0015] In one embodiment, the electrolyte also includes a sulfur-containing additive.

[0016] In one embodiment, the sulfur-containing additive includes one or more of 1,3-propanesulfonate lactone, sulfur-triallylamine copolymer, vinyl sulfate, and methylene disulfonate; and / or

[0017] The sulfur-containing additive has a mass content of 0.5% to 1.0% in the electrolyte.

[0018] Secondly, embodiments of the present invention provide a lithium-ion battery, including a positive electrode, a negative electrode, and the electrolyte described above.

[0019] In one embodiment, the negative electrode sheet includes a current collector and a negative electrode active material disposed on the current collector, wherein the negative electrode active material includes graphite and silicon carbide materials; and / or

[0020] The positive electrode includes a current collector and a positive electrode active material disposed on the current collector. The positive electrode active material includes a nickel-cobalt-manganese ternary material, the chemical formula of which is Li(Ni) x Co y Mn z O2, where x≥0.8, 0 <y≤0.2,0<z≤0.2,x+y+z=1

[0021] The beneficial effects of the embodiments of the present invention are as follows:

[0022] In an embodiment of the present invention, the N atom in the pyrimidine ring of additive A, which is attached to the carbonyl group, can combine with the H atom of HF generated by the side reaction of lithium salt in the electrolyte to form a complex, thereby reducing the acidity of the electrolyte and the amount of gas produced. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is the structural formula of additive A provided in this application;

[0025] Figure 2 This is the structural formula of additive A provided in Example 1 of this application;

[0026] Figure 3 This is the structural formula of additive A provided in Example 2 of this application;

[0027] Figure 4 This is the structural formula of additive A provided in Example 3 of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. Furthermore, in the description of this application, the term “comprising” means “including but not limited to”. The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish an order.

[0030] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0031] The technical solution of this application is as follows:

[0032] In a first aspect, embodiments of this application provide an electrolyte comprising a lithium salt, an organic solvent, and an additive A, wherein the additive A has the following structural formula:

[0033] ,

[0034] R1 and R2 independently include hydrogen, deuterium, amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid, aldehyde, mercapto, cyano, isocyanate, sulfonyl, unsubstituted or substituted acyl, unsubstituted or substituted C1-C4 olefin, unsubstituted or substituted C1-C4 alkyl, unsubstituted or substituted C3-C4 cycloalkyl, unsubstituted or substituted C1-C4 alkoxy, and unsubstituted or substituted C3-C4 alkoxy. The aryl group having 5 to 18 ring atoms substituted with a methyl group, the heteroaryl group having 5 to 18 ring atoms unsubstituted or substituted with a second substituent, the aryloxy group having 5 to 18 ring atoms unsubstituted or substituted with a second substituent, and the heteroaryloxy group having 5 to 18 ring atoms unsubstituted or substituted with a second substituent, wherein the second substituent may include one or more of halogen, hydroxyl, carboxyl, nitro, sulfonic acid, aldehyde, mercapto, cyano, acyl, sulfonyl, C1 to C4 alkyl, and C1 to C4 alkoxy.

[0035] In this application, the N atom in the pyrimidine ring of additive A, which is attached to the carbonyl group, has a lone pair of electrons. Since the lone pair of electrons of this N atom does not participate in conjugation, it can combine with the H atom of HF generated by the side reaction of lithium salt in the electrolyte to form a complex. This reduces the content of HF generated by the side reaction of lithium salt in the electrolyte, thereby reducing the acidity and gas production of the electrolyte and improving the high-temperature stability of the electrolyte. The anhydride group in additive A can form a uniform and stable interfacial film on the positive electrode surface, thereby effectively reducing the cracking of the SEI film and mitigating the irreversible phase transition of the positive electrode material, thus improving the overall performance of the lithium-ion battery.

[0036] In some embodiments, R1 and R2 are each independently one of alkyl, fluorine atom, fluoroalkyl, vinyl, propenyl, acetyl, fluoroacetyl, methanesulfonyl, isocyanate and cyano.

[0037] In some embodiments, the additive A has a mass content of 0.1% to 1.0% in the electrolyte, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc. This can effectively improve the overall performance of the lithium-ion battery.

[0038] In some embodiments, the electrolyte further includes vinylene carbonate (VC).

[0039] In some embodiments, the mass content of vinylene carbonate in the electrolyte is 0.2%-1.0%, for example, it can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc. This promotes the formation of a dense SEI film on the battery negative electrode while controlling the negative electrode impedance. When VC forms a film on the battery negative electrode, insufficient VC addition results in a low density of the SEI film, while excessive addition increases the negative electrode impedance and causes gas production. Adding additive A to the electrolyte can alleviate the problem of high gas production caused by VC.

[0040] In some embodiments, the electrolyte further includes fluoroethylene carbonate (FEC).

[0041] In this application, when the negative electrode material of the battery contains silicon, due to the high expansion and contraction of silicon, the negative electrode material particles are easily pulverized and detached. FEC can form a film on the negative electrode of the battery, thereby mitigating the damage to the SEI film caused by the expansion and contraction of silicon. However, FEC will react with LiPF6, EC, etc. at high temperature, resulting in an increase in electrolyte acidity and high gas production. By adding additive A, the problems of high electrolyte acidity and high gas production caused by FEC can be alleviated.

[0042] In some embodiments, the fluoroethylene carbonate (FEC) content in the electrolyte is 4%-12% by mass. This can mitigate the damage to the SEI film caused by the silicon anode material, while ensuring the battery's high-temperature storage performance and cycle performance. Excessive FEC addition will deteriorate the battery's high-temperature storage performance, while insufficient FEC addition will deteriorate the battery's cycle performance.

[0043] In some embodiments, the electrolyte further includes lithium salt additives. This can reduce the battery's internal resistance and improve its high-temperature storage performance.

[0044] In some embodiments, the lithium salt additive includes one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorophosphate (LiPO2F2), lithium bis(oxalato)borate (LiBOB), and lithium difluorobis(oxalato)phosphate (LiODFP).

[0045] In some embodiments, the lithium salt additive has a mass content of 0.5% to 1.0% in the electrolyte, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc.

[0046] In some embodiments, the electrolyte further includes sulfur-containing additives. In this application, the sulfur-containing additives can assist in film formation at the positive and negative electrodes of the battery and exhibit high thermal stability.

[0047] In some embodiments, the sulfur-containing additive includes one or more of 1,3-propanesulfonate lactone (PS), sulfur and triallylamine copolymer (PST), vinyl sulfate (DTD), and methylene disulfonate (MMDS).

[0048] In some embodiments, the sulfur-containing additive in the electrolyte has a mass content of 0.5% to 1.0%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc. This allows for the formation of a dense SEI film on the negative electrode of the battery, ensuring good cycle performance. Insufficient sulfur-containing additive results in a low density SEI film on the negative electrode, while excessive addition leads to over-film formation on the negative electrode, causing a decrease in battery cycle performance.

[0049] In some embodiments, the lithium salt includes one or more of lithium hexafluorophosphate (LiPF6) and lithium bisfluorosulfonylimide (LiFSI).

[0050] In some embodiments, the concentration of the lithium salt in the electrolyte is 1.0 mol / L to 1.3 mol / L, for example, it can be 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, etc.

[0051] In some embodiments, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0052] In some embodiments, the organic solvent includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate, wherein the volume ratio of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate is (20-40):(0-20):(0-20):(5-20):(30-50).

[0053] This application also provides a lithium-ion battery, including a positive electrode, a negative electrode, and the electrolyte described above.

[0054] In some embodiments, the negative electrode sheet includes a current collector and a negative electrode active material disposed on the current collector, wherein the negative electrode active material includes graphite and silicon carbide materials.

[0055] In some embodiments, the specific capacity of the negative electrode active material is ≥450 mAh / g. Thus, the negative electrode active material has a high specific capacity, meaning it has a high silicon content. By adding additive A to the electrolyte, the high-temperature cycle performance and storage performance of the battery can be effectively improved.

[0056] In some embodiments, the positive electrode sheet includes a current collector and a positive electrode active material disposed on the current collector. The positive electrode active material includes a nickel-cobalt-manganese ternary material, and the chemical formula of the nickel-cobalt-manganese ternary material is Li(Ni x Co y Mn z )O2, where x≥0.8, 0<y≤0.2, 0<z≤0.2, and x + y + z = 1. Thus, since the nickel-cobalt-manganese ternary material has a higher specific capacity, the capacity of the positive electrode active material can be improved. At the same time, due to the strong oxidizing property of the nickel-containing positive electrode, by adding additive A to the electrolyte, a uniform and stable interfacial film can be promoted to form on the positive electrode surface, alleviating the oxidation of the electrolyte at the positive electrode, reducing the dissolution of the transition metal at the positive electrode, and thereby improving the storage performance of the battery.

[0057] The present application will be specifically described below through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application. The raw materials used in the following embodiments are all commercially available products unless otherwise specified.

[0058] Example 1

[0059] An electrolyte and its preparation method include the following steps:

[0060] (1) Mix ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate according to a volume percentage of 20%:20%:60% to obtain an organic solvent;

[0061] (2) Under an argon atmosphere, add vinylene carbonate (VC), fluoroethylene carbonate (FEC), lithium difluorophosphate (LiPO2F2), 1,3-propane sultone (PS), and additive A (3-[2-amino-4,6-dimethylpyrimidine] maleic anhydride, the structural formula is as attached <00​​​​​​​​​(1) The negative electrode material (including graphite and silicon carbon with a specific capacity of 450mAh / g), conductive agent (acetylene black) and binder (CMC and SBR with a mass ratio of 2:3) are prepared into a slurry in a mass percentage of 94:1:2:3 and coated onto a copper foil current collector. The slurry is then dried under vacuum to obtain the negative electrode sheet.

[0065] (2) The positive electrode material NCM811, conductive agent (acetylene black) and binder (PVDF) are prepared into a slurry in a mass ratio of 94:3:3, coated on an aluminum foil current collector, and dried under vacuum to obtain a positive electrode sheet;

[0066] (3) Assemble the positive electrode, negative electrode, Celgard2400 separator and the above electrolyte into a soft pack battery.

[0067] Example 2

[0068] This embodiment is basically the same as Example 1, except that in this embodiment, additive A is 3-[2-amino-4,6-trifluoromethylpyrimidine]maleic anhydride (structural formula as shown in the attached figure). Figure 3 (As shown).

[0069] Example 3

[0070] This embodiment is basically the same as Example 1, except that in this embodiment, additive A is 3-[2-amino-4,6-dimethylsulfonyl]maleic anhydride (structural formula as shown in the attached figure). Figure 4 (As shown).

[0071] Example 4

[0072] This embodiment is basically the same as Embodiment 1, except that the mass fraction of additive A in the electrolyte is 0.1% in this embodiment.

[0073] Example 5

[0074] This embodiment is basically the same as Embodiment 1, except that the mass fraction of additive A in the electrolyte is 1.0% in this embodiment.

[0075] Example 6

[0076] This embodiment is basically the same as Embodiment 1, except that the mass fraction of vinylene carbonate in the electrolyte is 0.2% in this embodiment.

[0077] Example 7

[0078] This embodiment is basically the same as Embodiment 1, except that the mass fraction of vinylene carbonate in the electrolyte is 1.0% in this embodiment.

[0079] Comparative Example 1

[0080] This comparative example is basically the same as Example 1, except that additive A was not added in this comparative example.

[0081] Comparative Example 2

[0082] This comparative example is basically the same as Example 1, except that maleic anhydride is used instead of additive A in this comparative example.

[0083] Comparative Example 3

[0084] This comparative example is basically the same as Example 1, except that 2-amino-4,6-dimethylpyrimidine is used instead of additive A in this comparative example.

[0085] Test example:

[0086] The lithium-ion batteries obtained in the examples and comparative examples were subjected to electrochemical tests using the Xinwei charge-discharge test cabinet. The test results are shown in Table 1 below.

[0087] (1) Cycle performance test of lithium-ion batteries:

[0088] At 25°C, the lithium-ion battery was charged to 4.2V at a constant current and constant voltage of 0.5C (nominal capacity), then left to rest for 30 minutes, and finally discharged to 2.5V at a constant current of 1C. This constitutes one cycle. The lithium-ion battery was subjected to 600 charge-discharge cycles under the above conditions to obtain the capacity retention rate.

[0089] The capacity retention rate (%) of a lithium-ion battery after N cycles = (discharge capacity of the Nth cycle / initial discharge capacity) × 100%, where N is the number of cycles of the lithium-ion battery.

[0090] (2) High-temperature storage performance test of lithium-ion batteries:

[0091] At 25°C, the lithium-ion battery was charged at a constant current of 0.5C to a voltage of 4.2V, and then charged at a constant voltage of 4.2V to a current of 0.05C. The volume of the lithium-ion battery was measured as V0, and the initial capacity was measured as C0. After that, the lithium-ion battery was placed in a constant temperature chamber at 60°C and stored for 90 days. The volume of the lithium-ion battery was measured and recorded as V1, the capacity was kept as C1, and the capacity was restored to C2.

[0092] The volume expansion rate (%) of a lithium-ion battery after storage at 60°C for 90 days is calculated as (V1-V0) / V0×100%.

[0093] The capacity retention rate (%) of a lithium-ion battery after 90 days of storage at 60°C is (C1 / C0) × 100%, and the capacity recovery rate (%) of a lithium-ion battery after 90 days of storage at 60°C is (C2 / C0) × 100%.

[0094] (3) HF content test in electrolyte:

[0095] The electrolyte was stored at 60°C, and the HF content at 0d (0 days) and 90d (90 days) was tested by ice-water titration, and recorded as HF-0d and HF-90d respectively.

[0096] Table 1

[0097]

[0098]

[0099] As shown in Table 1:

[0100] Compared with Comparative Example 1, the lithium-ion battery of the embodiment has a higher capacity retention rate after 600 cycles at 25°C, a lower HF content after 90 days, a lower volume expansion rate after 90 days of storage at 60°C, a higher capacity retention rate after 90 days of storage at 60°C, and a higher capacity recovery rate after 90 days of storage at 60°C. It can be seen that by adding additive A to the electrolyte, this application can effectively reduce the acidity, gas production and volume expansion rate of the battery, and improve the capacity retention rate and capacity recovery rate of the battery.

[0101] Compared with Comparative Examples 2 and 3, the lithium-ion battery of the present invention has a higher capacity retention rate after 600 cycles at 25°C, a lower HF content after 90 days, a lower volume expansion rate after 90 days of storage at 60°C, a higher capacity retention rate after 90 days of storage at 60°C, and a higher capacity recovery rate after 90 days of storage at 60°C. It can be seen that by adding additive A to the electrolyte, this application can effectively reduce the acidity, gas production and volume expansion rate of the battery, and improve the capacity retention rate and capacity recovery rate of the battery compared with maleic anhydride and 2-amino-4,6-dimethylpyrimidine.

[0102] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An electrolyte, characterized by: comprises a lithium salt, an organic solvent and an additive A, the structural formula of the additive A is ， wherein R1 and R2 each independently comprise one or more of hydrogen, deuterium, amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid group, aldehyde group, mercapto, cyano, isocyanate group, sulfonyl group, acyl group which is unsubstituted or substituted with a second substituent, C1-C4 alkene group which is unsubstituted or substituted with a second substituent, C1-C4 alkyl group which is unsubstituted or substituted with a second substituent, C1-C4 alkoxy group which is unsubstituted or substituted with a second substituent, aryl group having 5 to 18 ring atoms which is unsubstituted or substituted with a second substituent, heteroaryl group having 5 to 18 ring atoms which is unsubstituted or substituted with a second substituent, aryloxy group having 5 to 18 ring atoms which is unsubstituted or substituted with a second substituent, heteroaryloxy group having 5 to 18 ring atoms which is unsubstituted or substituted with a second substituent, wherein the second substituent comprises one or more of halogen, hydroxyl, carboxyl, nitro, sulfonic acid group, aldehyde group, mercapto, cyano, acyl group, sulfonyl group, C1-C4 alkoxy group.

2. The electrolyte of claim 1, wherein: The additive A has a mass content of 0.1% to 1.0% in the electrolyte; and / or The lithium salt comprises one or more of lithium hexafluorophosphate and lithium bisfluorosulfonylimide; and / or The lithium salt has a concentration of 1.0 mol / L to 1.3 mol / L in the electrolyte.

3. The electrolyte of claim 1, wherein: The electrolyte further comprises vinylene carbonate, and the vinylene carbonate has a mass content of 0.2% to 1.0% in the electrolyte.

4. The electrolyte of claim 1, wherein: The electrolyte further comprises fluoroethylene carbonate, and the fluoroethylene carbonate has a mass content of 4% to 12% in the electrolyte.

5. The electrolyte of claim 1, wherein: The electrolyte further comprises a lithium salt additive.

6. The electrolyte of claim 5, wherein: The lithium salt additive comprises one or more of lithium bisfluorosulfonylimide, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate; and / or The lithium salt additive has a mass content of 0.5% to 1.0% in the electrolyte.

7. The electrolyte of claim 1, wherein: The electrolyte further comprises a sulfur-containing additive.

8. The electrolyte of claim 7, wherein: The sulfur-containing additive comprises one or more of 1,3-propane sultone, a copolymer of sulfur and triallylamine, vinyl sulfate, and methanedisulfonate; and / or The sulfur-containing additive has a mass content of 0.5% to 1.0% in the electrolyte.

9. A lithium-ion battery, characterized by: The battery comprises a positive electrode sheet, a negative electrode sheet and the electrolyte as claimed in any one of claims 1 to 8.

10. The lithium-ion battery of claim 9, wherein: The negative electrode sheet comprises a current collector and a negative active material disposed on the current collector, and the negative active material comprises graphite and silicon-carbon material; and / or The negative electrode sheet comprises a current collector and a negative active material disposed on the current collector, and the negative active material comprises graphite and silicon-carbon material; and / or The positive electrode tab includes a current collector and a positive electrode active material disposed on the current collector, the positive electrode active material including a nickel-cobalt-manganese ternary material, the nickel-cobalt-manganese ternary material having a chemical formula of Li(Ni x Co y Mn z )O2, where x≥0.8, 0

Images