Lithium ion battery

Abstract

The invention discloses a lithium ion battery which comprises a positive plate, a negative plate and a non-aqueous electrolyte, the negative plate is obtained by coating a current collector with negative slurry, the negative slurry comprises a carbon base, a silicon base, a binder and sodium carboxymethyl cellulose, and the non-aqueous electrolyte comprises a non-aqueous organic solvent, a lithium salt and an additive, the additive comprises a compound A as shown in a formula 1 or a formula 2: # imgabs0 #, wherein R1-R2 are respectively and independently selected from hydrogen, C1-C6 alkyl or halogen substituted C1-C6 alkyl; and R3 is C2-C5 cyclic saturated fatty amine. The lithium ion battery disclosed by the invention has relatively good high-temperature cycle performance and high-temperature storage performance, and is low in internal resistance growth rate and free from a lithium precipitation phenomenon.

Description

Technical Field

[0001] The present invention belongs to the technical field of secondary batteries, and particularly relates to a lithium-ion battery. Background Art

[0002] Silicon material is one of the promising anode materials for next-generation lithium-ion batteries due to its high weight specific capacity, volume specific capacity, and low lithiation potential. Therefore, using silicon as the anode material can provide more energy than traditional graphite-based lithium-ion batteries. However, there are also significant bottlenecks in the application of silicon anodes as follows: Silicon (Si) exhibits significant volume changes during charge and discharge processes, resulting in pulverization of the electrode structure, shedding of active materials, and repeated damage to the solid electrolyte interface film (SEI), accelerating electrolyte consumption. This process not only reduces the cycle life but also causes an increase in internal resistance and capacity attenuation; in addition, the lithium-ion diffusion coefficient of silicon is much lower than that of graphite, resulting in the inability of lithium ions to diffuse into the interior of silicon particles in a timely manner at high current densities and being forced to be reduced and deposited on the surface, i.e., lithium plating occurs.

[0003] Therefore, there is an urgent need for a lithium-ion battery to solve the deficiencies of the prior art. Summary of the Invention

[0004] In view of the above problems, the object of the present invention is to provide a lithium-ion battery that has good high-temperature cycle performance and high-temperature storage performance, and a low internal resistance growth rate and no lithium plating phenomenon.

[0005] To achieve the above object, the present invention provides a lithium-ion battery, including a positive electrode sheet, a negative electrode sheet, and a non-aqueous electrolyte. The negative electrode sheet is obtained by coating a negative electrode slurry on a current collector. The negative electrode slurry includes a carbon-based material, a silicon-based material, and sodium carboxymethyl cellulose. The non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive. The additive includes a compound A represented by Formula 1 or Formula 2:

[0006] Wherein, R1 to R2 are each independently selected from hydrogen, a C1-C6 alkyl group, or a halogen-substituted C1-C6 alkyl group; R3 is a C2-C5 cyclic saturated aliphatic amine.

[0007] Compared with the prior art, the present invention uses compound A shown in Formula 1 or Formula 2 as an additive. In this additive, the cyclic borate ester is connected to the double bond through a single bond, and the electronic effects of the R1-R3 substituents on the double bond do not significantly affect the electron cloud density of the double bond. That is, the double bond in compound A has high activity, which enables the double bond in compound A to further crosslink with the hydroxyl groups on the surface of silicon in the silicon-carbon negative electrode, enhancing the hydrogen bond interaction between -COOH in the original carboxymethyl cellulose CMC and Si-OH, thereby enhancing the toughness of the binder, and further inhibiting the electrolytic fragmentation and pulverization caused by the volume expansion of silicon particles, thus improving the high-temperature performance of the lithium-ion battery and reducing the growth rate of internal resistance. At the same time, the double bond structure in compound A gives it a lower oxidation potential, enabling it to be preferentially oxidized and passivated on the surface of the silicon-carbon negative electrode to form a stable SEI film. This SEI film is rich in a polycarbonate organic phase and Li x BO y inorganic phase, and the π electrons of the double bond can be hybridized with the sp 2 of the carbon-based material and interact with SiO on the surface of silicon x together, enhancing the surface stability of the silicon-carbon negative electrode, thereby further improving the high-temperature performance and further reducing the growth rate of internal resistance. In addition, due to the electron-deficient property of the B element, after it is solvated with lithium ions, it can participate in the formation of an SEI rich in inorganic components such as LiBO2, Li2O, and LiF on the surface of the silicon-carbon negative electrode, which can accelerate the interfacial migration and uniform distribution of Li + , regulate the deposition behavior of lithium ions on the silicon-carbon negative electrode, and thus inhibit the growth of lithium dendrites and reduce the generation of dead lithium. Therefore, the lithium-ion battery of the present invention has good high-temperature cycle performance and high-temperature storage performance, and has a low growth rate of internal resistance and no lithium precipitation phenomenon.

[0008] Further, the C1-C6 alkyl group in the present invention refers to a straight-chain or branched-chain saturated hydrocarbon group composed of 1 to 6 carbon atoms, such as, but not limited to, methyl (-CH3), ethyl (-CH2CH3), n-propyl (-CH2CH2CH3), n-butyl (-CH2CH2CH2CH3), etc. The halogen-substituted C1-C6 alkyl group refers to the partial or complete substitution of hydrogen atoms in the C1-C6 alkyl group by halogen (F, Cl, Br, I), such as, but not limited to, trifluoromethyl (-CF3), trifluoroethyl (-CH2CF3), etc. The C2-C5 cyclic saturated aliphatic amine refers to a nitrogen-containing saturated cyclic structure composed of 2 to 5 carbon atoms, such as, but not limited to, aziridine, azetidine, etc.

[0009] Further, compound A in the present invention is selected from at least one of compound 1 to compound 3: .

[0010] Furthermore, the CAS number of Compound 1 of the present invention is 75927-49-0; the CAS number of Compound 2 is 1799330-80-5; the CAS number of Compound 3 is 2699605-96-2.

[0011] Furthermore, the mass percentage of Compound A of the present invention in the non-aqueous electrolyte is 0.05 to 5%. Specifically, the mass percentage of Compound A in the non-aqueous electrolyte can be, but is not limited to, 0.05%, 1%, 1.25%, 1.5%, 2%, 2.4%, 2.8%, 3.2%, 3.5%, 4%, 4.2%, 4.5%, 4.8%, 5%. Preferably, the mass percentage of Compound A in the non-aqueous electrolyte is 0.1 to 2%.

[0012] Furthermore, the lithium salt of the present invention is selected from at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium lower aliphatic carboxylate, lithium difluorodioxalate phosphate (LiDFBP), lithium bis(fluorosulfonyl)imide (LiFSI), lithium chloroborane, and lithium tetraphenylborate. By way of example, the lithium salt is lithium hexafluorophosphate (LiPF6), but not limited thereto. Further, the lithium salt is a mixture of lithium hexafluorophosphate (LiPF6) and lithium bis(oxalato)borate (LiBOB), but not limited thereto.

[0013] Furthermore, the mass percentage of the lithium salt of the present invention in the non-aqueous electrolyte is 5 to 25%. Specifically, the mass percentage of the lithium salt in the non-aqueous electrolyte can be, but is not limited to, 5%, 8%, 12%, 15%, 18%, 20%, 22%, 25%.

[0014] Further, the non-aqueous organic solvent of the present invention is selected from at least one of γ-butyrolactone (GBL), γ-valerolactone (GVL), δ-valerolactone (DVL), methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP), butyl acetate (BAC), propyl propionate (PP), propyl butyrate (PRB), ethylene carbonate (EC), propylene carbonate (PCA), butylene carbonate (BC), methyl pentyl carbonate (MPC), vinylene carbonate (VEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), propylene carbonate (PC), 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), 2-trifluoromethyltetrahydrofuran (2-CF3-THF), dimethoxymethane (DMM), diethoxymethane (DEM), ethoxymethoxymethane (DCE), ethylene glycol di-n-propyl ether (EDP), ethylene glycol di-n-butyl ether (EDB), and diethylene glycol dimethyl ether (DEGME).

[0015] Further, the mass percentage of the non-aqueous organic solvent in the non-aqueous electrolyte of the present invention is 65% to 90%; specifically, the mass percentage of the non-aqueous organic solvent in the non-aqueous electrolyte can be, but is not limited to, 65%, 68%, 72%, 77%, 80%, 84%, 88%, 90%.

[0016] Further, the non-aqueous electrolyte of the present invention further includes an auxiliary agent, and the auxiliary agent is selected from at least one of ethylene sulfite (ES), 1,3-propanesultone (PS), 1,3-propenesultone (PST), 1,4-butanesultone (1,4-BS), disulfuric acid ethylene ester (DTD), and succinic anhydride (SA).

[0017] Further, the mass percentage of the auxiliary agent in the non-aqueous electrolyte of the present invention is 0.05% to 5%. Specifically, the mass percentage of the auxiliary agent in the non-aqueous electrolyte can be, but is not limited to, 0.05%, 1%, 1.25%, 1.5%, 1.8%, 2.2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%.

[0018] Further, the negative electrode paste of the present invention further includes a conductive agent, and the mass ratio of the carbon-based, silicon-based, conductive agent, binder, and sodium carboxymethyl cellulose is 70 to 75:18 to 22:1 to 3:0.5 to 1.5:0.5 to 1.5. Specifically, the carbon-based is selected from at least one of artificial graphite and natural graphite; the silicon-based is CVD vapor deposition pure silicon.

[0019] Further, the active material of the positive electrode sheet of the present invention is nickel cobalt manganese oxide, and the chemical formula of the nickel cobalt manganese oxide is LiNi xCo y Mn 1-x-y M z O2 or LiNi x Co y Al 1-x-y M z O2, where 0.6 ≤ x < 0.9, x + y < 1, 0 ≤ z < 0.08, and M is at least one of Al, Mg, Zr, and Ti. Among various currently available cathode materials, layered lithium transition metal oxides such as ternary high-nickel (such as NCM or NCA) are relatively promising cathode materials, which have a high theoretical capacity (~280 mAh / g) and a relatively high average working potential (3.6 V vs. Li / Li + ). Combining a silicon-carbon-based anode with a high-voltage nickel-rich NCM (or NCA) cathode can provide more energy than traditional graphite-based anode lithium-ion batteries. However, high-nickel cathodes are prone to lattice oxygen evolution and phase transformation (such as the transformation from a layered structure to a rock-salt phase) during deep de-lithiation, resulting in irreversible capacity loss and a decline in cycling performance. In the compound A of this application, the borate structure adsorbs on the cathode surface during the cycling process of the lithium-ion battery and undergoes oxidative decomposition to form a CEI layer rich in inorganic components such as B / F. This CEI film is thin and has higher mechanical strength, which can effectively alleviate the bulk and surface phase transformations of the high-nickel ternary cathode and improve the electrochemical stability of the high-nickel ternary cathode. Detailed Embodiments

[0020] To better illustrate the purpose, technical solution, and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the methods described in the following embodiments are further explanatory descriptions of the present invention and should not be construed as limitations on the present invention.

[0021] Example 1 (1) Preparation of non-aqueous electrolyte In a glove box filled with argon (O2 < 1 ppm, H2O < 1 ppm), ethylene carbonate (EC), ethyl methyl carbonate (EMC), ethyl propionate (EP), and propylene carbonate (PC) were mixed according to a weight ratio of EC:EMC:EP:PC = 3:16:8:1 to obtain 87 g of non-aqueous organic solvent. Then, 0.5 g of Compound 1 was added, dissolved and stirred thoroughly, and then 12.5 g of lithium hexafluorophosphate was added. After mixing evenly, a non-aqueous electrolyte was obtained.

[0022] (2) Preparation of cathode sheet NCM9055, binder PVDF, and conductive agent SuperP were mixed evenly according to a mass ratio of 95:1:4 to prepare a lithium-ion battery cathode slurry with a certain viscosity. The prepared slurry was coated on both sides of the aluminum foil, dried, and rolled to obtain a cathode sheet.

[0023] (3) Preparation of the negative electrode sheet The negative electrode active material graphite, CVD vapor deposition pure silicon, conductive agent Ketjen black, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose (CMC) were fully stirred and mixed evenly in a deionized water solvent system according to a mass ratio of 74:20:2:1:1, and then coated on a copper foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0024] (4) Preparation of the lithium-ion battery The positive electrode sheet, separator, and negative electrode sheet were wound to form a soft-pack battery cell, which was packaged with a polymer aluminum-plastic film. The non-aqueous electrolyte prepared above was filled, and after processes such as formation and grading, a lithium-ion battery with a capacity of 1000 mAh was manufactured.

[0025] The formulations of the non-aqueous electrolytes of Examples 1-10 and Comparative Examples 1-2 are shown in Table 1. The steps for preparing the non-aqueous electrolytes and lithium-ion batteries in Examples 2-10 and Comparative Examples 1-2 are the same as those in Example 1.

[0026] Table 1 Formulations of the non-aqueous electrolytes of each example and comparative example

[0027] Among them, Compound 4 is 5-methylfuran-2-boronic acid pinacol ester (cas: 338998-93-9), and its structure is shown as follows:

[0028] Compound 4 The lithium-ion batteries prepared in Examples 1-10 and Comparative Examples 1-2 were respectively subjected to high-temperature storage tests, high-temperature cycling performance tests, internal resistance growth rate tests, and lithium plating tests. The specific test conditions are as follows, and the performance test results are shown in Table 2.

[0029] High-temperature cycling capacity retention performance test At a constant temperature of 25 °C, the lithium-ion battery was charged at a constant current of 1C until the voltage reached 4.2V, then charged at a constant voltage of 4.2V until the current reached 0.05C, and then discharged at a constant current of 1C until the voltage reached 3.0V. The initial discharge capacity of the battery was recorded as C0. Then, the lithium-ion battery was placed in an incubator at 45 °C and left to stand for 30 minutes to reach a constant temperature. Then, after 300 charge-discharge cycles at 1C / 1C at 45 °C, it was discharged at a constant current and constant voltage of 1C / 1C to 3V at a constant temperature of 25 °C, and the discharge capacity was recorded as C1. The capacity retention rate of the lithium-ion battery at 45 °C for 300 cycles was calculated using the following formula.

[0030] Capacity retention rate = C1 / C0 × 100% Internal resistance growth rate test of lithium-ion battery The lithium-ion battery is charged at a constant current of 0.5C to the cut-off voltage of 4.2V at a constant temperature of 25°C, and the initial internal resistance of the battery is recorded. Then, the lithium-ion battery is placed in an incubator at 60°C and left to stand for 30 minutes. After the lithium-ion battery reaches a constant temperature, it is stored for 30 days. After that, the battery after 30 days of storage is discharged at a constant current and constant voltage of 0.5C to the cut-off voltage of 3.0V at 25°C, and then charged at a constant current and constant voltage to 4.2V, and the internal resistance of the battery is recorded.

[0031] The growth rate of the internal resistance of the battery after 30 days of high-temperature storage = (the internal resistance of the battery after 30 days of storage - the initial internal resistance) / the initial internal resistance × 100%.

[0032] Storage capacity retention test of lithium-ion battery The lithium-ion battery is charged at a constant current of 1C to a voltage of 4.2V at a constant temperature of 25°C, then charged at a constant voltage of 4.2V until the current is 0.05C, and then discharged at a constant current of 1C to a voltage of 3.0V. The first-cycle discharge capacity of the battery is recorded as C0. Then, the lithium-ion battery is placed in an incubator at 60°C and left to stand for 30 minutes to reach a constant temperature. Then, after storing for 30 days at 60°C, it is discharged at a constant current and constant voltage of 1C / 1C to 3V at a constant temperature of 25°C, and the discharge capacity is recorded as C1. The capacity retention rate of the lithium-ion battery stored at 60°C for 30 days is calculated using the following formula.

[0033] The capacity retention rate = C1 / C0 × 100%.

[0034] Lithium plating situation test: At a high temperature of 45°C, for the lithium-ion battery ①, it is charged at a constant current and constant voltage of 1C to 4.2V with a cut-off rate of 0.05C and left to stand for 5 minutes; ② discharged at a constant current of 1C to 3V and left to stand for 5 minutes; ③ steps ① to ② are repeated 100 times; ④ charged at a constant current and constant voltage of 1C to 4.2V with a cut-off rate of 0.05C and left to stand for 5 minutes; ⑤ disassemble the interface and observe the lithium deposition situation.

[0035] Table 2 Performance test results of lithium-ion batteries

[0036] Comparing Examples 1 to 10 with Comparative Examples 1 to 2, the lithium-ion batteries of Examples 1 to 10 have better high-temperature cycling performance and high-temperature storage performance, with a lower internal resistance growth rate and no lithium plating phenomenon. This is because the present invention uses Compound A shown in Formula 1 or Formula 2 as an additive. The cyclic borate ester in this additive is connected by a single bond and a double bond. At the same time, the electronic effects of the R1-R3 substituents on the double bond do not significantly affect the electron cloud density of the double bond, that is, the double bond in Compound A has high activity. This enables the double bond in Compound A to further crosslink with the hydroxyl groups on the surface of silicon in the silicon-carbon negative electrode, enhancing the hydrogen bond interaction between -COOH and Si-OH in the original carboxymethyl cellulose CMC, thereby enhancing the toughness of the binder, and further inhibiting the electrolytic fragmentation and pulverization caused by the volume expansion of silicon particles, thus improving the high-temperature performance of the lithium-ion battery and reducing the internal resistance growth rate; at the same time, the double bond structure in Compound A gives it a lower oxidation potential, enabling it to be preferentially oxidized and passivated on the surface of the silicon-carbon negative electrode to form a stable SEI film. This SEI film is rich in polycarbonate organic phase and Li x BO y inorganic phase, and the π electrons of the double bond can be hybridized with the sp 2 of the carbon-based material and interact with SiO on the surface of silicon together x to enhance the surface stability of the silicon-carbon negative electrode, thereby further improving the high-temperature performance and further reducing the internal resistance growth rate. In addition, due to the electron-deficient property of the B element, after it is solvated with lithium ions, it can participate in the formation of an SEI rich in inorganic components such as LiBO2, Li2O, and LiF on the surface of the silicon-carbon negative electrode. This can accelerate the interfacial migration and uniform distribution of Li + and regulate the deposition behavior of lithium ions on the silicon-carbon negative electrode, thereby inhibiting the growth of lithium dendrites and reducing the generation of dead lithium. Therefore, the lithium-ion batteries of the present invention have good high-temperature cycling performance and high-temperature storage performance, with a low internal resistance growth rate and no lithium plating phenomenon.

[0037] Comparing Examples 1 to 10, it can be seen that when Compound 2 is used in combination with the negative electrode film-forming additive FEC, the performance is better. This may be because the R3 of Compound 2 is a cyclic amino structure, and the N atom contains a pair of lone pair electrons, which can combine with HF generated by the defluorination of FEC during the charge and discharge process of the lithium-ion battery. Moreover, the double bond on its five-membered ring can undergo self-polymerization or copolymerization with EC in the electrolyte system to generate multi-component insoluble SEI organic components, making the SEI film denser and having a stronger ability to accommodate the expansion of the silicon-carbon negative electrode. Therefore, using Compound 2 and the negative electrode film-forming additive FEC in combination is more helpful for improving the performance of lithium-ion batteries.

[0038] Comparing Example 3 with Comparative Example 2, it can be seen that the high-temperature performance of the lithium-ion battery in Comparative Example 2 is worse than that in Example 3, and the internal resistance growth rate of the lithium-ion battery in Comparative Example 2 is also larger than that in Example 3. This may be because the B atom of Compound 4 is connected to the 5-methylfuran group, which is an aromatic heterocycle. Two double bonds and the lone pair electrons of oxygen participate in conjugation, which significantly reduces the activity of the carbon-carbon double bond connected to the B atom, and further prevents the double bond in Compound A from cross-linking with the hydroxyl group on the silicon surface of the silicon-carbon negative electrode, thus affecting the high-temperature performance and internal resistance growth rate of the lithium-ion battery. In addition, the presence of oxygen in the 5-methylfuran group will increase its solvation with lithium ions. When lithium ions are inserted into the silicon-based negative electrode after desolvation, due to the strong solvation effect, the desolvation energy barrier is strong, reducing the lithium ion migration speed, increasing battery polarization, and thus causing slight lithium plating in the battery.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it is not limited to the embodiments listed. Those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A lithium-ion battery, characterized in that, It includes a positive electrode sheet, a negative electrode sheet and a non-aqueous electrolyte. The negative electrode sheet is obtained by coating a negative electrode paste on a current collector. The negative electrode paste includes a carbon-based material, a silicon-based material, a binder and sodium carboxymethyl cellulose. The non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt and an additive. The additive includes a compound A represented by Formula 1 or Formula 2: Wherein, R1 to R2 are each independently selected from hydrogen, a C1-C6 alkyl group or a halogen-substituted C1-C6 alkyl group; R3 is a C2-C5 cyclic saturated aliphatic amine.

2. The lithium ion battery according to claim 1, wherein The compound A is selected from at least one of Compound 1 to Compound 3: 。 3. The lithium-ion battery according to claim 1, characterized in that, The mass percentage of the compound A in the non-aqueous electrolyte is 0.05-5%.

4. The lithium-ion battery according to claim 1, characterized in that, The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium lower aliphatic carboxylate, lithium difluoro(dioxalato)phosphate, lithium bis(fluorosulfonyl)imide, lithium chloroborane and lithium tetraphenylborate.

5. The lithium-ion battery according to claim 1, characterized in that, The mass percentage of the lithium salt in the non-aqueous electrolyte is 5-25%.

6. The lithium ion battery according to claim 1, characterized in that, The non-aqueous organic solvent is selected from at least one of γ-butyrolactone, γ-valerolactone, δ-valerolactone, methyl acetate, ethyl acetate, ethyl propionate, butyl acetate, propyl propionate, butyl propionate, ethylene carbonate, propylene carbonate, butylene carbonate, methyl pentyl carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, propylene carbonate, 1,3-dioxolane, 1,4-dioxane, crown ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2-trifluoromethyltetrahydrofuran, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether and diethylene glycol dimethyl ether.

7. The lithium-ion battery according to claim 1, characterized in that, The non-aqueous electrolyte further includes an auxiliary agent, and the auxiliary agent is selected from at least one of fluorinated ethylene carbonate, ethylene sulfite, 1,3-propane sultone, 1,3-propene sultone, 1,4-butane sultone, ethylene sulfate and succinic anhydride.

8. The lithium-ion battery according to claim 7, characterized in that, The mass percentage of the auxiliary agent in the non-aqueous electrolyte is 0.05-5%.

9. The lithium-ion battery according to claim 1, characterized in that, The negative electrode paste further includes a conductive agent, and the mass ratio of the carbon-based material, the silicon-based material, the conductive agent, the binder and the sodium carboxymethyl cellulose is 70-75:18-22:1-3:0.5-1.5:0.5-1.

5.

10. The lithium ion battery according to claim 1, characterized in that, The active material of the positive electrode plate is nickel cobalt manganese oxide, and the chemical formula of the nickel cobalt manganese oxide is LiNi x Co y Mn 1-x-y M z O2 or LiNi x Co y Al 1-x-y M z O2, where 0.6 ≤ x < 0.9, x + y < 1, 0 ≤ z < 0.08, and M is at least one of Al, Mg, Zr, and Ti.

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