Lithium ion battery

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery. In the lithium ion battery, a positive electrode active material is LiNixCoyMn1-x-yO2, x is more than or equal to 30% and less than or equal to 90%, and y is more than 0 and less than or equal to x; the electrolyte comprises a solvent, a lithium salt and an additive, the additive comprises ethylene sulfate and lithium difluoro (oxalato) borate, the weight percentage of ethylene sulfate in the electrolyte is a%, the weight percentage of lithium difluoro (oxalato) borate in the electrolyte is b%, and x, a and b meet the formula of # imgabs0 #. According to the lithium ion battery, through the synergistic effect of the optimized additive combination and the positive electrode material, the lithium-nickel mixing phenomenon in the positive electrode material is effectively inhibited, the side reaction of Ni catalytic electrolyte solvent oxidation is reduced, and the cycle performance, the storage performance and the high-temperature performance of the battery are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a lithium ion battery. Background Art

[0002] Lithium-ion secondary batteries offer stable voltage and current, a high voltage platform, high energy density, a wide operating temperature range, no memory effect, and are environmentally friendly and portable. They have become the mainstream power source for a wide range of consumer electronics, electric vehicles, and mechanical equipment. With the advent of the electric age, the application of lithium-ion secondary batteries is becoming increasingly widespread. Technological breakthroughs in low-altitude economy, electric transmission, and autonomous driving are driving higher demands on the energy density, cycle stability, and high-temperature performance of lithium-ion secondary batteries.

[0003] Lithium-ion secondary batteries are often made of nickel-based ternary positive electrode materials. Nickel has a high redox potential and a large capacity contribution, but nickel is prone to lithium-nickel mixing, and Ni catalyzes the oxidation of electrolyte solvents, resulting in reduced positive electrode interface stability and increased side reactions, thereby causing capacity loss, resulting in poor cycle performance and storage performance of lithium-ion secondary batteries. The impact is more serious at high temperatures (above 40°C). Summary of the Invention

[0004] The present invention provides a lithium ion battery for solving the problems of poor cycle performance, poor storage performance, poor high temperature performance and the like in existing lithium ion secondary batteries using nickel-based ternary positive electrode materials.

[0005] According to a first aspect of the present invention, the present invention provides a lithium-ion battery comprising a positive electrode sheet, a negative electrode sheet, a separator disposed between the positive electrode sheet and the negative electrode sheet, and an electrolyte; The positive electrode sheet includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material is a ternary LiNi x Co y Mn 1-x-y O2 cathode material, wherein 30%≤x≤90%, 0<y≤x; The electrolyte includes a solvent, a lithium salt, and an additive, wherein the additive includes vinyl sulfate and lithium bis(fluorooxalatoborate), wherein the weight percentage of the vinyl sulfate in the electrolyte is a%, and the weight percentage of the lithium bis(fluorooxalatoborate) in the electrolyte is b%, wherein x, a, and b satisfy: .

[0006] The lithium-ion battery of the present invention adopts a specific ternary positive electrode material LiNi x Co y Mn 1-x-yO2 (30% ≤ x ≤ 90%, 0 < y ≤ x) and a specific content range of vinyl sulfate and lithium bis(fluorooxalato)borate as additives electrolyte, LiNi x Co y Mn 1-x-y O2 has a higher voltage platform and capacity, which effectively improves the energy density of lithium-ion secondary batteries; at the same time, the electrolyte contains additives such as vinyl sulfate and lithium bis(fluorooxalate borate), and lithium bis(fluorooxalate borate) can generate a lithium-rich low-impedance inorganic CEI film, which effectively protects the ternary positive electrode interface structure and can inhibit the growth of DCR. And adding vinyl sulfate to generate an interface film rich in Li2SO3 and Li2SO4 can reduce the side reactions of the electrolyte on the surface of the positive electrode active material, inhibit gas production and improve high-temperature performance. The synergistic interface regulation effect of vinyl sulfate and lithium bis(fluorooxalate borate) significantly improves the storage performance and cycle performance of lithium-ion secondary batteries. The positive electrode material and the electrolyte in the lithium-ion battery of the present invention satisfy the relationship It can generate a low-impedance, high-stability and dense interface film at the interface between the positive and negative electrodes, reduce the catalytic oxidation of the electrolyte solvent by the positive electrode, improve the stability of the positive electrode interface, and ensure a low negative electrode interface impedance and suitable electrolyte viscosity. It can significantly improve the cycle stability, high-temperature performance and storage performance of the ternary battery cell, improve the stability and service life of the battery, and meet the demand for improved performance of lithium-ion batteries in existing technologies.

[0007] Furthermore, a>b, 1.0≤a≤3.0, 0.2≤b≤2.0.

[0008] Furthermore, within the parameter range of 1.0≤a≤2.0, 0.2≤b≤1.0, and 30%≤x≤60%, the battery's cycle stability, high-temperature performance, and storage performance can be significantly improved, while also ensuring the battery has lower impedance, thereby achieving higher energy density and better charge and discharge performance, further enhancing the battery's overall performance and making it more suitable for applications with higher performance requirements.

[0009] Furthermore, the additive also includes vinylene carbonate, and the weight percentage of vinylene carbonate in the electrolyte is 0.1-1%, preferably 0.4-0.6%. As an electrolyte additive, vinylene carbonate can further improve the performance of the battery. It can form a more stable passivation film on the positive and negative electrode surfaces of the battery, effectively inhibiting the decomposition of the electrolyte, reducing the self-discharge rate of the battery, and improving the high-temperature performance and cycle life of the battery. By adding vinylene carbonate, the stability and safety of the battery in high-temperature environments are enhanced, further improving the overall performance and reliability of the battery and broadening the application range of the battery.

[0010] A suitable solvent combination can optimize the physicochemical properties of the electrolyte, improve the electrolyte's ion transport efficiency, reduce the battery's internal resistance, and enhance the compatibility between the electrolyte and electrode materials, further improving the battery's cycling stability and high-temperature performance. Furthermore, the solvent is selected from one or more of ethylene carbonate (EC), ethyl methyl carbonate (EMC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), acrylate (PP), and propylene oxide (EP).

[0011] Preferably, the solvent includes ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), with the volume percentage of ethylene carbonate (EC) being 20-30%, the volume percentage of ethyl methyl carbonate (EMC) being 50-60%, and the volume percentage of diethyl carbonate (DEC) being 15-25%. By precisely controlling the type and ratio of the solvent, the battery can maintain excellent performance under different operating conditions, further enhancing its overall performance and application value.

[0012] The appropriate type and concentration of lithium salts are crucial to the electrochemical performance of the electrolyte. Furthermore, the lithium salt is selected from one or more of LiPF6, LiFSI, and LiClO4; the concentration of the lithium salt in the electrolyte is 0.9 mol / L-1.2 mol / L. These lithium salts can provide sufficient lithium ions in the electrolyte to ensure the normal charge and discharge process of the battery, and within the specified concentration range, can give the electrolyte good conductivity and stability. By rationally selecting the type of lithium salt and controlling its concentration, the performance of the electrolyte can be further optimized, the charge and discharge efficiency and cycle life of the battery can be improved, and the stable operation of the battery under various operating conditions can be ensured.

[0013] Furthermore, the positive electrode active material layer further includes a conductive material and a first binder, and the weight percentage ratio of the positive electrode active material, the conductive material and the first binder is (95-97): (1-3): (1-3).

[0014] By optimizing the composition of the positive electrode active material layer, the utilization rate of the positive electrode material can be increased, and the conductivity and structural stability of the positive electrode sheet can be enhanced. A reasonable positive electrode slurry ratio can ensure the uniformity and consistency of the positive electrode sheet coating, thereby further improving the overall performance and quality stability of the battery, making it more suitable for large-scale production and application.

[0015] Preferably, the conductive material is selected from one or more of conductive carbon black, carbon nanotubes and conductive graphite, preferably conductive carbon black; Preferably, the first binder is selected from PVDF.

[0016] The selection of suitable conductive materials and binders can effectively reduce the internal resistance of the positive electrode and improve the charge and discharge performance and cycle stability of the battery.

[0017] Furthermore, the negative electrode sheet negative active material layer comprises a negative electrode active material, a conductive additive and a second binder; the weight percentage ratio of the negative electrode active material, the conductive additive and the second binder is (95-97): (1-3): (0.5-1.5).

[0018] By optimizing the composition of the negative electrode sheet, the performance of the negative electrode material can be improved, and the conductivity and stability of the negative electrode sheet can be enhanced. A reasonable negative electrode slurry ratio can ensure the uniformity and consistency of the negative electrode sheet coating, thereby further improving the overall performance and quality stability of the battery, making it more suitable for large-scale production and application.

[0019] Preferably, the negative electrode active material is selected from artificial graphite.

[0020] Preferably, the conductive additive is selected from super-P.

[0021] Preferably, the second binder is selected from SBR.

[0022] The selection of suitable negative electrode active materials, conductive additives, thickeners and binders can effectively reduce the internal resistance of the negative electrode sheet and improve the charge and discharge performance and cycle stability of the battery.

[0023] Furthermore, the separator is selected from a PE film. By selecting the appropriate separator material, the safety and stability of the battery can be further improved, ensuring reliable operation under various operating conditions and extending the battery life. PE film has excellent chemical stability and mechanical strength, effectively isolating the positive and negative electrodes to prevent short circuits, while also ensuring electrolyte permeability and ion transmission efficiency.

[0024] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-mentioned lithium-ion battery, comprising the following steps: Prepare positive electrode sheets, negative electrode sheets and electrolyte; The prepared positive electrode sheet, the negative electrode sheet and the separator are made into a battery assembly through a lamination process, and are vacuum baked, injected with the electrolyte, sealed and allowed to stand; then pre-charged and formed; the pre-charged and formed method is: use constant current and constant voltage to charge to 4-5V, then discharge to 2.5-3.0V at a constant current, repeat the charge and discharge cycle, and charge to 3.8V.

[0025] The lithium-ion battery manufacturing method of the present invention includes the preparation of positive and negative electrode sheets and electrolyte, as well as the assembly and pre-charging of the battery components. This method optimizes the process parameters of each step. This specific manufacturing method ensures that the battery performance meets the expected design requirements, improves production efficiency and quality stability, and makes the battery more suitable for large-scale production and application.

[0026] Furthermore, the vacuum baking temperature is 80-90° C. and the time is 8-12 h; and / or the standing temperature is 40-50° C. and the time is 12-36 h.

[0027] Optimizing the vacuum baking and resting process parameters can better ensure the dryness and structural stability of battery components during assembly, further improving battery performance and quality stability. By precisely controlling these process parameters, stable battery operation under different operating conditions can be ensured, extending battery life and improving market competitiveness.

[0028] Beneficial effects of the present invention: The lithium-ion battery provided by the present invention significantly improves the cycle performance, high temperature performance and storage performance of the battery by adopting a specific ternary positive electrode material and an electrolyte with a specific content range of vinyl sulfate and lithium bis(fluorooxalato)borate as additives. Specifically, the synergistic effect of the optimized additive combination and the positive electrode material effectively suppresses the lithium-nickel mixing phenomenon in the positive electrode material, reduces the side reaction of Ni-catalyzed electrolyte solvent oxidation, and reduces the internal resistance of the battery. At the same time, by precisely controlling the content of additives in the electrolyte and the mass proportion of nickel elements in the positive electrode material, and optimizing the preparation process parameters of the battery, the comprehensive performance of the battery is further enhanced, so that it performs well in key performance indicators such as 500 cycle capacity retention rate at room temperature DCIR, low temperature -20℃ DCIR, 25℃ and 45℃, 60-day capacity recovery rate at high temperature storage, and high temperature storage volume change rate, meeting the demand for lithium-ion battery performance improvement in the existing technology, and has significant innovation and practicality. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] Example 1 This embodiment provides a lithium-ion battery, a positive electrode sheet, a negative electrode sheet, a separator disposed between the positive electrode sheet and the negative electrode sheet, and an electrolyte; The positive electrode sheet is made of raw materials including positive electrode active material, and the positive electrode active material is ternary LiNi x Co y Mn 1-x-y O2 cathode material, where x=30%, y=30%; The electrolyte includes a solvent, a lithium salt and an additive, wherein the additive includes vinylene carbonate, vinyl sulfate and lithium bisfluorooxalatoborate, the weight percentage of vinylene carbonate in the electrolyte is 0.5%, the weight percentage of vinyl sulfate in the electrolyte is a%, and the weight percentage of lithium bisfluorooxalatoborate in the electrolyte is b%, wherein a=1.0 and b=0.2.

[0031] This embodiment also provides a method for preparing the lithium-ion battery, comprising the following steps: Preparation of positive electrode sheet: LiNi x Co y Mn 1-x-y The O2 conductive carbon black and the binder PVDF are dispersed in the solvent NMP and mixed evenly to obtain the positive electrode slurry; the positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil, and after drying, cold pressing, slitting and cutting, the positive electrode sheet is obtained, wherein the positive electrode active material LiNi x Co y Mn 1-x-y The weight ratio of O2, conductive carbon black and binder PVDF is 96:2:2.

[0032] Preparation of negative electrode sheet: Dissolve the negative electrode active material artificial graphite, conductive additive super-P, thickener CMC, and binder SBR in deionized water at a mass ratio of 96:2:1:1, mix well to form negative electrode slurry, and evenly coat the negative electrode slurry on the current collector copper foil with a coating amount of 11.5 mg / cm 2 Then, after drying at 85°C, cold pressing, trimming, cutting, and striping are carried out, and then drying under vacuum conditions at 110°C for 4 hours, and the tabs are welded to produce lithium-ion battery negative electrodes that meet the requirements.

[0033] Preparation of the electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed uniformly in a volume ratio of 25:55:20 to obtain a non-aqueous organic solvent. 1.0 mol / L of LiPF6, 0.5 wt% vinylene carbonate, a% vinyl sulfate, and b% lithium difluorooxalatoborate (based on the weight percentage of the electrolyte) were dissolved in the non-aqueous organic solvent and mixed uniformly to obtain a lithium-ion battery electrolyte.

[0034] Preparation of lithium-ion batteries: The above-mentioned positive and negative electrode sheets and separators (PE films) are laminated to form a battery with a thickness of 8 mm, a width of 60 mm, and a length of 130 mm. The battery is then vacuum-baked at 85°C for 10 h, 6 g of electrolyte is injected, the battery is sealed, and the battery is allowed to stand at 45°C for 24 h. The battery is then pre-charged and formed. The pre-charge formation method is as follows: use a constant current and constant voltage charge of 0.1C (200 mA) to 4.4 V, then discharge at a constant current of 0.1C to 2.8 V, repeat the charge and discharge cycle once, and charge to 3.8 V at 0.1C to obtain a lithium-ion battery.

[0035] Example 2-17 Examples 2-17 each independently provide a lithium-ion battery, which differs from Example 1 in that a, b, and x are different, and the specific differences are shown in Table 1 below.

[0036] The preparation method is the same as that in Example 1.

[0037] Comparative Examples 1-10 Comparative Examples 1-10 each independently provide a lithium ion battery, which differs from Example 1 in that a, b, and x are different, and the specific differences are shown in Table 1 below.

[0038] The preparation method is the same as that in Example 1.

[0039] The performance of the lithium-ion batteries prepared in the examples and comparative examples was tested, and the specific testing methods are as follows: Battery Impedance Test: At room temperature (25°C), the cell was cycled three times at 0.33C, then charged to 4.4V using a constant current and constant voltage charge of 0.33C. The last discharge capacity was used as C1. The cell was discharged for 90 minutes at 0.33C to 50% SOC. After 15 minutes of rest, the cell was discharged at a constant current of 8A for 5 seconds. The battery impedance is the voltage difference during this test divided by the current. At low temperature (-20°C), the cell was cycled three times at 0.1C, then charged to 4.4V using a constant current and constant voltage charge of 0.1C. The last discharge capacity was used as C2. The cell was discharged for 5 hours at 0.1C2 to 50% SOC. After 30 minutes of rest, the cell was discharged at a constant current of 200mA for 5 seconds. The battery low-temperature impedance is the voltage difference during this test divided by the current.

[0040] Cycling test: In a constant temperature room at 25°C, discharge at a constant current of 1C to 2.8V, let it rest for 10 minutes, then charge at a constant current and voltage of 1C to 4.4V, let it rest for 10 minutes. Repeat this cycle for 500 cycles. The ratio of the discharge capacity after 500 cycles to the initial discharge capacity is used as the cell's 500-cycle capacity retention rate. For cycles at 45°C, change the oven temperature to 45°C and perform the cycle steps at room temperature.

[0041] Storage test: At 25°C, discharge at a constant current of 1C to 2.8V. After 10 minutes, charge at a constant current and voltage of 1C to 4.4V. Measure the cell volume (V0) using the water displacement method. Transfer the cell to a 55°C oven and store for two months before removal. Discharge at a constant current of 1C to 2.8V. The ratio of this discharge capacity to the initial capacity is the storage capacity retention rate. Charge at a constant current and voltage of 1C to 4.4V. The ratio of this charge capacity to the initial capacity is the storage capacity recovery rate. Again using the water displacement method, measure the cell volume (V1). Calculate the storage volume expansion rate: (V1 - V0) / V0 × 100%.

[0042] The test results of Examples 1-17 and Comparative Examples 1-10 are shown in Table 2.

[0043] Table 1

[0044] Table 2

[0045] The experimental data in Tables 1 and 2 demonstrate the effects of different additive contents and the nickel content of the positive electrode active material on the performance of lithium-ion batteries. The experimental results of Examples 1 to 17 show that when the contents of vinyl sulfate (a) and lithium bis(fluorooxalatoborate) (b) satisfy the conditions of 1.0% ≤ a ≤ 3.0%, 0.2% ≤ b ≤ 2.0%, and a> b, and the mass proportion x of the nickel element in the positive electrode active material is between 30% and 90%, the performance of the lithium-ion battery is significantly improved. Specifically, the lithium-ion batteries of these examples exhibited excellent performance in key performance indicators such as capacity retention after 500 cycles at room temperature DCIR, low temperature -20°C DCIR, 25°C and 45°C, capacity recovery after 60 days of high-temperature storage, and volume change rate during high-temperature storage. Among them, the DCIR at room temperature is less than 20mΩ, the DCIR at low temperature of -20℃ is less than 180mΩ, the capacity retention rate of 500 cycles at 25℃ is above 90%, the capacity retention rate of 500 cycles at 45℃ is above 89%, the capacity recovery rate after 60 days of high-temperature storage is above 90%, and the volume change rate of high-temperature storage is less than 10.5%. This shows that within the range of this specific additive content and positive electrode material nickel content, the battery impedance is low, the cycle performance and high-temperature storage performance are significantly improved, and the volume expansion rate is effectively controlled. This shows that within the range of this specific additive content and positive electrode material nickel content, the battery impedance is low, the cycle performance and high-temperature storage performance are significantly improved, and the volume expansion rate is effectively controlled. Furthermore, the lithium-ion battery performance of Examples 1-9 is relatively better, with a DCIR of less than 15mΩ at room temperature and less than 165mΩ at low temperature of -20°C. The capacity retention rate after 500 cycles at 25°C is above 95%, the capacity retention rate after 500 cycles at 45°C is above 94%, the capacity recovery rate after 60 days of high-temperature storage is above 94%, and the volume change rate during high-temperature storage is less than 2.2%.

[0046] By analyzing Example 1 and Comparative Example 1, it can be seen that the positive electrode material system with a nickel content of 30%, an additive content of vinyl sulfate of 1.0% and lithium bifluorooxalate borate of 0.20%, can satisfy the formula The room temperature DCR performance was 98.32% after 500 cycles, and 97.89% after 500 cycles at high temperature. Further addition of lithium bifluorooxalatoborate resulted in a 30% decrease in room temperature DCR, significantly reducing cycle performance. This is due to the inherent stability of the low-nickel-content single-crystal cathode material, which is less susceptible to lithium / nickel mixing and transition metal dissolution. The effective content of these two additives is not high; excessive additions can increase interfacial impedance and degrade cycle performance.

[0047] By analyzing Example 14 and Comparative Example 3, Example 17 and Comparative Example 4, it can be seen that the Ni content is ≥80%, which needs to meet the requirements , the content of a and b needs to be relatively high. This is because under high voltage conditions, the surface of the high nickel positive electrode is more prone to metal ion dissolution and CEI film damage. The interface stability requirement is higher, and vinyl sulfate and lithium bifluorooxalate borate need to work together to generate a highly stable CEI film to increase the protection of the positive electrode material. Therefore, by making the lithium ion battery and the electrolyte meet , while ensuring the high power performance of lithium-ion secondary batteries, it also obtains good cycle performance and high temperature performance.

[0048] 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A lithium-ion battery, characterized in that: It includes a positive electrode sheet, a negative electrode sheet, a separator arranged between the positive electrode sheet and the negative electrode sheet, and an electrolyte; The positive electrode sheet includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material is a ternary LiNi x Co y Mn 1-x-y O2 cathode material, wherein 30%≤x≤90%, 0<y≤x; The electrolyte includes a solvent, a lithium salt, and an additive, wherein the additive includes vinyl sulfate and lithium bis(fluorooxalatoborate), wherein the weight percentage of the vinyl sulfate in the electrolyte is a%, and the weight percentage of the lithium bis(fluorooxalatoborate) in the electrolyte is b%, wherein x, a, and b satisfy: .

2. The lithium-ion battery according to claim 1, wherein a>b, 1.0≤a≤3.0, 0.2≤b≤2.

0.

3. The lithium-ion battery according to claim 1 or 2, characterized in that 1.0≤a≤2.0, 0.2≤b≤1.0, 30%≤x≤60%.

4. The lithium-ion battery according to any one of claims 1 to 3, wherein: The additive further comprises vinylene carbonate, and the weight percentage of the vinylene carbonate in the electrolyte is 0.1-1%, preferably 0.4%-0.6%.

5. The lithium-ion battery according to any one of claims 1 to 4, characterized in that: The solvent is selected from one or more of ethylene carbonate, ethyl methyl carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, acrylic acid ester and propylene oxide.

6. The lithium-ion battery according to claim 5, characterized in that The solvent includes ethylene carbonate, ethyl methyl carbonate and diethyl carbonate, wherein the volume percentage of the ethylene carbonate in the solvent is 20-30%, the volume percentage of the ethyl methyl carbonate in the solvent is 50-60%, and the volume percentage of the diethyl carbonate in the solvent is 15-25%.

7. The lithium-ion battery according to any one of claims 1 to 6, characterized in that: The lithium salt is selected from one or more of LiPF6, LiFSI and LiClO4; the concentration of the lithium salt in the electrolyte is 0.9 mol / L-1.2 mol / L.

8. The lithium-ion battery according to any one of claims 1 to 7, characterized in that: The positive electrode active material layer further includes a conductive material and a first binder, and the weight percentage ratio of the positive electrode active material, the conductive material and the first binder is (95-97): (1-3): (1-3); Preferably, the conductive material is selected from one or more of conductive carbon black, carbon nanotubes and conductive graphite, preferably conductive carbon black; Preferably, the first binder is selected from PVDF.

9. The lithium-ion battery according to any one of claims 1 to 8, characterized in that: The negative electrode plate includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, a conductive additive and a second binder; the weight percentage ratio of the negative electrode active material, the conductive additive and the second binder is (95-97): (1-3): (0.5-1.5); Preferably, the negative electrode active material is selected from artificial graphite; Preferably, the conductive additive is selected from super-P; Preferably, the second binder is selected from SBR.

10. The lithium-ion battery according to any one of claims 1 to 9, characterized in that: The separator is selected from PE film.

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