A high-voltage, high-power lithium-ion battery

Abstract

This invention discloses a high-voltage, high-power lithium-ion battery, belonging to the field of lithium-ion batteries. The lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte. The slurry of the negative electrode comprises the following components by weight percentage: 48%–97% graphite, 1%–40% hard carbon, 1%–8% negative electrode conductive agent, and 1%–4% negative electrode binder. The slurry of the positive electrode comprises the following components by weight percentage: 50%–97% of one of lithium cobalt oxide, lithium manganese oxide, and lithium nickel cobalt manganese oxide, 1%–50% lithium manganese iron phosphate, 1%–8% positive electrode conductive agent, and 1%–2% positive electrode binder. The addition of additives to the electrolyte can mitigate the negative effects of adding hard carbon and lithium manganese iron phosphate. The additives can form a film on the electrode surface, reducing lithium-ion conduction resistance, increasing the overall power performance of the battery, and improving the battery's initial efficiency.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion batteries and relates to a high-voltage, high-power lithium-ion battery, and more particularly to a combination technology of positive electrode, negative electrode and electrolyte of a high-voltage, high-power lithium-ion battery. Background Technology

[0002] Energy is one of the most important issues facing the 21st century. Driven by accelerating global energy demand, particularly from portable devices, electric and hybrid electric vehicles (EVs and HEVs), and dwindling fossil fuel supplies, lithium-ion batteries (LIBs) have become the most popular energy storage method compared to other energy storage systems due to their high conversion efficiency and flexible size (from coin cells to grid storage systems). Reducing the cost and weight of LIBs and increasing their energy and power output density will be the primary research directions for researchers.

[0003] Power density is the maximum actual continuous output power per unit mass or volume. Power performance is particularly important in the practical use of lithium-ion batteries (LIBs) when high peak power is required to perform certain tasks, such as starting vehicle engines, regulating irregular currents or fast-charging EVs, and stabilizing grid operation. For irregular renewable energy sources (such as wind and solar power), a high-performance lithium-ion battery system is also needed as an energy storage device.

[0004] High-power, high-energy lithium-ion batteries have important applications in the electric vehicle field, such as HEVs, PHEVs, vehicle starter batteries, power tools, drones, and other fields. These important application fields all require batteries to have a certain power density to meet the power requirements of electrical appliances. To obtain lithium-ion batteries with both high energy density and high power density, material system optimization is usually carried out, such as reducing the particle size of materials and increasing the electron and ion transfer efficiency between electrode materials. However, reducing the particle size of materials increases the specific surface area of ​​battery materials and increases the side reactions of electrode materials, thereby affecting the cycle life of the battery and even the safety performance of the battery.

[0005] To address the aforementioned issues, the industry typically addresses them by introducing a higher proportion of conductive agents into the positive and negative electrode formulations or by adding conductive agents with superior conductivity, such as carbon nanotubes and graphene. However, this approach not only increases battery costs but also reduces the proportion of active materials due to the increased proportion of conductive agents, thereby lowering the battery's energy density. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems in the existing technology by providing a lithium-ion battery with high voltage and high power. This lithium-ion battery can simultaneously satisfy high power density and high voltage. The high voltage characteristic enables the battery to output high energy density. Therefore, the battery can simultaneously possess high energy density and high power density, and this type of battery has broad application prospects in reality.

[0007] The specific technical solution of this invention is as follows:

[0008] This invention provides a high-voltage, high-power lithium-ion battery, comprising a positive electrode, a negative electrode, an electrolyte, an aluminum-plastic film, and tabs; the slurry of the negative electrode comprises the following components by weight percentage: 48%–97% graphite, 1%–40% hard carbon, 1%–8% negative electrode conductive agent, and 1%–4% negative electrode binder, preferably with hard carbon comprising 10%–30%; the slurry of the positive electrode comprises the following components by weight percentage: 50%–97% lithium cobalt oxide, lithium manganese oxide, and nickel-cobalt oxide. The electrolyte contains one of the following: lithium manganese oxide, 1% to 50% lithium iron manganese phosphate, 1% to 8% positive electrode conductive agent and 1% to 2% positive electrode binder, wherein the lithium iron manganese phosphate content is preferably 10% to 40%; the electrolyte contains one, two or three of the following additives: BOP (benzotriazole-1-yloxytri(dimethylamino)phosphonium hexafluorophosphate), PyBOP (1H-benzotriazole-1-yloxytripyrrolidinyl hexafluorophosphate), and PyAOP ((7-azabenzotriazole-1-oxy)tripyrrolidinyl hexafluorophosphate).

[0009] Furthermore, the negative electrode conductive agent includes one or both of conductive carbon black (SP) and carbon nanotubes (CNT).

[0010] Furthermore, the negative electrode binder comprises a mixture of hydroxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR).

[0011] Furthermore, the positive electrode conductive agent includes one or both of electrolytic carbon black (SP) and carbon nanotubes.

[0012] Furthermore, the positive electrode binder is polyvinylidene fluoride (PVDF).

[0013] Furthermore, the additive accounts for 0.1% to 10% of the total weight of the electrolyte, preferably 0.5% to 5%.

[0014] Furthermore, the positive electrode is prepared by coating an aluminum foil with a paste from the positive electrode, and the negative electrode is prepared by coating a copper foil with a paste from the negative electrode.

[0015] Furthermore, the thickness of the aluminum foil is 10μm to 13μm; the thickness of the copper foil is 4μm to 8μm.

[0016] Furthermore, the formation temperature of the lithium-ion battery is 50°C to 60°C.

[0017] During the formation of the lithium-ion battery, additives form SEI films on the surfaces of the positive and negative electrode sheets, respectively.

[0018] The beneficial results of this invention are as follows: First, by combining graphite and hard carbon in the negative electrode, the interlayer spacing of the hard carbon material is larger than that of the graphite material, which is conducive to the transfer of lithium ions in the negative electrode material and increases the power performance of the battery system. Second, since the lithium deposition potential of hard carbon material is higher than that of graphite material, the addition of hard carbon material can increase the safety performance of the battery. Third, by combining one of lithium nickel cobalt manganese oxide, lithium cobalt oxide, and lithium manganese oxide in the positive electrode with lithium iron manganese phosphate, lithium iron manganese phosphate is coated on the surface of lithium nickel cobalt manganese oxide, lithium cobalt oxide, or lithium manganese oxide, the charge and discharge structure of lithium iron manganese phosphate is more stable, which can improve the safety performance of the battery and improve the stability of the battery under high voltage.

[0019] While the addition of hard carbon can improve battery power performance, it also reduces the battery's initial efficiency, resulting in a loss of active lithium ions in the positive electrode and a decrease in energy density. Furthermore, due to the poor rate performance of lithium manganese iron phosphate (LFP), although adding LFP to the positive electrode improves the battery's stability at high voltages, it negatively impacts the overall rate performance. To mitigate the negative effects of hard carbon and LFP, one, two, or three of the following additives—BOP, PyBOP, and PyAOP—are added to the battery electrolyte. The electrolyte additive BOP... PyBOP and PyAOP participate in the film-forming reaction during the first charge of the battery, i.e., during battery formation, forming films on the surfaces of the positive and negative electrodes. This reduces lithium-ion conduction resistance and increases the overall power performance of the battery, thereby offsetting the rate performance degradation caused by the addition of lithium manganese iron phosphate. In addition, BOP, PyBOP, and PyAOP can preferentially react with heteroatom groups on the surface of the hard carbon of the negative electrode, reducing the consumption of active lithium by heteroatom groups in the positive electrode, improving the low first-time efficiency of hard carbon, which is beneficial to the overall capacity of the battery, reducing the consumption of active lithium, and increasing the energy density of the battery.

[0020] It should also be noted that electrolytes containing BOP, PyBOP, and PyAOP additives require specific formation temperatures to coordinate with their film formation process at the positive and negative electrodes. Generally, the formation temperature of lithium-ion batteries is between 25℃ and 45℃, but electrolytes containing BOP, PyBOP, and PyAOP additives need to be formed between 50℃ and 60℃ to achieve the best results.

[0021] During the first charge cycle of the battery, the additives form a stable and efficient SEI film under specific formation conditions, while preventing the consumption of active lithium on hard carbon, increasing the battery's initial efficiency, and contributing to the utilization of battery energy density and the improvement of power density. Detailed Implementation

[0022] Preparation of the positive electrode sheet: The positive electrode slurry is stirred according to a certain formula ratio. The solvent used for stirring the positive electrode slurry is N-methylpyrrolidone (NMP). The positive electrode slurry includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. The positive electrode active material includes two types: one is one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, and lithium manganese oxide, with a weight percentage of 50% to 97% of the total weight of the positive electrode slurry; the other is lithium manganese iron phosphate, with a weight percentage of 1% to 40% of the total weight of the positive electrode slurry. The positive electrode conductive agent is one or both of SP and carbon nanotubes, with a weight percentage of 1% to 8% of the total weight of the positive electrode slurry. The positive electrode binder is PVDF, with a weight percentage of 1% to 4% of the total weight of the positive electrode slurry. The stirred positive electrode slurry is coated on an aluminum foil with a thickness of 10 μm to 13 μm.

[0023] Preparation of the negative electrode sheet: A negative electrode slurry is stirred according to a specific formula ratio. The solvent used for stirring the negative electrode slurry is deionized water. The negative electrode slurry includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The negative electrode active material is graphite and hard carbon, with graphite accounting for 48%–97% of the weight percentage of the negative electrode slurry, and hard carbon accounting for 1%–40% of the weight percentage. The negative electrode conductive agent is one or both of SP and carbon nanotubes, accounting for 1%–4% of the weight percentage of the negative electrode slurry. The negative electrode binder is CMC+SBR, accounting for 1%–4% of the weight percentage of the negative electrode slurry. The stirred negative electrode slurry is then coated onto a 4μm–8μm copper foil.

[0024] The coated positive and negative electrode sheets are then rolled, slited or die-cut, wound or stacked, and assembled into a complete cell.

[0025] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention. The present invention is not limited to these embodiments.

[0026] Example 1

[0027] Example 1 was tested in the form of a full cell. Example 1 was divided into the following groups. The positive and negative electrode formulations and electrolyte additives of each group are shown in Table 1. The charge and discharge efficiency (first efficiency) of each group of batteries during the first charge process, the rate performance and cycle performance under different charge and discharge voltage conditions were tested. The test results of each group are shown in Table 2.

[0028] Group A

[0029] The positive electrode uses lithium cobalt oxide (LCO) as the active material, and its composition is as follows (by weight percentage): 95% LCO + 2% PVDF + 3% SP. The negative electrode uses graphite as the active material, and its composition is as follows (by weight percentage): 95% graphite + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate, with a solute content of 1 mol / L. The electrolyte solvent is EC (…). Ethylene carbonate The electrolyte contains a mixed solvent of diethyl carbonate (DEC) and dimethyl carbonate (DMC) (volume ratio 3:4:3), and contains 2% vinylene carbonate (VC) and 2% FEC (FEC). Fluoroethylene carbonate As an additive, it was used to assemble full cells for testing. The assembled cells were produced using a stacking process, and the cell capacity was approximately 1.2 Ah.

[0030] Group B

[0031] The positive electrode uses lithium cobalt oxide as the active material, and the positive electrode formulation is as follows by weight percentage: 95% LCO + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as the active material, and the negative electrode formulation is as follows by weight percentage: 90% graphite + 5% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixed solvent of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC, 2% FEC, and 2% BOP as additives. A full cell was assembled and tested using a stacking process, and the battery capacity is approximately 1.2 Ah.

[0032] Group C

[0033] The positive electrode uses lithium cobalt oxide as the active material, and the positive electrode formulation is as follows by weight percentage: 95% LCO + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as the active material, and the negative electrode formulation is as follows by weight percentage: 75% graphite + 20% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixture of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC and 2% FEC as additives. A full cell was assembled and tested using a stacking process, and the battery capacity is approximately 1.2 Ah.

[0034] Group D

[0035] The positive electrode uses lithium cobalt oxide as the active material, and the positive electrode formulation is as follows by weight percentage: 95% LCO + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as the active material, and the negative electrode formulation is as follows by weight percentage: 75% graphite + 20% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixed solvent of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC, 2% FEC, and 2% BOP as additives. The assembled full cell was tested using a stacking process, and the battery capacity is approximately 1.2 Ah.

[0036] Group E

[0037] The positive electrode uses lithium cobalt oxide as the active material, and the positive electrode formulation is as follows by weight percentage: 95% LCO + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as the active material, and the negative electrode formulation is as follows by weight percentage: 55% graphite + 40% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixture of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC, 2% FEC, and 2% BOP as additives. A full cell was assembled and tested using a stacking process, and the battery capacity is approximately 1.2 Ah.

[0038] Table 1 Implementation Plans for Each Group

[0039]

[0040] Table 2 Battery Tests and Corresponding Battery Performance

[0041]

[0042] In Example 1, Group D showed the best performance. The addition of hard carbon to the negative electrode formulation of Group D significantly improved the rate performance of the battery. Compared with Group C, the addition of BOP to the electrolyte improved the problem of reduced first-time efficiency caused by the addition of hard carbon to the battery, while retaining the power performance improvement characteristics of hard carbon. In addition, compared with Group D (containing 20% ​​hard carbon), the batteries containing 5% and 40% hard carbon in Groups B and E showed the best performance.

[0043] Example 2

[0044] Example 2 was tested in the form of a full battery. Example 2 was divided into the following groups. The positive and negative electrode formulations and electrolyte additives of each group are shown in Table 3. The charge and discharge efficiency of each group during the first charge process, i.e., the first efficiency, the rate performance and cycle performance under different charge and discharge voltage conditions were tested. The test results of each group are shown in Table 4.

[0045] Group A

[0046] The positive electrode uses lithium cobalt oxide as the active material, and the positive electrode formulation is as follows by weight percentage: 95% LCO + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as the active material, and the negative electrode formulation is as follows by weight percentage: 75% graphite + 20% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixed solvent of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC, 2% FEC and 2% BOP as additives. The assembled full cell was tested using a stacking process, and the battery capacity is approximately 1.2 Ah.

[0047] Group B

[0048] The positive electrode uses lithium cobalt oxide and lithium manganese iron phosphate (LMFP) as active materials, and the positive electrode formulation is as follows by weight percentage: 90% LCO + 5% LMFP + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as active materials, and the negative electrode formulation is as follows by weight percentage: 75% graphite + 20% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixed solvent of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC, 2% FEC and 2% BOP as additives. The assembled full cell was tested using a stacking process, and the battery capacity is about 1.2 Ah.

[0049] Group C

[0050] The positive electrode uses lithium cobalt oxide and lithium manganese iron phosphate as active materials, and the positive electrode formulation is as follows by weight percentage: 80% LCO + 15% LMFP + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as active materials, and the negative electrode formulation is as follows by weight percentage: 75% graphite + 20% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixed solvent of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC and 2% FEC as additives. The assembled full cell was tested using a stacking process, and the battery capacity is approximately 1.2 Ah.

[0051] Group D

[0052] The positive electrode uses lithium cobalt oxide and lithium manganese iron phosphate as active materials, and the positive electrode formulation is as follows by weight percentage: 80% LCO + 15% LMFP + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as active materials, and the negative electrode formulation is as follows by weight percentage: 75% graphite + 20% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixed solvent of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC, 2% FEC and 2% BOP as additives. The assembled full cell was tested using a stacking process, and the battery capacity is about 1.2 Ah.

[0053] Group E

[0054] The positive electrode uses lithium cobalt oxide and lithium manganese iron phosphate as active materials, and the positive electrode formulation is as follows by weight percentage: 45% LCO + 50% LMFP + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as active materials, and the negative electrode formulation is as follows by weight percentage: 75% graphite + 20% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate with a solute content of 1 mol / L. The electrolyte solvent is a mixed solvent of EC (ethylene carbonate) + DEC (diethyl carbonate) + DMC (dimethyl carbonate) (solvent volume ratio of 3:4:3). The electrolyte contains 2% VC, 2% FEC and 2% BOP as additives. The assembled full cell was tested using a stacking process, and the battery capacity is about 1.2 Ah.

[0055] Table 3 Implementation Plans for Each Group

[0056]

[0057] Table 4 Battery Tests and Corresponding Battery Performance

[0058]

[0059]

[0060] In Example 2, Group D showed the best performance. Comparing the cycle performance of each group under high voltage, the battery with LMFP added to the positive electrode formulation had the best cycle performance. Group C added LMFP but did not add BOP to the electrolyte. Due to the influence of LMFP, the battery rate performance decreased and the cycle performance was slightly worse than that of Group D. Groups B and E were batteries with different amounts of LMFP. Compared with Group D, 5% LMFP content had limited improvement in cycle performance. Group D, with 50% LMFP content, had cycle performance close to that of Group D, but its rate performance deteriorated.

[0061] Example 3

[0062] Example 3 was tested in the form of a full cell. Example 3 was divided into the following groups. The positive and negative electrode formulations and electrolyte additives of each group are shown in Table 5. The charge and discharge efficiency (first efficiency) of each group of batteries during the first charge process, the rate performance and cycle performance under different charge and discharge voltage conditions were tested. The test results of each group are shown in Table 6. The positive and negative electrode formulations of each group in the comparative experiment of this example are the same, and the formation temperature of each group is different.

[0063] The positive electrode uses lithium cobalt oxide and lithium manganese iron phosphate as active materials, with the following weight percentage composition: 80% LCO + 15% LMFP + 2% PVDF + 3% SP. The negative electrode uses a mixture of graphite and hard carbon as active materials, with the following weight percentage composition: 75% graphite + 20% hard carbon + 2% SBR + 2% CMC + 1% SP. The separator is made of PE material. The electrolyte solute is lithium hexafluorophosphate, with a solute content of 1 mol / L, and the electrolyte solvent is... A mixed solvent of EC (ethylene carbonate), DEC (diethyl carbonate), and DMC (dimethyl carbonate) (solvent volume ratio 3:4:3) was used. The electrolyte contained 2% VC, 2% FEC, and 2% BOP as additives. Full cells were assembled and tested using a stacking process. The cell capacity was approximately 1.2 Ah. The formation temperatures of each group were different: Group A: 45℃, Group B: 50℃, Group C: 55℃, Group D: 60℃, and Group E: 65℃.

[0064] Table 5 Implementation Plans for Each Group

[0065]

[0066] Table 6 Battery Tests and Corresponding Battery Performance

[0067]

[0068] Test results show that the performance of Group C and Group D batteries is almost identical and the best, with the optimal formation temperature being between 50℃ and 60℃.

Claims

1. A lithium-ion battery, characterized in that, The lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte. The slurry of the negative electrode sheet comprises the following components by weight percentage: 48% to 97% graphite, 1% to 40% hard carbon, 1% to 8% negative electrode conductive agent and 1% to 4% negative electrode binder. The slurry of the positive electrode sheet comprises the following components by weight percentage: 50% to 97% of one of lithium cobalt oxide, lithium manganese oxide, and lithium nickel cobalt manganese oxide, 1% to 50% of lithium manganese iron phosphate, 1% to 8% of positive electrode conductive agent, and 1% to 2% of positive electrode binder. The electrolyte contains one, two, or three of the additives benzotriazole-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate, 1H-benzotriazole-1-yloxytripyrrolidinyl hexafluorophosphate, and (7-azabenzotriazole-1-oxy)tripyrrolidinyl hexafluorophosphate.

2. A lithium-ion battery according to claim 1, characterized in that, The negative electrode conductive agent and the positive electrode conductive agent are independently selected from one or both of conductive carbon black and carbon nanotubes.

3. A lithium-ion battery according to claim 1, characterized in that, The negative electrode binder comprises a mixture of hydroxymethyl cellulose and styrene-butadiene rubber.

4. A lithium-ion battery according to claim 1, characterized in that, The positive electrode binder is polyvinylidene fluoride.

5. A lithium-ion battery according to claim 1, characterized in that, The additive accounts for 0.1% to 10% of the total weight of the electrolyte.

6. A lithium-ion battery according to claim 1, characterized in that, The positive electrode sheet is prepared by coating an aluminum foil with a paste from the positive electrode sheet, and the negative electrode sheet is prepared by coating a copper foil with a paste from the negative electrode sheet.

7. A lithium-ion battery according to claim 6, characterized in that, The aluminum foil has a thickness of 10μm to 13μm; the copper foil has a thickness of 4μm to 8μm.

8. A lithium-ion battery according to claim 1, characterized in that, The formation temperature of the lithium-ion battery is 50℃~60℃.

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