Lithium ion battery and preparation method thereof
By using specific electrolyte additives in combination with silicon-based anode materials in ternary lithium-ion batteries, the problems of positive electrode interface stability and negative electrode expansion have been solved, resulting in lithium-ion batteries with high energy density, low impedance, and excellent cycle stability.
Patent Information
- Application Number
- CN202511828797.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-02-10
AI Technical Summary
In existing ternary lithium-ion batteries, the ternary cathode material and silicon-doped anode have problems such as lithium-nickel mixing, reduced cathode interface stability, and easy cracking of silicon anode, resulting in poor cycle performance and high-temperature performance.
By using specific electrolyte additives (ethylene sulfate, lithium difluorooxalate borate, and tripropynyl phosphate) in combination with silicon-based anode materials and strictly controlling the relationship between the electrolyte additive coefficient and the silicon content coefficient, a lithium-rich, low-impedance CEI film and a high-stability SEI film are generated, which protect the positive electrode interface and inhibit the expansion of the negative electrode.
It improves the energy density, cycle stability, power performance, and high-temperature storage performance of lithium-ion batteries, while reducing battery impedance and safety risks.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy technology, and to a lithium-ion battery and its preparation method. Background Technology
[0002] Lithium-ion rechargeable batteries offer stable voltage and current, boast a high voltage platform, high energy density, and a wide operating temperature range. They exhibit no memory effect and are environmentally friendly and portable, making them the mainstream power source for various consumer electronics, electric vehicles, and machinery. With the advent of the electrification era, the application of lithium-ion rechargeable batteries is becoming increasingly widespread. Continuous breakthroughs in technologies such as low-altitude economy, electric propulsion, and autonomous driving have led to higher demands on the energy density, cycle stability, and high-temperature performance of lithium-ion rechargeable batteries.
[0003] In ternary silicon-doped lithium-ion batteries, regarding the positive electrode side, nickel in the ternary positive electrode material has a high redox potential and a large capacity contribution. However, nickel is prone to the following problems: ① lithium-nickel mixing, ② Ni catalyzing electrolyte solvent oxidation, leading to reduced positive electrode interface stability, increased side reactions, and thus capacity loss. This results in poor cycle performance and storage performance of the lithium-ion secondary battery, with the effects being more severe at high temperatures (above 40°C). Regarding the negative electrode side, due to the presence of silicon-based materials in the silicon-doped negative electrode, its surface is prone to expansion and cracking, leading to repeated repair and reorganization of the SEI film and continuous solvent reduction and gas generation, seriously affecting the safety of the cell.
[0004] Therefore, how to overcome the disadvantages of both ternary cathode materials and silicon-doped anodes while ensuring their advantages, in order to obtain high energy density, excellent cycle stability and high-temperature performance, is a technical problem that urgently needs to be solved. Summary of the Invention
[0005] In view of the above-mentioned technical problems existing in the prior art, the purpose of the present invention is to provide a lithium-ion battery and a method for preparing the same.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] In a first aspect, the present invention provides a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, characterized in that the positive electrode comprises a positive electrode active material, the positive electrode active material comprising a ternary positive electrode material; the negative electrode comprises a negative electrode active material, the negative electrode active material comprising graphite and a silicon-based material, the silicon-based material comprising at least one of silicon-carbon material, silicon-oxygen material, and elemental silicon; and the electrolyte comprises a lithium salt, a solvent, and additives, the additives comprising vinyl sulfate, lithium difluorooxalate borate, and tripropyne phosphate.
[0008] The electrolyte additive coefficient and silicon content coefficient satisfy the following relationship: 1.5 ≤ y / e 0.872x ≤1.8;
[0009] Where x is the electrolyte additive coefficient, x = a / 1.2 + b / 1.5 + c / 8, a% is the mass percentage of vinyl sulfate in the electrolyte, b% is the mass percentage of lithium difluorooxalate borate in the electrolyte, c% is the mass percentage of tripropynyl phosphate in the electrolyte, a>0, b>0, c>0;
[0010] y is the silicon content coefficient, y=α / 2+β, α% is the mass percentage of silicon-carbon material in the negative electrode active material, and β% is the mass percentage of silicon-oxygen material and / or elemental silicon in the negative electrode active material.
[0011] In the lithium-ion battery of this invention, the ternary cathode material has a high voltage plateau and discharge capacity, thereby effectively improving the energy density of the lithium-ion battery. The anode active material simultaneously includes graphite and silicon-based materials (an anode with this characteristic is simply referred to as a silicon-doped anode), which can provide a higher lithium intercalation capacity and significantly improve the energy density of the cell. However, while the combined use of the ternary cathode and the silicon-doped anode is beneficial to improving the energy density of the lithium-ion battery, it also leads to problems such as lithium-nickel mixing, reduced cathode interface stability, and easy cracking of the silicon anode. To address these issues, this invention creatively introduces an electrolyte with specific components and strictly controls the relationship between the electrolyte additive coefficient and the silicon content coefficient. This ensures that the advantages of the ternary cathode material and the silicon-doped anode are maintained while overcoming the aforementioned problems, resulting in a lithium-ion battery with low impedance, high energy density, high safety, excellent cycle stability, power performance, and high-temperature storage performance.
[0012] In the lithium-ion battery of the present invention, ethylene sulfate, lithium difluorooxalate borate, and tripropynyl phosphate are used synergistically as additives in the electrolyte, and the electrolyte additive coefficient determined by these three substances satisfies the relationship 1.50≤y / e 0.872x With a viscosity ≤1.80, lithium-ion batteries can generate a lithium-rich, low-impedance, high-stability, and dense inorganic CEI film (which may contain components such as Li2SO3 and Li2SO4) during operation. This effectively protects the ternary cathode interface, reduces the catalytic oxidation of the electrolyte solvent by the cathode, inhibits DCR growth, and improves high-temperature performance. Furthermore, an SEI film is generated at the anode, which inhibits anode volume expansion and reduces anode interface impedance. At the same time, the electrolyte has a suitable viscosity. Under the combined effect of these factors, the cycle stability and storage performance of lithium-ion batteries are improved.
[0013] Preferably, the mass percentage a% of the vinyl sulfate in the electrolyte is 0.1% to 2.5%, for example, it can be 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, 1.2%, 1.3%, 1.5%, 1.7%, 1.8%, 2%, 2.1%, 2.3%, or 2.5%, etc.
[0014] Preferably, the mass percentage b% of the lithium difluorooxalate borate in the electrolyte is 0.1% to 2.5%, for example, it can be 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, 1.2%, 1.3%, 1.5%, 1.7%, 1.8%, 2%, 2.1%, 2.3%, or 2.5%, etc.
[0015] Preferably, the mass percentage (c%) of the tripropynyl phosphate in the electrolyte is 0.01% to 0.5%, for example, it can be 0.01%, 0.02%, 0.03%, 0.05%, 0.07%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. If the content of tripropynyl phosphate is too low, it will lead to increased gas production and reduced safety performance; if the content of tripropynyl phosphate is too high, it will lead to an excessively thick solid electrolyte film at the negative electrode interface, increased cell DCR, and affected power performance and fast charging performance.
[0016] Preferably, the mass percentage α% of the silicon-carbon material in the negative electrode active material is 0% to 7%, for example, it can be 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, or 7%, etc. Wherein, when the mass percentage of silicon-carbon material in the negative electrode active material is 0%, it indicates that the negative electrode active material does not contain silicon-carbon material.
[0017] Preferably, the mass percentage β% of the silicon-oxygen material and / or the elemental silicon in the negative electrode active material is 0% to 14% and does not include 0%, for example, it can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5% or 14%, etc.
[0018] Preferably, 0 < y ≤ 14, for example, it can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5 or 14, etc.
[0019] As a preferred embodiment of the lithium-ion battery of the present invention, the electrolyte further includes fluoroethylene carbonate.
[0020] Preferably, the fluoroethylene carbonate in the electrolyte has a mass percentage of 1% to 10.5%, for example, it can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or 10.5%, etc.
[0021] By further introducing an appropriate amount of fluoroethylene carbonate, it can be used in combination with tripropynyl phosphate to generate a network of highly elastic SEI film (which may contain LiF components) at the negative electrode, thereby better suppressing the volume expansion of the silicon negative electrode and improving cycle stability.
[0022] Preferably, the ternary cathode material is a nickel-cobalt-manganese ternary cathode material and / or a nickel-cobalt-aluminum ternary cathode material, wherein the molar percentage of nickel in the ternary cathode material is ≥80%.
[0023] In this invention, the nickel-cobalt-manganese ternary cathode material may or may not be doped, and the nickel-cobalt-aluminum ternary cathode material may or may not be doped. Those skilled in the art can choose according to their needs. For example, the ternary cathode material may be LiNi. 0.8 Co 0.1 Mn 0.1 Taking O2 as an example, the nickel element accounts for 80% of the molar ratio in the ternary cathode material.
[0024] Preferably, the positive electrode includes a positive electrode current collector and a positive electrode material layer disposed on at least one side surface of the positive electrode current collector, wherein the positive electrode material layer includes a positive electrode active material.
[0025] Preferably, the positive electrode material layer further includes a first conductive agent and / or a first binder.
[0026] The present invention does not specifically limit the composition of the first conductive agent and the first binder. Exemplarily, the first conductive agent may be at least one of conductive carbon black, graphene, and carbon nanotubes. The first binder may be PVDF.
[0027] Preferably, the negative electrode includes a negative electrode current collector and a negative electrode material layer disposed on at least one side surface of the negative electrode current collector, wherein the negative electrode material layer includes a negative electrode active material.
[0028] Preferably, the negative electrode material layer further includes a second conductive agent and / or a second binder.
[0029] The present invention does not specifically limit the composition of the second conductive agent and the second binder. Exemplarily, the second conductive agent may be at least one of conductive carbon black, graphene, and carbon nanotubes. The second binder may be SBR.
[0030] In a second aspect, the present invention provides a method for preparing a lithium-ion battery as described in the first aspect, the method comprising the following steps:
[0031] The raw materials for the positive electrode material layer are dispersed in a first solvent to obtain a positive electrode slurry. The positive electrode slurry is coated onto at least one side of the positive electrode current collector. After drying, a positive electrode material layer is formed on the surface of the positive electrode current collector to obtain a positive electrode.
[0032] The raw materials of the negative electrode material layer are dispersed in a second solvent to obtain a negative electrode slurry. The negative electrode slurry is coated onto at least one side of the negative electrode current collector. After drying, a negative electrode material layer is formed on the surface of the negative electrode current collector to obtain a negative electrode.
[0033] The positive electrode, negative electrode, and separator are made into a cell, and an electrolyte is injected and encapsulated to obtain an ion battery.
[0034] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0035] Compared with existing technologies, the present invention has the following beneficial effects:
[0036] The lithium-ion battery of the present invention utilizes a ternary cathode, a silicon-doped anode, and an electrolyte with specific components in synergy, and strictly limits the relationship between the electrolyte additive coefficient and the silicon content coefficient. This ensures that the advantages of the ternary cathode material and the silicon-doped anode are maintained, while enabling the lithium-ion battery to have low impedance, high energy density, high safety, excellent cycle stability, power performance, and high-temperature storage performance. Detailed Implementation
[0037] The technical solution of the present invention will be further illustrated below through specific embodiments.
[0038] The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.
[0039] In the embodiments of the present invention, unless otherwise specified, all substances used are commercially available products.
[0040] Example 1
[0041] This embodiment provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a positive current collector (aluminum foil) and a positive electrode material layer disposed on both sides of the positive current collector. The positive electrode material layer includes a ternary positive electrode material (LiNi). 0.8 Co 0.1 Mn 0.1 The ternary cathode material, the first conductive agent (conductive carbon black), and the first binder (PVDF) have a mass ratio of 96:2:2.
[0042] The negative electrode sheet includes a negative current collector (copper foil) and a negative electrode material layer disposed on both sides of the negative current collector. The negative electrode material layer includes a negative electrode active material, a second conductive agent (Super-P), a thickener (CMC), and a second binder (SBR). The mass ratio of the negative electrode active material, the second conductive agent, the thickener, and the second binder is 96:2:1:1. The negative electrode active material includes a silicon-based material and the balance being artificial graphite. The silicon-based material is a combination of silicon-carbon material and silicon-oxygen material. The mass percentage of silicon-carbon material in the negative electrode active material is α%, α=2, and the mass percentage of silicon-oxygen material in the negative electrode active material is β%, β=1.
[0043] The electrolyte comprises lithium salt (LiPF6), solvent, and additives. The concentration of lithium salt in the electrolyte is 1 mol / L. The solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), with a volume ratio of EC:EMC:DEC = 25:55:20. The additives include ethylene sulfate, lithium difluorooxalate borate, tripropynyl phosphate, and fluoroethylene carbonate. The mass percentage of ethylene sulfate in the electrolyte is a%, a = 0.20; the mass percentage of lithium difluorooxalate borate in the electrolyte is b%, b = 0.20; the mass percentage of tripropynyl phosphate in the electrolyte is c%, c = 0.10; and the mass percentage of fluoroethylene carbonate in the electrolyte is 2%.
[0044] Based on the aforementioned α and β, the silicon content coefficient y is calculated as y = α / 2 + β = 2.0. Based on the aforementioned a, b, and c, the electrolyte additive coefficient x is calculated as x = a / 1.2 + b / 1.5 + c / 8 = 0.313. x and y are then calculated based on y / e. 0.872x y / e 0.872x =1.52.
[0045] This embodiment also provides a method for preparing the above-mentioned lithium-ion battery, including the following steps:
[0046] Cathode preparation: using ternary cathode material (LiNi) 0.8 Co 0.1 Mn 0.1O2) is used as the positive electrode active material. The positive electrode active material, conductive carbon black and binder PVDF are dispersed in the solvent NMP at a mass ratio of 96:2:2 and mixed evenly to obtain a 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, a positive electrode sheet is obtained.
[0047] Negative electrode preparation: Negative electrode active materials (silicon-carbon, silicon-oxygen, and artificial graphite), Super-P, CMC, and SBR are dissolved in deionized water at a mass ratio of 96:2:1:1 and mixed evenly to form a negative electrode slurry. The negative electrode slurry is then uniformly coated onto the current collector copper foil with a coating amount of 8.5 mg / cm². 2 After drying at 85℃, the material is cold-pressed, trimmed, cut into pieces, and slit. Then, it is dried under vacuum at 110℃ for 4 hours, and the tabs are welded to form the negative electrode sheet.
[0048] Preparation of electrolyte: Ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate were mixed uniformly at a volume ratio of 25:55:20 to obtain a non-aqueous organic solvent. 1.0 mol / L LiPF6 and the prescribed amounts of ethylene sulfate, lithium difluorooxalate borate, tripropynyl phosphate, and fluoroethylene carbonate were dissolved in the above non-aqueous organic solvent and mixed uniformly to obtain the electrolyte.
[0049] The above-mentioned positive electrode, negative electrode, and separator (PE film) are stacked to form a cell with a thickness of 8mm, a width of 60mm, and a length of 130mm. The cell is then vacuum baked at 85℃ for 10h, injected with 6g of electrolyte, sealed, and left to stand at 45℃ for 24h. After that, pre-charge formation is performed. The pre-charge formation method is as follows: charge at 0.1C (200mA) constant current and constant voltage to 4.2V, then discharge at 0.1C constant current to 2.8V, repeat one charge-discharge cycle, and then charge at 0.1C to 3.8V to obtain a lithium-ion battery.
[0050] Examples 2-8
[0051] See Table 1 for the differences from Example 1.
[0052] Example 9
[0053] The difference from Example 1 is that the silicon-oxygen material is replaced with a combination of silicon-oxygen material and elemental silicon, with a mass ratio of silicon-oxygen material to elemental silicon of 1:1. In this example, the total mass of silicon-oxygen material and elemental silicon accounts for β% of the mass percentage of the negative electrode active material, and β=10.
[0054] Example 10
[0055] The difference from Example 1 is that the content of tripropynyl phosphate is different.
[0056]
[0057] Note: The content of each component in the silicon-based material is based on 100% of the total mass of the negative electrode active material, and the content of each component in the electrolyte additives is based on 100% of the total mass of the electrolyte.
[0058] The performance of the lithium-ion batteries in Examples 1-10 and Comparative Examples 1-5 was tested, and the specific test methods are as follows:
[0059] (1) Battery impedance test: At room temperature (25℃), the cell is subjected to 3 cycles of 0.33C, and then charged to 4.2V using 0.33C constant current and constant voltage. The last discharge capacity is taken as C1. 1C' indicates that the battery with capacity C1 is discharged in one hour. Discharged for 90 minutes using 0.33C' to 50% SOC, and then left to stand for 15 minutes. Then, discharged for 5 seconds using 8A constant current. The room temperature DCIR of the battery is the voltage difference divided by the current under this test.
[0060] At a low temperature (-20℃), the battery cell is subjected to three 0.1C cycles, then charged to 4.2V using a 0.1C constant current and constant voltage method. The capacity of the last discharge is taken as C2. 1C'' indicates that the battery with capacity C2 is discharged in one hour. The battery is discharged using 0.1C'' for 5 hours to 50% SOC. After resting for 30 minutes, it is discharged using a 200mA constant current for 5 seconds. The low-temperature DCIR of the battery is the voltage difference divided by the current under this test.
[0061] Cyclic testing: In a constant temperature room of 25℃, discharge at a constant current of 1C to 2.8V, let stand for 10 minutes, then charge at a constant current and constant voltage of 1C to 4.4V, let stand for 10 minutes, and repeat this charge-discharge cycle 500 times. The ratio of the discharge capacity after 500 cycles to the initial discharge capacity is taken as the capacity retention rate of the cell after 500 cycles at 25℃ 1C / 1C.
[0062] In a 45℃ oven, discharge at a constant current of 1C to 2.8V, let stand for 10 minutes, then charge at a constant current and constant voltage of 1C to 4.4V, let stand for 10 minutes, and repeat this charge-discharge cycle 500 times. The ratio of the discharge capacity after 500 cycles to the initial discharge capacity is taken as the capacity retention rate of the cell after 500 cycles at 45℃ 1C / 1C.
[0063] Storage Test: At 25℃, the cell was discharged at a constant current rate of 1C to 2.8V, allowed to stand for 10 minutes, and then charged at a constant current and constant voltage of 1C to 4.2V. The cell volume V0 was measured using the water displacement method. The cell was then transferred to a 55℃ oven and stored for 60 days. After 60 days, it was removed and charged at a constant current and constant voltage of 1C to 4.2V. The ratio of this charged capacity to the initial capacity is the capacity recovery rate after 60 days of high-temperature storage. The cell volume V1 was measured again using the water displacement method, and the storage volume expansion rate was calculated as follows: High-temperature storage volume expansion rate = (V1 - V0) / V0 × 100%.
[0064] The test results are shown in Table 2.
[0065]
[0066] As shown in Table 2, this invention introduces an electrolyte with a specific composition into a battery system consisting of a ternary cathode and a silicon-doped anode, and strictly limits the electrolyte additive coefficient and silicon content coefficient to satisfy the relationship: 1.50 ≤ y / e 0.872x A value of ≤1.80 allows the battery to have low impedance, excellent cycle stability, and good high-temperature storage performance.
[0067] A comparison between Example 1 and Example 10 shows that the content of tripropynyl phosphate should not be too high. Too high a content will lead to an excessively thick solid electrolyte film at the negative electrode interface, increasing DCIR at room temperature and affecting power performance and fast charging performance.
[0068] In Comparative Example 1, the electrolyte additive coefficient and silicon content coefficient do not satisfy the relationship: 1.50≤y / e 0.872x The actual value was 0.34, ≤1.80. From a formulation perspective, the excessive amount of sulfate additive led to an excessively high DCR, affecting cycle performance. The comparative example had a moderate silicon-oxygen content, eliminating the need to generate excessive solid electrolyte membranes to repair SEI membrane rupture caused by silicon expansion, thus improving design performance.
[0069] In Comparative Example 2, the electrolyte additive coefficient and silicon content coefficient do not satisfy the relationship: 1.50≤y / e 0.872x The actual value is 0.36, with a value ≤1.80. After 500 cycles at 25℃, the capacity retention rate is 85.65%, after 500 cycles at 45℃, the capacity retention rate is 83.12%, the capacity recovery rate after 60 days at high temperature is 93.90%, the DCIR at room temperature (25℃) reaches 43.70 mΩ, and the low-temperature DCR reaches 296.6 mΩ. The principle is similar to Comparative Example 1. This is because the current silicon doping level is low, making it less likely for the negative electrode material to expand and cause SEI rupture, leading to continuous solvent reduction and decomposition gas production. Therefore, the effective content of electrolyte additives is not high. Furthermore, excessive addition of additives can increase interfacial impedance and degrade cycle performance.
[0070] A comparison between Example 8 and Comparative Example 3 shows that changing the composition of the electrolyte causes the electrolyte additive coefficient and silicon content coefficient to no longer satisfy the relationship: 1.50≤y / e 0.872x The value is ≤1.80, which leads to a DCIR of 44.1 at room temperature (25℃) and a DCIR of 424.7 mΩ at low temperature. The cycling performance at 25℃ is significantly reduced, and gas production increases.
[0071] A comparison of Example 6 with Comparative Example 4, and Example 7 with Comparative Example 5, shows that changing the composition of the electrolyte causes the electrolyte additive coefficient and silicon content coefficient to no longer satisfy the relationship: 1.50≤y / e 0.872x With a strength ≤1.80, the cycling performance at 25℃ is significantly reduced, while the cycling performance at 45℃ and high-temperature storage performance show little difference. The cell exhibits severe gas generation issues. This is because a high silicon doping level coupled with a low additive coefficient results in insufficient additive dosage to ensure the formation of a sufficiently strong SEI film on the silicon anode surface. This leads to silicon anode expansion, continuous reduction and decomposition of the solvent and active lithium, and severe gas generation, thus degrading cycling and high-temperature storage performance.
[0072] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, characterized in that, The positive electrode includes a positive electrode active material, which includes a ternary positive electrode material; the negative electrode includes a negative electrode active material, which includes graphite and silicon-based materials, and the silicon-based materials include at least one of silicon-carbon materials, silicon-oxygen materials, and elemental silicon; the electrolyte includes lithium salt, solvent, and additives, and the additives include vinyl sulfate, lithium difluorooxalate borate, and tripropyne phosphate. The electrolyte additive coefficient and silicon content coefficient satisfy the following relationship: 1.5 ≤ y / e 0.872x ≤1.8; Where x is the electrolyte additive coefficient, x=a / 1.2+b / 1.5+c / 8, a% is the mass percentage of vinyl sulfate in the electrolyte, b% is the mass percentage of lithium difluorooxalate borate in the electrolyte, c% is the mass percentage of tripropynyl phosphate in the electrolyte, a>0, b>0, c>0; y is the silicon content coefficient, y=α / 2+β, α% is the mass percentage of silicon-carbon material in the negative electrode active material, and β% is the mass percentage of silicon-oxygen material and / or elemental silicon in the negative electrode active material.
2. The lithium-ion battery according to claim 1, characterized in that, The mass percentage (a%) of the vinyl sulfate in the electrolyte is 0.1% to 2.5%. Preferably, the mass percentage b% of the lithium difluorooxalate borate in the electrolyte is 0.1% to 2.5%.
3. The lithium-ion battery according to claim 1 or 2, characterized in that, The mass percentage (c%) of the tripropynyl phosphate in the electrolyte is 0.01% to 0.5%.
4. The lithium-ion battery according to any one of claims 1-3, characterized in that, The mass percentage α% of the silicon-carbon material in the negative electrode active material is 0%~7%; Preferably, the mass percentage β% of the silicon-oxygen material and / or the elemental silicon in the negative electrode active material is 0% to 14% and does not contain 0%.
5. The lithium-ion battery according to any one of claims 1-4, characterized in that, 0＜y≤14。 6. The lithium-ion battery according to any one of claims 1-5, characterized in that, The electrolyte also includes fluoroethylene carbonate.
7. The lithium-ion battery according to claim 6, characterized in that, The fluoroethylene carbonate has a mass percentage of 1% to 10.5% in the electrolyte.
8. The lithium-ion battery according to any one of claims 1-7, characterized in that, The ternary cathode material is a nickel-cobalt-manganese ternary cathode material and / or a nickel-cobalt-aluminum ternary cathode material, wherein the molar percentage of nickel in the ternary cathode material is ≥80%.
9. The lithium-ion battery according to any one of claims 1-8, characterized in that, The positive electrode includes a positive electrode current collector and a positive electrode material layer disposed on at least one side surface of the positive electrode current collector, wherein the positive electrode material layer includes a positive electrode active material; Preferably, the positive electrode material layer further includes a first conductive agent and / or a first binder; Preferably, the negative electrode includes a negative electrode current collector and a negative electrode material layer disposed on at least one side surface of the negative electrode current collector, wherein the negative electrode material layer includes a negative electrode active material; Preferably, the negative electrode material layer further includes a second conductive agent and / or a second binder.
10. A method for preparing a lithium-ion battery according to any one of claims 1-9, characterized in that, The preparation method includes the following steps: The raw materials for the positive electrode material layer are dispersed in a first solvent to obtain a positive electrode slurry. The positive electrode slurry is coated onto at least one side of the positive electrode current collector. After drying, a positive electrode material layer is formed on the surface of the positive electrode current collector to obtain a positive electrode. The raw materials of the negative electrode material layer are dispersed in a second solvent to obtain a negative electrode slurry. The negative electrode slurry is coated onto at least one side of the negative electrode current collector. After drying, a negative electrode material layer is formed on the surface of the negative electrode current collector to obtain a negative electrode. The positive electrode, negative electrode, and separator are made into a cell, and an electrolyte is injected and encapsulated to obtain an ion battery.