Hot gas constrained ternary lithium ion battery and preparation method thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a hot-gas-constrained ternary lithium ion battery and a preparation method thereof. The hot-gas-constrained ternary lithium ion battery comprises a battery cell formed by winding a positive plate, a diaphragm and a negative plate; the surface of the positive active material on the positive plate is provided with an organic-inorganic hybrid interface layer; according to the specification of the battery, in an empty electricity state, the gas production rate measured by placing the battery cell at the constant temperature of 85 DEG C for 24 hours after the battery cell is fully charged at constant current and constant voltage is V1; the cell is charged to an overcharge voltage at a constant current of 0.2 C at a normal temperature, and the gas production rate measured by overcharging for 6 hours at a constant voltage is V2; if so, V1 is less than 0.45 mL and V2 is less than 2.5 mL; according to the battery disclosed by the invention, the organic-inorganic hybrid interface layer is formed on the surface of the positive electrode active material and is cooperated with the specific composite binding phase, so that the prepared cylindrical lithium ion battery has a relatively low temperature rise coefficient, and the gas production risk is remarkably converged while the energy density CR500 of the lithium ion battery is improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a thermally confined ternary lithium-ion battery and its preparation method. Background Technology

[0002] Lithium-ion batteries are widely used due to their high energy density, long cycle life, and lack of memory effect. The cathode material is a key factor determining the performance and cost of lithium-ion batteries. Layered LiNi... 1-x-y Co x Mn y O2 (NCM) exhibits excellent ternary synergistic effects, resulting in high specific capacity, good cycle performance, low cost, and low toxicity. In layered NCM, nickel is the main redox reaction element; therefore, increasing the nickel content can effectively improve the specific capacity of NCM. High-nickel NCM materials (Ni molar fraction ≥ 0.6) possess high specific capacity and low cost, but also suffer from low capacity retention and poor thermal stability. When configured in cylindrical cells and operated under high rate and high temperature conditions, the cathode interface faces severe chemical and mechanical failure challenges. Specifically, under the combined effects of high voltage and thermal stress, the electrolyte solvent undergoes oxidative decomposition, lithium salts (such as LiPF6) degrade, and transition metal elements (especially nickel) on the cathode material surface dissolve and undergo catalytic side reactions. These processes not only accelerate the unstable growth of the electrolytic interphase (CEI), causing a continuous increase in interfacial impedance, but also lead to gas production (such as CO2, CO, etc.) and battery swelling, significantly reducing cycle life and safety performance. Furthermore, the winding structure used in cylindrical cells exacerbates these problems at the mechanical level. During charging and discharging, the positive electrode material undergoes periodic volume changes. Under the mechanical constraints in the radial and axial directions, phenomena such as interface crack propagation and local collapse of electrode pores are amplified, forming a positive feedback effect. This leads to the interruption of lithium-ion transport paths and the failure of active materials, thereby causing accelerated capacity decay.

[0003] Current mainstream modification strategies focus on cathode interface control, with common methods including bulk element doping and surface coating. Doping elements (such as Al, Mg, Ti, etc.) can improve crystal structure stability; while surface coating layers, such as inorganic solid electrolytes (LLZO, LATP, etc.) and low-dimensional carbon materials (carbon black, carbon nanotubes (CNTs) or a small amount of single-walled carbon nanotubes (SWCNTs), aim to build physical barriers, suppress side reactions, and enhance interfacial ion and electron conduction. However, these methods still have significant limitations: the thermal expansion coefficients of rigid coatings and cathode particles are mismatched, making them prone to brittle cracking and delamination during cycling; insufficient coupling between lithium conduction (lithium-ion migration) and conductivity (electron conduction) in lithium-ion batteries leads to increased internal resistance, adversely affecting rate performance and cycle life; in addition, the dispersion process of nanomaterials, coating uniformity, and batch consistency are difficult to guarantee, restricting their large-scale application.

[0004] Therefore, an interface / bonding synergy path that balances chemical passivation and mechanical compliance is needed, and the cell should be constrained by a quantifiable log-linear thermal boundary and a thermal-gas safety window to ensure that rate thermal management, cycle stability and gas generation risk are controlled within the engineering window. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a heat-confined ternary lithium-ion battery. This battery, through the formation of an organic-inorganic hybrid interface layer on the surface of the positive electrode active material, combined with a specific composite adhesive, results in a cylindrical lithium-ion battery with a low temperature rise coefficient, thereby improving the lithium-ion battery's energy density (CR). 500 At the same time, it significantly reduces the risk of gas production.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] A heat-confined ternary lithium-ion battery includes a positive electrode, a separator, and a negative electrode wound together to form a cell; the surface of the positive electrode active material on the positive electrode has an organic-inorganic hybrid interface layer.

[0008] According to the specifications of the ternary lithium-ion battery, in the empty state, the cell is charged to 4.20V with a constant current CC-constant voltage CV at 0.5C, and the constant voltage CV charging is stopped at 0.05C. Then, the gas production is measured as V1 after being placed at a constant temperature of 85℃ for 24 hours.

[0009] The cell is charged at a constant current of 0.2C to the overcharge voltage at room temperature, and the gas production is measured as V2 after being overcharged at constant voltage for 6 hours. The overcharge voltage is greater than the threshold of the safe working voltage during charging and less than 1.2 times the threshold.

[0010] Then the following conditions must be met: V1 is less than 0.45 mL and V2 is less than 2.5 mL.

[0011] Furthermore, the material of the organic-inorganic hybrid interface layer includes a composite of an inorganic phase and an organic phase; the inorganic phase is lithium phosphate and lithium silicate (such as Li2SiO3 and / or Li4SiO4), and the organic phase is a phosphazene-based polymer.

[0012] Furthermore, the organic-inorganic hybrid interface layer has a thickness of 3-8 nm, a coverage rate of at least 95%, and XPS detection shows characteristic peaks of P=N and P=O, with an N / P atomic ratio of 0.8-1.2, preferably an N / P atomic ratio of 1.

[0013] Furthermore, the method for obtaining the organic-inorganic hybrid interface layer includes the following steps:

[0014] S1. Under a protective atmosphere, phosphazene monomer and nucleophilic organic catalyst are dissolved in an aprotic polar solvent, cooled to below 10°C and maintained at the temperature, and a mixture of macromolecular polyol and organic amine is added dropwise. After the addition is complete, the temperature is raised and the reaction is stirred. After the reaction is completed, the precipitated crystal salt is removed by filtration, and the liquid is partially diluted to obtain the first solution.

[0015] S2. Lithium hydroxide and phosphoric acid were dissolved separately in an alcohol-water solvent under an ice bath. Then they were mixed according to the equimolar ratio of elemental lithium and elemental phosphorus. The pH value of the system was adjusted to the range of 1.5 to 2.5. The mixture was heated and refluxed to obtain lithium dihydrogen phosphate sol. After cooling to room temperature, lithium silicate sol was added and mixed evenly to obtain the second solution.

[0016] S3. Mix the first solution with the second solution, adjust the solid content, and obtain an organic-inorganic hybrid spraying liquid;

[0017] S4. The organic-inorganic hybrid spray liquid is deposited on the surface of the positive electrode active material under stirring, and an organic-inorganic hybrid interface layer is obtained on the surface of the positive electrode active material after thermal curing.

[0018] Furthermore, the phosphazene monomer is selected from hexafluorocyclotriphosphazene or hexachlorocyclotriphosphazene;

[0019] The macromolecular polyol is selected from polyethylene glycol and / or polypropylene glycol.

[0020] The nucleophilic organocatalyst is selected from pyridine compounds, such as 4-dimethylaminopyridine;

[0021] The organic amine is selected from one or more of trimethylamine, dimethylamine, triethylamine, diethylamine, tripropylamine, triisopropylamine, dipropylamine, diisopropylamine, tributylamine, triisobutylamine, dibutylamine, and diisobutylamine;

[0022] The aprotic polar solvent is selected from ethers (such as diethyl ether, tetrahydrofuran, dioxane, etc.), halogen compounds (chloromethane, chloroform, dichloromethane, carbon tetrachloride, etc.), ketones (acetone, methyl ethyl ketone, etc.), nitrogen-containing hydrocarbons (nitromethane, nitrobenzene, pyridine, acetonitrile, quinoline), sulfoxides (dimethyl sulfoxide), and amides (formamide, diformamide, N-methylpyrrolidone, dimethylacetamide, hexamethylphosphoramide, etc.).

[0023] Preferably, the molar ratio of the phosphazene monomer, the macromolecular polyol, the organic amine, and the nucleophilic organic catalyst in S1 is 1:(5.8-6.2):(5.8-6.2):(0.02-0.06).

[0024] The volume percentage of ethanol in the alcohol-water solvent is 60%-80%; step S2 is carried out according to the mass percentage of lithium phosphate and lithium silicate as 70%-90%: 30%-10%.

[0025] Further, in S1, the temperature is lowered to 0-5℃ before adding the mixture, the adding time of the mixture is controlled at 10-40 min, and after the addition of the mixture is completed, the temperature is raised to 23-30℃ and the reaction is continued to be stirred for 1-5 h; the liquid portion is diluted to 1%-5% by mass of the first solution, and then filtered through a 0.2 micron filter membrane;

[0026] In S2, the pH of the system is adjusted to 1.9-2.1, and the temperature of the reflux is 55-70℃ and the reflux time is 30-80 min.

[0027] In step S3, the organic-inorganic hybrid spraying liquid has a mass percentage of 1%-5%; the positive electrode active material and the solid content in the organic-inorganic hybrid spraying liquid are mixed at a mass ratio of 1:0.004-0.01 in step S4.

[0028] S4 uses a planetary mixing and spraying integrated equipment with a mixing speed of 200-500 rpm and an equipment temperature of 40-50℃. The organic-inorganic hybrid spraying liquid is atomized and sprayed at a rate of 10-12 g / min to maintain uniform particle distribution and prevent agglomeration. The parameters for the thermosetting are as follows: first, the solvent is removed at a low temperature of 70-90℃ for 10-30 minutes to slightly deagglomerate the particles, and then the oxygen content is reduced to below 2% under a protective atmosphere before the temperature is raised to 120-140℃ for curing for 20-40 minutes.

[0029] Furthermore, the positive electrode active material of the organic-inorganic hybrid interface layer is bonded to the coating area of ​​the current collector using a positive electrode coating slurry to form the positive electrode sheet; the solids in the positive electrode coating slurry include the positive electrode active material of the organic-inorganic hybrid interface layer, the conductive material and the composite binder phase compounded in a mass ratio of 95-99:0.2-0.5:1-3, and the solid content of the positive electrode coating slurry is at least 50wt%.

[0030] Furthermore, the composite binder phase is a compound of PVDF-HFP, sulfonated polymer, and PEDOT:PSS. The composite binder phase accounts for 1.2%-1.8% of the total solid mass on the positive electrode sheet, wherein the content of sulfonic acid groups in the composite binder phase is 0.3-0.8 mmol / g (preferably 0.45-0.7 mmol / g), and PEDOT:PSS accounts for 0.05%-0.2% of the total solid mass on the positive electrode sheet (preferably 0.08%-0.15%). The sulfonated polymer is selected from sulfonated polyarylene ether (SPAE) or sulfonated polyarylene ether sulfone (SPAES), and the sulfonic acid groups are sourced from PSS and the sulfonated polymer. The conductive material is selected from one or more of carbon fiber, carbon nanotubes, conductive carbon black, acetylene black, and graphene.

[0031] Furthermore, the conductive domain coverage of the coated area on the positive electrode sheet observed under a conductive atomic force microscope (C-AFM) is at least 70%, and the 180° peel strength of the coated area on the positive electrode sheet is ≥0.35N / mm.

[0032] Furthermore, the positive electrode active material is a lithium nickel cobalt manganese oxide material with a Ni molar fraction ≥ 0.6, or a coated derivative of lithium nickel cobalt manganese oxide material, or an element-doped derivative of lithium nickel cobalt manganese oxide material.

[0033] Furthermore, the gas production satisfies the following relationship: V2 is 4.75 to 5.15 times that of V1.

[0034] Furthermore, the battery cell meets the following performance requirements:

[0035] At discharge rates of 1C-10C, the battery's temperature rise characteristics satisfy the following linear relationship: y=AX+B, 1.05≤A≤1.55, 1.98≤B≤2.50, R 2 ≥0.96;

[0036] Where X = Lg I, I is the discharge current corresponding to the discharge rate, and the unit of I is amperes;

[0037] Where y = Lg m, m is the temperature rise coefficient corresponding to the discharge rate, and the unit of m is K / min.

[0038] Furthermore, both the positive electrode and the negative electrode have tabs formed by uncoated areas, with the width of the positive electrode tab being 1-1.8 mm and the width of the negative electrode tab being 0.8-1.5 mm.

[0039] Furthermore, the volume of the battery cell is S2, and the internal volume of the casing housing the battery cell is S1. Therefore, the space utilization coefficient S2 / S1 = 0.86 - 0.94. The apparent density of the assembled lithium-ion battery is ρ, and the actual density of the battery cell is Td, which satisfies 0.3 ≤ |ρd−ρ| ≤ 1.2. The units of ρ and Td are both g / cm³. 3 .

[0040] Furthermore, the negative electrode active material on the coating area of ​​the negative electrode sheet is selected from at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-carbon, silicon-oxygen, and pre-lithium silicon-oxygen, and the silicon content in the negative electrode active material is 1.0wt%-25.0wt%; the conductive agent used on the coating area of ​​the negative electrode sheet is selected from one or more of carbon fiber, carbon nanotubes, conductive carbon black, acetylene black, and graphene.

[0041] The compaction density of the negative electrode sheet is 1.2-1.7 g / cm³. 3 .

[0042] Furthermore, if the discharge capacity of the negative electrode is Cn and the discharge capacity of the positive electrode is Cp, then the Cn / Cp ratio must be within the range of 1.02-1.20. A Cn / Cp ratio < 1 will lead to the risk of lithium plating, while a ratio that is too large will result in excessively low energy density.

[0043] Furthermore, the ternary lithium-ion battery also includes an electrolyte, which comprises a lithium salt, a solvent, and additives; the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorosulfonylimide, lithium difluorophosphate, lithium difluorooxalate borate, and lithium bis(trifluoromethanesulfonylimide); the solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethylene carbonate, and methyl ethyl carbonate; the additives are selected from one or more of fluoroethylene carbonate, difluoroethylene carbonate, ethylene sulfate, ethylene sulfite, ethylene carbonate, and vinyl carbonate.

[0044] Another aspect of the present invention provides a method for preparing a heat-confined ternary lithium-ion battery, comprising the following steps:

[0045] (1) An organic-inorganic hybrid spray liquid is deposited on the surface of the positive electrode active material, and after thermal curing, an organic-inorganic hybrid interface layer with a thickness of 3-8 nm is obtained on the surface of the positive electrode active material;

[0046] The organic-inorganic hybrid spraying liquid comprises a composite liquid of organic phase sol and inorganic phase sol, wherein the organic phase sol comprises a phosphazene-based polymer and the inorganic phase sol comprises a lithium phosphate precursor and a lithium silicate sol.

[0047] (2) A positive electrode active material with an organic-inorganic hybrid interface layer is formed with a composite binder phase to form a positive electrode coating slurry, which is then coated on the coating area of ​​the positive electrode current collector, dried, and rolled to form a positive electrode sheet;

[0048] (3) The positive electrode, separator and negative electrode are wound to form a cell, assembled into a housing and injected with electrolyte, formed and sealed to obtain a thermally confined ternary lithium-ion battery.

[0049] Beneficial Technical Effects: The battery of this invention forms an organic-inorganic hybrid interface layer on the surface of the positive electrode active material and synergistically combines it with a specific composite binder phase to form a cylindrical lithium-ion battery. In this invention, the organic-inorganic hybrid interface is a phosphazene-glass interpenetrating thin film. By controlling the nitrogen-phosphorus atomic ratio and the glass phase composition ratio of lithium phosphate and lithium silicate, and combining it with a specific binder phase to construct an electron-ion dual network within a specific range of sulfonic acid group content and PEDOT content, the resulting positive electrode sheet possesses both density and low modulus. The resulting all-tab cylindrical battery exhibits a low temperature rise coefficient, improving the energy density (CR) of the lithium-ion battery. 500 At the same time, it significantly reduces the risk of gas production. Detailed Implementation

[0050] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that values ​​expressed, for example, as "within the range of ab" or "between the range of ab," do not include the endpoint values ​​a and b; values ​​expressed as "for ab," "is ab," or "ab" include the endpoint values ​​a and b.

[0052] Furthermore, it should be noted that the use of terms such as "first" and "second" to define the solution is merely for the purpose of distinguishing the steps. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0053] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0054] Test method for electrode compaction density: First, cut the positive electrode sheet, which has been washed with dimethyl carbonate and vacuum dried, into 6 standard-sized square samples (2.0cm × 2.0cm). Next, remove the active material from both sides of 3 of the square samples, rinse with ethanol, dry, weigh, and calculate the average mass M1. Simultaneously, measure the average thickness L1 of the sample using a micrometer. Then, weigh the remaining 3 square samples and calculate the average mass M2. Calculate the electrode thickness: L2 - L1, in cm. Calculate the electrode compaction density (in g / cm³) using the following formula. 3 ):

[0055] .

[0056] The method for testing the true density (Td) of a battery cell is based on the electrode-core system, calculated by measuring the mass and volume of the electrode and the structural parameters of the core. The specific steps are as follows: Cut a sample of the electrode to be tested from the core, ensuring the sample is representative; weigh the initial mass of the electrode (m1) using a high-precision electronic balance and record the mass of the aluminum foil (m2); measure the length, width, and thickness of the electrode using vernier calipers, and calculate the volume V = length × width × thickness. According to the formula: Td = (m1 - m2) / V, where m1 is the total mass of the electrode (including active material and aluminum foil), m2 is the mass of the aluminum foil, and V is the volume of the electrode. The unit for the true density Td is g / cm³. 3 .

[0057] The apparent density of the assembled battery is tested using the conventional specific gravity method. The density of the battery is calculated by weighing its mass and volume.

[0058] The substances used in the following cases are shown in Table 1 below.

[0059] Table 1. Substances used in the case study

[0060]

[0061] Example 1

[0062] I. Preparation of positive electrode active materials with organic-inorganic hybrid interface layers, including the following steps:

[0063] S1, HCCP:–OH:TEA:DMAP:anhydrous acetonitrile are prepared in a molar ratio of 1:6:6:0.04:64, with anhydrous acetonitrile as the solvent;

[0064] Under nitrogen protection in a three-necked flask, anhydrous acetonitrile, HCCP, and DMAP were added and stirred to dissolve. The mixture was then placed in an ice bath until the system temperature was below 5°C. A mixture of PEG-400 (–OH source) and TEA was added dropwise, with the addition completed within 30 minutes. During the addition, the system temperature was kept ≤10°C. After the addition was completed, the temperature was raised to 25°C and the reaction was continued for 3 hours with stirring. The precipitated crystal salt Et3NHCl was removed by filtration. The liquid portion was diluted with acetonitrile to a concentration of 2.0 wt%, and then filtered through a 0.2 μm PTFE membrane to obtain the first solution.

[0065] The main reaction equations involved in S1 are as follows, and the reaction process is nucleophilic substitution / condensation polymerization, with TEA acting as an acid-binding agent:

[0066] ,

[0067] Where R represents the PEG macromolecular chain segment; deposition thermosetting will further consume the residual P-Cl / P-OH, forming a slightly cross-linked flexible network, resulting in an N / P atomic ratio of 1.0 in the organic phase;

[0068] S2. Under ice bath conditions, LiOH·H2O was dissolved in an ethanol aqueous solution (70% ethanol by volume), and H3PO4 was dissolved in an ethanol aqueous solution (70% ethanol by volume). The two were mixed according to an equimolar ratio of lithium to phosphorus, the pH of the system was adjusted to 2.0, and the mixture was heated to 60℃ and refluxed for 60 min to obtain a transparent lithium phosphate precursor (LiH2PO4) sol.

[0069] Cool the temperature to 23°C, add Li2SiO3 sol at a lithium phosphate to lithium silicate mass ratio of 80:20, stir for 20 min, and mix evenly to obtain the second solution;

[0070] The reaction equations involved in S2 are as follows:

[0071] ;

[0072] S3. Mix the first solution and the second solution in an equal mass ratio, adjust the solid content to 2.0 wt% with acetonitrile and ethanol in an equal volume ratio, then filter through a 0.2 μm PTFE membrane and degas under vacuum for at least 10 min to obtain an organic-inorganic hybrid spraying liquid.

[0073] S4. Start the 5L planetary mixing and spraying integrated equipment. Set the mixing pot to 45℃ and the stirring speed to 300rpm. Add the positive electrode active material LiNi. 0.8 Co 0.1 Mn 0.1 O2 (NCM811), the positive electrode active material and the solid content in the organic-inorganic hybrid spraying liquid are atomized and sprayed into the organic-inorganic hybrid spraying liquid at a mass ratio of 1:0.006 at a rate of 10 g / min, with a total spraying time of 30 min, to maintain uniform particle distribution and no agglomeration in the system;

[0074] After spraying, the solvent is removed by low-temperature hot air at 80℃ for 20 minutes to slightly deagglomerate the material; then it is thermally cured at 130℃ (nitrogen atmosphere, oxygen content <2%) for 30 minutes to form a CEI coating with an organic-inorganic hybrid interface of 5.5±0.5nm on the surface of the positive electrode active material, thereby obtaining a positive electrode active material with an organic-inorganic hybrid interface layer.

[0075] Organic-inorganic hybrid interface layer structure mechanism: POR bridges and a small amount of crosslinks are generated in step S1, resulting in a low-modulus, dense, and lithiophilic interface after thermosetting; at the same time, LiH2PO4 forms lithium polyphosphate (LiPO3) during thermosetting. n The lithium polyphosphate glass phase forms a continuous Li⁺ current-carrying framework and interpenetrates with the organic network. Li₂SiO₃ improves the toughness and adhesion of the coating and reduces microcracks caused by particle expansion and contraction.

[0076] II. Preparation of positive electrode:

[0077] The above-prepared positive electrode active material with an organic-inorganic hybrid interface layer, conductive carbon black, and composite binder phase were mixed in a mass ratio of 98.15:0.35:1.5 to form a mixture. The composite binder phase was a mixture of PVDF-HFP, sulfonated polyarylene ether (SPAE), and PEDOT:PSS (based on solids) in a mass ratio of 68:27.1:4.9. The content of sulfonic acid group (–SO3H) in the composite binder phase was 0.55 mmol / g.

[0078] After thoroughly mixing the above mixture in an N-methylpyrrolidone solvent system, a positive electrode coating slurry with a solid content of approximately 70 wt% is obtained. The positive electrode coating slurry is then coated onto both sides of a 12.0 μm thick positive electrode current collector (aluminum foil). After drying and cold pressing, a positive electrode sheet is obtained. PEDOT:PSS accounts for 0.0735% of the total solid mass on the positive electrode sheet.

[0079] Conductive atomic force microscopy (C-AFM) observation of the coated area of ​​the positive electrode in this case showed that the conductive domain coverage of the coated area on the positive electrode was 73%, and the 180° peel strength of the coated area on the positive electrode was 0.36 N / mm.

[0080] III. Preparation of negative electrode:

[0081] The negative electrode sheet includes a negative current collector copper foil and a negative electrode coating material coated on both sides of the copper foil. By mass percentage, the negative electrode coating material includes 10.0% deposited silicon carbon, 86.0% graphite, 0.75% conductive agent SWCNT, 0.75% conductive carbon black, and 2.5% CMC. These substances are added to deionized water and stirred to form a negative electrode coating slurry with a solid content of 42%. The negative electrode coating slurry is then coated onto both sides of the negative current collector (copper foil). After drying and cold pressing, a negative electrode sheet is formed with a compaction density of 1.5 g / cm³. 3 .

[0082] The discharge capacity Cn of the negative electrode and the discharge capacity Cp of the positive electrode prepared above satisfy the condition that Cn / Cp is in the range of 1.02-1.20.

[0083] IV. Electrolyte preparation:

[0084] An electrolyte was prepared by mixing lithium salt lithium hexafluorophosphate (LiPF6), organic solvents ethylene carbonate (EC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), ethylene sulfate (DTD), and vinylene carbonate (VC) in a mass percentage ratio of 10.0:22.0:53.0:3.0:7.0:5.0.

[0085] V. Diaphragm

[0086] A high-porosity membrane with a porosity of at least 75% is selected. The membrane structure is a five-layer composite structure: in sequence, a PVDF membrane, an alumina ceramic membrane, an intermediate base membrane, an alumina ceramic membrane, and a PVDF membrane; the thickness of the intermediate base membrane PE is 9μm, and the thickness of the alumina ceramic membrane is 1.0μm.

[0087] VI. Ternary Lithium-ion Battery Assembly:

[0088] After the positive and negative electrode sheets are rolled and slit, the positive electrode sheet, separator, and negative electrode sheet are wound according to the set process (the coated areas of the positive and negative electrode sheets are placed opposite each other; the uncoated areas of the positive and negative electrode sheets are placed facing outwards, forming positive and negative electrode tabs respectively, with the positive electrode tab being 1.4 mm wide and the negative electrode tab being 1.1 mm wide), forming a 21700 cylindrical wound cell. Subsequently, the cell is fixed to the pre-made connecting piece by welding and installed in a metal battery casing. After completing key processes such as electrolyte injection, sealing, and formation, the ternary lithium-ion battery of this case is obtained.

[0089] The ternary lithium-ion battery in this case uses a cylindrical casing with an external dimension of 21.0 mm in diameter and 70.0 mm in length, conforming to the 21700 standard specification. The cell volume in this case is S2 = 20.50 cm³, and the internal cavity volume of the casing housing the cell is S1 = 22.77 cm³, resulting in a space utilization coefficient of S2 / S1 = 0.9. The apparent density of the assembled lithium-ion battery is ρ = 1.90 g·cm⁻³, and the actual density of the cell is Td = 2.50 g·cm⁻³, satisfying 0.3 ≤ |Td−T| ≤ 1.2.

[0090] Example 2

[0091] The preparation of the ternary lithium-ion battery in this case: The preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer in this case I are the same as those in Example 1. The difference is that the solid content of S3 is adjusted to 1.8wt%, and finally a 4.5nm organic-inorganic hybrid interface CEI coating is formed on the surface of the positive electrode active material.

[0092] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0093] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0094] Example 3

[0095] The preparation of the ternary lithium-ion battery in this case: The preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer in this case I are the same as those in Example 1. The difference is that the solid content of S3 is adjusted to 2.4wt%, and finally a 7nm organic-inorganic hybrid interface CEI coating is formed on the surface of the positive electrode active material.

[0096] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0097] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0098] Example 4

[0099] Preparation of ternary lithium-ion batteries in this case: The preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer in this case I are the same as those in Example 1. The difference is that HCCP, hydroxyl groups and TEA are prepared in a molar ratio of 1:6.2:6.2, so that the N / P atomic ratio in the organic phase prepared in S1 is 0.9.

[0100] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0101] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0102] Example 5

[0103] Preparation of ternary lithium-ion batteries in this case: The preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer in this case I are the same as those in Example 1. The difference is that HCCP, hydroxyl groups and TEA are prepared in a molar ratio of 1:5.8:5.8, so that the N / P atomic ratio in the organic phase prepared in S1 is 1.1.

[0104] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0105] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0106] Example 6

[0107] Preparation of ternary lithium-ion battery in this case: The preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer in this case I are the same as those in Example 1. The difference is that Li2SiO3 sol is added in S2 according to the mass ratio of lithium phosphate to lithium silicate of 90:10.

[0108] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0109] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0110] Example 7

[0111] Preparation of ternary lithium-ion battery in this case: The preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer in this case I are the same as those in Example 1. The difference is that Li2SiO3 sol is added in S2 according to the mass ratio of lithium phosphate to lithium silicate of 70:30.

[0112] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0113] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0114] Example 8

[0115] Preparation of ternary lithium-ion batteries in this case: The preparation method and material ratio of positive electrode II and negative electrode III in this case are the same as those in Example 1. The difference is that the composite binder phase is a mixture of PVDF-HFP, sulfonated polyarylene ether (SPAE), and PEDOT:PSS (based on solids) in a mass ratio of 75.75:19.35:4.9, so that the content of sulfonic acid group (–SO3H) in the composite binder phase is 0.45 mmol / g.

[0116] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0117] The operations for the other I, IV, V, and VI are the same as in Example 1.

[0118] Example 9

[0119] Preparation of ternary lithium-ion batteries in this case: The preparation method and material ratio of positive electrode II and negative electrode III in this case are the same as those in Example 1. The difference is that the composite binder phase is a mixture of PVDF-HFP, sulfonated polyarylene ether (SPAE), and PEDOT:PSS (based on solids) in a mass ratio of 56.52:38.58:4.9, so that the content of sulfonic acid group (–SO3H) in the composite binder phase is 0.70 mmol / g.

[0120] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0121] The operations for the other I, IV, V, and VI are the same as in Example 1.

[0122] Example 10

[0123] The preparation of the ternary lithium-ion battery in this case: The preparation method and material ratio of the positive electrode sheet in this case II are the same as those in Example 1, except that: the positive electrode active material with organic-inorganic hybrid interface layer prepared in I above, conductive carbon black, and composite binder phase are mixed at a mass ratio of 98.01:0.35:1.64, and PEDOT:PSS accounts for 0.0803% of the total solid mass on the positive electrode sheet.

[0124] The operations for the other I, III, IV, V, and VI are the same as in Example 1.

[0125] Example 11

[0126] Preparation of ternary lithium-ion batteries in this case: The preparation method and material ratio of the positive electrode sheet in this case II are the same as those in Example 1, except that: the positive electrode active material with organic-inorganic hybrid interface layer prepared in I above, conductive carbon black, and composite binder phase are mixed at a mass ratio of 96.59:0.35:3.06, and PEDOT:PSS accounts for 0.150% of the total solid mass on the positive electrode sheet.

[0127] The operations for the other I, III, IV, V, and VI are the same as in Example 1.

[0128] Comparative Example 1

[0129] In Case I, the preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer are the same as those in Example 1. The difference is that the solid content in S3 is adjusted to 1.1 wt%, and a 2 nm organic-inorganic hybrid interface CEI coating is finally formed on the surface of the positive electrode active material.

[0130] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0131] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0132] Comparative Example 2

[0133] In Case I, the preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer are the same as in Example 1. The difference is that the solid content of S3 is adjusted to 2.8wt%, and finally a 10nm organic-inorganic hybrid interface CEI coating is formed on the surface of the positive electrode active material.

[0134] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0135] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0136] Comparative Example 3

[0137] The preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer in Case I are the same as those in Example 1. The difference is that HCCP, hydroxyl groups and TEA are prepared in a molar ratio of 1:9:4, so that the N / P atomic ratio in the organic phase prepared by S1 is 0.5.

[0138] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0139] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0140] Comparative Example 4

[0141] The preparation method and material ratio of the positive electrode active material with organic-inorganic hybrid interface layer in Case I are the same as those in Example 1, except that Li2SiO3 sol is not added in S2.

[0142] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0143] The subsequent operations for III, IV, V, and VI are the same as in Example 1.

[0144] Comparative Example 5

[0145] The preparation method and material ratio of the positive electrode in Case II and the negative electrode in Case III are the same as those in Example 1. The difference is that the composite binder phase is a mixture of PVDF-HFP, sulfonated polyarylene ether (SPAE), and PEDOT:PSS (based on solids) in a mass ratio of 95.10:0:4.9, so that the content of sulfonic acid group (–SO3H) in the composite binder phase is 0.1 mmol / g.

[0146] In Case II, the positive electrode active material with an organic-inorganic hybrid interface layer prepared in Case I above, conductive carbon black, and composite binder phase are mixed in a mass ratio of 97.55:0.35:2.1, and PEDOT:PSS accounts for 0.103% of the total solid mass on the positive electrode sheet.

[0147] The operations for the other I, IV, V, and VI are the same as in Example 1.

[0148] Comparative Example 6

[0149] The preparation method and material ratio of the positive electrode sheet in Case II are the same as those in Example 1. The difference is that the positive electrode active material with organic-inorganic hybrid interface layer prepared in Case I, conductive carbon black, and composite binder phase are mixed in a mass ratio of 93.5:0.35:6.15, and PEDOT:PSS accounts for 0.301% of the total solid mass on the positive electrode sheet.

[0150] The operations for the other I, III, IV, V, and VI are the same as in Example 1.

[0151] Table 2 shows the relevant variables in the preparation of ternary lithium-ion batteries in the examples and comparative examples.

[0152] Table 2. Relevant variables for the examples and comparative examples.

[0153]

[0154] Test case

[0155] Test 1.5C discharge temperature rise coefficient

[0156] Temperature rise coefficient definition: The slope of the curve dT / dt of the temperature change over time in the linear section of the discharge plateau when the battery cell is discharged at 5C constant current; unit K / min.

[0157] After the battery cell formation is completed, let it stand for 24 hours.

[0158] Apply a 0.5°C CC-CV to 4.20°C, with CV cutoff at 0.05°C; allow to stand for 1 hour.

[0159] The thermocouple is fixed in the middle of the housing at the same height as the battery cell. A very thin layer of thermally conductive silicone grease is applied, and the thermocouple is wrapped with two loops of PI tape (to prevent it from falling off). The battery cell is placed in the chamber with the air circulation turned on, and the temperature is allowed to stabilize for 30 minutes.

[0160] Discharge at a constant current of 5C to 2.50V or 10% SOC (cut off when either condition is met); temperature, voltage, and current are sampled synchronously (≥1Hz). Select temperature T-time t data corresponding to the 10%-80% SOC range, remove the initial 30s preheating period, and then the temperature rise coefficient m = dT / dt (unit K / min).

[0161] Test 2: Capacity retention after 500 cycles at 45℃ and 3C.

[0162] Each battery was placed in a 45°C constant temperature chamber for 6 hours and tested according to the following steps:

[0163] (1) First round of constant current and constant voltage charging: Charge at a constant current of 0.1C to 4.20V, then switch to constant voltage charging until the current drops to 0.01C.

[0164] (2) Let it stand for 30 minutes after charging is complete.

[0165] (3) Perform constant current discharge, and discharge to 2.5V at a rate of 0.1C.

[0166] (4) Cyclic charging and discharging process: constant current charging at a rate of 3C to 4.20V, then constant voltage charging until the current drops to 0.1C.

[0167] (5) Let it stand for another 30 minutes.

[0168] (6) Discharge at a constant current rate of 3C to 2.5V.

[0169] (7) Let it stand for another 30 minutes.

[0170] (8) Repeat the above (4)-(7) charging and discharging process for a total of 500 cycles.

[0171] 1000-cycle capacity retention: The battery discharge capacities Q1 and Q500 are calculated after 1 and 500 cycles, and the battery capacity retention rate (CR) is calculated. 500 =Q500 / Q1×100%.

[0172] Test 3, Gas Production

[0173] (1) Gas production V1 at 85℃ for 24 hours

[0174] GB / T 31486 standard charging method (0.5C CC–CV to 4.20V, CV cutoff at 0.05C): After constant current charging (0.5C) to 4.20V, proceed to constant voltage charging. Stop charging when the charging current drops to 0.05C (i.e., fully charged), let stand for 1 hour, and then place the battery cell (end face up) at 85℃ for 24 hours. After removal, firmly attach the positive and negative terminals of the battery cell with insulating tape and immerse it in deionized water (the device should be pre-calibrated to zero). Record the volume of displacement liquid rise, which is determined as the gas production rate V1.

[0175] (2) Gas production V2 after 6 hours of overcharging at room temperature

[0176] At room temperature, charge at a constant current of 0.2C to an overcharge voltage of 5V (CV), and maintain this constant voltage for 6 hours. Record the voltage, current, and time curves. Within 10 minutes after completion, secure the positive and negative terminals with insulating tape, and immerse the cell face up in a pre-calibrated DI water bath. Record the volume of displacement liquid rise, which is determined as the gas production rate V2.

[0177] The results are shown in Table 3.

[0178] Table 3 Performance of Each Case

[0179]

[0180] Table 3 shows that, comparing Examples 1-3 (CEI coating thickness of 5.5 / 4.5 / 7.0 nm) with Comparative Example 1 (CEI coating thickness of 2.0 nm), it can be seen that when the coating is too thin, pinholes and localized exposure are more likely to appear on the particle surface. Ni 4+ The corrosion and oxidation reactions of the electrolyte are intensified, and the heat of interfacial side reactions increases, leading to an increase in the 5C discharge temperature rise coefficient and CR. 500 The temperature rise decreases; meanwhile, the byproduct gas produced after aging cannot be fully passivated and consumed, leading to an increase in V1 measured during immersion. A thin, continuous coating of 5-7 nm provides both electron / solvent barrier and does not excessively increase the Li⁺ migration barrier, resulting in a lower 5C discharge temperature rise coefficient and lower CR. 500 Higher, V1 smaller; if the thickness is further increased (such as the CEI coating thickness of 10nm in Comparative Example 2), the ion transmembrane resistance and polarization increase, and the discharge heat accumulation worsens the 5C discharge temperature rise coefficient and drags down the cycle.

[0181] Comparing Examples 4 / 1 / 5 (N / P atomic ratio of 0.9 / 1.0 / 1.1) with Comparative Example 3 (N / P atomic ratio of 0.5), it can be seen that: a low N / P ratio leads to an excessively high proportion of P=O segments, insufficient cross-linking and density, and a decrease in membrane mechanical integrity; it also makes the membrane more prone to cracking and secondary reactions at high temperatures and high potentials, manifested as a higher 5C discharge temperature rise coefficient and reduced CR. 500 The N / P atomic ratio is significantly reduced, while V1 increases. When the N / P atomic ratio is 0.9-1.1, the ratio of P=N to P=O functional groups is more balanced, maintaining both chemical passivation of the solvent / peroxide intermediate and a lower modulus to accommodate particle expansion and contraction, thereby suppressing side reactions and gas generation, resulting in a lower 5C discharge temperature rise coefficient and a higher CR. 500 and smaller V1; among them, the N / P atomic ratio of about 1.0-1.1 often balances compactness and lithophile coordination channels, and has the best overall performance.

[0182] Comparing Examples 7 / 1 / 6 (LiPO3:Li2SiO3 (wt% / wt%)=70:30 / 80:20 / 90:10) with Comparative Example 4 (LiPO3:Li2SiO3 (wt% / wt%)=100:0), it can be seen that when only LiPO3 is used, the Si-O framework of the membrane lacks toughening, and the volume bounce caused by rolling and cycling easily induces microcracks and permeation channels, increasing interfacial side reactions and gas production, which is manifested in an increase in the 5C discharge temperature rise coefficient and CR. 500 The temperature rise decreases, and V1 increases. Appropriate addition of Li2SiO3 (approximately 10%-30%) can form an interpenetrating network and reduce film brittleness, improve modulus matching and wetting spreading with the NCM surface, and inhibit microcracks and solvent intrusion. Therefore, the 5C discharge temperature rise coefficient is lower, and CR... 500 More stable, smaller V1.

[0183] Comparing Examples 8 / 1 / 9 (–SO3H ≈ 0.45 mmol / g / 0.55 mmol / g / 0.70 mmol / g) with Comparative Example 5 (extremely low –SO3H), it can be seen that –SO3H reflects the density of sulfonate channels and the wettability of the electrode. Excessively low –SO3H (Comparative Example 5) results in sparse ion channels, poor electrode wetting / rewetting with electrolyte, an imbalance in the electron-ion dual network, and significant polarization and thermal accumulation at high rates, manifested as a higher 5C discharge temperature rise coefficient and reduced CR. 500 Decreased, V1 increased. Increasing -SO3H to 0.45-0.70 mmol / g (Examples 8 / 1 / 9) can significantly improve the continuous transport of Li⁺ and the uniformity of electrolyte distribution without sacrificing mechanical strength, reduce local side reactions and gas generation, thus decreasing the 5C discharge temperature rise coefficient and CR. 500 The increase in V1 significantly reduces the risk of excessive liquid absorption and swelling; however, if the V1 value is too high, it may lead to excessive liquid absorption and swelling. Therefore, it needs to be optimized in conjunction with PEDOT:PSS and porosity.

[0184] Comparing Examples 10 / 1 / 11 (PEDOT:PSS accounts for 0.08% / 0.10% / 0.15% of the total solid mass on the positive electrode) with Comparative Example 6 (PEDOT:PSS accounts for 0.30% of the total solid mass on the positive electrode), it can be seen that: an appropriate amount of PEDOT:PSS as an electronic pathway can significantly reduce the contact resistance between particles, carbon black, and the current collector, construct a dense electronic network, and form a bicontinuous network with the ion channels provided by –SO3H, thereby reducing the 5C discharge temperature rise coefficient and CR. 500 The performance is improved, and V1 is smaller due to the more uniform distribution of interfacial current. However, excessive PEDOT:PSS (0.30%) tends to accumulate on the surface during the drying process, locally catalyzing the decomposition of the electrolyte and forming a reaction layer that is difficult to repair. This leads to an increase in side reactions and gas production (increased V1 as measured by immersion method). During cycling, the electrode bonding phase may also be eroded and powdered, resulting in a deterioration in overall performance.

[0185] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A thermal gas confinement lithium-ion battery, comprising a positive electrode sheet, a separator, and a negative electrode sheet wound to form a cell; characterized in that, The surface of the positive electrode active material on the positive electrode sheet has an organic-inorganic hybrid interface layer; According to the specification of the ternary lithium ion battery, in the empty state, the battery cell is charged to 4.20V at 0.5C constant current CC-constant voltage CV, and the gas production measured after being placed at 85℃ for 24h is V1; The battery cell is charged to overcharge voltage at 0.2C constant current at room temperature, and the gas production measured after constant voltage overcharge for 6h is V2, the overcharge voltage is greater than the threshold value of the safety working voltage during charging and less than 1.2 times the threshold value; Then it meets: V1 is less than 0.45mL and V2 is less than 2.5mL.

2. The hot gas constrained lithium-ion battery of claim 1, wherein, The material of the organic-inorganic hybrid interface layer includes a composite of inorganic phase and organic phase; the inorganic phase is lithium phosphate and lithium silicate, and the organic phase is phosphazene-based polymer; The thickness of the organic-inorganic hybrid interface layer is 3-8nm, the coating rate is at least 95%, and the N / P atomic ratio is 0.8-1.

2.

3. The hot gas constrained lithium-ion battery of claim 2, wherein, The method for obtaining the organic-inorganic hybrid interface layer includes the following steps: S1, under a protective atmosphere, dissolve phosphazene monomer and nucleophilic organic catalyst in an aprotic polar solvent, cool to below 10℃ and maintain the temperature, drop the mixed solution of macromolecular polyol and organic amine, after dropping, continue to stir and react, after the reaction is completed, remove the precipitated crystal salt by suction filtration, dilute the liquid part to obtain a first solution; S2, under ice bath, dissolve lithium hydroxide and phosphoric acid in alcohol-water solvent respectively, then mix according to the equimolar ratio of lithium element and phosphorus element, adjust the pH value of the system to be in the range of 1.5 to 2.5, heat to reflux to obtain lithium dihydrogen phosphate sol, after cooling to room temperature, add lithium silicate sol, mix uniformly to obtain a second solution; S3, mix the first solution and the second solution, adjust the solid content, and obtain an organic-inorganic hybrid spraying solution; S4, make the positive electrode active material deposit the organic-inorganic hybrid spraying solution on its surface under stirring, and obtain the organic-inorganic hybrid interface layer on the surface of the positive electrode active material after heat curing.

4. The hot gas constrained lithium-ion battery of claim 3, wherein, The phosphazene monomer is selected from hexafluorocyclotriphosphazene or hexachlorocyclotriphosphazene; The macromolecular polyol is selected from polyethylene glycol and / or polypropylene glycol; The nucleophilic organic catalyst is selected from pyridine compounds; The organic amine is selected from one or more of trimethylamine, dimethylamine, triethylamine, diethylamine, tripropylamine, triisopropylamine, dipropylamine, diisopropylamine, tributylamine, triisobutylamine, dibutylamine, diisobutylamine; The aprotic polar solvent is selected from one of ethers, halogen compounds, ketones, nitrogen-containing hydrocarbons, sulfoxides, and amides.

5. The hot gas containment ternary lithium ion battery according to claim 3, wherein, The molar ratio of the phosphazene monomer, the macromolecular polyol, the organic amine, and the nucleophilic organic catalyst in S1 is 1:(5.8-6.2):(5.8-6.2):(0.02-0.06); The volume percentage of ethanol in the alcohol-water solvent is 60%-80%; the mass percentage of lithium phosphate and lithium silicate in S2 step is 70%-90%:30%-10%. In S1, the mixed solution is dropped into the solution at a temperature of 0-5°C, the dropping time of the mixed solution is controlled at 10-40 min, and after the dropping of the mixed solution is completed, the temperature is increased to 23-30°C for continuous stirring reaction for 1-5 h; the liquid part is diluted to a mass percentage of 1%-5% of the first solution, and then filtered through a 0.2-micron filter membrane; In S2, the pH of the system is adjusted to 1.9-2.1, the temperature of the reflow is 55-70°C, and the reflow time is 30-80 min; In S3, the mass percentage of the organic-inorganic hybrid spraying liquid is 1%-5%; the solid content in the organic-inorganic hybrid spraying liquid and the positive active material are subjected to S4 operation at a mass ratio of 1:0.004-0.01; In S4, a planetary stirring and spraying integrated device is used for operation, the stirring speed is 200-500 rpm, the device temperature is set to 40-50°C, the organic-inorganic hybrid spraying liquid is atomized and sprayed at a speed of 10-12 g / min; the parameters of the thermal curing are as follows: first, the solvent is removed at 70-90°C for 10-30 min, and then the oxygen content is reduced to less than 2% under a protective atmosphere, and then the temperature is increased to 120-140°C for curing for 20-40 min.

6. A hot gas constrained lithium-ion battery of any one of claims 1-5, wherein, The positive active material with the organic-inorganic hybrid interface layer is bonded to the coated area of the current collector by using the positive electrode coating slurry to form the positive electrode sheet. The solid content in the positive electrode coating slurry includes the positive active material with the organic-inorganic hybrid interface layer, the conductive material, and the composite binder phase, which are compounded at a mass ratio of 95-99:0.2-0.5:1-3, and the solid content of the positive electrode coating slurry is at least 50 wt%.

7. The hot gas constrained lithium-ion battery of claim 6, wherein, The composite binder phase is a compound of PVDF-HFP, a sulfonated polymer, and PEDOT:PSS, the composite binder phase accounts for 1.2%-1.8% of the total solid mass on the positive electrode sheet, the content of sulfonic acid groups in the composite binder phase is 0.3-0.8 mmol / g, and PEDOT:PSS accounts for 0.05%-0.2% of the total solid mass on the positive electrode sheet. The sulfonated polymer is selected from sulfonated polyarylene ether or sulfonated polyarylene ether sulfone; the conductive material is selected from one or more of carbon fiber, carbon nanotube, conductive carbon black, acetylene black, and graphene.

8. The hot gas constrained lithium-ion battery of claim 1, wherein, The conductive domain coverage of the coated area of the positive electrode sheet observed under a conductive atomic force microscope is at least 70%, and the 180° peeling strength of the coated area of the positive electrode sheet is ≥0.35 N / mm. The positive active material is a lithium nickel cobalt manganese oxide material with a nickel mole fraction of ≥0.6, a coated derivative of the lithium nickel cobalt manganese oxide material, or an element-doped derivative of the lithium nickel cobalt manganese oxide material.

9. The hot gas constrained lithium-ion battery of claim 1, wherein, The gas production satisfies the following relationship: V2 is 4.75 times-5.15 times V1.

10. The hot gas constrained lithium-ion battery of claim 1, wherein, The battery satisfies the following performances: The temperature rise characteristics of the battery at a 1C-10C discharge rate satisfy the following linear relationship y=AX+B, 1.05≤A≤1.55, 1.98≤B≤2.50, R 2 ≥0.

96. wherein X=Lg I, I is the discharge current corresponding to the discharge rate, and I is in units of amperes; wherein y=Lg m, m is the temperature rise coefficient corresponding to the discharge rate, and m is in units of K / min.

11. The hot gas constrained lithium-ion battery of claim 1, wherein, The ternary lithium ion battery also satisfies at least one of the following conditions: (1) the positive electrode sheet and the negative electrode sheet each have a tab formed by a non-coated area, the width of the positive electrode tab is 1-1.8 mm, and the width of the negative electrode tab is 0.8-1.5 mm; (2) the volume of the battery cell is S2, the volume of the inner cavity of the shell accommodating the battery cell is S1, the space utilization coefficient S2 / S1=0.86-0.94; the apparent density of the assembled lithium ion battery is p, the true density of the battery cell is Td, and 0.3≤|Td-p|≤1.2 is met, the units of p and Td are both g / cm 3 ; (3) the discharge capacity of the negative electrode sheet is Cn, the discharge capacity of the positive electrode sheet is Cp, and the Cn / Cp ratio is in the range of 1.02-1.20; (4) the negative active material on the coated area of the negative electrode sheet is selected from at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-carbon, silicon-oxygen, and pre-lithiated silicon-oxygen, and the silicon content in the negative active material is 1.0wt%-25.0wt%; the conductive agent used on the coated area of the negative electrode sheet is selected from one or more of carbon fibers, carbon nanotubes, conductive carbon black, acetylene black, and graphene; (5) the compaction density of the negative electrode sheet is 1.2-1.7 g / cm 3 ; (6) the ternary lithium ion battery further comprises an electrolyte, the electrolyte comprises a lithium salt, a solvent, and an additive; the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bisfluorosulfonylimide, lithium difluorophosphate, lithium difluoro oxalate borate, and lithium bis-trifluoromethylsulfonylimide; the solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethylene carbonate, and methyl ethyl carbonate; and the additive is selected from one or more of fluoroethylene carbonate, bis-fluoroethylene carbonate, ethylene sulfate, ethylene sulfite, vinylene carbonate, and vinyl carbonate.

12. A method for preparing a thermally confined ternary lithium-ion battery, characterized in that, The battery described in any one of claims 1-11 is prepared by the following steps: (1) depositing an organic-inorganic hybrid spraying liquid on the surface of the positive active material, and obtaining an organic-inorganic hybrid interface layer with a thickness of 3-8 nm on the surface of the positive active material after heat curing; The organic-inorganic hybrid spraying liquid comprises a composite liquid of an organic phase sol and an inorganic phase sol, the organic phase sol comprises a phosphazene-based polymer, and the inorganic phase sol comprises a lithium phosphate precursor and a lithium silicate sol; (2) forming a positive electrode coating slurry by combining the positive active material with an organic-inorganic hybrid interface layer and a composite binder phase, and coating the positive electrode coating slurry on the coated area of the positive current collector, drying, and rolling to form a positive electrode sheet; (3) winding the positive electrode sheet, the separator, and the negative electrode sheet to form an electric core, assembling the electric core into a shell, injecting an electrolyte, forming, and sealing to obtain a hot gas constrained ternary lithium ion battery.

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