High-energy-density lithium ion battery and preparation method thereof

Abstract

The invention relates to the technical field of lithium ion batteries, and discloses a high-energy-density lithium ion battery which comprises a battery shell, an electrode frame is arranged in the battery shell, a plurality of electrode holes are formed in the outer surface of the electrode frame in a penetrating mode, a positive electrode end is arranged on the left side of the battery shell, and a negative electrode end is arranged on the right side of the battery shell. The electrode frame is made of self-repairing electrode slurry, and the battery shell is filled with bionic electrolyte; an electrode frame is prepared by adopting self-repairing electrode slurry, and by utilizing a reversible fracture and recombination mechanism of a disulfide bond, when the electrode frame generates microcracks due to volume change or mechanical stress in a battery charge-discharge cycle process, the disulfide bond can be spontaneously fractured and recombined, so that in-situ repairing of an electrode frame structure is realized; active substance falling and structure collapse are effectively prevented, so that the cycle life of the battery is remarkably prolonged.

Description

Technical Field

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

[0002] Lithium-ion battery is a rechargeable secondary battery whose core mechanism is to store and release energy through the intercalation and deintercalation of lithium ions between positive and negative electrode materials.

[0003] Lithium-ion batteries in existing technologies lack self-repair capabilities. During the charge and discharge cycle, microcracks and structural collapse caused by volume changes lead to a reduction in the contact area between the active material and the electrolyte, hindering electron transmission, and thus causing rapid decay of battery capacity and shortened cycle life. At the same time, the electrolyte in existing technologies has the problem of low ion transmission efficiency and obvious self-discharge, which affects the battery's performance and storage time. In addition, existing technologies often use high-temperature treatment processes, which can easily cause thermal damage to the material, change the crystal structure of the electrode material, and lead to degradation of material performance. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the deficiencies in the prior art, the present invention provides a high energy density lithium ion battery and a preparation method thereof, which solves the problems raised in the above background technology.

[0006] (2) Technical solution

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a high-energy-density lithium-ion battery, comprising a battery casing, an electrode frame provided inside the battery casing, a plurality of electrode holes penetrated through the outer surface of the electrode frame, a positive terminal provided on the left side of the battery casing, and a negative terminal provided on the right side of the battery casing, the electrode frame being made of a self-repairing electrode slurry, and the battery casing being filled with a bionic electrolyte.

[0008] Preferably, the self-repairing electrode slurry is prepared by selecting polysulfide rubber containing disulfide bonds as the self-repairing polymer, dissolving it in N-methylpyrrolidone to form a uniform solution, and adding the ternary material NCM, and preparing the electrode slurry with self-repairing function through stirring and ultrasonic treatment.

[0009] Preferably, the self-repairing electrode slurry mainly comprises 80%-85% of the ternary material NCM, 5%-8% of disulfide bond-containing polysulfide rubber, 3%-5% of conductive carbon black, and 7%-10% of the binder PVDF mixed in N-methylpyrrolidone to make a slurry with a solid content of 40%-50%.

[0010] Preferably, the electrode frame is a frame having a preset electrode hole structure obtained by printing the self-repairing electrode slurry using 3D printing technology.

[0011] Preferably, the bionic electrolyte is prepared by adding lithium hexafluorophosphate into a solvent base and stirring and dissolving it, then adding a crown ether bionic additive with a selective lithium ion complexing function and vinylene carbonate, stirring and mixing thoroughly, and filtering to remove impurities.

[0012] Preferably, the solvent base mainly includes 20%-30% ethylene carbonate, 40%-50% dimethyl carbonate, and 15%-25% ethyl methyl carbonate, the lithium hexafluorophosphate is 1.0-1.2 mol / L, the crown ether biomimetic additive content is 0.5%-2%, and the vinylene carbonate content is 1%-3%.

[0013] A method for preparing a high energy density lithium-ion battery comprises the following steps:

[0014] S1. Preparation of self-repairing electrode slurry: 80%-85% high nickel ternary material NCM is selected as the main active material, 5%-8% disulfide bond-containing polysulfide rubber is uniformly dispersed in N-methylpyrrolidone solvent, and high-speed stirring and ultrasonic dispersion technology are used to fully dissolve the disulfide bond polymer. Subsequently, 3%-5% conductive carbon black is added to enhance electronic conduction, and 7%-10% binder PVDF is added to improve the film-forming property of the slurry. By adjusting the amount of N-methylpyrrolidone, the solid content of the slurry is controlled at 40%-50%. When microcracks occur in the electrode, the disulfide bonds can be triggered by heat or stress to reversibly break and reorganize, thereby achieving structural self-repair.

[0015] S2. Preparation of a biomimetic electrolyte: 20%-30% ethylene carbonate, 40%-50% dimethyl carbonate, and 15%-25% ethyl methyl carbonate are mixed to form a solvent system, 1.0-1.2 mol / L lithium hexafluorophosphate is slowly added at room temperature and stirred until completely dissolved, 0.5%-2% of a crown ether biomimetic additive with a specific pore size is added, whose molecules can selectively complex lithium ions and optimize the ion transport path, and 1%-3% of vinylene carbonate is added as a film-forming additive. After filtering through a 0.22 μm microporous membrane, an electrolyte is obtained. The self-discharge rate of the electrolyte is reduced by more than 40% compared with the traditional electrolyte;

[0016] S3, 3D printing electrode framework: The self-healing electrode slurry prepared in S1 is injected into an extrusion-type 3D printer. Through layer-by-layer stacking technology, it is printed with a single layer thickness of 0.1-0.3mm to form an electrode framework with a preset porous structure. This can achieve precise control of the electrode microstructure and shorten the lithium ion diffusion path by more than 30%;

[0017] S4, low temperature plasma treatment: the 3D printed electrode frame is placed in a vacuum of 10 -3 -10 -4 Pa plasma processing chamber, introduces argon with a purity of ≥99.99% as the working gas, and the gas flow rate is controlled at 10-50sccm. The radio frequency power supply is turned on and excited at a frequency of 13.56MHz to generate low-temperature plasma. The electrode surface is treated in the plasma for 5-15 minutes. High-energy particle bombardment forms a dense oxide protective film of 5-20nm on the surface of the electrode frame, significantly reducing the interfacial impedance and improving the compatibility of the electrode with the electrolyte.

[0018] S5. Battery assembly: Place the processed electrode frame inside the battery shell and inject the bionic electrolyte, controlling the injection volume error to ≤±1%, and complete the battery sealing by laser welding.

[0019] (3) Beneficial effects

[0020] The present invention provides a high energy density lithium ion battery and a preparation method thereof, which have the following beneficial effects:

[0021] (1) The present invention adopts a self-repairing electrode slurry to prepare an electrode frame, and utilizes the reversible breakage and recombination mechanism of disulfide bonds. During the battery charge and discharge cycle, when the electrode frame generates microcracks due to volume change or mechanical stress, the disulfide bonds can spontaneously break and recombine, thereby realizing in-situ repair of the electrode frame structure, effectively preventing the active material from falling off and the structure from collapsing, and significantly extending the battery cycle life. Compared with traditional electrodes, it can reduce the cost and resource waste of frequent replacement, and greatly improve the long-term use stability and reliability of the battery; by adding crown ether biomimetic additives to the biomimetic electrolyte, the unique molecular structure of the crown ether biomimetic additive is utilized to selectively complex lithium ions to form a stable complex, guiding the lithium ions to migrate rapidly along the optimized transmission path, effectively reducing the ion transmission resistance, and reducing the self-discharge rate by more than 40%, completely improving the low ion transmission efficiency and serious self-discharge of the traditional electrolyte, ensuring that the battery can retain the power to the greatest extent during storage, and improving the battery's energy retention capacity and convenience of use.

[0022] (2) The present invention uses 3D printing technology to precisely control the microstructure of the electrode frame. According to different application scenarios and performance requirements of the battery, the size, shape and distribution parameters of the electrode frame pores can be flexibly customized to construct the most suitable electrode pore network, which shortens the lithium ion diffusion path by more than 30%, effectively improves the ion diffusion rate, and thus greatly improves the battery charging and discharging efficiency and energy density, meeting the stringent requirements of high-power equipment for fast battery charging and discharging and high energy storage; by subjecting the electrode frame to low-temperature plasma treatment, the high-energy particles in the plasma are used to bombard the electrode surface in a vacuum environment to form a dense oxide protective film of 5-20nm. The protective film effectively isolates the direct contact between the electrolyte and the electrode material, significantly reduces the interface impedance, enhances the compatibility between the electrode and the electrolyte, reduces the occurrence of side reactions, and avoids the damage to the crystal structure and performance of the material caused by the traditional high-temperature treatment process, while simultaneously achieving energy consumption reduction, improving production efficiency, reducing production costs, and promoting the development of battery preparation technology in a green and efficient direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the cross-sectional structure of the present invention;

[0024] Figure 2 It is a schematic diagram of the process flow of the present invention.

[0025] In the figure: 1. Battery casing; 2. Electrode frame; 3. Electrode hole; 4. Positive terminal. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] like Figure 1-2As shown, the present invention provides a technical solution: a high energy density lithium ion battery, comprising a battery shell 1, an electrode frame 2 is arranged inside the battery shell 1, a plurality of electrode holes 3 are arranged through the outer surface of the electrode frame 2, a positive terminal 4 is arranged on the left side of the battery shell 1, and a negative terminal is arranged on the right side of the battery shell 1, the electrode frame 2 is made of self-repairing electrode slurry, and the battery shell 1 is filled with a bionic electrolyte. Because the electrode frame 2 is made of self-repairing electrode slurry, it can automatically repair microcracks during charging and discharging, maintain the structural integrity of the electrode frame 2, and significantly extend the service life of the battery, and the electrode holes 3 on the outer surface of the electrode frame 2 can promote full infiltration of the bionic electrolyte, optimize the lithium ion transmission path, and improve the battery charging and discharging efficiency and energy density. The bionic electrolyte filled in the battery shell 1 optimizes ion transmission and reduces the self-discharge rate through special additives. The various parts cooperate with each other to achieve a comprehensive improvement in battery performance and effectively meet the requirements of high energy density and long battery life.

[0028] Furthermore, the self-repairing electrode slurry is to select polysulfide rubber containing disulfide bonds as the self-repairing polymer, dissolve it in N-methylpyrrolidone to form a uniform solution, and add the ternary material NCM, through stirring and ultrasonic treatment, to make an electrode slurry with self-repairing function. After the polysulfide rubber containing disulfide bonds is dissolved in N-methylpyrrolidone to form a solution, it is mixed with the ternary material NCM, and after stirring and ultrasonic treatment, the components can be evenly dispersed to ensure the uniformity and stability of the electrode slurry. Among them, the disulfide bonds in the electrode frame 2 are caused by volume changes, mechanical stress, etc. due to charge and discharge. When microcracks appear, reversible fracture and recombination can be triggered by heat or stress, thereby realizing automatic repair of the electrode frame 2 structure, effectively preventing the active material from falling off and the structure from collapsing due to crack expansion in the electrode frame 2, and significantly extending the battery cycle life; the ternary material NCM, as the main active material, provides the high specific capacity required for battery charging and discharging; and the good solubility of N-methylpyrrolidone ensures the full fusion of the various components, and the ultrasonic and stirring treatments further enhance the dispersion effect, effectively combining the self-repair function with the electrochemical performance, and improving the overall performance of the electrode frame 2 and the reliability of the battery.

[0029] Furthermore, the self-repairing electrode slurry mainly includes 80%-85% of the ternary material NCM (as the main active substance, providing high specific capacity and ensuring the energy output of the battery), 5%-8% disulfide bond-containing polysulfide rubber (giving the slurry self-repairing function. When microcracks are generated in the electrode frame 2, the disulfide bonds can be triggered by heat or stress to reorganize, maintain the structural stability of the electrode frame 2, and extend the battery cycle life), 3%-5% conductive carbon black (constructing an efficient electron transmission network, reducing the resistance of the electrode frame 2, and improving the charging and discharging efficiency), and 7%-10% binder PVDF (enhancing the bonding force between the components so that the electrode frame 2 maintains structural integrity during the charging and discharging process) mixed in N-methylpyrrolidone to make a slurry with a solid content of 40%-50%, ensuring good processing performance and coating effect. The various components complement each other, significantly optimize the comprehensive performance of the electrode frame 2, and achieve synergistic performance improvement.

[0030] Furthermore, the electrode frame 2 utilizes 3D printing technology to print the self-repairing electrode slurry into a frame with a preset electrode hole 3 structure. The three-dimensional structure of the electrode frame 2 can be accurately designed and formed according to the battery performance requirements, and the size, shape and distribution of the electrode holes 3 can be accurately controlled. By constructing an optimal pore network, the lithium ion diffusion path is shortened, and the battery charging and discharging efficiency and energy density are significantly improved. At the same time, the layer-by-layer stacking molding method of 3D printing makes the self-repairing electrode slurry evenly distributed, ensuring the uniform performance of each part of the electrode frame 2 and giving full play to the characteristics of the self-repairing material.

[0031] Furthermore, the preparation of the bionic electrolyte is to add lithium hexafluorophosphate into the solvent base and stir and dissolve it, and then add crown ether biomimetic additives and vinylene carbonate with the function of selectively complexing lithium ions, and obtain it by fully stirring, mixing and filtering to remove impurities. The solvent base is composed of vinylene carbonate, dimethyl carbonate, etc., which provides a good dissolution environment for lithium hexafluorophosphate and ensures the stable dissociation and transmission of lithium ions; the added crown ether biomimetic additive can optimize the ion transmission path, reduce the migration resistance, and greatly improve the ion conduction efficiency by virtue of the function of selectively complexing lithium ions, while effectively inhibiting the self-discharge phenomenon and reducing the power loss of the battery during storage; vinylene carbonate, as a film-forming additive, can form a stable solid electrolyte interface film (SEI film) on the surface of the electrode frame 2, protect the electrode material, enhance the compatibility of the electrode frame 2 with the electrolyte, and inhibit the occurrence of side reactions; the sufficient stirring, mixing and filtering to remove impurities process ensures the uniformity and purity of the electrolyte, and the synergistic effect of each component can significantly improve the battery charging and discharging efficiency, cycle stability and service life.

[0032] Furthermore, the solvent base mainly includes 20%-30% of ethylene carbonate, 40%-50% of dimethyl carbonate, 15%-25% of ethyl methyl carbonate, 1.0-1.2 mol / L of lithium hexafluorophosphate, 0.5%-2% of crown ether biomimetic additives, and 1%-3% of vinylene carbonate, which significantly improves the battery's charge and discharge efficiency, cycle life, and energy retention capacity, and synergistically optimizes battery performance.

[0033] A method for preparing a high energy density lithium-ion battery comprises the following steps:

[0034] S1. Preparation of self-repairing electrode slurry: First, 80%-85% of high nickel ternary material NCM (nickel, cobalt, manganese molar ratio of 8:1:1, particle size distribution D50 controlled at 5-8μm) is selected as the main active material. This material has a high specific capacity and can provide sufficient energy storage and release capacity for the battery. Then, 5%-8% of disulfide bond-containing polysulfide rubber (molecular weight of about 5000g / mol) is evenly dispersed in a reactor of N-methylpyrrolidone (NMP) solvent. To ensure uniform dispersion of the polysulfide rubber, a high-speed stirrer is used at 8 00r / min speed stirring for 30 minutes, and then combined with ultrasonic dispersion technology (ultrasonic frequency 40kHz, power 200W) for 20 minutes to fully dissolve the disulfide bond polymer. In this process, the disulfide bonds in the polysulfide rubber can be reversibly broken and reorganized by heat or stress triggering when the electrode frame 2 causes volume changes due to charge and discharge cycles or produces microcracks under mechanical stress when the battery is used in the future, thereby realizing the self-repair of the electrode frame 2 structure. Subsequently, 3%-5% conductive carbon black (model SuperP, specific surface area 130-150m 2 / g) enhances electronic conduction, and its nano-scale particles can build a continuous electronic conductive network in the electrode material, reduce the internal resistance of the electrode frame 2, and improve the charge and discharge efficiency of the battery. Then, 7%-10% of the binder PVDF (polyvinylidene fluoride, model Flex2851) improves the film-forming properties of the slurry. By adjusting the amount of N-methylpyrrolidone, the slurry solid content is controlled at 40%-50%. This solid content not only ensures good fluidity of the slurry, facilitating the subsequent coating process, but also ensures that the film layer of the electrode frame 2 has an appropriate thickness and density after drying;

[0035] S2. Prepare biomimetic electrolyte: 20%-30% ethylene carbonate (EC, purity ≥99.9%), 40%-50% dimethyl carbonate (DMC, purity ≥99.8%), and 15%-25% ethyl methyl carbonate (EMC, purity ≥99.7%) are mixed to form a solvent system. This solvent combination utilizes the high dielectric constant of ethylene carbonate that is conducive to the dissociation of lithium salts, combines the advantages of low viscosity and high flash point of dimethyl carbonate and ethyl methyl carbonate, and balances the ionic conductivity and safety of the electrolyte. At room temperature (25±2°C), 1.0-1.2 mol / L lithium hexafluorophosphate (LiPF6, moisture content <10ppm) is slowly added to the solvent system and stirred at a speed of 200r / min for 4 hours until completely dissolved, ensuring that the lithium salts are fully dissociated into lithium ions and PF6- ions, which is a good starting point for the battery electrochemical reaction. A stable ion source should be provided, and then 0.5%-2% of a crown ether biomimetic additive with a specific pore size (pore size adapted to the lithium ion radius) is added. Its molecules can selectively complex lithium ions and optimize the ion transmission path. Then 1%-3% of vinylene carbonate (VC, purity ≥99.5%) is added as a film-forming additive. During the first charge and discharge process of the battery, vinylene carbonate undergoes a reduction reaction on the surface of the electrode frame 2 before other solvents, forming a stable solid electrolyte interface film (SEI film) with a thickness of about 5-10nm. This film layer has good ion conductivity and electronic insulation, which can effectively prevent the continuous side reaction between the electrolyte and the electrode material, and improve the battery cycle stability. Finally, the electrolyte is obtained after filtration through a 0.22μm microporous filter membrane to ensure the purity of the electrolyte. The self-discharge rate of the electrolyte is reduced by more than 40% compared with traditional electrolytes.

[0036] S3, 3D printing electrode frame: The self-repairing electrode slurry prepared in S1 (temperature controlled at 25°C, viscosity adjusted to 10,000-12,000 mPa·s) is injected into an extrusion 3D printer and printed with a single layer thickness of 0.1-0.3 mm through layer-by-layer stacking molding technology. During the printing process, the nozzle movement speed is controlled at 30 mm / s and the extrusion pressure is set to 0.3 MPa to ensure uniform extrusion of the slurry and tight bonding between layers, ultimately forming an electrode frame 2 with a preset porous structure. This can achieve precise control of the microstructure of the electrode frame 2, shorten the lithium ion diffusion path by more than 30%, and enhance the contact area between the electrode frame 2 and the electrolyte, thereby improving the charge and discharge efficiency of the battery;

[0037] S4, low temperature plasma treatment: the 3D printed electrode frame 2 is placed in a vacuum of 10 -3 -10 -4Pa plasma processing chamber, into which argon gas with a purity of ≥99.99% is introduced as the working gas, and the gas flow rate is controlled at 10-50sccm. The argon gas is evenly diffused through the porous gas distribution plate at the top of the chamber to form a stable airflow. The radio frequency power supply is turned on, and the output power is set to 100W. The low-temperature plasma is excited at a frequency of 13.56MHz. At this time, the argon gas in the chamber is ionized under the action of the high-frequency electric field to form a plasma cloud containing argon ions, electrons and excited argon atoms. The surface of the electrode frame 2 is treated in the plasma for 5-15 minutes. During this period, the high-energy argon ions and electrons are ionized at a rate of about 10 5 -10 6 m / s bombards the surface of the electrode frame 2. On the one hand, it removes impurities, organic residues and oxide layers adsorbed on the surface through physical sputtering. On the other hand, it promotes the reaction between the surface atoms of the electrode frame 2 and the trace oxygen in the chamber to form a dense oxide protective film of 5-20nm. After the treatment is completed, high-purity nitrogen is filled into the chamber at a rate of 5sccm through the slow-speed filling system of the chamber to reduce the pressure, thereby avoiding damage to the structure of the electrode frame 2 caused by sudden changes in gas pressure, significantly reducing the interface impedance, improving the compatibility of the electrode frame 2 and the electrolyte, effectively inhibiting the occurrence of interface side reactions, and providing a guarantee for the long-term stable operation of the battery.

[0038] S5. Battery assembly: First, the electrode frame 2 treated with low-temperature plasma is carefully placed inside the cleaned battery casing 1 using a vacuum adsorption device to ensure that the electrode frame 2 maintains a uniform distance from the inner wall of the battery casing 1 to avoid the risk of short circuit, and bionic electrolyte is injected to control the injection amount error to ≤±1%. The injection process is carried out in a vacuum environment and the vacuum degree is maintained at -0.095MPa to eliminate bubbles in the electrolyte and improve the infiltration effect inside the battery. After the injection is completed, the battery is left to stand for 2 hours to allow the electrolyte to fully infiltrate the electrode frame 2. Finally, a pulsed fiber laser with a wavelength of 1064nm is selected, the laser power is set to 80W, the pulse width is 2ms, and the frequency is 20Hz. Circular welding is performed at the connection between the battery casing 1 and the cover plate to ensure the sealing of the battery casing 1 to prevent electrolyte leakage and external gas from entering.

[0039] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0040] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high energy density lithium ion battery, comprising a battery housing (1), characterized in that: An electrode frame (2) is provided inside the battery housing (1), a plurality of electrode holes (3) are provided through the outer surface of the electrode frame (2), a positive terminal (4) is provided on the left side of the battery housing (1), and a negative terminal is provided on the right side of the battery housing (1), the electrode frame (2) is made of self-repairing electrode slurry, and the battery housing (1) is filled with a bionic electrolyte.

2. A high energy density lithium ion battery according to claim 1, characterized in that: The self-repairing electrode slurry is prepared by selecting polysulfide rubber containing disulfide bonds as the self-repairing polymer, dissolving it in N-methylpyrrolidone to form a uniform solution, adding the ternary material NCM, and stirring and ultrasonically treating it to prepare an electrode slurry with self-repairing function.

3. A high energy density lithium ion battery according to claim 2, characterized in that: The self-repairing electrode slurry mainly comprises 80%-85% of the ternary material NCM, 5%-8% of disulfide bond-containing polysulfide rubber, 3%-5% of conductive carbon black, and 7%-10% of the binder PVDF, which are mixed in N-methylpyrrolidone to form a slurry with a solid content of 40%-50%.

4. A high energy density lithium ion battery according to claim 1, characterized in that: The electrode frame (2) is a frame having a preset electrode hole (3) structure, which is formed by printing the self-repairing electrode slurry using 3D printing technology.

5. A high energy density lithium ion battery according to claim 1, characterized in that: The bionic electrolyte is prepared by adding lithium hexafluorophosphate into a solvent base, stirring and dissolving the mixture, then adding a crown ether bionic additive with a selective lithium ion complexing function and vinylene carbonate, stirring and mixing the mixture thoroughly, and filtering to remove impurities.

6. A high energy density lithium ion battery according to claim 5, characterized in that: The solvent base mainly includes 20%-30% of ethylene carbonate, 40%-50% of dimethyl carbonate, and 15%-25% of ethyl methyl carbonate. The lithium hexafluorophosphate is 1.0-1.2 mol / L, the content of the crown ether biomimetic additive is 0.5%-2%, and the content of the vinylene carbonate is 1%-3%.

7. A method for preparing a high energy density lithium-ion battery, characterized in that: The following steps are included: S1. Preparation of self-repairing electrode slurry: 80%-85% high nickel ternary material NCM is selected as the main active material, 5%-8% disulfide bond-containing polysulfide rubber is uniformly dispersed in N-methylpyrrolidone solvent, and high-speed stirring and ultrasonic dispersion technology are used to fully dissolve the disulfide bond polymer. Subsequently, 3%-5% conductive carbon black is added to enhance electronic conduction, and 7%-10% binder PVDF is added to improve the film-forming property of the slurry. By adjusting the amount of N-methylpyrrolidone, the solid content of the slurry is controlled at 40%-50%. When microcracks occur in the electrode, the disulfide bonds can be triggered by heat or stress to reversibly break and reorganize, thereby achieving structural self-repair. S2. Preparation of a biomimetic electrolyte: 20%-30% ethylene carbonate, 40%-50% dimethyl carbonate, and 15%-25% ethyl methyl carbonate are mixed to form a solvent system, 1.0-1.2 mol / L lithium hexafluorophosphate is slowly added at room temperature and stirred until completely dissolved, 0.5%-2% of a crown ether biomimetic additive with a specific pore size is added, whose molecules can selectively complex lithium ions and optimize the ion transport path, and 1%-3% of vinylene carbonate is added as a film-forming additive. After filtering through a 0.22 μm microporous membrane, an electrolyte is obtained. The self-discharge rate of the electrolyte is reduced by more than 40% compared with the traditional electrolyte; S3, 3D printing electrode frame: injecting the self-repairing electrode slurry prepared in S1 into an extrusion 3D printer, and printing with a single layer thickness of 0.1-0.3 mm through layer-by-layer stacking molding technology to form an electrode frame (2) with a preset porous structure, which can achieve precise control of the electrode microstructure and shorten the lithium ion diffusion path by more than 30%; S4, low temperature plasma treatment: the 3D printed electrode frame (2) is placed in a vacuum of 10 -3 -10 -4 Pa plasma processing chamber, introduces argon gas with a purity of ≥99.99% as working gas, controls the gas flow rate at 10-50 sccm, turns on the radio frequency power supply, excites and generates low-temperature plasma at a frequency of 13.56 MHz, and treats the electrode surface in the plasma for 5-15 minutes. High-energy particle bombardment forms a dense oxide protective film of 5-20 nm on the surface of the electrode frame (2), significantly reduces the interface impedance, and improves the compatibility of the electrode with the electrolyte; S5. Battery assembly: placing the processed electrode frame (2) inside the battery housing (1), injecting bionic electrolyte, controlling the injection amount error to be ≤±1%, and completing the battery sealing by laser welding.

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