Free radical polymer lithium supplement agent and preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a free radical polymer lithium supplement agent and a preparation method and application thereof. The invention provides the free radical polymer lithium supplement agent, the lithium element in the lithium supplement agent is high in stability and controllable in content, and the free radical polymer lithium supplement agent can be used as a novel lithium supplement agent with active lithium supply capability and interface regulation and control function; active lithium consumed in the processes of solid electrolyte interface film formation and the like in the first cycle can be supplemented, and the first-circle discharge capacity of the battery is greatly improved; meanwhile, the long-term cycle performance can be effectively improved in a commercial total battery system, the capacity fading trend is relieved, and the service life of the battery is prolonged. The preparation process of the polymer lithium supplement agent is simple and convenient, the obtained material structure eliminates the possibility of coating layer stripping in the prior art, and the research and development and application of the polymer lithium supplement agent have important practical significance and industrialization value for promoting the high reliability of the lithium ion battery industry.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a free radical polymer lithium supplement agent, its preparation method and application. Background Technology

[0002] In recent years, lithium-ion battery technology has made continuous breakthroughs driven by new energy vehicles, energy storage systems, and other fields, with significant improvements in electrode specific capacity, cycle stability, and rate performance, laying the foundation for the development of high-energy-density devices. However, the two major problems of irreversible capacity loss during the first charge and volume expansion caused by gas generation during charge and discharge are intertwined, becoming key obstacles to the large-scale application of high-energy materials such as silicon-based anodes and high-nickel ternary cathodes. Specifically, during the first charge, the formation of a solid electrolyte interphase (SEI) film on the anode, irreversible phase transitions of the electrode, and interfacial side reactions consume a large amount of active lithium, leading to a significant decline in the actual battery capacity and first coulombic efficiency (ICE). At the same time, these reactions and side reactions during the pre-lithiation and lithium replenishment process produce gases such as H2 and CO2, which accumulate in the sealed battery and cause volume expansion, damaging the electrode structure, accelerating performance degradation, and posing safety hazards, creating a vicious cycle.

[0003] To address the aforementioned technical challenges, pre-lithiation technology has emerged as a key strategy for mitigating initial irreversible capacity loss due to its core logic of "actively replenishing active lithium." This technology precisely compensates for initial lithium loss by introducing an additional active lithium source into the electrode material or electrolyte system during battery manufacturing, effectively improving the battery's initial coulombic efficiency and energy density, and providing crucial support for the application of high-energy electrode materials. Among various pre-lithiation schemes, organic lithium replenishing agents have attracted significant attention due to their advantages of "designable molecular structure and high active lithium release efficiency," becoming an important research direction in pre-lithiation technology. Against this backdrop, a Chinese patent application proposes a core-shell structured positive electrode lithium replenisher. This lithium replenisher, through a composite structure design of "positive electrode lithium replenishment material core + hydrophobic encapsulation layer + polymer coating layer," aims to reduce gas generation and battery volume expansion during the charging and discharging process of lithium-ion batteries, while ensuring lithium replenishment effect and electrochemical performance stability. It provides a new path to solve the problem of "difficulty in simultaneously achieving lithium replenishment and gas generation suppression" in traditional lithium replenishers. However, it still has significant room for optimization: First, the multi-layer core-shell structure leads to a complex preparation process, and the shell-layer interface bonding depends on physical action, which can easily lead to shell-layer separation during long-term cycling, resulting in the failure of lithium replenishment effect and increased loss of active lithium; Second, the actual release efficiency of active lithium and the accuracy of lithium replenishment are unclear, limiting the practical application scenarios of this technology.

[0004] Therefore, there is an urgent need to develop a cathode lithium replenishing agent that is easy to prepare and can simultaneously achieve excellent lithium replenishment effect and stable electrochemical performance, so as to meet the needs of large-scale application of high-energy electrode materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of existing positive electrode lithium replenishment agents that cannot simultaneously achieve simple preparation process, excellent lithium replenishment effect and electrochemical performance, and to provide a class of free radical polymer lithium replenishment agents.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned free radical polymer lithium supplement.

[0007] Another object of the present invention is to provide the application of the above-mentioned free radical polymer lithium supplement in the preparation of positive electrode lithium supplement.

[0008] Another object of the present invention is to provide a positive electrode lithium replenishing agent.

[0009] Another object of the present invention is to provide a full battery.

[0010] The above-mentioned objective of this invention is achieved through the following technical solution: This invention protects a class of free radical polymer lithium supplements, the structural formula of which is shown below: ; Wherein, R is C 1~6 Alkane or hydrogen; n = 500~2000.

[0011] This invention provides a class of free radical polymer lithium replenishers. These replenishers exhibit high lithium stability and controllable lithium content, making them novel lithium replenishers that combine active lithium supply capacity with interface regulation functions. Introducing them into lithium-ion battery systems can replenish active lithium lost during the first cycle due to processes such as the formation of a solid electrolyte interfacial film, significantly increasing the battery's first-cycle discharge capacity. Simultaneously, they can effectively improve long-term cycle performance in commercial full-cell systems, mitigating capacity decay and extending battery life. The research and application of this type of polymer lithium replenisher has significant practical and industrial value for promoting high reliability in the lithium-ion battery industry.

[0012] Furthermore, the structural formula of the free radical polymer lithium supplement is shown below: ; Wherein, R is C 1~3 Alkane or hydrogen; n = 500~2000.

[0013] Furthermore, the free radical polymer lithium supplement has any of the following structural formulas: , ; Wherein, n = 500~2000.

[0014] This invention protects a method for preparing the above-mentioned free radical polymer lithium supplement, comprising the following steps: Free radical polymers can be used to prepare free radical polymer lithium supplements through chemical synthesis or electrochemical synthesis. The preparation method of the chemical synthesis includes the following steps: A free radical polymer and a reducing agent undergo a reduction reaction to form a free radical polymer intermediate. The obtained free radical polymer precursor is then reacted with lithium hydroxide to obtain the free radical polymer lithium supplement. The reaction pathway for chemical synthesis is shown below: ; The definition of R remains consistent with the above, and n = 500~2000; The preparation method of the electrochemical synthesis includes the following steps: In a protective gas environment, a free radical polymer composite electrode and a lithium metal sheet are assembled into a half cell. The voltage of the half cell is adjusted to 1.5~2.5 V, and the free radical polymer undergoes a reduction reaction to generate a free radical polymer lithium supplement. The free radical polymer composite electrode comprises a free radical polymer and a self-supporting conductive substrate.

[0015] In this invention, the core of preparing the free radical polymer lithium supplement lies in using chemical or electrochemical methods to drive the free radical polymer to react with Li. + A directional redox reaction occurs to achieve chemical bonding; while simply combining free radical polymers with Li... + In physical blending, the redox reaction cannot occur due to a lack of energy or suitable media conditions, thus failing to obtain the lithium replenishing agent described in this invention. Compared to physically blended systems, the lithium replenishing agent prepared in this application possesses Li... + Combining the core advantages of stability, excellent interfacial compatibility, and superior safety, this method can significantly improve battery cycle life and performance consistency. The free radical polymer lithium supplement in this application relies on chemical bonding to solve the problem of Li in the physical mixing system. + Addressing the pain points of easy aggregation, low utilization rate, and high interface impedance, this technology achieves a dual improvement in battery lithium replenishment effect and safety performance.

[0016] Furthermore, the weight-average molecular weight (Mw) of the free radical polymer is 300,000 to 500,000.

[0017] Furthermore, the weight-average molecular weight of the free radical polymer is 360,000 to 450,000.

[0018] In this invention, the weight-average molecular weight of the free radical polymer was determined by gel permeation chromatography, and the test solvent was tetrahydrofuran.

[0019] Furthermore, the polydispersity index (PDI) of the free radical polymer is 2 to 3.

[0020] Furthermore, the polydispersity index (PDI) of the free radical polymer is 2.4 to 2.7.

[0021] Furthermore, the free radical polymer can be obtained commercially or in-house.

[0022] Furthermore, as a preferred embodiment, the method for preparing the free radical polymer includes the following steps: S1. Under a protective gas atmosphere, free radical polymer monomers, initiators, and organic solvents are mixed and subjected to free radical polymerization reaction, followed by post-treatment to obtain intermediates; S2. Mix the intermediate obtained in step S1 with the oxidant, carry out an oxidation reaction, and then perform post-treatment to obtain the free radical polymer; The structural formula of the free radical polymer monomer is shown below: ; The definition of R is consistent with that described above.

[0023] Furthermore, the free radical polymer monomer can be obtained commercially or in-house.

[0024] Furthermore, as a preferred method, the preparation of the free radical polymer monomer includes the following steps: Under a protective gas atmosphere, tetramethylpiperidinol, the precursor, and the catalyst were mixed in an organic solvent, reacted thoroughly, and then post-treated to obtain a free radical polymer monomer. The structural formula of the precursor is shown below: ; The definition of R is consistent with that described above.

[0025] Furthermore, the protective gas includes one or more of nitrogen, argon, and helium.

[0026] Furthermore, the molar ratio of the tetramethylpiperidinol to the precursor is 1:(3~6).

[0027] Furthermore, the catalyst includes one or more of tetrabutyl titanate, dibutyltin dilaurate, and p-toluenesulfonic acid.

[0028] Furthermore, the catalyst is tetrabutyl titanate.

[0029] Furthermore, the molar ratio of the tetramethylpiperidinol to the catalyst is 1:(0.005~0.1).

[0030] Preferably, the catalyst is added in batches. Adding the catalyst in batches allows for more precise control of the reaction rhythm through real-time monitoring of the reaction process, which is more conducive to ensuring the reaction proceeds fully and improving reaction efficiency and the yield of the target product.

[0031] Furthermore, the organic solvent includes one or more of toluene, o-xylene, and ethylbenzene.

[0032] Furthermore, the organic solvent is toluene.

[0033] Furthermore, the mass-to-volume ratio of the tetramethylpiperidinol to the organic solvent is 1 g: (10~30) mL.

[0034] Furthermore, the temperature for the complete reaction is 100~150 °C.

[0035] Furthermore, the time for the full reaction is 1 to 5 hours.

[0036] Furthermore, the post-processing includes cooling, extraction, filtration, rotary evaporation, and drying.

[0037] Furthermore, the solvent for extraction is a 1wt% to 10wt% sodium bicarbonate solution.

[0038] Furthermore, the initiator includes one or more of azobisisobutyronitrile, dimethyl azobisisobutyrate, and tert-butyl peroxide.

[0039] Further, in step S1, the organic solvent includes one or more of methanol, ethanol, and propanol.

[0040] Preferably, the mass ratio of the initiator to the free radical polymer monomer is 1:(200~400).

[0041] Preferably, the mass-to-volume ratio of the free radical polymer monomer to the organic solvent is 1 g: (40~60) mL.

[0042] Furthermore, the temperature of the free radical polymerization reaction is 50~80 °C.

[0043] Furthermore, the free radical polymerization reaction takes 8 to 24 hours.

[0044] Further, in step S1, the post-processing includes collecting the precipitate, drying, extraction, solvent removal, and drying.

[0045] Furthermore, the collection of precipitate includes adding water to the reaction solution to cause the precipitate to fall out, and then collecting the solid precipitate by centrifugation.

[0046] Preferably, the volume ratio of the reaction solution to water is (5~8):1.

[0047] Preferably, the centrifugation speed is 8000~10000 r / min.

[0048] More preferably, the centrifugation time is 15-30 min.

[0049] Furthermore, the drying process is vacuum drying.

[0050] Preferably, the vacuum drying temperature is 50~60 ℃.

[0051] Preferably, the vacuum degree of the vacuum drying is 0.08~0.1 MPa.

[0052] Preferably, the vacuum drying time is 4 to 6 hours.

[0053] Furthermore, the extraction reagents are ethyl acetate and n-hexane.

[0054] Preferably, the volume ratio of ethyl acetate to n-hexane is 1:(15~20).

[0055] Furthermore, in step S1, to obtain an intermediate with higher purity, the post-processing operation can be repeated.

[0056] Furthermore, as a preferred embodiment, the intermediate is soluble in an organic solvent and formulated into a solution.

[0057] Furthermore, the organic solvent includes one or more of dichloromethane, chloroform, N-methylpyrrolidone, and acetone.

[0058] Furthermore, the mass concentration of the intermediate solution is 5% to 10%.

[0059] Furthermore, the oxidant includes one or more of hydrogen peroxide, 3-chloroperoxybenzoic acid, and sodium hypochlorite.

[0060] Furthermore, the oxidant is hydrogen peroxide.

[0061] Preferably, the concentration of hydrogen peroxide is 20wt% to 50wt%.

[0062] Furthermore, the mass-to-volume ratio of the intermediate to the oxidant is 1 g: (15~30) mL.

[0063] Preferably, the oxidant is added in batches. Adding it in batches is more conducive to the complete oxidation of the intermediate.

[0064] Furthermore, the oxidation reaction is carried out at a temperature of 60-70 °C.

[0065] Furthermore, the oxidation reaction takes 24 to 30 hours.

[0066] Furthermore, in step S2, the post-processing includes cooling, filtration, washing, and drying.

[0067] Furthermore, the cooling refers to cooling the reaction solution to room temperature.

[0068] Furthermore, the filtration process involves passing the reaction solution through a filter membrane and collecting the filter cake.

[0069] Preferably, the pore size of the filter membrane is 0.2~0.4 μm.

[0070] Furthermore, the washing process involves washing the filter cake with water.

[0071] Preferably, the mass ratio of the filter cake to water is 1:(5~10).

[0072] Furthermore, the drying process is vacuum drying.

[0073] Preferably, the vacuum drying temperature is 80~90 ℃.

[0074] Preferably, the vacuum degree of the vacuum drying is 0.09~0.1 MPa.

[0075] Preferably, the vacuum drying time is 24-36 hours.

[0076] Furthermore, the reducing agent includes one or more of ascorbic acid, sulfurous acid, and lithium naphthalene.

[0077] Furthermore, the mass ratio of the free radical polymer to the reducing agent is 1:(4~5).

[0078] Furthermore, the temperature of the reduction reaction is 20~30 °C.

[0079] Furthermore, the reduction reaction takes 24 to 30 hours.

[0080] Furthermore, the mass ratio of the free radical polymer to lithium hydroxide is 1:(2~3).

[0081] Furthermore, the reaction temperature is 20~30 °C.

[0082] Furthermore, the reaction time is 24-30 h.

[0083] Furthermore, the protective gas includes one or more of nitrogen, argon, and helium.

[0084] Furthermore, the working principle of adjusting the half-cell voltage to 1.5~2.5V is as follows:

[0085] When the half-cell voltage is in the range of 1.5~2.5 V, the nitroxide free radical (free radical polymer) in the middle undergoes a reduction reaction, gaining an electron, causing the nitroxide group to move from the electrically neutral "NO" group. "becomes a negatively charged "NO" - "; In order to maintain charge balance, Li in the system + It will be embedded into the material structure simultaneously, thereby completing the lithium-ion storage during the discharge process, that is, generating a free radical polymerized lithium replenishing agent to complete the lithium replenishment process; When the half-cell voltage is in the 3~4V range, it will drive the negatively charged structure (NO) with compensated Li. - Li + The "NO" undergoes an oxidation reaction, losing an electron, causing the negatively charged structure to change from "NO". - "Revert to electrically neutral" NO "Li", originally used to balance negative charges + "It will be extracted from the structure and return to the electrolyte, which is the delithiation process."

[0086] Furthermore, the self-supporting conductive substrate includes one or more of single-walled carbon nanotubes, carbon black, and graphene.

[0087] Furthermore, the self-supporting conductive base is a single-walled carbon nanotube.

[0088] This invention protects the application of the above-mentioned free radical polymer lithium supplement in the preparation of positive electrode lithium supplement.

[0089] This invention protects a positive electrode lithium replenishing agent, which includes the aforementioned free radical polymer lithium replenishing agent.

[0090] This invention protects a full battery, the full battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator; the positive electrode comprises a composite electrode; the negative electrode is a graphite electrode; The composite electrode includes an active material and a self-supporting conductive substrate. The active material is the aforementioned positive electrode lithium replenishing agent, and the self-supporting conductive substrate is a single-walled carbon nanotube. The graphite in the graphite electrode must meet the following conditions: (1) D 50 The diameter is 8~10 μm; (2) Specific surface area ≤ 1.5 m² 2 / g.

[0091] Furthermore, the graphite in the graphite electrode must meet the following conditions: (1) D 50 The diameter is 9~9.5 μm; (2) Specific surface area is 1.25~1.45 m² 2 / g.

[0092] In this invention, D 50 The diameter was measured using a laser particle size analyzer.

[0093] In this invention, the specific surface area is measured by nitrogen adsorption method.

[0094] Furthermore, the graphite in the graphite electrode must also meet one or two of the following conditions: (1) The content of magnetic materials is 0~0.1 ppm, based on the total amount of iron, chromium, nickel and zinc elements; (2) Tap density ≥ 1 g / cm³ 3 .

[0095] Furthermore, the graphite in the graphite electrode must also meet one or two of the following conditions: (1) The content of magnetic materials is 0.05~0.07 ppm based on the total amount of iron, chromium, nickel and zinc elements; (2) Tap density is 1.05~1.2 g / cm³ 3 .

[0096] In this invention, the magnetic materials are tested using ICP-MS.

[0097] In this invention, the tap density was measured in accordance with GB / T 5162-2018.

[0098] Furthermore, the graphite electrode comprises graphite, a conductive agent, and a binder.

[0099] Furthermore, the conductive agent includes one or more of carbon black, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0100] Preferably, the conductive agent is carbon black.

[0101] Furthermore, the adhesive includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, and perfluoroethylene propylene.

[0102] Preferably, the adhesive is polyvinylidene fluoride.

[0103] Furthermore, the electrolyte comprises an electrolyte and an organic solvent.

[0104] Furthermore, the electrolyte comprises LiPF6 and / or LiTFSI.

[0105] Furthermore, the organic solvent includes one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC).

[0106] Preferably, the concentration of the electrolyte is 0.5~1.5 mol / L.

[0107] More preferably, the concentration of the electrolyte is 1 mol / L.

[0108] Furthermore, the diaphragm is a polypropylene diaphragm.

[0109] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a type of free radical polymer lithium replenisher. This type of lithium replenisher exhibits high lithium stability and controllable lithium content, serving as a novel lithium replenisher that combines active lithium supply capability with interface regulation function. Introducing it into lithium-ion battery systems can replenish the active lithium lost during the first cycle due to processes such as the formation of the solid electrolyte interface film, significantly increasing the battery's first-cycle discharge capacity. Simultaneously, it can effectively improve long-term cycle performance in commercial full-cell systems, mitigating capacity decay and extending battery life. The preparation process of this polymer lithium replenisher is simple, and the resulting material structure eliminates the possibility of coating layer peeling in existing technologies. Its research and application have significant practical and industrial value in promoting the high reliability and long lifespan upgrade of the lithium-ion battery industry. Attached Figure Description

[0110] Figure 1 This is a graph showing the weight-average molecular weight of the free radical polymer PTMA in Example 1.

[0111] Figure 2 This is a graph showing the weight-average molecular weight of the free radical polymer PTPA in Example 5.

[0112] Figure 3 This is a graph showing the capacity change of the graphite full cell before and after lithium replenishment in Example 1.

[0113] Figure 4 This is a graph showing the capacity change of the graphite full cell before and after lithium replenishment in Example 5. Detailed Implementation

[0114] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0115] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0116] Single-walled carbon nanotube 1#: SWCNT-XFS22, 101372, produced by Xianfeng Nano; Single-walled carbon nanotubes #2: SWCNT-TUBALL, BK-TUBALL BATT H2O, produced by Shanghai Haiyi Science & Trade Co., Ltd. Fast-charging graphite b: MA-EN-AN-0013, content of magnetic materials (based on total iron, chromium, nickel and zinc elements) = 0.06ppm, D 50 Diameter = 9.26 μm, specific surface area BET = 1.38 m² 2 / g, tap density TD=1.12 g / cm³ 3 Produced by Kelode; Fast-charging graphite: MA-EN-AN-0012, Magnetic material content (based on total iron, chromium, nickel, and zinc elements) = 0.26ppm, D 50 Diameter = 13.26 μm, specific surface area BET = 1.62 m² 2 / g, tap density TD=0.89 g / cm³ 3 Produced by Kelode; Ratio-enhancing graphite: MA-EN-AN-0016, non-magnetic material, D 50 Diameter = 20.42 μm, specific surface area BET = 0.72 m² 2 / g, tap density TD=0.79 g / cm³ 3 Produced by Kelode; MS-QCG-X type artificial graphite: 02511222, non-magnetic material, D 50 Diameter = 13.4 μm, specific surface area BET = 1.52 m² 2 / g, tap density TD=1.10 g / cm³ 3 It is produced by Kejing.

[0117] Electrolyte: LB-002, composition: 1 mol / L LiPF6 dissolved in a mixed solvent of dimethyl carbonate, ethyl methyl carbonate and ethylene carbonate in a volume ratio of 1:1:1, produced by Zhengzhou Aikem Chemical Co., Ltd.

[0118] Separator: Polypropylene separator, KELOD 2500 separator, manufactured by KELOD.

[0119] Example 1: Preparation of a free radical polymer lithium supplement, electrode, and full cell 1. Preparation of the free radical polymer PTMA: S1. In a 500 mL three-necked flask, add tetramethylpiperidinol (18 g, 114.5 mmol), methyl methacrylate (42 mL, 465.9 mmol), and 300 mL of toluene. After stirring until homogeneous, add tetrabutyl titanate (0.36 mL, 1.05 mmol). Reflux at 110 °C for 2 h. Then, add 0.36 mL of tetrabutyl titanate to the reaction solution and continue refluxing for 20 h under nitrogen protection. After cooling to room temperature, use 100 mL of 5wt% [a specific reagent / component]. The reaction solution was extracted and washed with NaHCO3 solution in a separatory funnel to completely hydrolyze unreacted tetrabutyl titanate into titanium dioxide. After removing the titanium dioxide by filtration, the solution was placed in a separatory funnel to separate the organic layer. Most of the toluene was removed by rotary evaporation. The concentrated solution was placed in a watch glass and the residual toluene was evaporated in a fume hood. The product was fully crystallized into a white solid 2,2,6,6-tetramethyl-4-piperidinyl methacrylate (TMPM), which is a free radical polymer monomer. S2. In a three-necked flask, 5 g of 2,2,6,6-tetramethyl-4-piperidinol methacrylate (TMPM) obtained in step S1, 17.8 mg of azobisisobutyronitrile (AIBN), and 250 mL of methanol were mixed. After assembling a reflux apparatus, nitrogen gas was introduced for deoxygenation for 30 min. Subsequently, the mixture was placed in a 65 ℃ oil bath and stirred for 10 h to induce free radical polymerization. Then, deionized water was added at a volume ratio of 4:1 to precipitate the intermediate PTMPM in the reaction solution. The crude product was collected by centrifugation at 9000 r / min for 20 min and dried at 55 ℃ under vacuum of 0.09 MPa for 5 h. The dried crude product was dissolved in 25 mL of ethyl acetate, and 400 mL of n-hexane was added to reverse the precipitation. After stirring for 45 min, the upper solvent layer was discarded. This operation was repeated 2-3 times for purification, and the product was then dried under vacuum under the above conditions to obtain the purified intermediate PTMPM. S3. Dissolve 1 g of purified PTMPM obtained in step S2 in dichloromethane to prepare a 5 wt% solution. Add 10 mL of 30 wt% hydrogen peroxide and stir at 65 °C for 24 h to complete the first oxidation. Then add an equal amount of 30 wt% H2O2 and continue the reaction at 65 °C for 24 h for a second oxidation to ensure that the piperidine ring is completely converted into a nitroxide free radical structure. After the system is cooled to room temperature, filter the filter cake through a 0.22 μm organic filter membrane. Wash the filter cake three times with deionized water (each time the amount of water used is 6 times the mass of the filter cake). Dry the filter cake at 80 °C and 0.1 MPa vacuum for 24 h to obtain the free radical polymer PTMA. The weight-average molecular weight (Mw) was determined by gel permeation chromatography (using tetrahydrofuran as solvent), and the result was 378217 (see [link to relevant documentation]). Figure 1 Polydispersity index (PDI) = weight-average molecular weight (Mw) / number-average molecular weight (Mn) = 2.67; The reaction pathways for steps S1 to S3 are shown below: .

[0120] 2. Electrode Preparation (1) Free radical polymer composite electrode PTMA (a free radical polymer) and SWCNT (a single-walled carbon nanotube) were weighed at a mass ratio of 1:2, serving as the active material and the self-supporting conductive substrate, respectively, with N,N-dimethylformamide (DMF) as the dispersion solvent. First, the weighed PTMA was added to DMF and stirred at a constant temperature of 80 °C until fully dissolved, forming a homogeneous PTMA solution. Then, SWCNT was added to the solution and ultrasonically dispersed at 60 W for 1 hour to ensure no agglomeration of the carbon nanotubes, ultimately forming a uniformly dispersed electrode slurry. This uniform slurry was poured into a mold of a predetermined size, and after casting, it was first dried in a 60 °C forced-air drying oven for 12 hours, then transferred to an 80 °C vacuum drying oven for another 12 hours. After drying and shaping, a self-supporting PTMA electrode, i.e., a PTMA / SWCNT composite electrode, was obtained. (2) Graphite electrode Weigh out fast-charging graphite b, conductive carbon black (SP), and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as a solvent, transfer the above components together into a ball mill jar and add steel balls. Mix by stirring until a uniform slurry is formed. Use a doctor blade coating method to uniformly coat the above slurry onto the surface of copper foil with a wet film thickness of 150 μm. After coating, first place it in a 60 ℃ forced-air drying oven for 12 h, and then transfer it to an 80 ℃ vacuum drying oven for 12 h. After drying, the doctor blade coated fast-charging graphite b electrode is obtained.

[0121] 3. Preparation of full cells In a glove box under nitrogen atmosphere, using LB-002 as the electrolyte and KELOD 2500 separator as the separator, a PTMA / SWCNT composite electrode (positive electrode) and a lithium metal sheet (negative electrode) were first assembled into a coin cell. The half-cell was then subjected to constant current discharge using a blue discharge testing system until the voltage dropped to 2 V. At this point, the nitrile radicals of PTMA undergo a reduction reaction, gaining an electron, causing the nitrile group to move from the electrically neutral "NO" group. "becomes a negatively charged "NO" -To maintain charge balance, lithium ions in the system are inserted into PTMA, generating in situ a free radical polymer lithium supplement PTMA-Li, thus obtaining the PTMA-Li / SWCNT composite electrode. Subsequently, the coin cell half-cell is disassembled in the same glove box, and the PTMA-Li / SWCNT composite electrode is taken out and used as the positive electrode, the fast-charging graphite electrode as the negative electrode, LB-002 as the electrolyte, and KELOD 2500 separator as the separator. The whole battery system is assembled according to the conventional assembly process of lithium-ion batteries.

[0122] Example 2: Preparation of a free radical polymer lithium supplement, electrode, and full cell The difference from Example 1 is that in the electrode preparation step (1), single-walled carbon nanotube 1# is replaced with single-walled carbon nanotube 2#.

[0123] The other steps and conditions are the same as in Example 1.

[0124] Example 3: Preparation of a free radical polymer lithium supplement, electrode, and full cell The difference from Example 1 is that in the battery preparation step (2), the thickness of the wet film is replaced from 150 μm to 130 μm.

[0125] The other steps and conditions are the same as in Example 1.

[0126] Example 4: Preparation of a free radical polymer lithium supplement, electrode, and full cell The difference from Example 1 is that PTMA-Li was prepared by chemical synthesis, the specific process of which is as follows: 1. Preparation of the free radical polymer lithium supplement PTMA-Li: S1. In a 500 mL three-necked flask, add tetramethylpiperidinol (18 g, 114.5 mmol), methyl methacrylate (42 mL, 465.9 mmol), and 300 mL of toluene. After stirring until homogeneous, add tetrabutyl titanate (0.36 mL, 1.05 mmol). Reflux at 110 °C for 2 h. Then, add 0.36 mL of tetrabutyl titanate to the reaction solution and continue refluxing for 20 h under nitrogen protection. After cooling to room temperature, use 100 mL of 5wt% [a specific reagent / component]. The reaction solution was extracted and washed with NaHCO3 solution in a separatory funnel to completely hydrolyze unreacted tetrabutyl titanate into titanium dioxide. After removing the titanium dioxide by filtration, the solution was placed in a separatory funnel to separate the organic layer. Most of the toluene was removed by rotary evaporation. The concentrated solution was placed in a watch glass and the residual toluene was evaporated in a fume hood. The product was fully crystallized into a white solid 2,2,6,6-tetramethyl-4-piperidinyl methacrylate (TMPM), which is a free radical polymer monomer. S2. In a three-necked flask, 5 g of 2,2,6,6-tetramethyl-4-piperidinol methacrylate (TMPM) obtained in step S1, 17.8 mg of azobisisobutyronitrile (AIBN), and 250 mL of methanol were mixed. After assembling a reflux apparatus, nitrogen gas was introduced for deoxygenation for 30 min. Subsequently, the mixture was placed in a 65 ℃ oil bath and stirred for 10 h to induce free radical polymerization. Then, deionized water was added at a volume ratio of 4:1 to precipitate the intermediate PTMPM in the reaction solution. The crude product was collected by centrifugation at 9000 r / min for 20 min and dried at 55 ℃ under vacuum of 0.09 MPa for 5 h. The dried crude product was dissolved in 25 mL of ethyl acetate, and 400 mL of n-hexane was added to reverse the precipitation. After stirring for 45 min, the upper solvent layer was discarded. This operation was repeated 2-3 times for purification, and the product was then dried under vacuum under the above conditions to obtain the purified intermediate PTMPM. S3. Dissolve 1 g of purified PTMPM obtained in step S2 in dichloromethane to prepare a 5 wt% solution. Add 10 mL of 30 wt% hydrogen peroxide and stir at 65 °C for 24 h to complete the first oxidation. Then add an equal amount of 30 wt% H2O2 and continue the reaction at 65 °C for 24 h for a second oxidation to ensure that the piperidine ring is completely converted into a nitroxide free radical structure. After the system is cooled to room temperature, filter the filter cake through a 0.22 μm organic filter membrane and wash it three times with deionized water (each time the amount of water used is 6 times the mass of the filter cake). Dry the filter cake at 80 °C and 0.1 MPa vacuum for 24 h to obtain the free radical polymer PTMA. S4. Mix 500 mg of the free radical polymer PTMA obtained in step S3 with 2 g of oxalic acid and react at 25 °C for 24 h to obtain a free radical polymer intermediate; then add 1 g of lithium hydroxide and react at 25 °C for 24 h to obtain the free radical polymer lithium supplement PTMA-Li; The reaction pathways for steps S1 to S4 are shown below: .

[0127] 2. Electrode Preparation (1) Free radical polymer lithium supplement composite electrode PTMA-Li, a free radical polymer lithium supplement, and single-walled carbon nanotubes (SWCNTs) were weighed at a mass ratio of 1:2 as the active material and substrate material, respectively, with N,N-dimethylformamide (DMF) as the dispersion solvent. First, the weighed PTMA-Li was added to DMF and stirred at a constant temperature of 80 °C until fully dissolved, forming a homogeneous PTMA solution. Then, SWCNTs were added to the solution and ultrasonically dispersed at 60 W for 1 hour to ensure no agglomeration of the carbon nanotubes, ultimately forming a uniformly dispersed electrode slurry. This uniform slurry was poured into a mold of a predetermined size, and after casting, it was first dried in a 60 °C forced-air drying oven for 12 hours, then transferred to an 80 °C vacuum drying oven for another 12 hours. After drying and shaping, a self-supporting PTMA-Li electrode, i.e., a PTMA-Li / SWCNT composite electrode, was obtained. (2) Graphite electrode Weigh out fast-charging graphite b, conductive carbon black (SP), and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as a solvent, transfer the above components together into a ball mill jar and add steel balls. Mix by stirring until a uniform slurry is formed. Use a doctor blade coating method to uniformly coat the above slurry onto the surface of copper foil with a wet film thickness of 150 μm. After coating, first place it in a 60 ℃ forced-air drying oven for 12 h, and then transfer it to an 80 ℃ vacuum drying oven for 12 h. After drying, the doctor blade coated fast-charging graphite b electrode is obtained.

[0128] 3. Preparation of full cells Using a PTMA-Li / SWCNT composite electrode as the positive electrode, a fast-charging graphite electrode as the negative electrode, LB-002 as the electrolyte, and KELOD 2500 separator as the separator, a complete battery system was assembled according to the conventional assembly process of lithium-ion batteries.

[0129] Example 5: Preparation of a free radical polymer lithium supplement, electrode, and full cell The difference from Example 1 is that methyl acrylate is replaced with methyl methacrylate in the preparation of the free radical polymer. The specific steps are as follows: 1. Preparation of free radical polymer PTPA: S1. Weigh out tetramethylpiperidinol (18 g, 114.5 mmol) and methyl acrylate (42 mL, 465.9 mmol) in a 500 mL three-necked flask. Dissolve them in 300 mL of toluene. After stirring thoroughly, add tetrabutyl titanate (0.36 mL, 1.05 mmol) to the system using a syringe. Reflux at 110 °C for 2 h. Then, add 0.36 mL of tetrabutyl titanate to the reaction solution and continue refluxing for 20 h under nitrogen protection. After cooling to room temperature, use 100 mL of 5wt%... The reaction solution was extracted and washed with NaHCO3 solution in a separatory funnel to completely hydrolyze unreacted tetrabutyl titanate into titanium dioxide. After removing the titanium dioxide by filtration, the solution was placed in a separatory funnel to separate the organic layer. Most of the toluene was removed by rotary evaporation. The concentrated solution was placed in a watch glass and the residual toluene was evaporated in a fume hood. The product was fully crystallized into a white solid, 2,2,6,6-tetramethyl-4-piperidinyl acrylate, which is a free radical polymer monomer. S2. In a three-necked flask, 5 g of 2,2,6,6-tetramethyl-4-piperidinol acrylate obtained in step S1, 17.8 mg of azobisisobutyronitrile (AIBN), and 250 mL of methanol were mixed. After assembling a reflux apparatus, nitrogen gas was introduced for deoxygenation for 30 min. Subsequently, the mixture was placed in a 65 ℃ oil bath and stirred for 10 h to induce free radical polymerization. Then, deionized water was added at a volume ratio of 4:1 to precipitate the intermediate in the reaction solution. The crude product was collected by centrifugation at 9000 r / min for 20 min and dried at 55 ℃ under vacuum of 0.09 MPa for 5 h. The dried crude product was dissolved in 25 mL of ethyl acetate, and 400 mL of n-hexane was added for reverse precipitation. After stirring for 45 min, the upper solvent layer was discarded. This operation was repeated 2-3 times for purification, and the product was then dried under vacuum under the above conditions to obtain the purified PTPA intermediate. S3. Dissolve 1 g of the purified PTPA intermediate obtained in step S2 in dichloromethane to prepare a 5 wt% solution. Add 10 mL of 30 wt% hydrogen peroxide and stir at 65 °C for 24 h to complete the first oxidation. Then add an equal amount of 30 wt% H2O2 and continue the reaction at 65 °C for 24 h for a second oxidation to ensure that the piperidine ring is completely converted into a nitroxide free radical structure. After the system is cooled to room temperature, filter the filter cake through a 0.22 μm organic filter membrane. Wash the filter cake three times with deionized water (each time the amount of water used is 6 times the mass of the filter cake). Dry the filter cake at 80 °C and 0.1 MPa vacuum for 24 h to obtain the free radical polymer PTPA. The weight-average molecular weight (Mw) was determined by gel permeation chromatography (using tetrahydrofuran as solvent), and the result was 444725 (see [link to relevant documentation]). Figure 2 Polydispersity index (PDI) = weight-average molecular weight (Mw) / number-average molecular weight (Mn) = 2.44; The reaction pathways for steps S1 to S3 are shown below: .

[0130] The other steps and conditions are the same as in Example 1.

[0131] Comparative Example 1: Preparation of a free radical polymer lithium supplement, electrode, and full cell The difference from Example 1 is that in the electrode preparation step (1), the self-supporting free radical polymer composite electrode is replaced with a blade-coated free radical polymer composite electrode. The specific steps are as follows: (1) Free radical polymer composite electrode Accurately weigh each solid component according to the mass ratio of PTMA: conductive carbon black (SP): polyvinylidene fluoride (PVDF) = 6:3:1. Using N-methylpyrrolidone (NMP) as the dispersion solvent, first add the weighed PTMA to NMP and stir continuously at a constant temperature of 80 ℃ until PTMA is completely dissolved, forming a uniform, transparent PTMA solution without visible particles. After the solution stabilizes, add the weighed conductive carbon black (SP) and polyvinylidene fluoride (PVDF) to it and mix initially until the solid components are initially dispersed. Then, transfer the mixture to a ball mill jar and add steel balls for ball milling and dispersion until a uniformly dispersed black slurry without agglomeration is obtained. Use a doctor blade coating method to coat the uniform slurry onto the surface of aluminum foil with a wet film thickness of 400 μm. After coating, first place it in a 60 ℃ forced-air drying oven for 12 h, and then transfer it to an 80 ℃ vacuum drying oven for another 12 h. After drying, the doctor blade coated PTMA electrode is obtained.

[0132] The other steps and conditions are the same as in Example 1.

[0133] Comparative Example 2: Preparation of a free radical polymer lithium supplement, electrode, and full cell The difference from Example 1 is that in the electrode preparation step (2), the fast-charging graphite b is replaced with rate-type graphite.

[0134] The other steps and conditions are the same as in Example 1.

[0135] Comparative Example 3: Preparation of a free radical polymer lithium supplement, electrode, and full cell The difference from Example 1 is that in the electrode preparation step (2), fast-charging graphite b is replaced with fast-charging graphite.

[0136] The other steps and conditions are the same as in Example 1.

[0137] Comparative Example 4: Preparation of a free radical polymer lithium supplement, electrode, and full cell The difference from Example 1 is that in the electrode preparation step (2), the fast-charging graphite b is replaced with MS-QCG-X type artificial graphite.

[0138] The other steps and conditions are the same as in Example 1.

[0139] Comparative Example 5: Preparation of a free radical polymer lithium supplement, battery, and full cell. The difference from Example 1 is that, in the full-cell step, the PTMA / SWCNT composite electrode was not lithium-added. The specific steps are as follows: 1. Preparation of the free radical polymer PTMA: S1. Weigh 18 g (114.5 mmol) of tetramethylpiperidinol and 42 mL (465.9 mmol) of methyl methacrylate into a 500 mL three-necked flask. Dissolve the methyl methacrylate in 300 mL of toluene. After stirring thoroughly, add 0.36 mL (1.05 mmol) of tetrabutyl titanate to the system using a syringe. Reflux the mixture at 110 °C for 2 h. Then, add 0.36 mL of tetrabutyl titanate to the reaction solution and continue refluxing for 20 h under nitrogen protection. After cooling to room temperature, use 100 mL of 5 wt%... The reaction solution was extracted and washed with NaHCO3 solution in a separatory funnel to completely hydrolyze unreacted tetrabutyl titanate into titanium dioxide. After removing the titanium dioxide by filtration, the solution was placed in a separatory funnel to separate the organic layer. Most of the toluene was removed by rotary evaporation. The concentrated solution was placed in a watch glass and the residual toluene was evaporated in a fume hood. The product was fully crystallized into a white solid, 2,2,6,6-tetramethyl-4-piperidinyl methacrylate, which is a free radical polymer monomer. S2. In a three-necked flask, 5 g of 2,2,6,6-tetramethyl-4-piperidinol methacrylate obtained in step S1, 17.8 mg of azobisisobutyronitrile (AIBN), and 250 mL of methanol were mixed. After assembling a reflux apparatus, nitrogen gas was introduced for deoxygenation for 30 min. Subsequently, the mixture was placed in a 65 ℃ oil bath and stirred for 10 h to induce free radical polymerization. Then, deionized water was added at a volume ratio of 4:1 to precipitate the intermediate in the reaction solution. The crude product was collected by centrifugation at 9000 r / min for 20 min and dried at 55 ℃ under vacuum of 0.09 MPa for 5 h. The dried crude product was dissolved in 25 mL of ethyl acetate, and 400 mL of n-hexane was added to reverse the precipitation. After stirring for 45 min, the upper solvent layer was discarded. This operation was repeated 2-3 times for purification, and the purified intermediate was dried under vacuum under the above conditions to obtain the purified intermediate. S3. Dissolve 1 g of the purified intermediate obtained in step S2 in dichloromethane to prepare a 5 wt% solution. Add 10 mL of 30 wt% hydrogen peroxide and stir at 65 °C for 24 h to complete the first oxidation. Then add an equal amount of 30 wt% H2O2 and continue the reaction at 65 °C for 24 h for a second oxidation to ensure that the piperidine ring is completely converted into a nitroxide free radical structure. After the system is cooled to room temperature, filter the filter cake through a 0.22 μm organic filter membrane. Wash the filter cake three times with deionized water (each time the amount of water used is 6 times the mass of the filter cake). Dry the filter cake at 80 °C and 0.1 MPa vacuum for 24 h to obtain the free radical polymer PTMA. The weight-average molecular weight was determined by gel permeation chromatography (using tetrahydrofuran as solvent), and the result was 378217 (see [link to relevant documentation]). Figure 1 Polydispersity index (PDI) = weight-average molecular weight (Mw) / number-average molecular weight (Mn) = 2.67; The reaction pathways for steps S1 to S3 are shown below: .

[0140] 2. Electrode Preparation (1) Free radical polymer composite electrode Free radical polymer PTMA and single-walled carbon nanotubes (SWCNTs) were weighed at a mass ratio of 1:2 as the active material and substrate material, respectively, with N,N-dimethylformamide (DMF) as the dispersion solvent. First, the weighed PTMA was added to DMF and stirred at a constant temperature of 80 °C until fully dissolved, forming a homogeneous PTMA solution. Then, SWCNTs were added to the solution and ultrasonically dispersed at 60 W for 1 hour to ensure no agglomeration of the carbon nanotubes, ultimately forming a uniformly dispersed electrode slurry. This uniform slurry was poured into a mold of a predetermined size, and after casting, it was first dried in a 60 °C forced-air drying oven for 12 hours, then transferred to an 80 °C vacuum drying oven for another 12 hours. After drying and shaping, a self-supporting PTMA electrode, i.e., a PTMA / SWCNT composite electrode, was obtained. (2) Graphite electrode Weigh out fast-charging graphite b, conductive carbon black (SP), and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as a solvent, transfer the above components together into a ball mill jar and add steel balls. Mix by stirring until a uniform slurry is formed. Use a doctor blade coating method to uniformly coat the above slurry onto the surface of copper foil with a wet film thickness of 150 μm. After coating, first place it in a 60 ℃ forced-air drying oven for 12 h, and then transfer it to an 80 ℃ vacuum drying oven for 12 h. After drying, the doctor blade coated fast-charging graphite b electrode is obtained.

[0141] 3. Preparation of full cells In a glove box with an inert gas atmosphere, a full battery system was assembled using a PTMA / SWCNT composite electrode as the positive electrode, a fast-charging graphite electrode as the negative electrode, LB-002 as the electrolyte, and a KELOD 2500 separator as the separator, following the conventional assembly process for lithium-ion batteries.

[0142] In this comparative example, since the PTMA / SWCNT composite electrode was not subjected to electrochemical lithium replenishment treatment, the resulting full cell is a full cell of an unreplenished lithium system.

[0143] Comparative Example 6: Preparation of a free radical polymer lithium supplement, battery, and full cell The difference from Example 5 is that, in the full-cell step, the PTPA / SWCNT composite electrode was not lithium-added. The specific steps are as follows: 1. Preparation of free radical polymer PTPA: S1. In a 500 mL three-necked flask, add tetramethylpiperidinol (18 g, 114.5 mmol), methyl acrylate (42 mL, 465.9 mmol), and 300 mL of toluene. After stirring evenly, add tetrabutyl titanate (0.36 mL, 1.05 mmol) to the system. After refluxing at 110 °C for 2 h, add 0.36 mL of tetrabutyl titanate to the reaction solution and continue refluxing for 20 h under nitrogen protection. After cooling to room temperature, use 100 mL of 5wt% NaHCO3 solution to extract and wash the reaction solution in a separatory funnel to completely hydrolyze the unreacted tetrabutyl titanate into titanium dioxide. After removing the titanium dioxide by filtration, place the solution in a separatory funnel to separate the organic layer. Rotary evaporate to remove most of the toluene. Place the concentrated solution in a watch glass and evaporate the residual toluene in a fume hood. The product is fully crystallized into a white solid 2,2,6,6-tetramethyl-4-piperidinyl acrylate, which is a free radical polymer monomer. S2. In a three-necked flask, 5 g of 2,2,6,6-tetramethyl-4-piperidinol acrylate obtained in step S1, 17.8 mg of azobisisobutyronitrile (AIBN), and 250 mL of methanol were mixed. After assembling a reflux apparatus, nitrogen gas was introduced for deoxygenation for 30 min. Subsequently, the mixture was placed in a 65 ℃ oil bath and stirred for 10 h to induce free radical polymerization. Then, deionized water was added at a volume ratio of 4:1 to precipitate the intermediate in the reaction solution. The crude product was collected by centrifugation at 9000 r / min for 20 min and dried at 55 ℃ under vacuum of 0.09 MPa for 5 h. The dried crude product was dissolved in 25 mL of ethyl acetate, and 400 mL of n-hexane was added for reverse precipitation. After stirring for 45 min, the upper solvent layer was discarded. This operation was repeated 2-3 times for purification, and the product was then dried under vacuum under the above conditions to obtain the purified PTPA intermediate. S3. Dissolve 1 g of the purified PTPA intermediate obtained in step S2 in dichloromethane to prepare a 5 wt% solution. Add 10 mL of 30 wt% hydrogen peroxide and stir at 65 °C for 24 h to complete the first oxidation. Then add an equal amount of 30 wt% H2O2 and continue the reaction at 65 °C for 24 h for a second oxidation to ensure that the piperidine ring is completely converted into a nitroxide free radical structure. After the system is cooled to room temperature, filter the filter cake through a 0.22 μm organic filter membrane. Wash the filter cake three times with deionized water (each time the amount of water used is 6 times the mass of the filter cake). Dry the filter cake at 80 °C and 0.1 MPa vacuum for 24 h to obtain the free radical polymer PTPA. The weight-average molecular weight was determined by gel permeation chromatography (using tetrahydrofuran as solvent), and the result was 444725 (see [link to relevant documentation]). Figure 2 Polydispersity index (PDI) = weight-average molecular weight (Mw) / number-average molecular weight (Mn) = 2.44; The reaction pathways for steps S1 to S3 are shown below: .

[0144] 2. Electrode Preparation (1) Free radical polymer composite electrode Free radical polymer PTPA and single-walled carbon nanotubes (SWCNTs) were weighed at a mass ratio of 1:2, serving as the active material and substrate material, respectively, with N,N-dimethylformamide (DMF) as the dispersion solvent. First, the weighed PTPA was added to DMF and stirred at a constant temperature of 80 °C until fully dissolved, forming a homogeneous PTPA solution. Then, SWCNTs were added to the solution and ultrasonically dispersed at 60 W for 1 hour to ensure no agglomeration of the carbon nanotubes, ultimately forming a uniformly dispersed electrode slurry. This uniform slurry was poured into a mold of a predetermined size, and after casting, it was first dried in a 60 °C forced-air drying oven for 12 hours, then transferred to an 80 °C vacuum drying oven for another 12 hours. After drying and shaping, a self-supporting PTPA electrode, i.e., a PTPA / SWCNT composite electrode, was obtained. (2) Graphite electrode Weigh out fast-charging graphite b, conductive carbon black (SP), and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as a solvent, transfer the above components together into a ball mill jar and add steel balls. Mix by stirring until a uniform slurry is formed. Use a doctor blade coating method to uniformly coat the above slurry onto the surface of copper foil with a wet film thickness of 150 μm. After coating, first place it in a 60 ℃ forced-air drying oven for 12 h, and then transfer it to an 80 ℃ vacuum drying oven for 12 h. After drying, the doctor blade coated fast-charging graphite b electrode is obtained.

[0145] 3. Preparation of full cells In a glove box with an inert gas atmosphere, a full battery system was assembled using a PTPA / SWCNT composite electrode as the positive electrode, a fast-charging graphite electrode as the negative electrode, LB-002 as the electrolyte, and a KELOD 2500 separator as the separator, following the conventional assembly process for lithium-ion batteries.

[0146] In this comparative example, since the PTPA / SWCNT composite electrode was not subjected to electrochemical lithium replenishment treatment, the resulting full cell is a full cell of an unreplenished lithium system.

[0147] Experimental Example 1: Electrochemical Performance Testing of Half-Cells 1. Experimental Methods (1) Free radical polymer composite electrode: Half-cell assembly: Using the free radical polymer composite electrodes from Examples 1-2 and Comparative Example 1 as working electrodes, lithium metal sheets as counter electrodes, LB-002 as electrolyte, and KELOD 2500 as separator, CR2025 coin cells were assembled in an argon-protected glove box (water and oxygen content <0.1ppm) and left to stand for 12 hours to ensure that the electrolyte fully wets the electrodes and separator.

[0148] Room temperature cycle test: The assembled half-cell was placed in a constant temperature environment of 25 ℃ and the electrochemical performance was tested using a battery testing system: The charge and discharge voltage range was set to 3.0~4.0 V (the conventional battery test voltage), and the charge and discharge cycle test was performed at a current density of 1C. The 1C charge specific capacity and 1C discharge specific capacity were obtained through the capacity-voltage curve. Initial coulombic efficiency = (initial discharge capacity / initial charge capacity) × 100%; Capacity retention rate = (30th cycle discharge capacity / first discharge capacity) × 100%.

[0149] (2) Graphite electrode: Half-cell assembly: Using the graphite electrodes from Examples 1, 3, and Comparative Examples 2-4 as working electrodes, lithium metal sheets as counter electrodes, LB-002 as electrolyte, and KELOD 2500 as separator, CR2032 coin cells were assembled in an argon-protected glove box (water and oxygen content <0.1ppm) and allowed to stand for 12 hours to ensure that the electrolyte fully wetted the electrodes and separator.

[0150] Room temperature cycling test: The assembled half-cell was placed in a constant temperature environment of 25 ℃ and the electrochemical performance was tested using a battery testing system: The charge and discharge voltage range was set to -1.0~2.0 V. First, two cycles of charge and discharge activation were performed at a current density of 0.1C, and then charge and discharge cycle test was performed at a current density of 1C. The 1C charge specific capacity and 1C discharge specific capacity were obtained through the capacity-voltage curve. Initial coulombic efficiency = (initial discharge capacity / initial charge capacity) × 100%; Capacity retention rate = (300th cycle discharge capacity / first discharge capacity) × 100%.

[0151] 2. Experimental Results Table 1. Statistical table of half-cell electrochemical performance based on free radical polymer composite electrode

[0152] Table 2. Statistical table of electrochemical performance of half-cells based on graphite electrodes

[0153] As shown in Table 1, the free radical polymer composite electrodes obtained in Examples 1 and 2 exhibit excellent electrochemical performance after being prepared as self-supporting electrodes due to the good adhesion and compatibility of the free radical polymer and single-walled carbon nanotubes. Specific indicators are as follows: 1C charge specific capacity ≥ 100 mAh / g, 1C discharge specific capacity ≥ 92 mAh / g, initial coulombic efficiency ≥ 92%, and 30-cycle capacity retention ≥ 94%. Based on these excellent performances, the free radical polymer composite electrodes of Examples 1 and 2 were selected as the matrix material for further electrochemical activation—by controlling the voltage to trigger a reduction reaction, in-situ generation of a free radical polymer lithium supplement, and using this free radical polymer lithium supplement / single-walled carbon nanotube composite electrode as the positive electrode for subsequent full cells. In contrast, Comparative Example 1, by replacing the self-supporting electrode with a conventional blade-coated electrode, experienced a decrease in electrode structural stability and interfacial compatibility, leading to a decrease in the 30-cycle capacity retention.

[0154] As shown in Table 2, the graphite electrodes obtained in Examples 1 and 3, by selecting fast-charging graphite b as the active material, not only optimize lithium-ion transport by utilizing its intrinsic material properties, but also form good compatibility with the electrode system, ensuring the stability of the electrode structure and not affecting ion insertion and extraction, ultimately exhibiting excellent electrochemical performance. The key parameters are: 1C charging specific capacity ≥367 mAh / g, 1C discharging specific capacity ≥450 mAh / g, initial coulombic efficiency ≥90%, and capacity retention rate ≥85% after 300 cycles. In comparison, Comparative Example 2, by replacing fast-charging graphite b with rate-capacity graphite, suffers from a decrease in 1C charging specific capacity, initial coulombic efficiency, and 300-cycle capacity retention due to the inferior material properties and electrode system compatibility of the latter. Comparative Example 3, by replacing fast-charging graphite b with fast-charging graphite, also suffers from a decrease in initial coulombic efficiency and 300-cycle capacity retention due to the inferior material properties and electrode system compatibility of the former. Comparative Example 4, by replacing fast-charging graphite b with MS-QCG-X type artificial graphite, also suffers from a decrease in initial coulombic efficiency and 300-cycle capacity retention due to the dual defects in material properties and electrode system compatibility.

[0155] Experiment Example 2: Performance Testing of a Full Battery 1. Experimental Methods (1) Capacity change test and calculation before and after lithium replenishment: Two sets of experiments were set up. Example 1 (full cell assembled after lithium replenishment treatment) and Comparative Example 5 (full cell assembled without lithium replenishment) were the first set of corresponding samples, and Example 5 (full cell assembled after lithium replenishment treatment) and Comparative Example 6 (full cell assembled without lithium replenishment) were the second set of corresponding samples. The full cells were placed in a constant temperature environment of 25 °C and electrochemical performance was tested using a battery testing system. The first charge / discharge cycle test was performed using a 1C current in the charge / discharge voltage range of 3.0 to 4.0 V, and the first charge / discharge capacity of the full cells was recorded. The capacity change before and after lithium replenishment for each group was calculated by subtracting the first discharge capacity of the example (after lithium replenishment) from the first discharge capacity of the comparative example (before lithium replenishment).

[0156] (2) 1C charge specific capacity, 1C discharge specific capacity, initial coulombic efficiency, and capacity retention: The assembled full cells of each embodiment and comparative example were placed in a constant temperature environment of 25 ℃ and electrochemical performance was tested using a battery testing system: the charge and discharge voltage range was set to 3.0~4.0 V, and charge and discharge cycle tests were performed at a current density of 1C. The 1C charge specific capacity and 1C discharge specific capacity were obtained through the capacity-voltage curve. Initial coulombic efficiency = (initial discharge capacity / initial charge capacity) × 100%; Capacity retention rate = (Discharge capacity in the 100th cycle / Initial discharge capacity) × 100%.

[0157] 2. Experimental Results Table 3. Statistical table of full-cell performance data for each embodiment and comparative example.

[0158] The capacity changes before and after lithium supplementation are as follows: Figures 3-4 As shown: Example 1 (after lithium replenishment) showed a 57.8% increase in first-cycle discharge capacity compared to Comparative Example 5 (before lithium replenishment). Figure 3 Example 5 (after lithium replenishment) showed a 57.7% increase in first-cycle discharge capacity compared to Comparative Example 6 (before lithium replenishment). Figure 4 The above results indicate that both types of free radical polymers involved in this application exhibit excellent lithium replenishment effects, which can effectively compensate for the active lithium lost during the formation of the negative electrode solid electrolyte interphase (SEI) film, thereby significantly improving the actual usable capacity of the battery.

[0159] As shown in Table 3, Examples 1-3, due to the use of the free radical polymer lithium supplementer PTMA-Li as the positive electrode active material, exhibited excellent performance in terms of 1C charging specific capacity, 1C discharging specific capacity, initial coulombic efficiency, and capacity retention of the full cell. Although Example 4 differed from Examples 1-3 in terms of the type of free radical polymer, resulting in a difference in theoretical capacity and slightly inferior performance compared to Examples 1-3, it still met the basic performance requirements of this application. The specific indicators are: 1C charging specific capacity ≥ 89 mAh / g, 1C discharging specific capacity ≥ 71 mAh / g, initial coulombic efficiency ≥ 73%, and 100-cycle capacity retention ≥ 73%.

[0160] In contrast, Comparative Example 1, which replaced the PTMA self-supporting electrode with a PTMA coated electrode, resulted in a significant decrease in the full-cell charge specific capacity, discharge specific capacity, initial coulombic efficiency, and capacity retention. Comparative Examples 2-4, which replaced the fast-charging graphite b with rate-capacity graphite, ordinary fast-charging graphite, and artificial graphite, respectively, resulted in a decrease in charge specific capacity, discharge specific capacity, initial coulombic efficiency, and capacity retention due to insufficient compatibility between graphite material characteristics and the electrode system. Comparative Examples 5-6, which did not perform lithium replenishment treatment on the free radical polymer, resulted in a decrease in charge specific capacity, discharge specific capacity, and capacity retention.

[0161] The changes in lithium replenishment capacity of the free radical polymer lithium replenishing agents in Examples 2-4 are basically the same as those in Example 1, and will not be repeated here.

[0162] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A type of free radical polymer lithium supplement, characterized in that, The structural formula of the free radical polymer lithium supplement is shown below: ； Wherein, R is C 1~6 Alkane or hydrogen; n = 500~2000.

2. The free radical polymer lithium supplement according to claim 1, characterized in that, The structural formula of the free radical polymer lithium supplement is shown below: ； Wherein, R is C 1~3 Alkane or hydrogen; n = 500~2000.

3. The method for preparing the free radical polymer lithium supplement according to claim 1 or 2, characterized in that, Includes the following steps: Free radical polymers can be used to prepare free radical polymer lithium supplements through chemical synthesis or electrochemical synthesis. The preparation method of the chemical synthesis includes the following steps: A free radical polymer and a reducing agent undergo a reduction reaction to form a free radical polymer intermediate. The obtained free radical polymer intermediate is then reacted with lithium hydroxide to obtain the free radical polymer lithium supplement. The reaction pathway for chemical synthesis is shown below: ； The definition of R is consistent with that of claim 1 or 2 above, and n = 500~2000; The preparation method of the electrochemical synthesis includes the following steps: In a protective gas environment, a free radical polymer composite electrode and a lithium metal sheet are assembled into a half cell. The voltage of the half cell is adjusted to 1.5~2.5 V, and the free radical polymer undergoes a reduction reaction to generate a free radical polymer lithium supplement. The free radical polymer composite electrode comprises a free radical polymer and a self-supporting conductive substrate.

4. The preparation method according to claim 3, characterized in that, The weight-average molecular weight of the free radical polymer is 300,000 to 500,000.

5. The preparation method according to claim 3, characterized in that, The reducing agent includes one or more of ascorbic acid, sulfurous acid, and lithium naphthalene.

6. The preparation method according to claim 3, characterized in that, The self-supporting conductive substrate includes one or more of single-walled carbon nanotubes, carbon black, and graphene.

7. The use of the free radical polymer lithium supplement agent according to claim 1 or 2 in the preparation of positive electrode lithium supplement agents.

8. A positive electrode lithium replenishing agent, characterized in that, The positive electrode lithium supplement includes the free radical polymer lithium supplement as described in claim 1 or 2.

9. A full battery, characterized in that, The full cell includes a positive electrode, a negative electrode, an electrolyte, and a separator; the positive electrode includes a composite electrode; the negative electrode is a graphite electrode; The composite electrode comprises an active material and a self-supporting conductive substrate, wherein the active material is the positive electrode lithium replenishing agent as described in claim 8, and the self-supporting conductive substrate is a single-walled carbon nanotube. The graphite in the graphite electrode must meet the following conditions: (1) D 50 The diameter is 8~10 μm; (2) Specific surface area ≤ 1.5 m² 2 / g.

10. The full battery according to claim 9, characterized in that, The graphite electrode comprises graphite, a conductive agent, and a binder.

Images