Carbon nanotube loaded nano lithiated carbon microsphere conductive agent, preparation method thereof and lithium ion battery

Abstract

The invention discloses a carbon nanotube loaded nano lithiated carbon microsphere conductive agent, a preparation method thereof and a lithium ion battery, and relates to the technical field of lithium ion battery conductive agents. The preparation method comprises the following steps: preparing carbon nanotube loaded nano alloy aluminum bismuth particles by a laser stirring method, preparing nano carbon microspheres deposited on metal by a vapor deposition method, preparing carbon nanotube loaded nano carbon microspheres by a chemical dealloying method, and preparing carbon nanotube loaded lithiated carbon microspheres by a melting method. The conductive agent has excellent conductivity and high surface area, can effectively enhance the conductivity of the composite material, reduces the internal resistance of the lithium ion battery, and improves the overall performance of the lithium ion battery. The lithiated carbon microspheres can provide good lithium ion migration ability in the electrode material, and the fast charging performance and the cycling stability of the battery are optimized. Meanwhile, the lithiated carbon structure is beneficial to formation of a stable SEI film on the surface of the battery in the charging and discharging process, reduction of consumption of lithium ions in an electrolyte is facilitated, and the energy density of the lithium ion battery is improved.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery conductive agents, and in particular to a carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent and a preparation method thereof, and a lithium ion battery. Background Art

[0002] Lithium-ion batteries are indispensable energy storage systems for modern electronic devices and electric vehicles, and the improvement of their performance is closely related to the optimization of various materials. Conductive agents, as an important component of lithium-ion battery electrode materials, play a vital role. The main function of lithium-ion battery conductive agents is to improve the conductivity of electrode materials. Lithium-ion batteries are generally composed of positive electrodes, negative electrodes, electrolytes and separators. The conductivity of electrode materials directly affects the cycle performance and charge and discharge rate of the battery. In electrode materials, active substances usually have poor conductivity. The addition of conductive agents can improve the overall electronic conductivity of the electrode and promote the rapid migration of lithium ions in the electrode, thereby improving the energy density and power density of the battery.

[0003] Common lithium-ion battery conductive agents are mainly divided into the following categories: ① Carbon-based conductive agents: including carbon black, carbon nanotubes, graphite and conductive graphite. Carbon-based materials have good conductivity and chemical stability and are widely used in the positive and negative electrodes of lithium-ion batteries. Carbon black is a common conductive agent and is widely used in lithium-ion batteries due to its high specific surface area and excellent conductivity. ② Metal conductive agents: such as metal aluminum, copper powder, etc. These materials usually have higher conductivity, but their potential electrochemical reaction problems need to be overcome when used in batteries. ③ Conductive polymers: such as polyaniline, polypyrrole, etc. These materials have good conductivity and flexibility, can improve the mechanical properties of electrode materials, and enhance the cycle life of batteries. ④ Composite conductive agents: In recent years, studies have shown that carbon materials can be composited with other conductive materials (such as conductive polymers, metal oxides, etc.) in order to improve conductivity and stability and promote the further development of lithium-ion batteries.

[0004] The performance of lithium-ion battery conductive agents is affected by many factors, including their particle size, shape, specific surface area, dispersibility and addition amount. ① Particle size and specific surface area: The smaller the particle size of the conductive agent, the larger the specific surface area, and the more conductive paths provided, thereby improving the conductivity and power conversion efficiency of the electrode. ② Shape and dispersibility: The shape of the conductive agent will affect its dispersibility in the electrode. Good dispersibility can effectively reduce the electronic conduction impedance in the electrode and improve the rapid charging and discharging capabilities of the battery. ③ Addition amount: Although increasing the amount of conductive agent added can improve the conductivity of the electrode material, when it exceeds a certain proportion, the impact of the conductive agent may cause a decrease in battery capacity. Therefore, the optimal design of the conductive agent needs to strike a balance between conductivity and battery capacity.

[0005] As the world pays more attention to renewable energy and electric vehicles, the market demand for lithium-ion batteries is growing. Conductive agents are important additives for improving battery performance, and their development and application prospects are broad. In the future, the research on conductive agents will focus on the following directions: ① Development of new conductive materials: Exploring higher-performance conductive materials, such as conductive nanocomposites, graphene, etc., to improve the overall performance of lithium-ion batteries. ② Functional conductive agents: Combine conductive agents with other functional materials to give them more electrochemical functions, such as enhancing the cycle stability and safety of batteries. ③ Green and environmentally friendly conductive agents: With the strengthening of environmental awareness, research and exploration of environmentally friendly conductive materials will be an important trend in the development of lithium-ion battery conductive agents. ④ Balance between performance and cost: While pursuing high performance, reduce the production cost of conductive agents so that lithium-ion batteries can be promoted in a wider range of application fields. In general, lithium-ion battery conductive agents play an indispensable role in improving battery performance. With the advancement of science and technology and changes in market demand, the research and application of conductive agents will continue to expand and contribute to the innovation of lithium battery technology.

[0006] Although conductive agents play an important role in battery performance, there are also some problems and challenges: (1) Insufficient conductivity. The low conductivity of some conductive agents may lead to insufficient conductivity of the electrode, thus affecting the battery's charge and discharge performance and power output. (2) Poor chemical stability. Conductive agents may degrade at high temperatures or in extreme electrochemical environments, resulting in reduced battery performance or shortened life. (3) Low battery energy density. The addition of conductive agents may increase the total mass of the electrode, thereby reducing the battery's energy density. Summary of the invention

[0007] The present invention successfully prepares a carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent by laser stirring method, vapor deposition method, chemical dealloying method and melting method. The conductive agent has excellent conductivity and high surface area, can effectively enhance the conductivity of the composite material, reduce the internal resistance of lithium-ion batteries, and improve the overall performance of lithium-ion batteries. Secondly, the lithiated carbon microspheres can provide good lithium ion migration ability in the electrode material, optimize the fast charging performance and cycle stability of the battery. At the same time, the lithiated carbon structure helps the battery to form a stable solid electrolyte interface film (SEI film) on the surface during the charge and discharge process, which is beneficial to reduce the consumption of lithium ions in the electrolyte and improve the energy density of lithium-ion batteries.

[0008] One of the purposes of the present invention is to provide a method for preparing a carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent.

[0009] The second object of the present invention is to provide a carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent prepared by the above preparation method.

[0010] The third object of the present invention is to provide a lithium ion battery prepared by the above-mentioned carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent.

[0011] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0012] In a first aspect, the present invention provides a method for preparing a carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent, comprising the following steps:

[0013] The carbon nanotubes and aluminum-bismuth alloy are mixed and laser stirred to obtain carbon nanotube-loaded nano-alloy aluminum-bismuth particles; carbon microspheres are vapor-deposited on the carbon nanotube-loaded nano-alloy aluminum-bismuth particles, and then the aluminum-bismuth particles are removed to obtain carbon nanotube-loaded nano-carbon microspheres; metallic lithium is melted and then poured onto the carbon nanotube-loaded nano-carbon microspheres for a lithiation reaction to obtain carbon nanotube-loaded nano-lithiated carbon microspheres.

[0014] Preferably, the mass ratio of the carbon nanotubes to the aluminum-bismuth alloy is 2-4:1-2.

[0015] Preferably, the conditions for laser stirring include: power of 5W to 10W, pulse frequency of 800Hz to 1000Hz, pulse width of 0.5ms to 1ms, and stirring time of 30 to 60min.

[0016] Preferably, the conditions for vapor deposition include: the carbon source is methane, the gas flow rate is 200-400 sccm, the deposition temperature is 500-700° C., and the deposition time is 1-3 hours.

[0017] Preferably, the aluminum-bismuth particles are removed by acid immersion, the acid is preferably a 5-6 mol / L hydrochloric acid solution, and the immersion time is 36-48 hours.

[0018] Preferably, the mass ratio of metallic lithium to carbon nanotube-loaded nanocarbon microspheres is 0.5-1:1-2, the melting temperature of metallic lithium is 200-350° C., and the lithiation reaction time is 1-2 hours, preferably 1.5 hours.

[0019] In a specific embodiment, the preparation method of the carbon nanotube-supported nano-lithiated carbon microsphere conductive agent is as follows Figure 1 As shown, the following steps are included:

[0020] S1: Preparation of carbon nanotube-loaded nano-alloy aluminum-bismuth particles by laser stirring method: 200-400 mg of carbon nanotubes and 100-200 mg of aluminum-bismuth alloy are placed in a container, and laser stirring parameters are set: power is 5W-10W, pulse frequency is 800Hz-1000Hz, pulse width is 0.5ms-1ms, and reaction time is 30-60min, to obtain carbon nanotube-loaded nano-alloy aluminum-bismuth particles;

[0021] S2: Preparation of metal-deposited nano-carbon microspheres by vapor deposition: 300-600 mg of the carbon nanotube-loaded nano-alloy aluminum-bismuth particles in step S1 above are placed in a reaction porcelain boat, placed in a tubular furnace, and methane (CH4) is used as a carbon source. The gas flow rate is 200-400 sccm, the reaction temperature is 500-700°C, and the reaction time is 1-3 hours. After cooling to room temperature, the metal-deposited nano-carbon microspheres are obtained;

[0022] S3: Preparation of carbon nanotube-loaded nanocarbon microspheres by chemical dealloying: 200-400 mg of the powder in step S2 is placed in a beaker, 40-60 mL of 5-6 mol / L hydrochloric acid (HCl) solution is added, and the mixture is soaked for reaction for 36-48 h to remove the metal aluminum and bismuth. After the reaction is completed, the mixture is washed and dried to obtain carbon nanotube-loaded nanocarbon microspheres;

[0023] S4: Preparation of carbon nanotube-loaded lithiated carbon microspheres by melting method: 100-200 mg of carbon nanotube-loaded nanocarbon microspheres obtained in step S3 are placed in a reaction porcelain boat, 50-100 mg of lithium is melted at 200-350°C, and the molten lithium is slowly poured onto the carbon nanotube-loaded nanocarbon microspheres. The reaction time is 1-2 hours, and the carbon nanotube-loaded lithiated carbon microspheres are formed after cooling to room temperature.

[0024] The preparation principle of the present invention is as follows Figure 2 As shown, the lithium-bismuth alloy and the carbon nanotubes are adsorbed and bonded, and the alloy particles are loaded on the surface of the carbon nanotubes. Subsequently, the carbon microspheres are loaded on the outside of the metal particles by vapor deposition. In addition to the metal-carbon bond, there is also a carbon-carbon bond, which makes the carbon microspheres stably loaded on the surface of the carbon nanotubes and the metal alloy. Then, the chemical dealloying method is used to remove the alloy particles coated inside the carbon microspheres to obtain the carbon nanotube-loaded carbon microsphere material. Finally, the prepared carbon nanotube-loaded carbon microsphere material is subjected to lithium treatment, which not only improves the stability of the material structure, but also provides lithium ions for the reaction, thereby increasing the service life of the battery cell.

[0025] In a second aspect, the present invention provides a carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent, which is prepared by the above-mentioned preparation method.

[0026] In a third aspect, the present invention provides a lithium-ion battery prepared from the above-mentioned carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent.

[0027] In one embodiment, the preparation method of a lithium ion battery comprises the following steps:

[0028] S1': preparing positive and negative electrode slurries of lithium-ion batteries respectively, wherein the positive electrode slurry comprises solid components and solvents, and the solid components comprise positive electrode materials, adhesives and conductive agents; the negative electrode slurry comprises solid components and solvents, and the solid components comprise negative electrode materials, adhesives, thickeners and conductive agents;

[0029] Preferably, the positive electrode material in the positive electrode slurry is lithium iron phosphate, the binder is polyvinylidene fluoride, and the conductive agent is the above-mentioned carbon nanotube-loaded lithiated carbon microspheres;

[0030] Preferably, the mass percentages of the components in the positive electrode slurry are respectively positive electrode material (96-98%), binder (1-2%) and conductive agent (1-2%).

[0031] Preferably, the negative electrode material in the negative electrode slurry is graphite, the binder is styrene-butadiene rubber, the thickener is sodium carboxymethyl cellulose, and the conductive agent is the above-mentioned carbon nanotube-loaded lithiated carbon microspheres;

[0032] Preferably, the mass percentages of the components in the negative electrode slurry are respectively negative electrode material (94-97%), binder (1-2%), thickener (1-2%) and conductive agent (1-2%).

[0033] S2': coating the positive and negative electrode slurries on the positive and negative electrode current collectors respectively to prepare positive and negative electrode sheets;

[0034] Preferably, the positive electrode current collector is aluminum foil, and the negative electrode current collector is copper foil.

[0035] Preferably, the positive and negative electrode slurries are coated on the positive and negative electrode current collectors respectively, and the positive and negative electrode sheets are obtained through rolling, slitting, die-cutting and baking.

[0036] S3': stacking, packaging, injecting, soaking, forming, degassing, aging, capacity testing and sorting the positive and negative electrode sheets and separators to obtain a lithium-ion battery.

[0037] Preferably, the positive electrode and the negative electrode are separated by a separator, and the electrolyte, the separator, the positive electrode and the negative electrode are located inside the shell. The conductive agent is the novel conductive agent material prepared in the present invention.

[0038] Preferably, the lithium-ion battery is a three-electrode soft pack, a square soft pack or a square shell.

[0039] Technical effects:

[0040] The present invention realizes the effective combination of carbon nanotubes and nano alloy aluminum bismuth through laser stirring method, forms relatively stable metal-carbon bonding, effectively improves the electrical conductivity and mechanical strength of the material, and provides sufficient metal binding sites for subsequent carbon microsphere adsorption. Secondly, the vapor deposition method deposits nano carbon microspheres on the metal surface, further enhancing the structural stability and electrical conductivity of the composite material. Subsequently, the aluminum bismuth metal is removed by chemical dealloying to obtain a pure carbon-based material, which not only retains the excellent properties of carbon nanotubes and nano microspheres, but also removes the internal alloy to obtain hollow nano microspheres, thereby improving the specific surface area and stable lithium insertion vacancies of the material. Finally, the lithium loading is realized by melting method, and the loaded lithium not only improves the structural stability of the composite material, but also the internal lithium metal provides lithium ion reserves for subsequent cycles, improves the subsequent cycle performance, and prepares lithiated carbon microspheres with good lithium ion migration.

[0041] The conductive agent prepared by the present invention not only improves the overall performance of lithium-ion batteries, but also ensures safety, providing new ideas and directions for the research and development of conductive agents for future high-performance lithium batteries.

[0042] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention is a flow chart for preparing the carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent;

[0044] Figure 2 This is a schematic diagram of the preparation principle of the carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent of the present invention. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0046] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, methods in the art.

[0047] The specific specification of aluminum-bismuth alloy is a product with 10% Bi content.

[0048] Example 1

[0049] Preparation of carbon nanotube-loaded lithiated carbon microsphere conductive agent:

[0050] First, the laser stirring method was used to prepare carbon nanotube-loaded nano alloy aluminum-bismuth particles. 300 mg of carbon nanotubes (powder: 200-300 mg / cm2) were taken. 2 / g, average tube diameter 7-11nm), 150mg aluminum-bismuth alloy in a container. Set the laser stirring parameters: power 7W, pulse frequency 900Hz, pulse width 0.7ms, reaction time 45min, and carbon nanotube-loaded nano alloy aluminum-bismuth particles can be obtained.

[0051] Secondly, the metal-deposited carbon nanospheres were prepared by vapor deposition. 400 mg of carbon nanotube-loaded nano-alloy aluminum-bismuth particles were added to a reaction porcelain boat and placed in a tube furnace. Methane (CH4) was used as the carbon source, the gas flow rate was 300 sccm, the reaction temperature was 600°C, the reaction time was 2 h, and the metal-deposited carbon nanospheres were obtained after cooling to room temperature.

[0052] Next, the carbon nanotube-loaded nanocarbon microspheres were prepared by chemical dealloying. 300 mg of metal-deposited nanocarbon microsphere powder was placed in a beaker, 50 mL of 6 mol / L hydrochloric acid (HCl) solution was added, and the mixture was soaked for 48 hours to remove the metal aluminum and bismuth. After the reaction was completed, the carbon nanotube-loaded nanocarbon microspheres were washed and dried to obtain the carbon nanotube-loaded nanocarbon microspheres.

[0053] Finally, carbon nanotube-loaded lithiated carbon microspheres were prepared by melting method. 200 mg of carbon nanotube-loaded nanocarbon microspheres were placed in a reaction porcelain boat, 100 mg of lithium was melted at 350 °C, and the molten lithium was slowly poured onto the carbon nanotube-loaded nanocarbon microspheres. The reaction time was 1.5 h, and carbon nanotube-loaded lithiated carbon microspheres were formed after cooling to room temperature.

[0054] Preparation of lithium-ion batteries:

[0055] Dissolve 100g of polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP) solvent, and then add lithium iron phosphate (LiFePO4) positive electrode material and carbon nanotube-loaded lithiated carbon microsphere conductive agent and mix them evenly. Among them, the lithium-ion battery positive electrode slurry is LiFePO4 (98%), PVDF (1%) and conductive agent (1%) according to weight percentage. Dissolve 100g of sodium carboxymethyl cellulose (CMC) in deionized water, and then add negative electrode material graphite, carbon nanotube-loaded lithiated carbon microsphere conductive agent, and styrene-butadiene rubber (SBR) and mix them evenly. Among them, the lithium-ion battery negative electrode slurry is graphite negative electrode material (97%), carbon nanotube-loaded lithiated carbon microsphere (1%), CMC (1%) and SBR (1%) according to weight percentage.

[0056] The obtained positive electrode slurry of lithium-ion battery is coated on aluminum foil current collector, and the negative electrode slurry is coated on copper foil current collector. Finally, the positive and negative electrode sheets are manufactured through rolling, slitting, die-cutting and baking.

[0057] The positive and negative electrode sheets are assembled with a separator, an electrolyte (1 mol / L LiPF6, i.e., solute: lithium hexafluorophosphate (LiPF6), solvent: ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1) and a shell into a lithium-ion battery.

[0058] Example 2

[0059] The preparation method of this embodiment is different from that of embodiment 1 only in that the molten lithiation reaction time is changed to 1 hour.

[0060] Example 3

[0061] The preparation method of this embodiment is different from that of embodiment 1 only in that the molten lithiation reaction time is changed to 2 hours.

[0062] Comparative Example 1

[0063] A lithium ion battery was prepared according to the method of Example 1 using carbon nanotubes (NMP series conductive paste: carbon nanotube solid content 2.8±0.15%) as a conductive agent.

[0064] Comparative Example 2

[0065] A lithium ion battery was prepared according to the method of Example 1 using conductive carbon black as a conductive agent.

[0066] Comparative Example 3

[0067] A lithium ion battery was prepared according to the scheme of Example 1 using carbon nanotubes + conductive carbon black as a mixed conductive agent, and the ratio of the mixed conductive agent was carbon nanotubes: conductive carbon black = 0.6%: 0.4%.

[0068] Test example:

[0069] The specific surface area of ​​the carbon nanotube-loaded lithiated carbon microspheres prepared in the examples and comparative examples was measured, and the internal resistance, 2C rate charge, 3C rate discharge, room temperature cycle retention rate, and high temperature cycle retention rate of the further prepared lithium ion battery were tested. The test method is as follows:

[0070] The internal resistance is tested using a DC internal resistance device, and the 2C rate charge, 3C rate discharge, and normal temperature (25°C) / high temperature (45°C) cycles are all tested using Qingyan equipment. The positive and negative poles of the charging and discharging equipment are connected to the positive and negative poles of the battery for charging and discharging tests at different rates, and the normal / high temperature cycles are tested using the 1C / 1C standard.

[0071] The results are shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] The lithium ion battery conductive agents of the embodiments all have good properties, mainly in the conductive agent specific surface area, lithium ion battery internal resistance, 2C rate charging, 3C rate discharging, room temperature cycle retention rate, high temperature cycle retention rate test items performance is higher than the comparative example, indicating that the carbon nanotube loaded lithiated carbon microsphere conductive agent material prepared by the present invention, due to its high specific surface area and good conductivity, effectively reduces the internal resistance of the battery, is conducive to the rapid migration of lithium ions during the charging and discharging process, so that the lithium ion battery exhibits excellent electrical properties at high rates, and both room temperature cycles and high temperature cycles show a high retention rate. Further, the effect of Example 1 is better than that of Examples 2-3, indicating that the lithiation time has a significant effect on the material properties, as shown in the following three points:

[0076] ① Lithium reaction degree: Too short lithiation time may lead to insufficient reaction between lithium and carbon microspheres, poor stability of the formed composite material, and possible decline in cycle performance. Too long lithiation time may lead to excessive reaction of lithium, forming lithium byproducts or lithium aggregation, affecting the structural stability and electrochemical performance of the material.

[0077] ② Microstructure of the material: Changes in lithiation time will affect the microstructure of the material, such as porosity, specific surface area, etc. These characteristics directly affect the material's electrical conductivity and lithium storage capacity.

[0078] ③Electrochemical properties: Different lithiation times will lead to different electrochemical properties of lithiated carbon microspheres (such as specific capacity, cycle stability, etc.). Appropriate lithiation time can optimize these properties, while too short or too long time may lead to performance degradation.

[0079] In summary, lithiation time is a key factor affecting the performance of carbon nanotube-loaded lithiated carbon microspheres, and needs to be optimized through experiments to obtain the best material properties.

[0080] From the above, it can be concluded that the present invention has good electrochemical performance when the lithiation time is 1.5h.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A method for preparing a carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent, characterized in that: The following steps are involved: The carbon nanotubes and aluminum-bismuth alloy are mixed and laser stirred to obtain carbon nanotube-loaded nano-alloy aluminum-bismuth particles; carbon microspheres are vapor-deposited on the carbon nanotube-loaded nano-alloy aluminum-bismuth particles, and then the aluminum-bismuth particles are removed to obtain carbon nanotube-loaded nano-carbon microspheres; metallic lithium is melted and then poured onto the carbon nanotube-loaded nano-carbon microspheres for a lithiation reaction to obtain carbon nanotube-loaded nano-lithiated carbon microspheres.

2. The preparation method according to claim 1, characterized in that: The mass ratio of carbon nanotubes to aluminum-bismuth alloy is 2-4:1-2.

3. The preparation method according to claim 1, characterized in that: The conditions of laser stirring include: power of 5W to 10W, pulse frequency of 800Hz to 1000Hz, pulse width of 0.5ms to 1ms, and stirring time of 30 to 60min.

4. The preparation method according to claim 1, characterized in that: The conditions for vapor deposition include: the carbon source is methane, the gas flow rate is 200-400 sccm, the deposition temperature is 500-700° C., and the deposition time is 1-3 hours.

5. The preparation method according to claim 1, characterized in that: The aluminum-bismuth particles are removed by acid immersion for 36 to 48 hours.

6. The preparation method according to claim 1, characterized in that: The mass ratio of metallic lithium to carbon nanotube-loaded nanocarbon microspheres is 0.5-1:1-2.

7. The preparation method according to claim 1, characterized in that: The melting temperature of metallic lithium is 200-350°C, and the lithiation reaction time is 1-2h.

8. A carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. A lithium ion battery, characterized in that: The lithium-ion battery is prepared by the carbon nanotube-loaded nano-lithiated carbon microsphere conductive agent according to claim 8.

10. The lithium ion battery according to claim 9, characterized in that: The preparation method of a lithium-ion battery comprises the following steps: S1': preparing positive and negative electrode slurries of lithium-ion batteries respectively, wherein the positive electrode slurry comprises solid components and solvents, and the solid components comprise positive electrode materials, adhesives and conductive agents; the negative electrode slurry comprises solid components and solvents, and the solid components comprise negative electrode materials, adhesives, thickeners and conductive agents; S2': coating the positive and negative electrode slurries on the positive and negative electrode current collectors respectively to prepare positive and negative electrode sheets; S3': stacking the positive electrode, negative electrode sheets and separator to obtain a lithium-ion battery.

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