A method for preparing a sub-micron ti2ctx lithium-ion battery anode with high yield and high capacity

Abstract

This invention relates to the field of lithium-ion batteries, specifically to a submicron Ti2CT with high yield and high capacity. x A method for preparing a lithium-ion battery negative electrode. The method includes the following steps: (1) synthesizing submicron Ti2AlC using a molten salt method; (2) using submicron Ti2AlC as the etching target, adding a polyol to an acidic etching solution to prepare submicron Ti2CT. x (3) Using Ti2CT x The submicron Ti2CT prepared in this invention was used as an anode to characterize its electrochemical performance in lithium-ion batteries. x The yield and chemical stability were significantly improved, resulting in a substantial increase in electrochemical performance when used as a lithium-ion battery anode material. Furthermore, the process is simple and easy to operate. Therefore, this invention solves the problem of preparing submicron Ti2CT. x The process presents challenges such as low yield and easy oxidative degradation. This invention is applicable to the preparation of various maicoene materials, especially some maicoene materials that are easily oxidized and degraded.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, specifically to a submicron Ti2CT with high yield and high capacity. x Methods for preparing the negative electrode of a lithium-ion battery. Background Technology

[0002] With the rapid development of industries such as electric vehicles and portable electronic devices, people have increasingly higher requirements for the fast charging and discharging capabilities of lithium-ion batteries (Weiss M., Ruess R., Kasnatscheew J., et al. Fast Charging of Lithium-Ion Batteries: A Review of Materials Aspects[J]. Advanced Energy Materials, 2021, 11(33): 2101-126.). Charging time has become one of the important indicators for devices powered by lithium-ion batteries, such as electric vehicles and mobile phones. The fast charging and discharging capabilities of lithium-ion batteries mainly depend on the rate performance of the positive and negative electrode materials. At present, materials with high rate performance, such as nano-lithium iron phosphate, have been developed for the positive electrode, while the rate performance of graphite, which is commonly used for the negative electrode, is difficult to meet the current requirements. Excessively fast charging speeds cause lithium metal to deposit on the surface of graphite particles. On the one hand, this hinders the diffusion of lithium ions into the graphite interlayer, reducing capacity. On the other hand, it easily forms lithium dendrites, which can puncture the separator, causing short circuits, leading to thermal runaway and even explosions (Cai W., Yan C., Yao YX, et al. The Boundary of Lithium Plating in Graphite Electrode for Safe Lithium-Ion Batteries[J]. Angewandte Chemie International Edition, 2021, 60(23): 13007-12.). Therefore, it is urgent to develop a new generation of novel anode materials with excellent rate performance and good safety performance.

[0003] To overcome the bottlenecks in anode materials, researchers have been continuously exploring breakthroughs and conducting extensive scientific research. Recently, a novel two-dimensional layered compound, MXene, has emerged, exhibiting excellent rate performance due to its unique structure and properties, and is expected to become a next-generation anode material for lithium-ion batteries. (The text then abruptly shifts to a seemingly unrelated topic: Ti2CT...) x Maicoene, represented by [a specific enzyme name], boasts the highest theoretical specific capacity of 383 mAh g. -1(Xie Y., Naguib M., Mochalin VN, et al. Role of SurfaceStructure onLi-Ion Energy Storage Capacity of Two-Dimensional Transition-Metal Carbides[J]. Journal of the American Chemical Society, 2014, 136(17):6385-94.). However, Ti2CT x The rate performance depends on the length of the lithium-ion diffusion path and the size of the specific surface area available for adsorption. Therefore, the control of Ti2CT by synthesizing submicron Ti2AlC is crucial. x The grain size of maicoene is a key factor in solving Ti2CT. x An effective means to improve rate performance. Traditional high-temperature synthesis of Ti2AlC leads to rapid grain growth, making the preparation of submicron-sized Ti2AlC challenging. Researchers have demonstrated that submicron-sized Ti2AlC can be synthesized using nanoscale carbon black, aluminum, and titanium hydride as raw materials via a molten salt method. Etching the submicron-sized Ti2AlC yields submicron Ti2CT. x (Cui C.,Dai R.,Zhang C.,et al.Submicron Ti2CT x MXene Particulates as High-Rate Intercalation Anode Materials for Li-Ion Batteries[J]. Journal of Materials Chemistry A, 2022, 10(29): 15474-84). However, in the preparation of Ti2CT using submicron Ti2AlC... x The process exhibits high reactivity, readily etching away surface Ti atoms to form Ti vacancies or vacancy clusters. Furthermore, Ti2CT... x The layers are relatively thin and have low chemical stability (Liu S., Liu J., Liu X., et al. Hydrogen Storage in Incompletely Etched Multilayer Ti2CT). x at RoomTemperature[J].Nature Nanotechnology,2021,16(3):331-6.). Therefore, in the preparation of submicron Ti2CT x The process still faces challenges such as low yield and easy oxidation and degradation. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a submicron Ti2CT with high yield and high capacity. x A method for preparing lithium-ion battery anodes has been developed, solving the problem of preparing submicron Ti2CT. x The process still faces challenges such as low yield and easy oxidation and degradation, but the electrochemical performance has also been significantly improved, which can meet the requirements of future new energy electric vehicles.

[0005] The technical solution of this invention is:

[0006] A submicron Ti2CT with high yield and high capacity x The preparation method of the lithium-ion battery anode involves first synthesizing submicron Ti2AlC using the molten salt method; then, synthesizing submicron Ti2CT using a polyol-assisted etching method. x Submicron Ti2CT x Mix with conductive agent and binder to form a uniform slurry, coat it with current collector and dry it in a vacuum oven, then cut and assemble it into a button cell.

[0007] The aforementioned submicron Ti2CT with high yield and high capacity x The specific steps for preparing the negative electrode of a lithium-ion battery are as follows:

[0008] (1) Submicron Ti2AlC was synthesized by molten salt method using Ti powder, Al powder and carbon black as reactants;

[0009] (2) Using submicron Ti2AlC as the etching target, submicron Ti2CT was prepared by polyol-assisted etching. x ;

[0010] (3) Submicron Ti2CT x The mixture is mixed with conductive agent and binder to form a uniform slurry, coated onto current collector and dried in a vacuum oven, cut into pieces and assembled into coin cells, and its electrochemical performance is tested.

[0011] The aforementioned submicron Ti2CT with high yield and high capacity xIn the preparation method of lithium-ion battery negative electrode, in step (1), the molar ratio of Ti, Al and C in the reactants used to synthesize submicron Ti2AlC is (1.90~2.10):(0.95~1.10):(0.70~0.90); at least two of KCl, NaCl and LiCl are used as molten salt media, the molar ratio of KCl, NaCl and LiCl is (0~2.10):(0~2.10):(0~2.10), the mass ratio of reactants to molten salt media is (0.5~2.50):(3.50~5.50), the molten salt media and reactants are dispersed in anhydrous ethanol and mixed, and the mixing ball milling time is 5~20h to form a reactant containing molten salt media.

[0012] The aforementioned submicron Ti2CT with high yield and high capacity x In the preparation method of lithium-ion battery anode, in step (1), when synthesizing submicron Ti2AlC, the reactants containing molten salt medium are heated in a tube furnace at a temperature of 900-1200℃ and a holding time of 0.5-5h, and the prepared submicron Ti2AlC grain size is 100-500nm.

[0013] The aforementioned submicron Ti2CT with high yield and high capacity x In the preparation method of the negative electrode of a lithium-ion battery, in step (2), the polyol is one or more of ethylene glycol, propylene glycol, glycerol, and polyglycerol, and the acidic etching solution is one or two of hydrofluoric acid or hydrochloric acid + lithium fluoride, with a concentration of 5-12 mol / L. -1 Wherein: hydrochloric acid + lithium fluoride is a hydrochloric acid solution of lithium fluoride, and the concentration of lithium fluoride is 3-10 mol / L. -1 The volume ratio of acidic solution to polyol was (0.5–2.00):(0.5–5.00), the reaction temperature was 25–35℃, and the reaction time was 0.5–15 days, to prepare submicron Ti2CT. x The grain size is 100–500 nm.

[0014] The aforementioned submicron Ti2CT with high yield and high capacity x In the preparation method of the negative electrode of a lithium-ion battery, in step (3), submicron Ti2CT x It is mixed with conductive agent Super P and binder polyvinylidene fluoride in a mass ratio of (7-9):(0.5-1.5):(0.5-1.5), and ground and mixed evenly with N-methylpyrrolidone as dispersant. N-methylpyrrolidone accounts for 80-97% of the total mass of the slurry.

[0015] The aforementioned submicron Ti2CT with high yield and high capacity xPreparation method of lithium-ion battery anode, submicron Ti2CT x The performance parameters of the lithium-ion battery anode material are as follows: at a 0.05C rate, the specific charging capacity is 300–500 mAh g. -1 At a 5C rate, the charging specific capacity is 100–300 mAh g. -1 After 400 cycles at 1C, the charging specific capacity is 100-300mAh g. -1 .

[0016] The design concept of this invention is:

[0017] This invention introduces polyols (such as ethylene glycol, propylene glycol, glycerol, polyglycerol, etc.) into an acidic etching solution. This not only slows down the etching rate but also allows for selective adsorption onto Ti-C sheets, masking defects and edges, thus creating a stable submicron Ti2CT. x The structure acts as a "fortress," inhibiting its oxidative degradation.

[0018] In addition, the present invention uses a specific acidic etching solution, which is one or two of hydrofluoric acid or hydrochloric acid + lithium fluoride. The hydrochloric acid + lithium fluoride solution is a hydrochloric acid solution of lithium fluoride. The role of lithium fluoride is: it can form hydrofluoric acid in situ with hydrochloric acid, which can effectively slow down the etching reaction. At the same time, it can spontaneously intercalate, increase the interlayer spacing, and facilitate lithium ion diffusion.

[0019] The advantages and beneficial effects of this invention are:

[0020] 1. This invention utilizes the ability of hydroxyl groups on polyols to interact with Ti-C sheets and their tendency to adsorb onto Ti2CT. x The defects and edges of the maicoene are protected from attack by water molecules and dissolved oxygen in the etching solution during the etching process, thus inhibiting its oxidative degradation. This fundamentally solves the problem of submicron Ti2CT. x The fundamental challenges are low yield and poor chemical stability.

[0021] 2. The polyol in this invention affects submicron Ti2CT x The rate performance and specific capacity are significantly improved.

[0022] 3. Preparation of submicron Ti2CT using this invention x With high yield and chemical stability, submicron Ti2CT x The yield of the battery anode material is increased by more than 50% compared to that without the addition of polyols. This polyol-assisted etching method can be applied to other easily oxidized two-dimensional layered materials, and has broad application prospects.

[0023] 4. This invention is applicable to the preparation of various submicron maicoene materials, especially some maicoene materials that are easily oxidized and degraded. Attached Figure Description

[0024] Figure 1 The image shows the XRD pattern of submicron Ti2AlC prepared in Example 1; in the figure, the horizontal axis 2θ represents the diffraction angle (°) and the vertical axis Intensity represents the diffraction peak intensity (au).

[0025] Figure 2 This is a transmission electron microscope image of the submicron Ti2AlC prepared in Example 1.

[0026] Figure 3 Submicron Ti2CT in Example 1 x The XRD pattern is shown; in the figure, the horizontal axis 2θ represents the diffraction angle (°), and the vertical axis Intensity represents the diffraction peak intensity (au).

[0027] Figure 4 Submicron Ti2CT in Example 1 x The charge / discharge curves are shown; in the figure, the horizontal axis Capacity represents the capacity (mAh / g). -1 The vertical axis, Voltage, represents voltage (V vs. Li / Li). + ).

[0028] Figure 5 Submicron Ti2CT in Example 1 x The rate performance test chart shows that the horizontal axis (Cycle number) represents the number of cycles, and the left vertical axis (Charge capacity) represents the specific charging capacity (mAh g). -1 The right vertical axis, Coulombicefficiency, represents the Coulomb efficiency (%).

[0029] Figure 6 Submicron Ti2CT in Example 1 x Cyclic stability test graph; in the graph, the horizontal axis Cycle number represents the number of cycles, and the left vertical axis Charge capacity represents the specific charging capacity (mAh g). -1 The right vertical axis, Coulombicefficiency, represents the Coulomb efficiency (%).

[0030] Figure 7 Submicron Ti2CT in Example 2 x The charge / discharge curves are shown; in the figure, the horizontal axis Capacity represents the specific capacity (mAh g). -1 The vertical axis, Voltage, represents voltage (V vs. Li / Li).+ ).

[0031] Figure 8 Submicron Ti2CT in Example 2 x Rate performance test chart; in the chart, the horizontal axis Cycle number represents the number of cycles, and the left vertical axis Charge capacity represents the charging specific capacity (mAh g). -1 The right vertical axis, Coulombicefficiency, represents the Coulomb efficiency (%).

[0032] Figure 9 Submicron Ti2CT in Example 2 x Cyclic stability test graph; in the graph, the horizontal axis Cycle number represents the number of cycles, and the left vertical axis Charge capacity represents the specific charging capacity (mAh g). -1 The right vertical axis, Coulombicefficiency, represents the Coulomb efficiency (%). Detailed Implementation

[0033] In practical implementation, this invention proposes a submicron Ti2CT with high yield and high capacity. x The preparation method of lithium-ion battery negative electrode includes the following steps: (1) using Ti powder, Al powder and carbon black as reactants, submicron Ti2AlC is synthesized by molten salt method; (2) using submicron Ti2AlC as etching target, a polyol is introduced into the acidic etching solution, and submicron Ti2CT is prepared by polyol-assisted etching method. x (3) Using submicron Ti2CT x As a negative electrode material for lithium-ion batteries, submicron Ti2CT x A homogeneous slurry was prepared by mixing the conductive agent and binder, coated onto the current collector, and dried in a vacuum oven. The slurry was then cut into wafers and assembled into coin cells. The electrochemical performance was then tested. This method not only solves the problem of submicron Ti2CT... x The preparation process presents challenges such as low yield and poor chemical stability, but the preparation process is simple, quick, and easy to commercialize.

[0034] To make the contents of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, the following embodiments are merely simple examples of this invention and do not represent or limit the scope of protection of this invention. The scope of protection of this invention is determined by the claims.

[0035] The feasibility of the present invention will be further verified below through examples.

[0036] Example 1

[0037] In this embodiment, a submicron Ti2CT with high yield and high capacity is described. x The preparation method of lithium-ion battery negative electrode is as follows:

[0038] (1) First, the synthesis of submicron Ti₂AlC: 9.57 g of Ti powder, 2.83 g of Al powder, 0.96 g of C powder, 29.97 g of KCl, and 23.50 g of NaCl were dispersed in 100 mL of anhydrous ethanol and ball-milled for 10 h. After drying, the mixture was placed in a tube furnace and kept at 1000 °C for 1 h. After cooling, NaCl and KCl were washed away, and the mixture was dried for later use. Figure 1 As shown, Ti2AlC was obtained as a pure phase, and the synthesized Ti2AlC was a sheet with a diameter of approximately 200 nm. Figure 2 As shown.

[0039] (2) Submicron Ti2CT x Preparation: First, prepare an acidic mixture of ethylene glycol and hydrofluoric acid, with a hydrofluoric acid concentration of 22.4 mol / L. -1 Ethylene glycol and hydrofluoric acid stock solution were mixed at a volume ratio of 1:1. 1 g of submicron Ti₂Al₃ was slowly added to 10 mL of the acidic mixture. The reaction temperature was 25 °C, and the reaction time was 1 day, until no more bubbles were generated. The mixture was then washed, filtered, and dried for later use. The resulting submicron Ti₂Al₃ was then ready for use. x The grain size is 200nm.

[0040] like Figure 3 As shown, the submicron Ti2CT in Example 1 x The XRD pattern shows that all the Al atoms in Ti2AlC have been etched away, and the interlayer spacing has increased significantly, which is conducive to the diffusion of lithium ions between layers.

[0041] (3) Submicron Ti2CT x Battery anode material preparation: First, submicron Ti2CT... x Super P and polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 8:1:1, and N-methylpyrrolidone (NMP) was used as a dispersant to grind and mix into a slurry. NMP accounted for 94% of the total slurry mass. The slurry was uniformly coated onto copper foil and dried in a vacuum oven at 140℃ for 12 hours. Then, the foil was cut and assembled into coin cells, and its electrochemical performance was tested. Submicron Ti2CT was obtained by ethylene glycol-assisted etching. x High chemical stability effectively reduces the surface Ti vacancy concentration of Ti-C sheets, exhibiting excellent electrochemical performance: such as Figure 4 As shown, at a charging rate of 0.05C, the specific charging capacity reaches 243mAh g. -1 Even at a high 5C charging rate, the charging capacity remains at 124mAh.-1 It exhibits excellent electrochemical performance. For example... Figure 5 As shown, this material exhibits excellent rate performance, submicron Ti2CT x It not only exhibits excellent rate performance but also high cycle stability. For example... Figure 6 As shown, after 400 cycles at a high 1C rate, the charging capacity still reaches 195mAh. -1 The capacity shows almost no decay. Meanwhile, submicron Ti2CT... x The yield of battery anode materials is increased by 50% compared to when no polyols are added.

[0042] Example 2

[0043] In this embodiment, a submicron Ti2CT with high yield and high capacity is described. x The preparation method of lithium-ion battery negative electrode is as follows:

[0044] The only difference from Example 1 is that glycerol was used as the auxiliary etching polyol. This was applied to the preparation of submicron Ti2CT using glycerol-assisted etching. x At that time, glycerol can better mask Ti2CT. x The defects and edges at which the reaction speed is slowed down more significantly, and the Ti2CT is also reduced. x Defect concentration significantly improves electrochemical performance while increasing yield and chemical stability: for example Figure 7 As shown, at a charging rate of 0.05C, the specific charging capacity reaches 591mAh g. -1 Even at a high 5C charging rate, the charging capacity remains at 196mAh g. -1 Its high-rate performance surpasses that of currently commercially available graphite. For example... Figure 8 As shown, this material exhibits excellent rate performance. Figure 9 As shown, submicron Ti2CT x It not only exhibits excellent rate performance but also high cycle stability, maintaining a charging capacity of 181mAh g after 400 cycles at 1C. -1 Meanwhile, submicron Ti2CT x The yield of battery anode materials is nearly 85% higher than that without the addition of polyols.

[0045] Example 3

[0046] In this embodiment, a submicron Ti2CT with high yield and high capacity is described. x The preparation method of lithium-ion battery negative electrode is as follows:

[0047] (1) Synthesis of submicron Ti2AlC: Same as step (1) in Example 1, except that the temperature for preparing submicron Ti2AlC is 900℃ and held for 3h.

[0048] (2) Submicron Ti2CT x Preparation: Same as step (2) in Example 1, except that hydrochloric acid and lithium fluoride are selected as acidic etching solutions, wherein: the concentration of hydrochloric acid is 12 mol / L. -1 The concentration of lithium fluoride is 5.0 mol L. -1 .

[0049] This embodiment prepares submicron Ti2CT. x The performance parameters of the battery negative electrode material are as follows: at a 0.1C rate, the charging specific capacity is 465 mAh g. -1 Even at a 5C rate, the charging capacity is still 215mAh. -1 After 400 cycles at a 1C rate, the charging capacity is only 235mAh g. -1 Meanwhile, submicron Ti2CT x The yield of battery anode materials is increased by 70% compared to those without polyols.

[0050] Example 4

[0051] In this embodiment, a submicron Ti2CT with high yield and high capacity is described. x The preparation method of lithium-ion battery negative electrode is as follows:

[0052] (1) Synthesis of submicron Ti2AlC: Same as step (1) in Example 1, except that the temperature for preparing submicron Ti2AlC is 1100℃ and held for 0.5h.

[0053] (2) Submicron Ti2CT x Preparation: Same as step (2) in Example 1, except that propylene glycol is mixed with acidic etching solution.

[0054] This embodiment prepares submicron Ti2CT. x The performance parameters of the battery negative electrode material are as follows: at a 0.1C rate, the charging specific capacity is 445 mAh g. -1 Even at a 5C rate, the charging capacity is still 203mAh. -1 After 400 cycles at a 1C rate, the charging capacity is only 220mAh g. -1 Meanwhile, submicron Ti2CT x The yield of battery anode materials is increased by 80% compared to when no polyols are added.

[0055] Example 5

[0056] In this embodiment, a submicron Ti2CT with high yield and high capacity is described. x The preparation method of lithium-ion battery negative electrode is as follows:

[0057] (1) Synthesis of submicron Ti2AlC: Same as step (1) in Example 1.

[0058] (2) Submicron Ti2CT x Preparation: Same as step (2) in Example 1, except that ethylene glycol and glycerol are selected as auxiliary additives and mixed in a volume ratio of 1:1. Then, the mixed polyol is mixed with acidic etching solution in a volume ratio of 2:1 to etch submicron Ti2AlC.

[0059] (3) Submicron Ti2CT x Battery negative electrode material preparation: Same as step (3) in Example 1, at a charging rate of 0.1C, the charging specific capacity is as high as 495mAhg. -1 Even at a 5C rate, the charging capacity is still 275mAh g. -1 After 400 cycles at a 1C rate, the charging specific capacity reaches 208mAh g. -1 Meanwhile, submicron Ti2CT x The yield of battery anode materials is nearly 80% higher than that without the addition of polyols.

[0060] Example 6

[0061] In this embodiment, a submicron Ti2CT with high yield and high capacity is described. x The preparation method of lithium-ion battery negative electrode is as follows:

[0062] (1) Synthesis of submicron Ti2AlC: Same as step (1) in Example 1.

[0063] (2) Submicron Ti2CT x Preparation: Same as step (2) in Example 1, except that ethylene glycol, propylene glycol and glycerol are used as auxiliary additives and mixed in a volume ratio of 1:1:1. Then the mixed polyols are mixed with acidic etching solution in a volume ratio of 3:1 to etch submicron Ti2AlC.

[0064] (3) Submicron Ti2CT x Battery negative electrode material preparation: Same as step (3) in Example 1, at a charging rate of 0.1C, the charging specific capacity is as high as 475mAhg. -1 Even at a 5C rate, the charging capacity is still 245mAh g. -1 After 400 cycles at 1C rate, the charging specific capacity reaches 190mAh g. -1 Meanwhile, submicron Ti2CTx The yield of battery anode materials is nearly 80% higher than that without the addition of polyols.

[0065] Comparative Example 1

[0066] In this comparative example, a submicron Ti2CT with high yield and high capacity is described. x The preparation method of lithium-ion battery negative electrode is as follows:

[0067] (1) Synthesis of submicron Ti2AlC: Same as step (1) in Example 1.

[0068] (2) Submicron Ti2CT x Preparation: Same as step (2) in Example 1, except that no polyol is added.

[0069] (3) Submicron Ti2CT x Battery negative electrode material preparation: Same as step (3) in Example 1. At a 0.1C rate, the charging specific capacity is only 195 mAh g. -1 At a 5C rate, the charging capacity is only 105mAh g. -1 After 400 cycles at a 1C rate, the charging capacity is only 158mAh g. -1 .

[0070] The results of the examples and comparative examples demonstrate that the present invention provides submicron Ti2CT with high yield and high capacity. x The preparation method of lithium-ion battery anodes is simple, rapid, and inexpensive, which not only significantly improves the submicron Ti2CT... x Yield and chemical stability, and submicron Ti2CT x The electrochemical performance has also been significantly improved. This invention is applicable to the preparation of various maicoene materials, and has broad application prospects, especially for maicoene materials with poor chemical stability.

[0071] The above description is only a preferred embodiment of the present invention, but the implementation of the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications made by those skilled in the art based on the present invention shall fall within the protection scope of the present invention.

Claims

1. A submicron Ti2C with high yield and high capacity T x A method for preparing a lithium-ion battery negative electrode, characterized in that, The specific steps are as follows: (1) Submicron Ti2AlC was synthesized by molten salt method using Ti powder, Al powder and carbon black as reactants; (2) Using submicron Ti2AlC as the etching target, a polyol is introduced into the acidic etching solution. The polyol is one or more of ethylene glycol, propylene glycol, glycerol, and polyglycerol. The acidic etching solution is one or two of hydrofluoric acid and lithium fluoride hydrochloric acid solution. Submicron Ti2C is prepared using the polyol-assisted etching method. T x ; (3) Submicron Ti2C T x The mixture is mixed with conductive agent and binder to form a uniform slurry, coated onto the current collector and dried in a vacuum oven, cut into pieces and assembled into coin cells, and its electrochemical performance is tested.

2. The submicron Ti2C with high yield and high capacity according to claim 1 T x A method for preparing a lithium-ion battery negative electrode, characterized in that, In step (1), the molar ratio of Ti, Al, and C in the reactants used to synthesize submicron Ti2AlC is (1.90 ~ 2.10):(0.95 ~ 1.10):(0.70 ~ 0.90); at least two of KCl, NaCl, and LiCl are used as molten salt media, with a molar ratio of KCl, NaCl, and LiCl of (0 ~ 2.10):(0 ~ 2.10):(0 ~ 2.10), and a mass ratio of reactants to molten salt media of (0.5 ~ 2.50):(3.50 ~ 5.50). The molten salt media and reactants are dispersed in anhydrous ethanol and mixed. The mixing and ball milling time is 5 ~ 20 h to form a reactant containing molten salt media.

3. The submicron Ti2C with high yield and high capacity according to claim 2 T x A method for preparing a lithium-ion battery negative electrode, characterized in that, In step (1), when synthesizing submicron Ti2AlC, the reactants containing molten salt medium are heated in a tube furnace at a temperature of 900 ~ 1200 °C and a holding time of 0.5 ~ 5 h. The resulting submicron Ti2AlC grains have a size of 100 ~ 500 nm.

4. The submicron Ti2C with high yield and high capacity according to claim 1 T x A method for preparing a lithium-ion battery negative electrode, characterized in that, In step (2), the concentration of the acidic solution is 5 ~ 12 mol•L -1 The concentration of lithium fluoride in the hydrochloric acid solution is 3~10 mol•L. -1 The volume ratio of acidic solution to polyol was (0.5 ~ 2.00):(0.5 ~ 5.00), the reaction temperature was 25 ~ 35 °C, and the reaction time was 0.5 ~ 15 days, to prepare submicron Ti2C. T x The grain size is 100 ~ 500 nm.

5. The submicron Ti2C with high yield and high capacity according to claim 1 T x A method for preparing a lithium-ion battery negative electrode, characterized in that, In step (3), submicron Ti2C T x It is mixed with conductive agent Super P and binder polyvinylidene fluoride in a mass ratio of (7~9):(0.5~1.5):(0.5~1.5), and ground and mixed evenly with N-methylpyrrolidone as dispersant. N-methylpyrrolidone accounts for 80~97% of the total mass of the slurry.

6. Submicron Ti2C with high yield and high capacity according to any one of claims 1 to 5 T x A method for preparing a lithium-ion battery negative electrode, characterized in that, Submicron Ti2C T x The performance parameters of the lithium-ion battery anode material are as follows: at a 0.05 C rate, the specific charging capacity is 300 ~ 500 mAh•g. -1 At a 5C rate, the charging specific capacity is 100 ~ 300 mAh•g. -1 After 400 cycles at a 1C rate, the charging specific capacity is 100 ~ 300 mAh•g. -1 .

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