Carboxyl functionalized MXene ink for lithium ion battery and preparation method of carboxyl functionalized MXene ink
By combining carboxylic functionalized MXene ink with silicon-carbon materials, a stable conductivity Internet network is formed, which solves the poor conductivity and cycle stability of silicon-carbon anode materials for lithium-ion batteries, and realizes a lithium-ion secondary battery with high energy density and high magnification.
Patent Information
- Application Number
- CN202510211062.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2025-06-13
AI Technical Summary
The silicon carbon anode materials of existing lithium-ion batteries have problems such as poor conductivity, unstable nanoification and peeling from the current collector, resulting in low energy density and poor cycle stability.
Carboxylic functionalized MXene ink is used to combine with silicon-carbon material. After mixing and evenly mixing in the homogenizer, it is cast on the copper foil with a scraper and vacuum-dried to form a stable conductive Internet network, which enhances the conductivity of the silicon-carbon negative electrode.
It has achieved a high-stability and high-magnification lithium-ion secondary battery, which has improved the conductivity and cycle stability of the silicon carbon negative electrode, and has important scientific research value and practical significance.
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Figure CN120149409A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a carboxyl-functionalized MXene ink for lithium-ion batteries and a preparation method thereof. Background Art
[0002] Due to the characteristics of intermittency and uneven distribution of most clean energy sources, it is difficult to be directly utilized, and an energy storage system is needed to balance the contradiction between the low power generation valley and the high power consumption peak.
[0003] As a representative of green energy storage systems, lithium-ion batteries have been widely used in fields such as movable portable electronic devices and electric vehicles in recent years due to their many advantages such as high working voltage, high specific energy, long cycle life, and low environmental pollution.
[0004] Based on the intercalation reaction, the theoretical specific capacity of the graphite negative electrode of lithium-ion batteries is only 372 mAh g -1 , and the energy density is relatively low (100 - 265 Wh kg -1 ), which greatly restricts the application scenarios of lithium-ion batteries. The new generation of lithium secondary batteries with silicon-carbon as the negative electrode, whose theoretical energy density is much higher than the theoretical capacity of the current commercial lithium cobalt oxide / graphite lithium-ion batteries, are regarded as promising high-energy density energy storage devices.
[0005] However, silicon-carbon negative electrodes usually encounter: 1) nanosizing of silicon-carbon negative electrode materials; 2) peeling of silicon-carbon materials from the current collector, losing electrical contact; 3) poor conductivity of silicon.
[0006] Therefore, developing a carboxyl-functionalized MXene ink to form a stable and conductive interconnected network for silicon-carbon negative electrodes, avoiding the peeling of silicon-carbon from the current collector, enhancing the conductivity of silicon-carbon negative electrodes, and thus realizing high-stability and high-rate lithium-ion secondary batteries has important scientific research value and practical significance. Summary of the Invention
[0007] The purpose of the present invention is to overcome the above-mentioned shortcomings and deficiencies of the prior art, and provide a carboxyl-functionalized MXene ink for lithium-ion batteries and a preparation method thereof. The carboxyl-functionalized MXene ink obtained by the present invention enables the formation of a stable and conductive interconnected network for silicon-carbon negative electrodes.
[0008] The preparation process of the present invention effectively solves the problem of peeling of silicon-carbon materials from the current collector, enhances the conductivity of silicon-carbon negative electrodes, and thus realizes high-stability and high-rate lithium-ion secondary batteries, which has important scientific research value and practical significance.
[0009] The ink obtained by the present invention has no additives and is suitable for the continuous production process of blade coating printing, which is of great significance for promoting the commercialization of lithium-ion silicon-carbon negative electrodes.
[0010] The present invention is achieved by the following technical solutions:
[0011] A preparation method of carboxyl-functionalized MXene ink for silicon-carbon anode of lithium-ion battery, comprising the following steps:
[0012] Step 1, synthesis of terminal group MXene-Ti 3 C 2 T x :
[0013] Weigh the MAX phase according to the molar fraction ratio and slowly add it to the mixed solution containing HCl and LiF, heat and stir. Then, centrifuge and wash with HCl, LiCl and deionized water respectively to obtain the reaction product;
[0014] Step 2, synthesis of carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x :
[0015] Add the reaction product of Step 1 to the diazonium salt solution, and then stir evenly. After the reaction is completed, ultrasonicate and centrifuge the solution, and wash with water, acetone and ethanol in sequence to remove salts to obtain Ti 3 C 2 (COOH) x ;
[0016] Step 3, preparation of carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x ink:
[0017] After pouring out the supernatant, redisperse the precipitate by shaking vigorously in deionized water to obtain Ti 3 C 2 (COOH) x ink;
[0018] Step 4, preparation of carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x ink-based silicon-carbon anode:
[0019] Mix the Ti 3 C 2 (COOH) x ink obtained in Step 3 and the silicon-carbon composite material in a ratio of 1:9 to 2:8 in a homogenizer. Then, cast the mixed slurry onto the copper foil using a scraper, and then dry it in vacuum to remove the residual moisture to obtain the Ti 3 C 2 (COOH) x ink-based silicon-carbon anode;
[0020] The MAX phase described in Step 1 is Ti 3 AlC 2 , Ti 3 AlCN or Nb 2 AlC. Weigh the reaction raw materials according to the molar ratio of MAX phase: HCl and LiF mixed solution = 1:2 - 8. Mix the weighed raw materials evenly in a reaction flask, stir at 25 - 40 °C for 12 - 36 h, then centrifuge at 1500 - 3500 rpm, and finally wash with 1M HCl, 1M LiCl and deionized water 3 - 5 times respectively.
[0021] The phenylcarboxylic acid diazonium salt described in Step 2 is one of benzoic acid diazonium salt or phthalic acid diazonium salt; add 140 - 280 mg of sodium hydroxide and 480 - 960 mg of p-aminobenzoic acid to 40 - 80 ml of water. Subsequently, maintain the temperature at 0 - 5 °C and slowly add 263 - 526 ml of sodium nitrite to the solution. Finally, quickly add 3 - 6 ml of hydrochloric acid solution (20%, 6.4M, 19.2 mmol), stir for 30 - 60 min, and the solution turns light yellow to prepare the diazonium salt solution. Then, add 10 - 30 ml of the diazonium salt solution to 50 - 100 ml of the MXene colloidal solution and stir at 1000 rpm for 2 - 5 h. After the reaction, the solution is ultrasonically treated for 15 - 30 min and centrifuged at 9000 rpm for 30 - 100 min, pour out the upper liquid, and wash with water, acetone and ethanol in turn to remove salts.
[0022] After pouring out the upper liquid of the reaction product in Step 3, redisperse the precipitate in 10 - 30 ml of deionized water by shaking vigorously for 10 - 30 min to obtain Ti 3 C 2 (COOH) x ink. The concentration of MXene in the ink is 20 - 50 mg / mL.
[0023] By the above preparation method, carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x ink can be obtained.
[0024] A silicon-carbon anode for a lithium-ion battery is prepared from the Ti 3 C 2 (COOH) x ink and silicon-carbon materials. The preparation steps are as follows: Ti 3 C 2 (COOH) xThe ink and the silicon carbide composite material are mixed in a homogenizer at a ratio of 1:9 to 2:8. Then, the mixed slurry is cast onto a copper foil using a scraper, and then vacuum dried to remove residual moisture to obtain carboxyl-functionalized Ti 3 C 2 T x ink-based silicon-carbon negative electrode.
[0025] The silicon-carbon negative electrode and Ti 3 C 2 (COOH) x The dosage relationship of the ink satisfies that 0.27 - 0.83 mg of carboxyl-functionalized Ti 3 C 2 T x ink is flatly laid per square centimeter of the negative electrode plane;
[0026] The capacity of the silicon-carbon negative electrode material is 400 mAh g -1 , 500 mAh g -1 or 600 mAh g -1 in one of them.
[0027] Compared with the prior art, the present invention has the following advantages and effects:
[0028] 1) The carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x ink used in the present invention has a high yield, a simple method, and is easy to industrialize;
[0029] 2) The carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x in the present invention realizes the selective synthesis of other terminal group MXenes except -F and -OH. The specific carboxyl group can reduce the lithium ion diffusion barrier, more effectively guide the uniform deposition of lithium ions, and play a key role in adjusting the lithium ion solvation structure;
[0030] 3) The present invention prepares carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x ink without any additives for lithium ion batteries. Subsequently, the Ti 3 C 2 (COOH) x ink is uniformly mixed with the silicon-carbon material. Using a commercial copper foil as the substrate, the Ti 3 C 2 (COOH) x ink is evenly scraped and coated, and after vacuum drying, Ti 3 C 2(COOH) x Ink-based silicon-carbon anode
[0031] 4) The carboxyl-functionalized MXene-Ti of the present invention 3 C 2 (COOH) x has a strong adsorption effect on lithium ions. The lithium-ion battery assembled with the separator modified by this material has an ultra-high cycling rate, good cycling stability, and this material also has the characteristics of good conductivity, environmental protection and large-scale preparation, and has very good prospects for large-scale production. Brief Description of the Drawings
[0032] Figure 1 Scanning electron microscope (SEM) photograph of the multi-layer Ti 3 CNT x obtained in Example 1.
[0033] Figure 2 Transmission electron microscope (TEM) photograph of the Ti 3 C 2 (COOH) x obtained in Example 1.
[0034] Figure 3 Optical photograph of the Ti 3 C 2 (COOH) x ink obtained in Example 1.
[0035] Figure 4 Long cycle test chart of the SiC||Li half-cell assembled with the composite silicon-carbon anode material obtained in Example 1.
[0036] Figure 5 Long cycle test chart of the SiC||Li half-cell assembled with the composite silicon-carbon anode material obtained in Example 2.
[0037] Figure 6 Long cycle test chart of the SiC||NCM622 full-cell assembled with the composite silicon-carbon anode material obtained in Example 3.
[0038] Figure 7 Long cycle test chart of the SiC||Li half-cell assembled with the composite silicon-carbon anode material obtained in Comparative Example 1.
[0039] Figure 8 Long cycle test chart of the SiC||NCM622 full-cell assembled with the commercial binder PAA-based silicon-carbon anode obtained in Comparative Example 2. Detailed Description of the Invention
[0040] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below.
[0041] Example 1:
[0042] (1) Synthesis of Ti 3 C 2 T x : 2 g of Ti 3 AlC 2 was slowly added to 40 ml of an aqueous solution containing 9 M HCl and 2 g of LiF. After the mixture was stirred at 40 °C for 24 h, the product was centrifuged at 3500 rpm and washed three times each with 1 M HCl, 1 M LiCl, and deionized water;
[0043] (2) Synthesis of carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x : 280 mg of sodium hydroxide and 960 mg of 4-aminobenzoic acid were added to 80 ml of water. Subsequently, the temperature was maintained at 5 °C, and 526 mg of sodium nitrite was slowly added. Finally, 6 ml of HCl solution (20%, 6.4 M, 19.2 mmol) was rapidly added to the solution and stirred for 45 min, and the solution turned light yellow. Then, 30 ml of the diazonium salt solution was added to 40 ml of MXene colloidal solution (5 mg / ml) and stirred at 1000 rpm for 4 h. After the reaction time ended, the solution was sonicated for 15 min and centrifuged at 9000 rpm for 30 min, and then the upper liquid was poured out and washed successively with water, acetone, and ethanol to remove salts (each washing for 5 min, 9000 rpm);
[0044] (3) Preparation of carboxyl-functionalized MXene-Ti 3 C 2 (COOH) x ink: After pouring out the upper liquid, the precipitate was redispersed in 10 ml of 15 ml of deionized water by shaking vigorously to obtain Ti 3 C 2 (COOH) x aqueous ink;
[0045] (4) Preparation of carboxyl-functionalized Ti 3 C 2 T x -Ti 3 C 2 (COOH) x ink-based silicon-carbon anode: The Ti 3 C 2 (COOH) x dispersion was mixed with that having 500 mAh g -1The theoretical capacity and a silicon-carbon composite material with a silicon content of approximately 5% are mixed in a ratio of 1:9. Then, the slurry is cast onto a copper foil using a doctor blade and slowly dried at 40 °C for 2 h, followed by vacuum drying at 60 °C for 12 h to remove residual moisture;
[0046] (5) The lithium-ion battery negative electrode (negative electrode material) obtained in step (4) is used as the negative electrode of a button battery to assemble a lithium-ion battery.
[0047] Figure 1 For the multi-layer Ti 3 C 2 T x scanning electron microscope (SEM) photograph, Figure 2 For the single-layer Ti 3 C 2 (COOH) x transmission electron microscope (TEM) photograph, Figure 3 For the Ti 3 C 2 (COOH) x optical photograph of the ink. From Figure 1 , 2, 3, it can be seen that the method of the present invention is used to prepare a Ti 3 C 2 (COOH) x ink with high viscosity and no additives. The negative electrode material obtained in this example is assembled into a Ti 3 C 2 (COOH) x -SiC||Li half-cell (in a glove box filled with argon, in the order of the positive electrode case, lithium metal sheet, separator, Ti 3 C 2 (COOH) x -SiC negative electrode, spacer, and negative electrode case to assemble a 2025-type button battery. The electrolyte is 1.2 M lithium hexafluorophosphate (LiPF 6 ) dissolved in ethylene carbonate (EC) / diethyl carbonate (DEC) = 1:1 V / V%, and 10% fluoroethylene carbonate (FEC) is added to observe its long-term cycle stability. As Figure 4 shown, the composite negative electrode has excellent cycle stability and still maintains good cycle stability under the long-term cycle test conditions at a rate of 30C, with a stable cycle approaching 200 cycles.
[0048] Example 2:
[0049] (1) Synthesis of Ti 3 CNT x : 2 g of Ti 3AlCN was slowly added to 60 ml of an aqueous solution containing 12 M HCl and 3 g of LiF. After the mixture was stirred at 40 °C for 24 h, the product was centrifuged at 1500 rpm and washed 5 times each with 1 M HCl, 1 M LiCl, and deionized water;
[0050] (2) Synthesis of carboxyl-functionalized Ti 3 CNT x : 140 mg of sodium hydroxide and 480 mg of 4-aminobenzoic acid were added to 80 ml of water. Subsequently, the temperature was maintained at 0 °C, and 263 mg of sodium nitrite was slowly added. Finally, 3 ml of HCl solution (20%, 6.4 M) was quickly added to the solution and stirred for 60 min, and the solution turned light yellow. Then, 10 ml of the diazonium salt solution was added to 50 ml of the MXene colloidal solution (5 mg / ml), and stirred at 1000 rpm for 5 h. After the reaction time ended, the solution was ultrasonicated for 30 minutes and centrifuged at 9000 rpm for 60 min. Then, the upper liquid was poured out and washed successively with water, acetone, and ethanol to remove salts (each wash for 5 min, 9000 rpm);
[0051] (3) Preparation of carboxyl-functionalized MXene-Ti 3 CN(COOH) x Preparation of aqueous ink: After pouring out the upper liquid, the precipitate was redispersed in 20 ml of deionized water by shaking vigorously for 30 min to obtain Ti 3 C 2 (COOH) x aqueous ink;
[0052] (4) Carboxyl-functionalized Ti 3 C 2 T x -Ti 3 CN(COOH) x Preparation of ink-based silicon-carbon anode: The Ti 3 CN(COOH)dispersion was mixed with a silicon-carbon composite material having a theoretical capacity of 400 mAh g x and a silicon content of approximately 5% in a ratio of 1.5:8.5. Then, the slurry was cast onto a copper foil using a doctor blade and slowly dried at 40 °C for 2 h, followed by vacuum drying at 60 °C for 12 h to remove residual moisture; -1
[0053] (5) The lithium-ion battery anode (anode material) obtained in step (4) was used as the anode of a button battery to assemble a lithium-ion battery.
[0054] Figure 5 The anode material obtained in this example was assembled into Ti 3 CN(COOH)x -SiC||Li half-cell (in an argon-filled glove box, assembled into a 2025-type button cell in the order of the positive electrode case, lithium metal sheet, separator, Ti 3 CN(COOH) x -SiC negative electrode, gasket and negative electrode case, and the electrolyte is 1.2 M lithium hexafluorophosphate (LiPF 6 ) dissolved in ethylene carbonate (EC) / diethyl carbonate (DEC) = 1:1 V / V%, and 10% fluoroethylene carbonate (FEC) is added, and its long-term cycling stability is observed. As Figure 5 shown, the composite negative electrode has excellent cycling stability and still maintains good cycling stability under the long cycling test conditions at a rate of 10C, with a stable cycle approaching 280 cycles and a capacity retention rate of 81.3%.
[0055] Example 3:
[0056] (1) Synthesis of Nb 2 CT x : Slowly add 2 g of Nb 2 AlC to 40 ml of aqueous solution containing 12 M HCl and 5 g of LiF. After the mixture is stirred at 40 °C for 36 h, the product is centrifuged at 2500 rpm and washed 5 times each with 2 M HCl, 2 M LiCl and deionized water;
[0057] (2) Synthesis of carboxyl-functionalized Nb 2 CT x : Add 200 mg of sodium hydroxide and 400 mg of 4-aminobenzoic acid to 60 ml of water. Subsequently, keep the temperature at 5 °C and slowly add 352 mg of sodium nitrite. Finally, quickly add 5 ml of HCl solution (20%, 6.4 M) to this solution and stir for 60 min, and the solution turns light yellow. Then add 20 ml of the diazonium salt solution to 80 ml of MXene colloidal solution (5 mg / ml) and stir at 1000 rpm for 5 h. After the reaction time ends, the solution is ultrasonically treated for 30 minutes and centrifuged at 9000 rpm for 70 min, then pour out the upper liquid and wash it successively with water, acetone and ethanol to remove salts (each wash for 5 min, 9000 rpm);
[0058] (3) Preparation of carboxyl-functionalized MXene-Nb 2 C(COOH) x aqueous ink: After pouring out the upper liquid, redisperse the precipitate in 20 ml of deionized water by shaking vigorously for 30 min to obtain Ti 3 C 2 (COOH) x aqueous ink;
[0059] (4) Carboxyl-functionalized Ti 3 C 2 T x -Nb 2 C(COOH) x Preparation of the ink-based silicon-carbon anode: Mix the dispersion of Nb 2 C(COOH) x with a silicon-carbon composite material having a theoretical capacity of 600 mAh g -1 and a silicon content of approximately 5% in a ratio of 2:8. Then, cast the slurry onto a copper foil using a doctor blade and slowly dry it at 40 °C for 2 h, followed by vacuum drying at 60 °C for 12 h to remove residual moisture;
[0060] (5) Use the lithium-ion battery anode (anode material) obtained in step (4) as the anode of a button battery to assemble a lithium-ion battery.
[0061] Figure 6 Assemble the anode material obtained in this example into an Nb 2 C(COOH) x -SiC||NCM622 full battery (in a glove box filled with argon, assemble a 2025-type button battery in the order of the positive electrode case, NCM622 positive electrode sheet, separator, Nb 2 C(COOH) x -SiC anode, spacer, and negative electrode case. The electrolyte is 1.2 M lithium hexafluorophosphate (LiPF 6 ) dissolved in ethylene carbonate (EC) / diethyl carbonate (DEC) = 1:1 V / V%, and 10% fluoroethylene carbonate (FEC) is added. Observe its long-term cycling stability. As Figure 6 shown, this composite anode has excellent cycling stability and still maintains good cycling stability under the long-term cycling test conditions at a rate of 5C and a high voltage of 4.5 V, with a stable cycle approaching 420 cycles and a capacity retention rate of 70.0%.
[0062] Comparative Example 1:
[0063] (1) Weigh the reaction raw materials: Weigh 2 g of LiF and add it to 40 mL of 9 M HCl solution, and then slowly add 2 g of Ti 3 AlC 2 -MAX phase, stir at 35 °C and 3500 rpm for 24 h;
[0064] (2) Wash and purify the reaction product: Add deionized water to wash the reactants until the pH is neutral, add the obtained precipitate to deionized water and pass an inert gas to sonicate for 1 h;
[0065] (4) Monolayer Ti 3 C2 T x Preparation of MXene ink: The ultrasonicated solution was centrifuged at 3500 rpm for 1 h, and the supernatant was collected. Finally, it was centrifuged at 7000 rpm for 1 h, and the precipitate was collected to obtain monolayer Ti 3 C 2 T x MXene ink;
[0066] (5) Ti 3 C 2 T x Preparation of SiC negative electrode based on MXene ink: The Ti 3 C 2 T x ink was mixed with a silicon-carbon composite material with a theoretical capacity of 500 mAh g -1 and a silicon content of approximately 5% in a ratio of 1:9. Then the slurry was cast onto a copper foil using a doctor blade and slowly dried at 40 °C for 2 h, and then vacuum dried at 60 °C for 12 h to remove residual moisture;
[0067] (6) The silicon-carbon negative electrode obtained in step (5) was used as the negative electrode of a button battery to assemble a lithium-ion battery.
[0068] Figure 7 The composite negative electrode obtained in this comparative example was assembled into a Ti 3 C 2 T x -SiC||Li half-cell (in a glove box filled with argon, assembled into a 2025-type button battery in the order of positive electrode case, lithium metal sheet, composite separator, Ti 3 C 2 T x -SiC negative electrode sheet, spacer and negative electrode case. The electrolyte was 1.2 M lithium hexafluorophosphate (LiPF 6 ) dissolved in ethylene carbonate (EC) / diethyl carbonate (DEC) = 1:1 V / V%, and 10% fluoroethylene carbonate (FEC) was added, and its long-term cycling stability was observed. The capacity of this battery began to decline rapidly after 170 cycles.
[0069] Comparative example 2:
[0070] Figure 8 The SiC||LFP full cell assembled with the silicon-carbon negative electrode using PAA binder obtained in this comparative example (in a glove box filled with argon, assembled into a 2025-type button battery in the order of positive electrode case, LFP positive electrode sheet, composite separator, silicon-carbon negative electrode sheet, spacer and negative electrode case. The electrolyte was 1.2 M lithium hexafluorophosphate (LiPF 6)Dissolved in ethylene carbonate (EC) / diethyl carbonate (DEC) = 1:1 V / V%, and 10% fluoroethylene carbonate (FEC) was added, and its long-term cycle stability was observed. The initial capacity of the NCM622 full cell was 156 mAh g under the condition of 0.5C -1 , and the capacity retention rate after 420 cycles was 70.2%, and the cycle stability was poor.
[0071] As can be seen from the above analysis, compared with Comparative Examples 1-2, the cycle stability of the batteries in Examples 1-3 is significantly better. Compared with Comparative Examples 1-2, the SiC||Li half cells and SiC||NCM622 assembled with the composite silicon-carbon negative electrodes obtained in Examples 1-3 have better rate performance and cycle stability. It shows that the materials obtained by the preparation method of the present invention can improve the lithium ion conductivity and electron conductivity of the silicon-carbon negative electrode. At the same time, the ink obtained by this preparation method has no any additives, is suitable for the continuous production process of blade coating printing, and has good industrial application prospects.
[0072] As described above, the present invention can be preferably realized.
[0073] The implementation manners of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement manners and are all included in the protection scope of the present invention.
Claims
1. A method for preparing a carboxyl functionalized MXene ink for a lithium-ion battery silicon-carbon negative electrode, characterized in that The steps include: Step 1: Mixing end group MXene-Ti3C2T x Synthesis of Step 2: Carboxyl functionalization of MXene-Ti3C2(COOH) x Synthesis of Step 3: Carboxyl functionalization of MXene-Ti3C2(COOH) x Preparation of water-based inks; Step 4: Carboxyl functionalization of MXene-Ti3C2(COOH) x Preparation of water-based ink-based silicon-carbon anode.
2. The method for preparing the carboxyl functionalized MXene ink for the silicon-carbon negative electrode of a lithium ion battery according to claim 1, characterized in that Step 1 specifically includes the following steps: The mixed solution of MAX phase, HCl and LiF is weighed according to the molar fraction ratio, placed in a reactor and stirred thoroughly, an inert gas is introduced into the mixed reaction raw materials to remove oxygen in the solution, and an etching reaction is carried out in an inert gas atmosphere.
3. The method for preparing the carboxyl functionalized MXene ink for the silicon-carbon negative electrode of a lithium ion battery according to claim 2, characterized in that Step 2 specifically includes the following steps: The reaction product in step 1 is washed with deionized water to remove residual chloride ion salts, and the washed reaction product is stirred in a hydrochloric acid solution to dissolve the metal element in the reaction product; the reaction product washed with hydrochloric acid is then repeatedly centrifuged and washed with deionized water until the pH is 6, and finally the precipitate after centrifugation is taken and dried in a vacuum drying oven to obtain Ti3C2(COOH) x Material.
4. The method for preparing the carboxyl functionalized MXene ink for the silicon-carbon negative electrode of a lithium ion battery according to claim 3, characterized in that Step 3 specifically includes the following steps: After pouring the supernatant, the precipitate was vigorously shaken and re-dispersed in deionized water to obtain Ti3C2(COOH) x Water-based ink.
5. The method for preparing the carboxyl functionalized MXene ink for the silicon-carbon negative electrode of a lithium ion battery according to claim 4, characterized in that Step 4 specifically includes the following steps: The Ti3C2(COOH) obtained in step 3 x The ink and the silicon-carbon composite material are mixed in a homogenizer according to a certain proportion; The mixed slurry is then cast onto a copper foil using a scraper and then vacuum dried to remove residual moisture to obtain Ti3C2(COOH) x Ink-based silicon-carbon anode.
6. The method for preparing the carboxyl functionalized MXene ink for the silicon-carbon negative electrode of a lithium ion battery according to claim 2, characterized in that: The etching reaction is carried out in an inert gas atmosphere in step 2, specifically heating to 25-40° C. at a rate under an argon atmosphere, stirring for 12-36 hours, and the reaction products are respectively filtered with 1M HCl, 1M LiCl and deionized water, specifically vacuum filtering with HCl, LiCl and deionized water for more than five times.
7. The method for preparing the carboxyl functionalized MXene ink for the silicon-carbon negative electrode of a lithium ion battery according to claim 4, characterized in that: The precipitate in step 3 is dispersed in 10-30 ml of deionized water for 10-30 minutes by vigorous shaking to obtain Ti3C2(COOH) x Ink; MXene concentration in ink is 20-50 mg mL -1 .
8. The method for preparing the carboxyl functionalized MXene ink for the silicon-carbon negative electrode of a lithium ion battery according to claim 5, characterized in that: In step 4, Ti3C2(COOH) x The ink and the silicon-carbon composite material were mixed in a homogenizer at a ratio of 1:9 to 2:
8. The mixed slurry was then cast onto a copper foil using a scraper and then vacuum dried at 50 to 80 °C to remove residual moisture to obtain carboxyl-functionalized Ti3C2T x Ink-based silicon-carbon anode.
9. A carboxyl functionalized MXene-Ti3C2(COOH) x Ink, characterized in that The method is prepared by any one of claims 1 to 8.
10. A lithium ion battery silicon-carbon negative electrode, characterized in that Comprising the carboxyl functionalized MXene-Ti3C2(COOH) as claimed in claim 9 x Ink; Ti3C2(COOH) x The ink and the silicon-carbon composite material were mixed in a homogenizer at a ratio of 1:9 to 2:
8. The mixed slurry was then cast onto a copper foil and vacuum dried to obtain a carboxyl-functionalized Ti3C2T x Ink-based silicon-carbon anode.