A TiC skeleton-supported high-performance hard carbon negative electrode material and its preparation method and application

Abstract

The present invention belongs to the technical field of sodium ion battery negative electrode materials, and discloses a TiC skeleton-supported high-performance hard carbon negative electrode material, its preparation method, and application. The method is to use a certain proportion of a carbohydrate carbon source and Ti3C2 as raw materials, collect a carbide precursor by hydrothermal carbonization, and perform secondary carbonization of the precursor under the protection of an inert gas to obtain a TiC / C composite material. The preparation process of the present invention is simple and environmentally friendly, and provides a new idea for regulating the hydrothermal carbonization morphology of carbohydrates. The prepared TiC / C composite material has the characteristics of high specific capacity, good cycle performance, and good rate performance as a sodium ion battery negative electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion battery negative electrode materials, and specifically relates to a structural modification method for forming a two-dimensional hard carbon negative electrode material by using Ti3C2MXene to induce sugar-derived hard carbon to undergo two-step carbonization, the hard carbon negative electrode material prepared therefrom, and its application as a negative electrode material for sodium ion batteries. Background Art

[0002] Over the past few decades, lithium-ion batteries have been successfully applied in the fields of mobile devices and new energy vehicles. However, due to limitations in raw materials and costs, challenges still exist in large-scale energy storage systems. Sodium-ion batteries, studied during the same period, have become one of the alternatives. One of its negative electrode materials, hard carbon (HC), is widely popular due to its low sodium storage potential, wide source, and good stability. Hard carbon is a non-graphitizable carbon containing low-crystallinity, disordered graphite-like microcrystals with closed pores and defects inside. Excessive electrolyte will be consumed during the first discharge process, and the traditional hard carbon sodium ion transfer kinetics are poor, resulting in poor initial coulombic efficiency (ICE) and rate performance, which seriously limits the further application of hard carbon negative electrode materials. There are currently many strategies to improve the electrochemical performance of hard carbon, using strategies such as structural design, surface modification, heteroatom doping, and electrolyte modification for different storage mechanisms.

[0003] He et al. in situ synthesized pyridine-N-doped carbon nanotubes on a hard carbon surface via the carbonization of zeolitic imidazolate frameworks (ZIFs), achieving a high initial Coulombic efficiency of 98% and a high charge / discharge capacity of 389.4 mAh g -1The reversible capacity of Pyridinic N-Dominated Hard Carbon with Accessible Carbonyl Groups Enabling98%Initial Coulombic Efficiency for Sodium-Ion Batteries.Advanced FunctionalMaterials 2024, 34, 2403144.). Huang et al. increased the proportion of cellulose by using sodium hydroxide to low-temperature etch lignin and hemicellulose in bamboo fiber, thereby enhancing the order of hard carbon and adding more closed pores (Huang, Z.; Huang, J.; Zhong, L.; Zhang, W. and Qiu, X., Deconstruction Engineering of Lignocellulose Toward High-Plateau-Capacity Hard Carbon Anodes for Sodium-Ion Batteries. Small 2024, 20, 2405632.). However, the above studies failed to clarify the correlation between sodium ion transfer kinetics and material structure, which also highlights the difficulty of optimizing the electrochemical performance of hard carbon anodes. Therefore, further exploration is still needed in this field. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention proposes a new hard carbon morphology control strategy to prepare a TiC skeleton-supported high-performance hard carbon negative electrode material and its application in the field of sodium ion batteries.

[0005] The technical solution of the present invention is described in detail below.

[0006] The present invention provides a method for preparing a high-performance hard carbon anode material supported by a TiC skeleton. The method uses sugar as a carbon source, mixes Ti3C2MXene with the carbon source and disperses it in deionized water, collects the carbide precursor through hydrothermal carbonization, and then performs a secondary carbonization of the precursor under the protection of an inert gas to obtain a TiC / C composite material, a hard carbon anode material. The specific preparation method includes the following steps:

[0007] S1. Dissolve a sugar carbon source in deionized water, add Ti3C2MXene and fully disperse it in an inert atmosphere to obtain a precursor solution;

[0008] S2, the precursor solution undergoes a hydrothermal carbonization reaction to obtain a precursor;

[0009] S3. The precursor undergoes a secondary carbonization reaction under an inert atmosphere to obtain a hard carbon negative electrode material TiC / C composite material.

[0010] Preferably, the carbohydrate carbon source in step S1 is a combination of one or more of sucrose, fructose or glucose.

[0011] Preferably, the preparation method of Ti3C2MXene in step S1 is: using HCl and LiF to react to generate HF, etching Ti3AlC2MAX, and then centrifuging and washing to obtain a monodispersed Ti3C2MXene dispersion. More preferably, 9 mol L -1 HCl solution, weigh 0.8g LiF and 0.5g Ti3AlC2MAX, first add LiF into the HCl solution and stir for 10min, then add Ti3AlC2MAX for etching, stir and react in a water bath at a constant temperature of 37℃ for 24h, after multiple centrifugal washings, the pH of the solution is close to 7, and ultrasonic centrifuge again to remove the upper suspension, which is the Ti3C2MXene dispersion.

[0012] Preferably, the mass ratio of the carbohydrate carbon source to Ti3C2MXene in step S1 is 80 to 240:1, more preferably one of 240:1, 120:1 and 80:1.

[0013] Preferably, in step S1, dispersion is performed by ultrasound, the ultrasound power is 500w, and the ultrasound time is 1h.

[0014] Preferably, the hydrothermal carbonization temperature in step S2 is 180-230° C., and the hydrothermal carbonization time is 12-18 hours. More preferably, the hydrothermal carbonization time at 180° C. is 12 hours.

[0015] Preferably, after the hydrothermal carbonization reaction in step S2 is completed, the product is washed with deionized water for multiple times and then filtered and dried; more preferably, the drying temperature is 80° C. and the drying time is 6 h.

[0016] Preferably, the secondary carbonization in step S3 is performed in a tube furnace.

[0017] Preferably, the heating rate of the secondary carbonization in step S3 is 2-10°C min -1 The holding temperature is 1100-1500℃ and the holding time is 60-150min. The more preferred heating rate is 2℃min -1 , the holding temperature is 1100℃ and the holding time is 60min.

[0018] Preferably, after the secondary carbonization reaction in step S3 is completed and cooled to room temperature, the product is taken out, fully ground and sieved. More preferably, the sieve has a 300 mesh.

[0019] Preferably, the inert atmosphere of the present invention is one or a combination of nitrogen and argon.

[0020] The present invention also provides a TiC skeleton-supported high-performance hard carbon negative electrode material prepared by any of the above preparation methods.

[0021] The present invention also provides an application of the TiC skeleton-supported high-performance hard carbon negative electrode material in the field of sodium ion battery negative electrode materials.

[0022] This paper proposes a new hard carbon morphology control strategy, which is a new idea for regulating the morphology of sugar hydrothermal carbonization. Based on the dehydration condensation reaction of sugar solution in the hydrothermal process, Ti3C2 MXene is used for morphology induction, and further reaction is carried out in the subsequent secondary carbonization process to generate a TiC skeleton in situ. The reaction process is shown in the attached figure. Figure 1 The preparation process of the present invention is environmentally friendly and pollution-free, provides a new idea for regulating the hydrothermal carbonization morphology of sugars, and the prepared TiC / C composite material has excellent electrochemical properties.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention provides a new method for preparing TiC / C composite materials with simple reaction, environmental friendliness and ease of industrial large-scale preparation.

[0025] (2) The TiC / C composite material provided by the present invention has the characteristics of high specific capacity, good cycle performance and good rate performance as a negative electrode material for sodium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a reaction principle diagram for preparing TiC / C and HC in the embodiments of the present invention and the comparative examples; Figure 2 X-ray diffraction (XRD) patterns of TiC / C and HC prepared in Example 1 and Comparative Example;

[0027] Figure 3 is the SEM image of Ti3C2 MXene in the present invention;

[0028] Figure 4 Scanning electron microscope (SEM) images of TiC / C and HC prepared in Example 1 of the present invention and the comparative example;

[0029] Figure 5Nitrogen adsorption / desorption curves (BET) and small-angle X-ray scattering (SAXS) of TiC / C and HC prepared in Example 1 of the present invention and the comparative example;

[0030] Figure 6 Cycling performance diagram of simulated sodium ion battery after assembling TiC / C and HC pole pieces prepared in Example 1 of the present invention and the comparative example;

[0031] Figure 7 The rate performance diagram of the simulated sodium ion battery after assembling the TiC / C and HC pole pieces prepared in Example 1 of the present invention and the comparative example;

[0032] Figure 8 Constant current intermittent titration (GITT) diagram of a simulated sodium ion battery after assembling the TiC / C and HC pole pieces prepared in Example 1 of the present invention and the comparative example. DETAILED DESCRIPTION

[0033] In order to better clarify and understand the purpose, process scheme and advantages of the present invention, the technical scheme and implementation method of the present invention are further clearly, completely and in detail described below through specific examples and comparative examples, and in combination with the accompanying drawings. It should be noted that the embodiments described in the present invention are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operating processes are given, but they are only part of the embodiments of the present invention, not all of the embodiments. The specific implementation methods described are limited to illustrating and explaining the present invention, and do not limit the present invention. Based on the embodiments in the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] Unless otherwise specified, the experimental methods and conditions used in the embodiments of the present invention are conventional methods and conventional conditions. The materials, reagents, or instruments used in the embodiments, unless otherwise specified, can be obtained from commercial sources or prepared by conventional methods. The reaction conditions embodied in the summary of the invention of the present invention are all capable of achieving the described reactions and obtaining products with the desired effects. Due to space limitations, some examples are listed below to further illustrate the advantages of the technical solutions of the present invention.

[0035] Example 1:

[0036] Prepare 0.5 mol L -1Measure 70 mL of sucrose solution, add 50 mg of freshly prepared Ti3C2 into it and fully ultrasonically disperse it under nitrogen protection atmosphere; pour the solution into a polytetrafluoroethylene container, put it into a stainless steel sleeve and fix it, put the device into an oven, adjust the oven insulation temperature to 180 ° C and the insulation time to 12 h; take out the oven after cooling to room temperature, wash the product twice with deionized water and filter it to dry, weigh an appropriate amount of the dried product into a quartz boat, place the quartz boat in a corundum tube, and seal both ends; under nitrogen atmosphere, heat up at a rate of 2 ° C min -1 , the holding temperature is 1100℃ and the holding time is 60min. After the heating is completed and cooled to room temperature, the product is taken out, fully ground and sieved to obtain a TiC / C composite material.

[0037] Using N-methylpyrrolidone (NMP) as solvent, conductive carbon black (super-P), polyvinylidene fluoride (PVDF), and active material (the above-mentioned TiC / C composite material) were mixed into a slurry with a mass percentage of 10:10:80 and evenly coated on aluminum foil. The coating amount was generally 1 mg cm 2 After drying at 120°C under vacuum for 12 hours, the cells were cut into electrode sheets for later use. These electrode sheets were then assembled into a sodium-ion half-cell in an argon-filled glove box. First, the positive electrode shell, the electrode sheet, the separator, the sodium sheet, the stainless steel gasket, the spring, and the negative electrode shell were stacked in sequence. The appropriate electrolyte was then added dropwise and packaged. The battery shell used was CR2032, the separator was glass fiber (waterman), and the electrolyte was 1 mol NaPF6-DME.

[0038] As attached Figure 2 It can be seen that after the preparation strategy of the present invention, the sample of Example 1 has a TiC peak, indicating that the material contains TiC components. Figure 3 and attached Figure 4 The SEM images of the three samples show that the originally spherical HC is induced by the morphology of Ti3C2MXene flakes, and finally a TiC / C composite material with layered distribution is prepared. The structural parameters of TiC / C and HC are shown in the attached figure. Figure 5 As shown in the figure, based on the BET and SAXS tests of the two samples, it can be seen that the TiC / C material has more closed pores inside, and the average pore diameter is less than 10mm, which is mesopore, meeting the optimal size required for sodium ion insertion / desorption, and the number of closed pores determines the total amount of sodium ions that the material can store. The TiC / C and HC pole pieces prepared in Example 1 and the comparative example were assembled through the above steps to obtain a half-cell simulating a sodium ion battery. The electrochemical performance of the battery was tested by setting cycle steps with different parameters on a battery rack that can perform charge and discharge experiments on the battery.

[0039] Figure 6The sodium ion battery of Example 1 and the comparative example is simulated at 2Ag -1 , 0.01 ~ 3.0V voltage range of the cycle performance diagram, it can be seen that the discharge capacity of Example 1 after 500 cycles is greater than 266mAh g -1 , excellent cycle performance. Figure 7 The sodium ion batteries simulated in Example 1 and the comparative example were 0.05, 0.1, 0.5, 1, 2, 4, and 8 Ag. -1 ,from Figure 5 It can be seen from the rate performance diagram that TiC / C at 8Ag -1 It also has an ultra-high current density of 194 mAh g -1 The capacity of the material indicates that the material has ultra-high sodium ion conductivity, which is closely related to the unique layered morphology of TiC / C. To further characterize the performance difference between Example 1 and the comparative example in sodium ion transfer kinetics, a constant current intermittent titration technique (GITT) test was performed on both. This test can intuitively reflect the migration coefficient of sodium ions in the material during the battery charge and discharge process, as shown in the attached figure. Figure 8 As shown in the figure, the sodium ion migration coefficient of TiC / C is significantly higher than that of HC, which is consistent with the conclusion obtained from the rate performance test.

[0040] Example 2:

[0041] Prepare 0.5 mol L -1 fructose solution, measure 70 mL of the solution, add 100 mg of freshly prepared Ti3C2 into it and fully ultrasonically disperse it under nitrogen protection atmosphere; pour the solution into a polytetrafluoroethylene container, put it into a stainless steel sleeve and fix it, put the device into an oven, adjust the oven insulation temperature to 200 ° C and the insulation time to 15 h; after the oven cools to room temperature, take it out, wash the product twice with deionized water and filter it to dry, weigh an appropriate amount of the dried product into a quartz boat, place the quartz boat in a corundum tube, and seal both ends; under nitrogen atmosphere, heat it up at a rate of 5 ° C min -1 , the holding temperature is 1300℃ and the holding time is 100min. After the heating is completed and cooled to room temperature, the product is taken out, fully ground and sieved to obtain a TiC / C composite material.

[0042] The TiC / C composite material prepared in Example 2 was subjected to the same pole piece preparation and battery assembly as described above. The specific performance parameters are shown in Table 1.

[0043] Example 3:

[0044] Prepare 0.5 mol L -1The glucose solution was measured and 70 mL of solution was added to 150 mg of freshly prepared Ti3C2 and fully ultrasonically dispersed under nitrogen atmosphere. The solution was poured into a polytetrafluoroethylene container and fixed in a stainless steel sleeve. The device was placed in an oven and the oven temperature was adjusted to 230 °C and the insulation time was 18 h. After the oven cooled to room temperature, it was taken out and the product was washed twice with deionized water and filtered and dried. An appropriate amount of the dried product was weighed into a quartz boat, which was placed in a corundum tube and sealed at both ends. The temperature was raised at a rate of 10 °C min under nitrogen atmosphere. -1 , the holding temperature is 1500℃ and the holding time is 150min. After the heating is completed and cooled to room temperature, the product is taken out, fully ground and sieved to obtain a TiC / C composite material.

[0045] The TiC / C composite material prepared in Example 3 was subjected to the same pole piece preparation and battery assembly as described above. The specific performance parameters are shown in Table 1.

[0046] Comparative Example:

[0047] Prepare 0.5 mol L -1 Measure 70 mL of sucrose solution and fully disperse it by ultrasonication under nitrogen atmosphere; pour the solution into a polytetrafluoroethylene container, place it in a stainless steel sleeve and fix it, place the device in an oven, adjust the oven insulation temperature to 180 ° C and the insulation time to 12 h; take it out after the oven cools to room temperature, wash the product twice with deionized water and filter it to dry, weigh an appropriate amount of the dried product into a quartz boat, place the quartz boat in a corundum tube, and seal both ends; under nitrogen atmosphere, heat it at a rate of 2 ° C min -1 , the holding temperature is 1100°C and the holding time is 60 minutes. After the heating is completed and cooled to room temperature, the product is taken out, fully ground and sieved to obtain the HC material.

[0048] The HC material prepared in the comparative example was subjected to the same electrode preparation and battery assembly as above. The specific performance is detailed in Example 1 and the accompanying drawings.

[0049] In order to further compare the superiority of the technical solution of the present invention, the performance of the batteries prepared in the embodiment and the comparative example are compared as follows:

[0050] Table 1 Summary of hard carbon materials and properties of various embodiments and comparative examples

[0051]

[0052] The comparison results show that the composite hard carbon material prepared by the present invention exhibits significantly better performance than the comparative example in terms of cycle stability and first coulombic efficiency. By implementing the technical solution of the present invention, the comprehensive performance of the negative electrode material of sodium ion battery can be effectively improved.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a TiC skeleton-supported high-performance hard carbon negative electrode material, characterized by: The method comprises dispersing a sugar carbon source and Ti3C2MXene in water, collecting a carbide precursor after hydrothermal carbonization, and performing secondary carbonization on the precursor under inert gas protection to obtain a hard carbon negative electrode material; the hydrothermal carbonization temperature is 180-230°C, and the hydrothermal carbonization time is 12-18 hours; the mass ratio of the sugar carbon source to Ti3C2MXene is 80-240:1; the heating rate of the secondary carbonization is 2-10°C / min, the holding temperature is 1100-1500°C, and the holding time is 60-150 minutes.

2. The method for preparing a TiC skeleton-supported high-performance hard carbon negative electrode material according to claim 1, characterized in that: The method comprises the following steps: S1. Dissolve a sugar carbon source in water, add Ti3C2MXene and disperse under an inert atmosphere to obtain a precursor solution; S2, the precursor solution undergoes a hydrothermal carbonization reaction to obtain a precursor; S3. The precursor undergoes a secondary carbonization reaction under an inert atmosphere to obtain a hard carbon negative electrode material.

3. The method for preparing a TiC skeleton-supported high-performance hard carbon negative electrode material according to claim 2, characterized in that: In step S1, the carbohydrate carbon source is a combination of one or more of sucrose, fructose or glucose.

4. The method for preparing a TiC skeleton-supported high-performance hard carbon negative electrode material according to claim 2, characterized in that: The preparation method of Ti3C2MXene in step S1 is: using HCl and LiF to react to generate HF, etching Ti3AlC2MAX, and obtaining a monodispersed Ti3C2MXene dispersion.

5. The method for preparing a TiC skeleton-supported high-performance hard carbon negative electrode material according to claim 2, characterized in that: The hydrothermal carbonization temperature was 180°C and the hydrothermal time was 12 h.

6. The method for preparing a TiC skeleton-supported high-performance hard carbon negative electrode material according to claim 2, characterized in that: In step S3, the heating rate of the secondary carbonization is 2° C. / min, the holding temperature is 1100° C., and the holding time is 60 min.

7. A TiC skeleton-supported high-performance hard carbon negative electrode material prepared by the preparation method according to any one of claims 1 to 6.

8. Application of the TiC skeleton-supported high-performance hard carbon negative electrode material as claimed in claim 7 in the field of negative electrode materials for sodium ion batteries.

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