High interfacial stability tin-carbon negative electrode material and application thereof

Abstract

The application relates to the technical field of electrochemical energy storage materials, in particular to a tin-carbon negative electrode material with high interface stability and application thereof. SnS2 powder and graphene sheets are weighed according to a mass ratio of 1:1, and then added into N,N-dimethylformamide solutions respectively, oscillated to be initially dispersed, and corresponding solution a and solution b are obtained; ultrasonic waves and magnetic stirring are respectively carried out; solution a and solution b are fully mixed, ultrasonic wave and stirring treatment are carried out, and dispersion liquid c is prepared; solid-liquid separation is carried out, and a solid-phase product is collected; the solid-phase product is washed with deionized water, and ultrasonic cleaning is carried out after each washing; the washed solid-phase product is placed in a vacuum drying oven at 60-80 DEG C for 20-30 hours, a precursor is obtained; the precursor is uniformly laid in the middle of a quartz tube, graphite electrodes are symmetrically arranged at both ends, vacuumizing is carried out, FJH technology is used for treatment, the product is ground into a powder, and a tin-carbon composite negative electrode material is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical energy storage materials, in particular to a tin-carbon negative electrode material with high interface stability and application thereof. BACKGROUND

[0002] With the wide application of electric vehicles and various portable electronic devices, high-energy-density energy storage materials have become a research hotspot, among which secondary batteries are particularly important. Lithium-ion batteries have become the current mainstream energy storage battery technology due to their high energy density and excellent cycle performance. However, lithium-ion batteries also have limitations. First, the content of lithium resources in the earth's crust is low, and the distribution of lithium resources is uneven, resulting in high cost. Sodium-ion batteries have the advantage of resource because the content of sodium element is much higher than that of lithium element, and they have a similar "rocking chair" charging and discharging mechanism as lithium-ion batteries. Therefore, sodium-ion batteries have become the most potential alternative technology in the energy storage field. However, sodium-ion batteries also have their corresponding core bottlenecks. Because the radius of sodium ion is significantly larger than that of lithium ion, the traditional graphite electrode material cannot effectively embed sodium ions, resulting in the inability to form effective capacity.

[0003] To break through the performance bottleneck of sodium-ion battery negative electrode materials and obtain a negative electrode material with high capacity and long cycle stability, the present application combines the high theoretical specific capacity of tin material with the high conductivity of carbon-based material to construct a tin-carbon composite material to realize the synergistic effect of the two, thereby solving the problems of poor conductivity of pure tin-based materials and volume expansion during the charging and discharging process, and suppressing the generation of side reactions by reducing the direct contact between tin and electrolyte, thereby improving the electrode interface stability.

[0004] In view of the core bottleneck of tin-based negative electrode materials for sodium-ion batteries, the existing technology for preparing tin-carbon composite materials has three major limitations: (1) tin-based materials will undergo significant volume expansion (expansion rate usually up to 200-400%) during sodiumization, causing stress concentration in the electrode, leading to active particle breakage and detachment from the current collector, and ultimately causing a cliff-like decay of battery capacity; (2) the electrical conductivity of tin-based materials is low, which seriously restricts the electron transport dynamics, reducing the charging and discharging efficiency and rate performance of the battery; (3) in traditional tin-carbon composite materials, tin and carbon matrix are physically mixed or combined through weak van der Waals forces, which cannot effectively buffer the volume expansion stress and also cannot inhibit the aggregation and detachment of active materials. To solve the above problems, there is an urgent need for a preparation method that can enhance the interaction between tin and carbon, improve the structural stability and electrochemical performance of the composite material. SUMMARY

[0005] The present application provides a tin-carbon negative electrode material with high interface stability and application thereof to solve the above problems.

[0006] The first object of the present application is to provide a preparation method of a high-interface-stability tin-carbon negative electrode material, which specifically comprises the following steps:

[0007] S1. SnS2 powder and graphene sheets are weighed according to a mass ratio of 1:1, and are respectively added into N,N-dimethylformamide solution, oscillated to preliminary dispersion, and correspondingly obtained as solution a and solution b;

[0008] S2. The solution a and the solution b are respectively subjected to ultrasonic treatment for 2-4 h and magnetic stirring for 20-30 h; the solution a and the solution b are fully mixed, subjected to ultrasonic treatment for 0.5-1.5 h and magnetic stirring treatment for 20-30 h, and a dispersion liquid c is prepared;

[0009] S3. The dispersion liquid c is subjected to solid-liquid separation, and the solid-phase product is collected; the solid-phase product is washed with deionized water for 2-3 times, and is subjected to ultrasonic cleaning after each washing; the cleaned solid-phase product is placed at 60-80 DEG C under vacuum drying for 20-30 hours, and a precursor is obtained;

[0010] S4. The precursor is uniformly laid in the middle of a quartz tube, and graphite electrodes are symmetrically installed at both ends; vacuum is drawn, and FJH technology is used for treatment; after the quartz tube is naturally cooled to room temperature, the product is taken out and ground into a powder, and a tin-carbon composite negative electrode material is obtained.

[0011] Preferably, the solid-liquid ratio of the SnS2 powder, the graphene sheets and the N,N-dimethylformamide solution is 2-5 mg:1 mL.

[0012] Preferably, the solid-liquid ratio of the SnS2 powder, the graphene sheets and the N,N-dimethylformamide solution is 2 mg:1 mL.

[0013] Preferably, the power of the ultrasonic treatment in step S2 is 300-500 W, and the rate of the magnetic stirring is 300-500 r / min.

[0014] Preferably, the power of the ultrasonic cleaning in step S3 is 200-300 W, and the frequency is 40 kHz.

[0015] Preferably, step S3 uses suction filtration for solid-liquid separation; the temperature of the vacuum drying is 80 DEG C, and the time is 24 hours.

[0016] The second object of the present application is to provide a high-interface-stability tin-carbon negative electrode material, which is prepared by using the preparation method of the high-interface-stability tin-carbon negative electrode material.

[0017] The third object of the present application is to provide an application of the high-interface-stability tin-carbon negative electrode material in the preparation of a sodium ion battery.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0019] This invention utilizes an innovative process combining liquid-phase stepwise dispersion with instantaneous Joule heating (FJH) to construct a strong Sn-C covalent bond interface in the SnS2 / graphene composite system. This overcomes the core defects of traditional tin-based materials, such as large volume expansion and easy detachment of active components, forming a continuous and interconnected conductive network that significantly improves electron transport efficiency. Compared to traditional high-temperature calcination methods, this process eliminates the need for prolonged high-temperature treatment, resulting in lower energy consumption, a simpler process, and higher batch-to-batch product stability. It is also environmentally friendly and easily scalable. Sodium-ion batteries based on this material can achieve high performance at 0.5A. g -1 After 100 cycles at current density, the specific capacity remains at 250mAh. g -1 The above features a coulombic efficiency close to 100%, excellent long-cycle stability and rate performance, and readily available and cost-controllable raw materials, making it fully suitable for practical applications of sodium-ion batteries such as large-scale energy storage. It has significant technological advantages and commercial potential. Attached Figure Description

[0020] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the Sn@G tin-carbon composite anode material provided in the embodiments of the present invention (where G in Sn@G is an abbreviation for Graphene, and Graphene represents graphene).

[0021] Figure 2 This is an HR-TEM image of the Sn@G tin-carbon composite anode material provided in an embodiment of the present invention.

[0022] Figure 3 The results show the cycle performance of the Sn@G tin-carbon composite anode material provided in the embodiments of the present invention.

[0023] Figure 4 The figures show the charge-discharge curves of the Sn@G tin-carbon composite anode material provided in the embodiments of the present invention. Detailed Implementation

[0024] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0026] The present application aims to overcome the technical defects of high volume expansion rate, poor electrical conductivity, weak interface force between tin-carbon components, and further leading to fast cycle performance decay and poor rate performance of existing sodium-ion battery tin-based negative electrode materials, and provides a sodium-ion battery tin-carbon composite negative electrode material based on Flash Joule Heating (FJH) technology and a preparation method thereof. By finely dispersing the tin-based raw material and the carbon-based raw material in the liquid phase, a Sn@G precursor with uniformly dispersed components is obtained, and then the instantaneous high-temperature thermal-electric coupling field effect of the FJH technology is used to induce the formation of strong interactive Sn-C covalent bonds between the tin-based components and the carbon-based materials, instead of traditional physical mixing or weak van der Waals force combination; at the same time, the extremely fast heating-rapid quenching characteristics of the FJH technology within 100ms can effectively retain the metastable structure and active components formed during the reaction, and lock the electronic interaction between tin and carbon.

[0027] The material source of the present application: SnS2 (hexagonal CdI2 structure tin disulfide powder) reagent is supplied by Aladdin Reagent Co., Ltd. (T302369, ≥99.5%); unmodified graphene is produced by Changzhou Fufen Technology Co., Ltd. (FXG-005, ≥93.0%); N, N-dimethylformamide (DMF) solution (AR, ≥99.5%) is produced by National Pharmaceutical Reagent.

[0028] A preparation method of a high-interface-stability tin-carbon negative electrode material, specifically comprising the following steps:

[0029] S1. SnS2 powder and graphene sheets are weighed according to a mass ratio of 1:1 of SnS2 to graphene sheets, and are respectively added to N, N-dimethylformamide (DMF) solution, and are oscillated to be initially dispersed, to obtain solution a and solution b correspondingly; the solid-liquid ratio of SnS2, graphene sheets and DMF is 2-5 mg:1 mL;

[0030] Preferably, the solid-liquid ratio of SnS2, graphene sheets and DMF is 2 mg:1 mL.

[0031] S2. The solution a and the solution b are respectively subjected to 3h ultrasonic treatment and 24h magnetic stirring; the solution a and the solution b are fully mixed to prepare a dispersion liquid c; the dispersion liquid c is sequentially subjected to 1h ultrasonic treatment and 24h magnetic stirring treatment;

[0032] Preferably, the ultrasonic treatment power is 300-500W, and the magnetic stirring rate is 300-500r / min.

[0033] S3. solid-liquid separation is carried out on the dispersion liquid c, and a solid-phase product is collected; the solid-phase product is washed with deionized water for 2-3 times, and after each washing, ultrasonic cleaning is carried out for 10 minutes, so that residual DMF solvent is removed; the washed solid-phase product is placed at 60-80 DEG C under vacuum drying for 20-30 hours, and a precursor is obtained;

[0034] Preferably, solid-liquid separation is carried out by suction filtration; the power of ultrasonic cleaning is 200-300 W, and the frequency is 40 kHz; the temperature of vacuum drying is 80 DEG C, and the time is 24 hours.

[0035] S4. The precursor is uniformly laid in the middle of the quartz tube, graphite electrodes are symmetrically installed at both ends of the quartz tube, the electrodes are in close contact with the precursor, vacuum is drawn in the interior of the quartz tube to a vacuum degree of ≤10 -2 Pa, and then FJH technology is used for processing; after the quartz tube is naturally cooled to room temperature, the product is taken out and ground into powder in an agate mortar, and a tin-carbon composite negative electrode material is obtained.

[0036] Preferably, the specific parameters of FJH are as follows: the applied voltage is 50-100 V, the current density is 10 4 ~10 5 A / m 2 , and the duration of instantaneous high-temperature processing is 100 ms; the Sn-C covalent bond between SnS2 and graphene is formed by using a thermoelectric coupling field.

[0037] The preparation method is simple to operate, and does not need a large amount of organic solvent to participate; by constructing a strong bonding tin-carbon interface, on the one hand, the volume expansion of the tin-based material in the charging and discharging process is efficiently regulated, and the active particle crushing and shedding are inhibited; on the other hand, a continuous and through conductive network is constructed, and the electronic transmission efficiency of the material is simultaneously improved, so that the structural stability and cycle performance of the sodium ion battery tin-carbon composite negative electrode material are significantly enhanced.

[0038] Example 1

[0039] A preparation method of a high-interface-stability Sn@G tin-carbon negative electrode material specifically comprises the following steps:

[0040] S1. 100 mg of SnS2 powder is placed in a beaker, 50 ml of N,N-dimethylformamide (DMF) solution is added, and oscillation is carried out until preliminary dispersion is obtained, so that solution a is obtained; 100 mg of graphene sheet is placed in another beaker, 50 ml of DMF solution is added, and oscillation is carried out until preliminary dispersion is obtained, so that solution b is obtained.

[0041] S2. The solution a and the solution b are respectively subjected to 3 hours of ultrasonic treatment (ultrasonic power 300-500 W, frequency 40 kHz) and 24 hours of magnetic stirring treatment (stirring rate 300-500 r / min); then the solution a and the solution b are mixed to prepare the dispersion c; the dispersion c is subjected to 1 hour of ultrasonic treatment (parameters are the same as above) and 24 hours of magnetic stirring treatment (parameters are the same as above) in sequence, so as to ensure that the SnS2 and the graphene sheet are uniformly dispersed.

[0042] S3. The dispersion c treated in S2 is subjected to solid-liquid separation by filtration, and the solid-phase product is collected; the solid-phase product is washed twice with deionized water, and after each washing, 10 minutes of ultrasonic cleaning (power 200-300 W, frequency 40 kHz) is supplemented, so as to sufficiently remove the residual DMF solvent; then the washed solid-phase product is placed in a vacuum drying box at 80 ℃ for drying for 24 hours, to obtain the Sn@G precursor.

[0043] S4. The Sn@G precursor is uniformly laid in the middle of a quartz tube, graphite electrodes are symmetrically installed at both ends of the quartz tube, and the electrodes are in close contact with the precursor; the inside of the quartz tube is vacuumized to a vacuum degree ≤10 -2 Pa, and then the FJH technology is used for treatment; after the quartz tube is naturally cooled to room temperature, the product is taken out and ground into a powder state in an agate mortar, to obtain the Sn@G tin-carbon composite negative electrode material.

[0044] The specific parameters of the FJH are as follows: applied voltage 50-100 V, current density 10 4 ~10 5 A / m 2 , and the duration of the instantaneous high-temperature treatment is 100 ms; the Sn-C covalent bond between SnS2 and graphene is formed by using a thermoelectric coupling field.

[0045] The Sn@G tin-carbon composite negative electrode material prepared above is subjected to phase, morphology and electrochemical performance characterization, and the results are as follows:

[0046] Figure 1 is an X-ray diffraction (XRD) spectrum of the Sn@G material; the characteristic diffraction peaks corresponding to (001), (002) and (101) appear in the spectrum; by comparison with the standard card, it can be known that the SnS2 in the precursor has undergone phase transition in the FJH treatment process, and no characteristic peak of SnS2 is left in the product; the position and intensity of the characteristic peaks match the phase characteristics of the tin-based component, which indicates that the reduction and phase transition of the tin-based component are successfully realized by the FJH technology, and no impurity phase is introduced.

[0047] Figure 2HR-TEM image of Sn@G material, combined with a scale (10 nm), shows that the particle size of Sn@G composite particles is about 20-30 nm, showing a uniform nanoscale size distribution; the internal lattice fringes of the particles are clear and continuous, indicating that the tin-based component is uniformly dispersed in the graphene matrix without obvious agglomeration, which verifies the dispersion effect of the process; at the same time, the interface between the particles and the graphene matrix is tightly combined, which reflects the strong bonding effect of Sn-C induced by the FJH technology.

[0048] The prepared Sn@G material was mixed with conductive carbon black and a binder as an active negative material, coated on a copper foil current collector to form a negative electrode sheet; a metal sodium sheet was used as a positive electrode to assemble a battery (CR2025 battery shell). The electrochemical performance analysis results are shown in Figures 3-4 . The cycle performance results are shown in Figure 3 At a current density of 0.5 A g -1 , the specific capacity of the Sn@G material remained at 250 mAh g -1 after 100 cycles; the coulombic efficiency was close to 100%; compared with traditional tin-carbon materials, the capacity decay rate was significantly reduced, indicating that the strong Sn-C bonding effectively inhibited the volume expansion of the tin-based material and improved the cycle stability. The charge-discharge curve is shown in Figure 4 The charge-discharge curves of the first, second and third cycles have a high degree of overlap, and the voltage platform is stable, indicating that the material has a stable structure during the cycle process and does not undergo obvious active component shedding or interface side reactions, further verifying its excellent electrochemical reversibility.

[0049] Comparative Example 1

[0050] This comparative example provides a traditional high-temperature calcination method for preparing a tin-carbon negative electrode material, and the preparation steps include: taking raw materials in a mass ratio of SnS2 to graphene sheet 1:1, adding them into DMF solution respectively, mixing directly after simple stirring for 30 min, and continuing to stir for 2 h to obtain a mixed dispersion liquid; after suction filtration, deionized water washing and vacuum drying at 80℃ for 24 h, a precursor is obtained; the precursor is placed in a tube furnace, heated to 600℃ at a heating rate of 5℃ / min under an argon protective atmosphere, naturally cooled to room temperature after holding for 2 h, and ground to obtain a traditional tin-carbon composite material (Sn / C-calcination material).

[0051] Performance test results: the Sn / C-calcination material was subjected to the same electrochemical performance test as the present application (assembly of CR2025 type sodium ion half battery, cycle test at a current density of 0.5 A g -1 ), and the results showed that the initial discharge specific capacity was 280 mAh g -1, the specific capacity is reduced to 120 mAh after 50 cycles g - ¹, the capacity retention rate is only 42.9%, and the specific capacity is further reduced to 85 mAh after 100 cycles g -1 , the coulombic efficiency fluctuates below 90%, and the morphology characterization shows that the material has obvious agglomeration and particle breakage after 50 cycles, and the interface between the tin-based component and the carbon matrix is seriously peeled off (because the traditional calcination only forms a weak van der Waals force combination, which cannot inhibit the volume expansion).

[0052] Compared with the comparative example, the core advantages of the present application are: (1) the cycle stability is significantly improved: the capacity retention rate of the material of the present application is > 80% (the specific capacity is ≥ 250 mAh g -1 ) after 100 cycles, while the capacity retention rate of the comparative example is less than 45% after 50 cycles, which fully proves that the strong Sn-C covalent bond formed by the FJH technology of the present application can effectively inhibit the volume expansion and the shedding of the active component. (2) The process efficiency is better: the comparative example needs high temperature for 2 h, the heating rate is slow, and the energy consumption is high, while the FJH technology of the present application only needs 100 ms of instantaneous treatment, and the process is more efficient and the energy consumption is lower. (3) The interface stability is stronger: the interface of the material of the comparative example is seriously peeled off after cycling, and the material of the present application still maintains a close tin-carbon interface after cycling, and the structural integrity is better, which guarantees the electrochemical reversibility in long-term cycling.

[0053] Compared with other traditional high-temperature calcination processes based on thermodynamic equilibrium which tend to form thermodynamic stable products, the "metastable interface engineering" is innovatively prepared, and the atomic-level structure is regulated from inside to outside, which is different from the simple mixing and complex solvent participation in the prior art. The method is simple, clean and energy-saving, and the reaction process is rapid. By using the millisecond non-equilibrium dynamics characteristics of FJH, this unique atomic-level anchoring mechanism is significantly better than the traditional physical coating, effectively inhibiting the volume expansion in the alloying reaction, and establishing a new criterion and universal paradigm for synthesizing high-performance metastable metal composites by FJH.

[0054] It should be understood that the various forms of flow shown above can be reordered, added to, or deleted from. For example, the steps described in the present disclosure can be executed in parallel, in sequence, or in a different order, as long as the desired results of the technical solutions of the present disclosure can be achieved, which is not limited herein.

[0055] The above detailed description does not limit the scope of the application. Various modifications, combinations, sub-combinations and alternatives can be made to the detailed description. Any modification, equivalent replacement and improvement etc. made within the spirit and principle of the application shall be included in the scope of the application.

Claims

1. A method for preparing a high interfacial stability tin-carbon anode material, characterized by: Specifically comprising the following steps: S1. SnS2 powder and graphene sheets are weighed according to a mass ratio of 1:1, and then added into N,N-dimethylformamide solution respectively, oscillated to preliminary dispersion, and then solution a and solution b are obtained respectively; S2. Solution a and solution b are subjected to ultrasonic treatment for 2-4 h and magnetic stirring for 20-30 h respectively; solution a and solution b are mixed thoroughly, subjected to ultrasonic treatment for 0.5-1.5 h and magnetic stirring for 20-30 h, and then dispersion liquid c is prepared; S3. Solid-liquid separation is performed on dispersion liquid c, and solid-phase product is collected; the solid-phase product is washed with deionized water for 2-3 times, and ultrasonic cleaning is performed after each washing; the cleaned solid-phase product is placed in a vacuum drying oven at 60-80 ℃ for 20-30 hours, and then precursor is obtained; S4. The precursor is uniformly laid in the middle of a quartz tube, graphite electrodes are symmetrically installed at both ends, vacuum is drawn, FJH technology is used for treatment, the product is taken out and ground into powder after the quartz tube is naturally cooled to room temperature, and then tin-carbon composite negative electrode material is obtained; The specific parameters of FJH are: applied voltage 50~100 V, current density 10 4 ~10 5 A / m 2 , the instantaneous high temperature treatment time is 100 ms, and the Sn-C covalent bond between SnS2 and graphene is formed by using a thermoelectric coupling field.

2. The preparation method of the high interfacial stability tin-carbon negative material according to claim 1, characterized in that: The solid-liquid ratio of the SnS2 powder, the graphene sheets and the N,N-dimethylformamide solution is 2-5 mg:1 mL.

3. The method of claim 2, wherein the tin-carbon anode material has a high interfacial stability. The solid-liquid ratio of the SnS2 powder, the graphene sheets and the N,N-dimethylformamide solution is 2 mg:1 mL.

4. The preparation method of the high interfacial stability tin-carbon negative material according to claim 1, characterized in that: The power of ultrasonic treatment in step S2 is 300-500 W, and the rate of magnetic stirring is 300-500 r / min.

5. The method of claim 1, wherein the tin-carbon anode material has high interfacial stability. The power of ultrasonic cleaning in step S3 is 200-300 W, and the frequency is 40 kHz.

6. The method of claim 1, wherein the tin-carbon anode material has a high interfacial stability. Step S3 adopts suction filtration for solid-liquid separation; the temperature of vacuum drying is 80 ℃, and the time is 24 hours.

7. A high interfacial stability tin-carbon anode material, characterized in that: A high-interface-stability tin-carbon negative electrode material is prepared by using the preparation method of claim 1.

8. Application of the high-interface-stability tin-carbon negative electrode material of claim 7 in the preparation of sodium ion batteries.

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