Silicon-based negative electrode plate capable of stabilizing interface, preparation method of silicon-based negative electrode plate and all-solid-state lithium ion battery

Abstract

The invention relates to the technical field of silicon-based negative electrode plates, in particular to a silicon-based negative electrode plate capable of stabilizing an interface, a preparation method of the silicon-based negative electrode plate and an all-solid-state lithium ion battery. The invention provides a preparation method of a silicon-based negative electrode plate capable of stabilizing an interface, which comprises the following steps: dripping a lithium borohydride solution on the surface of the silicon-based negative electrode plate, and drying to obtain the silicon-based negative electrode plate capable of stabilizing the interface. According to the preparation method of the silicon-based negative electrode plate capable of stabilizing the interface, the lithium borohydride solution is dripped on the silicon-based negative electrode plate, and the high-stability lithium borohydride interface layer formed on the surface of the silicon-based negative electrode plate can reduce the contact area between the silicon-based negative electrode plate and the sulfide solid electrolyte; insulation products generated by side reaction between the two are effectively reduced, and rapid increase of interface impedance and continuous consumption of active substances are avoided.

Description

Technical Field

[0001] This invention relates to the field of silicon-based anode electrode technology, specifically to silicon-based anode electrodes with stable interfaces and their preparation methods, and all-solid-state lithium-ion batteries. Background Technology

[0002] Currently, commercially available graphite anodes have a low theoretical specific capacity (372 mAh / g), and lithium metal anodes are prone to side reactions with solid electrolytes. In contrast, silicon (Si) anodes possess a higher theoretical specific capacity (3579 mAh / g) and a lower lithium intercalation potential (0.4 V vs. Li / Li). + With its abundant natural reserves and stable chemical properties, it is considered the most promising next-generation all-solid-state lithium-ion battery anode material.

[0003] Among different solid electrolytes, the sulfide system has the highest lithium-ion conductivity (10). -3 ~10 -2 The sulfide solid electrolyte exhibits excellent mechanical properties (~20 GPa) and high conductivity (S / cm). Its ultra-high ionic conductivity promotes rapid lithium-ion transport, enabling fast charging and discharging, while its excellent mechanical ductility can buffer the significant volume fluctuations of the silicon-based anode during cycling. Furthermore, the internal stress generated by the latter can further improve the solid-solid contact within the electrode and at the interface. By comprehensively utilizing the advantages of both silicon-based anodes and sulfide solid electrolytes, the disadvantages of silicon-based anodes can be mitigated to some extent, further enhancing the advantages of both material systems, thus facilitating the commercialization of high-performance silicon-based all-solid-state batteries.

[0004] However, silicon is a semiconductor with poor intrinsic conductivity; its electronic conductivity is only 10⁻⁶. -3 S / m, low lithium-ion diffusion coefficient (10) -14 ~10 -13 cm 2The addition of conductive carbon and solid electrolytes is necessary to promote electron / ion transport in silicon-based anodes. However, sulfide solid electrolytes have poor chemical stability and readily react with conductive carbon. Furthermore, they undergo various electrochemical reactions with silicon during lithium-ion migration, which not only reduce coulombic efficiency but also shorten battery cycle life. Currently, researchers mainly improve the chemical compatibility between silicon-based anodes and sulfide solid electrolytes by constructing carbon-free electrodes. The Meng Ying team (Darren HS Tan1, Yu-Ting Chen1, Hedi Yang, et al. “Carbon-free high-loading silicon anodes enabled by sulfide solid electrolytes”. Science, 2021, 353(6562): 1494-1499) used a carbon-free 99.9 wt.% micron-sized silicon anode matched with a sulfide solid electrolyte, eliminating the adverse effects of conductive carbon on the sulfide solid electrolyte. However, this method places extremely high demands on the electrode fabrication process. Song Jiangxuan et al. (Zhilu Wang, Xuefeng Shen, Shengjie Chen, et al. “Large-Scale Fabrication of Stable Silicon Anode in Air for Sulfide SolidState Batteries via Ionic-Electronic Dual Conductive Binder”. Advanced Materials, 2024, 36(32):2405025) prepared an electronic / ionic dual conductive binder Ag@PAP for silicon-based anodes, avoiding side reactions between conductive carbon additives and sulfide solid electrolytes. However, this electronic / ionic dual conductive binder is prepared by in-situ polymerization, which is a complex preparation method. Publication number CN119230811A discloses a silicon-based anode composed of silicon, sulfide solid electrolyte, lithium alloy as lithium supplement, and metal powder as electronic conductive agent. It does not contain conductive carbon and has good compatibility with sulfide solid electrolytes. However, it requires multiple ball milling processes, which is a complex preparation method and results in a low proportion of active material, which is not conducive to leveraging the high specific capacity advantage of silicon-based anodes. Publication number CN116053433B discloses a method for in-situ generation of Li-rich materials on the surface of silicon and silicon alloy particles. x MS y The resulting protective layer exhibits high stability against sulfide solid electrolyte materials, mitigating the incompatibility between silicon and its alloy anode materials and sulfide solid electrolyte materials. However, the assembled lithium... Silicon solid-state batteries have low capacity and limited improvement in cycle performance.

[0005] Therefore, in order to address the problem of poor chemical compatibility between silicon-based anodes and sulfide solid electrolytes, there is an urgent need for a new modification method that is simple to prepare and can effectively improve the chemical compatibility between silicon-based anodes and sulfide solid electrolytes, thereby enhancing the cycle stability of all-solid-state lithium-ion batteries. Summary of the Invention

[0006] The present invention aims to overcome the defect of poor chemical compatibility between silicon-based anodes and sulfide solid electrolytes in the prior art, and provides a silicon-based anode electrode sheet with a stable interface, its preparation method, and an all-solid-state lithium-ion battery to overcome the above defects.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a method for preparing a silicon-based negative electrode sheet with a stable interface, comprising: dripping a lithium borohydride solution onto the surface of the silicon-based negative electrode sheet and drying it to obtain a silicon-based negative electrode sheet with a stable interface.

[0008] This application utilizes a simple dripping method to coat the surface of a silicon-based anode electrode with lithium borohydride, allowing it to fully penetrate into the interior of the electrode. The lithium borohydride introduced onto the surface of the silicon-based anode electrode and the lithium-boron alloy generated in situ during cycling promote interfacial ion transport and improve the battery's kinetic performance.

[0009] Furthermore, lithium borohydride exhibits excellent chemical compatibility with silicon-based anode electrodes. The lithium borohydride on the surface of the silicon-based anode electrode can reduce the contact between the silicon-based anode electrode and the sulfide solid electrolyte, thereby reducing the occurrence of side reactions and achieving a stable electrode interface; at the same time, it improves the compatibility between the silicon-based anode electrode and the sulfide solid electrolyte.

[0010] Preferably, the concentration of the lithium borohydride solution is 1~5 mg / mL; and / or, the solvent in the lithium borohydride solution includes at least one of tetrahydrofuran, diethyl ether, and acetonitrile.

[0011] Preferably, the silicon-based negative electrode sheet is a porous silicon-based negative electrode sheet.

[0012] The pores on the porous silicon-based anode electrode sheet help lithium borohydride solution to quickly penetrate into the interior of the silicon-based anode electrode sheet, allowing lithium borohydride to grow firmly together with the silicon-based anode electrode sheet, effectively isolating the silicon-based anode electrode sheet from the sulfide solid electrolyte.

[0013] Preferably, the silicon-based negative electrode sheet includes a current collector and an active material coated on the surface of the current collector, wherein the active material includes silicon-tin powder.

[0014] Preferably, the active material is coated onto the current collector after being mixed with a conductive agent and a binder.

[0015] Preferably, the conductive agent is at least one of conductive graphite, carbon nanotubes, hydroxylated carbon nanotubes, carbon nanofibers, hydroxylated carbon nanofibers, acetylene black, and Super P.

[0016] Preferably, the binder is at least one selected from sodium alginate, carboxymethyl cellulose, carboxyethyl cellulose, polyvinyl alcohol, polyacrylic acid, gelatin, xanthan gum, and lithium polyacrylate.

[0017] Preferably, the active material further includes at least one of micron-sized silicon particles, nano-sized silicon particles, silicon-oxygen complexes, silicon-carbon complexes, and silicon-based alloys.

[0018] Preferably, the mass ratio of lithium borohydride to the active material in the lithium borohydride solution is (0.01~0.1):1.

[0019] Preferably, the mass ratio of lithium borohydride to the active material in the lithium borohydride solution is (0.01~0.05):1.

[0020] Preferably, the mass ratio of lithium borohydride to the active material in the lithium borohydride solution is (0.01~0.04):1.

[0021] Preferably, the method for preparing the silicon-tin powder includes: mixing silicon blocks and tin particles and then induction melting them under an argon atmosphere to obtain a silicon-based composite material ingot; subsequently, crushing the ingot into powder and placing it in a vacuum rotary quenching furnace for induction melting under an argon atmosphere; transferring the obtained melt through a nozzle carrying an argon gas flow and spraying it onto a high-speed rotating copper roller; collecting the rapidly quenched product after cooling; and sand milling the rapidly quenched product to obtain silicon-tin powder.

[0022] Preferably, the drying temperature is 50~100℃ and the time is 1~5 h; and / or, the drying method is vacuum drying, and the vacuum degree during vacuum drying is <-0.08 MPa.

[0023] The present invention provides a silicon-based negative electrode sheet with a stable interface, the silicon-based negative electrode sheet with a stable interface includes a silicon-based negative electrode sheet and an interface layer loaded on the silicon-based negative electrode sheet.

[0024] Lithium borohydride is coated on the surface of the silicon-based negative electrode sheet and penetrates into the interior of the silicon-based negative electrode sheet. After drying, an interface layer is formed on the surface of the silicon-based negative electrode sheet to isolate the silicon-based negative electrode sheet from the sulfide-based solid electrolyte.

[0025] This invention provides an all-solid-state lithium-ion battery, comprising a silicon-based negative electrode sheet with a stable interface and a sulfide-based solid electrolyte.

[0026] The lithium borohydride introduced onto the surface of the silicon-based anode electrode promotes interfacial ion transport, effectively reduces the contact area between the silicon-based anode electrode and the sulfide solid electrolyte, and alleviates side reactions between the two, thereby achieving a stable electrode interface. The lithium borohydride introduced into the silicon-based anode electrode is a soft solid filler relative to silicon particles, providing a buffer for the volume expansion of silicon particles, thus improving the cycle stability of the all-solid-state lithium-ion battery.

[0027] Preferably, the sulfide-based solid electrolyte includes Li3PS4, Li7P2S8I, and Li7P3S 11 Li6PS5Cl, Li 5.5 PS 4.5 Cl 1.5 Li6PS5Br, Li6PS5I, Li 10 GeP2S 12 Li 3.25 Ge 0.25 P 0.75 S4 and Li 10 SnP2S 12 At least one of them.

[0028] Therefore, the present invention has the following beneficial effects: (1) The method for preparing a silicon-based negative electrode sheet with a stable interface provided by the present invention involves dripping a lithium borohydride solution onto the silicon-based negative electrode sheet. The highly stable lithium borohydride interface layer formed on the surface of the silicon-based negative electrode sheet can reduce the contact area between the silicon-based negative electrode sheet and the sulfide solid electrolyte, effectively reducing the generation of insulating products caused by side reactions between the two, and avoiding a sharp increase in interface impedance and continuous consumption of active materials.

[0029] (2) The silicon-based negative electrode sheet with stable interface provided by the present invention forms an interface layer on the surface of the silicon-based negative electrode sheet by dripping lithium borohydride solution onto the silicon-based negative electrode sheet to isolate the silicon-based negative electrode sheet and the sulfide-based solid electrolyte, which greatly increases the compatibility between the two and solves the problem of poor chemical compatibility between silicon-based negative electrode and sulfide solid electrolyte, laying the foundation for obtaining all-solid-state lithium-ion batteries with high cycle stability and high coulombic efficiency.

[0030] (3) This invention utilizes lithium borohydride solution as the interface layer source. As a fast lithium-ion conductor, it can effectively improve ion transport at the interface between the silicon-based anode and the sulfide solid electrolyte. Furthermore, lithium borohydride can generate lithium-boron alloy (Li₂O₃) in situ during cycling. x B), Lix The existence of B makes Li + It enables efficient transmission at the interface layer, reduces the overall interface impedance of the battery, and thus improves the dynamic performance of the all-solid-state battery.

[0031] (4) The lithium borohydride solution used in this invention has good permeability and can fully penetrate into the interior of the silicon-based electrode. The lithium borohydride that penetrates into the electrode is a soft solid filler relative to the silicon particles, which can provide buffer space and mechanical support for the volume expansion of the silicon particles and maintain the structural integrity of the electrode during the cycling process.

[0032] (5) The method for preparing silicon-based negative electrode sheet provided by the present invention is simple, easy to operate and easy to promote. Attached Figure Description

[0033] Figure 1 Cyclic performance of all-solid-state lithium-ion batteries fabricated from silicon-based anode electrodes made of different hydrides at a current density of 1500 mA / g.

[0034] Figure 2 Cyclic performance of all-solid-state lithium-ion batteries fabricated from silicon-based anode electrode sheets with different LiBH4 addition amounts at a current density of 1500 mA / g.

[0035] Figure 3 Rate performance of all-solid-state lithium-ion batteries fabricated from silicon-based anode electrode sheets with different LiBH4 addition amounts.

[0036] Figure 4 The images are EIS diagrams of Example 1 and Comparative Example 1 before cycling.

[0037] Figure 5 The XPS spectra of Example 1 and Comparative Example 1 after 200 cycles are shown. Detailed Implementation

[0038] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0039] In this section, the raw materials were sourced as follows: sodium alginate from Aladdin; conductive graphite (SFG-6) from Cyber ​​Electrochemical; copper current collector from Cyber ​​Electrochemical; lithium metal sheets from Tianjin Lithium Industry; indium metal sheets from Changsha Youcheng; and LPSCl (Li 5.5 PS4.5 Cl 1.5 The following were purchased from Hefei Kejing: LiBH4 from Sigma-Aldrich; NaBH4, Mg(BH4)2 and NaAlH4 from Aladdin; tetrahydrofuran, diethyl ether and acetonitrile from Aladdin; and CaH2 from Aladdin.

[0040]

Example

[0041] Step 2: After mechanically crushing the ingot, the powder sample is placed in a quartz tube, which is then placed in a vacuum rotary quenching furnace. First, the furnace cavity is evacuated, then argon gas is introduced to 0.5 atmospheres for suspension melting, which lasts for 5 minutes. After the melt is completely melted, it is sprayed through a nozzle supplied with argon gas at 2.5 atmospheres onto a high-speed rotating copper roller for rapid cooling. The linear speed of the copper roller is 40 m / s, and the spraying distance is 2 meters. After cooling, the obtained rapid quenching product is collected.

[0042] Step 3: Grind the rapidly quenched product using a sand mill. Use anhydrous ethanol as the grinding medium, zirconia grinding beads, and a sand mill speed of 2000 rpm for 25 minutes. After drying, silicon-tin powder is obtained.

[0043] Example 1 S1. The silicon-tin powder, SFG-6, and sodium alginate binder prepared according to the above method are weighed at a mass ratio of 64:16:20. The mixture is then degassed and stirred at 600 rpm for 120 s, 2000 rpm for 2400 s, and 2200 rpm for 180 s, repeated three times to form a uniformly mixed slurry. This uniformly mixed slurry is then coated onto a current collector copper foil using a 0.15 mm scraper. After air drying, it is placed in a 70℃ oven for vacuum drying for 9 h. After cooling to room temperature, the dried silicon-based negative electrode sheet is pressed at 10 MPa for 1 min, and then cut into 10 mm round pieces with a loading of 1.0 mg / cm² per piece. 2 The cut discs were transferred to an oven at 105°C and vacuum dried for 11 hours. After cooling to room temperature, they were transferred to a glove box filled with argon gas and left to stand for 24 hours.

[0044] S2. Weigh 24 mg of LiBH4 and add it to 10 mL of tetrahydrofuran solution (CaH2 dehydrated). Stir at room temperature until a homogeneous solution is formed. The concentration of the resulting LiBH4-tetrahydrofuran solution is 2.4 mg / mL.

[0045] S3. The LiBH4-tetrahydrofuran solution obtained in S2 is dripped onto the surface of the silicon-based anode, and the amount of LiBH4 added is controlled to be 0.0306 of the mass of silicon-tin powder, so as to obtain a silicon-based anode electrode sheet with a stable interface.

[0046] S4. The silicon-based negative electrode sheet with a stable interface obtained in S3 is vacuum dried at 70 °C for 2 h.

[0047] Example 2 This embodiment is basically the same as that of Embodiment 1, except that: in S2, the concentration of LiBH4-tetrahydrofuran solution is 1.2 mg / mL, and the amount of LiBH4 added is controlled to be 0.0153 of the mass of silicon-tin powder, so as to obtain a silicon-based negative electrode sheet with a stable interface.

[0048] Example 3 This embodiment is basically the same as that of Embodiment 1, except that: in S2, the concentration of LiBH4-tetrahydrofuran solution is 4.8 mg / mL, and the amount of LiBH4 added is controlled to be 0.0611 of the mass of silicon-tin powder, so as to obtain a silicon-based negative electrode sheet with a stable interface.

[0049] Comparative Example 1 This comparative example is basically the same as Example 1, except that S2 and S3 are omitted and LiBH4 is not added; a silicon-based negative electrode sheet is obtained.

[0050] Comparative Example 2 This comparative example is basically the same as Example 3, except that LiBH4 in S2 is replaced with NaBH4, the final concentration of NaBH4-tetrahydrofuran solution is 4.8 mg / mL, and the amount of NaBH4 added is controlled to be 0.0611 of the mass of silicon-tin powder.

[0051] Comparative Example 3 This comparative example is basically the same as Example 3, except that LiBH4 in S2 is replaced with Mg(BH4)2, the final concentration of Mg(BH4)2-tetrahydrofuran solution is 4.8 mg / mL, and the amount of Mg(BH4)2 added is controlled to be 0.0611 of the mass of silicon-tin powder.

[0052] Comparative Example 4 This comparative example is basically the same as Example 3, except that LiBH4 in S2 is replaced with NaAlH4, the final concentration of NaAlH4-tetrahydrofuran solution is 4.8 mg / mL, and the amount of NaAlH4 added is controlled to be 0.0611 of the mass of silicon-tin powder.

[0053] [Performance Testing] The silicon-based negative electrode sheets prepared in Examples 1-3 and Comparative Examples 1-4 were assembled into all-solid-state lithium-ion batteries in a vacuum glove box with a water oxygen level of less than 0.01 ppm. The prepared silicon-based negative electrode sheets were used as the positive electrode, and the Li-In alloy sheet was used as the negative electrode. LPSCl (Li 5.5 PS 4.5 Cl 1.5 It is used as a solid electrolyte.

[0054] Weigh 70 mg of LPSCl and press it at 3 MPa for 1 min. Place a silicon-based negative electrode sheet on one side of the LPSCl and press it at 5 MPa for 3 min. Place a metal In sheet and a metal Li sheet on the other side of the LPSCl and press it at 3 MPa for 1 min. Apply a force of 10 Nm using a torque wrench to provide the test stacking pressure.

[0055] The assembled batteries were left to stand at 30 °C for 10 h. The electrochemical performance was tested using the Xinwei Battery Testing System (5 V, 10 mA) with constant current testing. The voltage range was -0.6 to 0.5 V, the testing rate was 1 C (1500 mA / g), and the testing temperature was 30 °C. 1. Screening of hydrides Before preparing the silicon-based anode electrode sheet stabilized by LiBH4, the inventors explored the effects of silicon-based anode electrode sheets stabilized by different hydrides. In Example 3 and Comparative Examples 1-4, the electrochemical performance of all-solid-state lithium-ion batteries assembled from silicon-based anode electrode sheets stabilized by different hydrides was tested. The obtained electrochemical performance is shown in Table 1 and... Figure 1 As shown.

[0056] As shown in Table 1, the all-solid-state lithium-ion battery assembled with a NaAlH4-stabilized silicon-based anode electrode did not show significant improvement in cycle performance, while the silicon-based anode electrodes stabilized by the three borohydrides all improved the battery's cycle performance. In the case where no hydrides were introduced into the silicon-based anode electrode, Comparative Example 1 showed a high initial specific capacity, but its capacity rapidly decayed during cycling, with a charging specific capacity of only 445.98 mAh / g after 200 cycles, corresponding to a capacity retention of only 39.82%. The all-solid-state lithium-ion battery assembled with a LiBH4-stabilized silicon-based anode electrode showed a significant improvement in cycle performance, with the initial coulombic efficiency increasing from 68.31% to 71.83%, and the capacity retention after 200 cycles increasing from 39.82% to 84.07%. The all-solid-state lithium-ion battery assembled from a NaBH4-stabilized silicon-based anode electrode exhibited a rapid capacity decrease during the first 25 cycles, after which the rate of decrease slowed, maintaining a similar cycling trend to the LiBH4 battery in Example 3. After 200 cycles, the capacity retention rate was 56.66%. The all-solid-state lithium-ion battery assembled from a Mg(BH4)2-stabilized silicon-based anode electrode showed an initial coulombic efficiency of only 59.35% and an initial charge / discharge specific capacity of only 542.23 / 613.29 mAh / g at 1 C.

[0057] Therefore, it is evident that the LiBH4 silicon-based anode electrode exhibits the best chemical compatibility with LPSCl, significantly improving the cycle stability of all-solid-state lithium-ion batteries. However, as borohydrides, LiBH4, NaBH4, and Mg(BH4)2 show varying degrees of chemical compatibility with LPSCl, leading to different degrees of performance changes in the silicon-based anode electrode and thus affecting the performance of all-solid-state lithium-ion batteries.

[0058] Table 1: Effect of hydrides on the performance of silicon-based anode electrodes

[0059] 2. Exploration of LiBH4 addition amount Furthermore, the inventors investigated the amount of LiBH4 added to screen for the optimal mass ratio of LiBH4 to silicon-tin powder. (See Table 2 and...) Figure 2It can be seen that as the concentration of LiBH4-tetrahydrofuran solution increases, the battery capacity at 1 C shows a trend of first increasing and then decreasing. When the concentration of LiBH4 solution-tetrahydrofuran is 2.4 mg / mL (mass ratio of LiBH4 to silicon-tin powder is 0.0306:1), Example 1 obtained a high initial coulombic efficiency and good cycle stability, with the initial coulombic efficiency increasing to 73.34% and the capacity retention rate increasing to 85.12% after 200 cycles. When the concentration of LiBH4-tetrahydrofuran solution is 1.2 mg / mL (mass ratio of LiBH4 to silicon-tin powder is 0.0153:1) and 4.8 mg / mL (mass ratio of LiBH4 to silicon-tin powder is 0.0611:1), the capacity retention rates of Examples 2 and 3 after 200 cycles are both higher than that of Comparative Example 1 (39.82%), at 61.06% and 84.07%, respectively. Based on the above results, the comparison shows that the cycle stability of all-solid-state lithium-ion batteries assembled from silicon-based anode electrode sheets with different amounts of LiBH4 addition is greatly improved. Among them, when the concentration of LiBH4-tetrahydrofuran solution is 2.4 mg / mL (the mass ratio of LiBH4 to silicon-tin powder is 0.0306:1), higher rate capacity and better cycle stability can be obtained.

[0060] Table 2: Effect of LiBH4 addition amount

[0061] 3. Ratio Performance Test Rate performance tests were conducted on Examples 1-3 and Comparative Example 1, and the results are as follows: Figure 3 As shown in the figure. Analysis reveals that Examples 1 and 2 exhibit improved rate performance, while Example 3 shows deteriorated rate performance. This indicates that an appropriate amount of LiBH4 is beneficial for improving the lithium-ion diffusion kinetics of the battery. However, an excessively thick LiBH4 interface layer implies that Li... + Reaching the silicon-based anode requires traversing a longer distance, which actually slows down the overall battery dynamics. 4. EIS Testing The initial interface impedances of Example 1 and Comparative Example 1 were tested using EIS: R1 of Comparative Example 1 was... ct It is 346.4 Ω, while R in Example 1 is 346.4 Ω. ct Only 65.55 Ω. From Figure 4 As can be seen, the all-solid-state lithium-ion battery R is assembled from silicon-based anode electrode sheets stabilized by LiBH4. ct The significant reduction indicates that the silicon-based anode electrode stabilized by LiBH4 can improve the interfacial ion transport capacity and chemical compatibility between the silicon-based electrode and LPSCl, thereby enhancing the kinetic performance of the all-solid-state battery.

[0062] 5. XPS Test To reveal the reason for the improved cycle performance of silicon-based all-solid-state batteries after introducing LiBH4 into the silicon-based anode electrode sheet, XPS in-depth profiling tests were performed on the silicon-based anode electrode sheets of Example 1 and Comparative Example 1 after 200 cycles. Figure 5 The results showed that the all-solid-state lithium-ion battery assembled with a silicon-based anode electrode plate stabilized by LiBH4 generated less Li2S and LiCl after cycling. This indicates that introducing LiBH4 onto the electrode surface can suppress side reactions between the silicon-based electrode and LPSCl, thereby obtaining a stable interface and improving the battery's cycle performance. The B 1s spectrum of Example 1 shows the presence of Li... x The characteristic peak of B indicates that LiBH4 is generated in situ during the cycling process, producing Li. x B. In silicon-based anode electrodes without LiBH4 stabilization, the silicon-based anode reacts directly with the LPSCl solid electrolyte, forming a high-resistivity, continuously thickening SEI layer. Silicon-based anode electrodes stabilized with LiBH4 not only reduce the high-resistivity products but also enable in-situ formation of Li... x B, Li x B is a good lithium-ion conductor, and its presence makes Li... + It enables efficient and uniform transmission at the interface, reducing the overall interface impedance of the battery and thus improving the battery's rate performance.

Claims

1. A method for preparing a silicon-based negative electrode sheet with a stable interface, characterized in that, include: A lithium borohydride solution is dripped onto the surface of a silicon-based negative electrode sheet, and then dried to obtain a silicon-based negative electrode sheet with a stable interface.

2. The preparation method according to claim 1, characterized in that, The concentration of the lithium borohydride solution is 1~5 mg / mL; and / or, the solvent in the lithium borohydride solution includes at least one of tetrahydrofuran, diethyl ether and acetonitrile.

3. The preparation method according to claim 1, characterized in that, The silicon-based negative electrode sheet is a porous silicon-based negative electrode sheet.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The silicon-based negative electrode sheet includes a current collector and an active material coated on the surface of the current collector, wherein the active material includes silicon-tin powder; Preferably, the active material is coated onto the current collector after being mixed with a conductive agent and a binder; Preferably, the conductive agent is at least one of conductive graphite, carbon nanotubes, hydroxylated carbon nanotubes, carbon nanofibers, hydroxylated carbon nanofibers, acetylene black, and Super P. Preferably, the binder is at least one selected from sodium alginate, carboxymethyl cellulose, carboxyethyl cellulose, polyvinyl alcohol, polyacrylic acid, gelatin, xanthan gum, and lithium polyacrylate; Preferably, the active material further includes at least one of micron-sized silicon particles, nano-sized silicon particles, silicon-oxygen complexes, silicon-carbon complexes, and silicon-based alloys.

5. The preparation method according to claim 4, characterized in that, The mass ratio of lithium borohydride to the active material in the lithium borohydride solution is (0.01~0.1):

1.

6. The preparation method according to claim 1, characterized in that, The drying temperature is 50~100℃, and the time is 1~5h; and / or the drying method is vacuum drying, and the vacuum degree during vacuum drying is <-0.08 MPa.

7. The silicon-based negative electrode sheet with a stable interface prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The silicon-based negative electrode sheet with a stable interface includes a silicon-based negative electrode sheet and an interface layer loaded on the silicon-based negative electrode sheet.

8. A fully solid-state lithium-ion battery, characterized in that, It includes a silicon-based negative electrode sheet with a stable interface prepared by any of the preparation methods described in claims 1 to 6, or a silicon-based negative electrode sheet with a stable interface as described in claim 7, and a sulfide-based solid electrolyte.

9. The all-solid-state lithium-ion battery as described in claim 8, characterized in that, The sulfide-based solid electrolyte includes Li3PS4, Li7P2S8I, and Li7P3S. 11 Li6PS5Cl, Li 5.5 PS 4.5 Cl 1.5 Li6PS5Br, Li6PS5I, Li 10 GeP2S 12 Li 3.25 Ge 0.25 P 0.75 S4 and Li 10 SnP2S 12 At least one of them.

Images