Ag / sulfhydrylation SiO2 nanosphere modified negative current collector for negative-electrode-free lithium metal battery and preparation method of Ag / sulfhydrylation SiO2 nanosphere modified negative current collector

Abstract

The invention discloses an Ag / sulfhydrylated SiO2 nanosphere modified negative current collector for a negative-electrode-free lithium metal battery and a preparation method of the Ag / sulfhydrylated SiO2 nanosphere modified negative current collector, Ag / sulfhydrylated SiO2 and polyacrylonitrile are dispersed in a solvent to form stable and uniform composite slurry, and then the surface of a copper current collector is coated with the composite slurry. According to the method, the battery performance is optimized by coating the surface of a copper current collector with an Ag / sulfhydrylated SiO2 modification layer, the Ag with high lithium affinity can effectively reduce the lithium nucleation energy barrier, the polar sulfydryl is beneficial to promoting and guiding the migration of Li < + >, the rich-OH groups on the surfaces of SiO2 nanospheres can adsorb lithium ions, and the Ag, the polar sulfydryl and PAN are synergistically induced to form an SEI film rich in inorganic components (LiF, Li3N and Li2S), so that the battery performance is improved. The composite SEI not only can effectively inhibit the side reaction between the lithium metal and the electrolyte, but also can reduce the interface charge transfer resistance, finally realizes the uniform deposition / stripping of lithium, and obviously improves the cycling stability of the negative-electrode-free lithium metal battery.

Description

Technical Field

[0001] This invention belongs to the field of negative electrode-free lithium metal battery technology, specifically relating to an Ag / thiolized SiO2 nanosphere modified negative electrode current collector for negative electrode-free lithium metal batteries and its preparation method. Background Technology

[0002] Lithium metal batteries, with their ultra-high theoretical specific capacity and extremely low electrochemical potential, have shown irreplaceable application potential in the field of next-generation high-energy-density energy storage and are widely recognized as a highly competitive core candidate system. However, the high chemical activity of lithium metal anodes presents them with many technical bottlenecks: on the one hand, lithium metal is prone to side reactions with the electrolyte, leading to low battery coulombic efficiency and a significant reduction in cycle life; on the other hand, the severe volume expansion and lithium dendrite growth problems accompanying lithium deposition not only exacerbate interface instability but may also puncture the separator and cause internal short circuits, greatly limiting the commercialization of traditional lithium metal batteries.

[0003] To overcome these challenges, electrodeless lithium metal batteries have emerged. This system uses copper foil as the negative electrode current collector, initially containing no lithium metal. It not only possesses excellent chemical stability and high safety but also significantly reduces battery manufacturing costs, becoming a crucial technological path to address the pain points of traditional lithium metal batteries. However, the inherent roughness of the copper current collector surface induces preferential lithium ion adsorption, forming uneven nucleation sites, leading to non-uniform lithium deposition and lithium dendrite growth, ultimately threatening battery safety. Therefore, surface modification of the copper current collector to regulate lithium deposition behavior has become a key factor in improving the performance of electrodeless lithium metal batteries.

[0004] Existing copper current collector modification techniques still have many shortcomings that need to be addressed: Hu et al. constructed a lithium-loving polyaniline-modified three-dimensional copper mesh current collector to induce uniform lithium deposition. A half-cell fabricated using this polyaniline-modified three-dimensional copper mesh achieved a current collector density of 1 mA cm⁻¹. -2 1 mA h cm -2 Under these conditions, the average CE was 97.6% (J. Mater. Chem. A 2020, 08, 33). However, the insufficient conductivity and stability of conductive polymers greatly limit their application in lithium metal batteries. Wang et al. regulated lithium deposition by constructing a stable lithium-metal alloy interface. This interface effectively reduced the nucleation energy barrier of lithium, enhanced the interaction between the interface and lithium ions, and made the lithium deposit dense and firmly bonded to the substrate. Their lithium-tin alloy modified copper foil current collector achieved a CE of 97.6% at 1 mA cm⁻¹. -2 and 1 mAh cm -2Under these conditions, the average coulombic efficiency reached 94.1% after 400 cycles, demonstrating excellent lithium plating / stripping cycle stability (Energy Storage Materials, 2022, 49, 08). However, the alloying method usually requires high-temperature heat treatment under high vacuum or protective atmosphere, which has problems such as large equipment investment, high energy consumption, and long production cycle. Moreover, the high-temperature environment may change the microstructure and mechanical properties of the copper foil itself, resulting in a decrease in its strength and toughness. Patent CN120319820A discloses a process for preparing a three-dimensional copper-based composite current collector. The process involves thermally oxidizing copper foam to obtain a three-dimensional copper-based framework, followed by electrodeposition of lithium-containing compounds. The lithium-affinity sites formed during the electrodeposition process induce in-situ nucleation of lithium metal. The interfacial chemical stability is improved through pre-regulation of interfacial components, and a solid electrolyte interphase (SEI) film rich in inorganic components is formed to inhibit lithium dendrite growth. However, this preparation process has stringent requirements for process parameters. Thermal oxidation requires a high-temperature environment, and electrodeposition requires specific electrolytes and conditions. The operation is difficult, making it hard to achieve high-speed continuous production. The production efficiency is low, which is not conducive to large-scale manufacturing. Furthermore, the SEI film formed by electrodeposition has low mechanical strength and is prone to cracking during long-term battery cycling, affecting battery stability.

[0005] In summary, developing a cathode current collector for electrodeless lithium metal batteries that is simple to prepare, low in cost, and possesses high mechanical strength, structural stability, and long cycle life has become a pressing technical challenge in this field. Summary of the Invention

[0006] To overcome the shortcomings of existing copper current collector modification technologies for electrodeless lithium metal batteries, such as complex preparation processes, high costs, insufficient mechanical strength, and poor cycle stability, this invention proposes an Ag / thiolized SiO2 nanosphere-modified negative electrode current collector for electrodeless lithium metal batteries and its preparation method. The core objective is to achieve rapid migration and uniform distribution of lithium ions by constructing an Ag / thiolized SiO2 composite modification layer, inducing uniform and dense nucleation of lithium metal on the current collector surface, thereby fundamentally inhibiting the growth and propagation of lithium dendrites. Simultaneously, it optimizes the stability of the electrode / electrolyte interface, reduces side reactions, and thus significantly improves the initial coulombic efficiency, cycle stability, and long-term electrochemical reliability of electrodeless lithium metal batteries. Ultimately, it provides a simple, low-cost, structurally stable, and high-performance negative electrode current collector solution.

[0007] To achieve its objectives, the present invention employs the following technical solution: This invention discloses a method for preparing Ag / thiolized SiO2 nanospheres modified negative electrode current collectors for negative electrode-free lithium metal batteries. This method achieves lithium deposition behavior regulation and battery performance improvement through stepwise synthesis of composite modification materials and surface modification of copper current collectors. The specific steps are as follows: Step 1: Preparation of SiO2 nanospheres Ethanol, deionized water and ammonia were added to a reaction vessel and stirred at room temperature until the system was homogeneous and a stable reaction base liquid was formed. Then, a premixed solution of silicon source and ethanol was rapidly added dropwise and the reaction was continuously stirred at 30°C for 2 h. After the reaction was completed, the product was collected by centrifugation and washed at least 3 times with alternating ethanol and deionized water to remove unreacted raw materials and impurities. Finally, the product was dried to obtain pure SiO2 nanospheres.

[0008] Step 2: Preparation of thiolized SiO2 nanospheres The SiO2 nanospheres obtained in step 1 were uniformly dispersed in methanol, and a functionalizing reagent containing a thiol group was added. Under the protection of an inert gas (such as nitrogen), the functionalization reaction was carried out by heating and stirring. After the reaction was completed, the system was cooled to room temperature, the product was collected by centrifugation, washed with methanol 3 to 5 times to remove unreacted functionalizing reagents, and dried to obtain thiolized SiO2 nanospheres.

[0009] Step 3: Preparation of Ag / thiolized SiO2 nanosphere composite material The thiolized SiO2 nanospheres obtained in step 2 were uniformly dispersed in ethylene glycol. Polyvinylpyrrolidone (PVP) and silver nitrate (AgNO3) were then added to the resulting dispersion in sequence and stirred until homogeneous. The resulting mixture was heated to the reaction temperature, and potassium chloride (KCl) solution was slowly added dropwise under continuous magnetic stirring. After the addition was completed, the reaction was continued at the temperature. After the reaction was completed, the product was collected by centrifugation, washed at least three times with deionized water and ethanol alternately, and dried to obtain the Ag / thiolized SiO2 nanosphere composite material.

[0010] Step 4: Preparation of Ag / thiolized SiO2 nanospheres to modify the negative electrode current collector The Ag / thiolized SiO2 nanosphere composite material obtained in step 3 was uniformly dispersed in a solvent, and polyacrylonitrile (PAN) was added. The mixture was magnetically stirred to obtain a free-agglomerating and highly fluid slurry. The slurry was uniformly coated onto the surface of a copper current collector, and the coating thickness was controlled. The coated copper current collector was then placed in an oven and dried to constant weight at a set temperature to obtain the Ag / thiolized SiO2 nanosphere modified negative electrode current collector.

[0011] Preferably, in step 1: the silicon source is selected from at least one of tetraethyl orthosilicate, methyl orthosilicate, and sodium silicate; the centrifugation speed is 8000~10000 rpm, the centrifugation time is 5~10 min; the drying temperature is 60~80℃, and the drying time is 12~24 h.

[0012] Preferably, in step 2: the functionalizing reagent containing a thiol group is selected from at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropylmethyldimethoxysilane; the functionalization reaction temperature is 40~60℃, and the reaction time is 20~24 h; the centrifugation speed and drying conditions are the same as in step 1.

[0013] Preferably, in step 3, the mass ratio of AgNO3 to thiolized SiO2 nanospheres is 2~6:1; the amount of PVP added is 1-2 times the mass of AgNO3; the reaction temperature is 120~140℃, the total reaction time is 4~6 h; the concentration of KCl solution is 5~10 mg / mL; and the centrifugation speed and drying conditions are the same as in step 1.

[0014] Preferably, in step 4, the solvent is selected from at least one of water, ethanol, methanol, N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), ethylene glycol, aqueous acetone solution, aqueous ethanol solution, and aqueous methanol solution; the mass ratio of Ag / mercaptolated SiO2 nanospheres to polyacrylonitrile is 2~8:1, and the total stirring time is 10~12 h; the thickness of the copper current collector is 6~20 μm; the coating thickness of the mixed slurry is 50~100 μm; the drying temperature is 80~100 ℃, and the drying time is 8~10 h.

[0015] Compared with existing technologies, this invention modifies the surface of copper current collectors by constructing an Ag / thiolized SiO2 composite modification layer, forming a lithium deposition regulation system with "multi-component synergistic regulation," thereby achieving a breakthrough improvement in the overall performance of electrodeless lithium metal batteries. Specific technical effects are reflected in: 1. Ag nanoparticles possess ultra-high lithiumophilic activity, which can significantly reduce the lithium nucleation energy barrier and provide uniform nucleation sites for lithium metal; the strong polarity of the thiol group (-SH) can construct a fast lithium-ion transport channel, guiding Li... + Directed migration and uniform distribution; the abundant -OH groups on the surface of SiO2 nanospheres capture lithium ions through electrostatic adsorption, further optimizing the lithium ion concentration gradient. The three factors work synergistically to inhibit the nucleation and growth of lithium dendrites from the source, promoting the deposition of lithium metal in a dense and uniform form on the surface of the current collector.

[0016] 2. The inorganic rigid framework of SiO2, the polymeric bonding effect of PAN, and the functional properties of thiol groups synergistically induce the formation of a composite solid electrolyte interphase (SEI) film rich in inorganic components such as LiF, Li3N, and Li2S during battery cycling. This SEI film possesses both high mechanical strength and excellent ionic conductivity, effectively preventing direct contact between lithium metal and the electrolyte, suppressing side reactions to reduce active lithium loss, and reducing interfacial charge transport resistance, thus ensuring the reversibility of the lithium deposition / stripping process.

[0017] 3. The negative electrode-free lithium metal battery using the current collector modified by this invention exhibits significantly improved initial coulombic efficiency and cycle stability, and significantly reduced voltage polarization during long-term cycling, demonstrating excellent electrochemical reliability. Simultaneously, the composite modification layer bonds firmly with the copper current collector, adapting to volume changes during battery cycling and preventing the modification layer from detaching or cracking, further extending battery life.

[0018] 4. The preparation process of this invention adopts liquid phase synthesis and coating technology, which does not require high temperature vacuum equipment or complex and harsh reaction conditions. The operation is simple, the process is controllable, and it is easy to achieve large-scale continuous production. The raw materials used are inexpensive and readily available, and there is no consumption of expensive alloy raw materials, which significantly reduces the preparation cost of current collectors. The modified current collector retains the original high mechanical strength and structural stability of copper foil, and has both practicality and economy. Attached Figure Description

[0019] Figure 1 FT-IR image of SiO2 nanospheres prepared for the example.

[0020] Figure 2 For a current density of 1 mA cm -2 The lithium plating amount is 0.5 mAh cm⁻¹ -2 The coulombic efficiency diagrams of lithium plating / stripping for half-cells assembled with copper current collectors modified with different materials prepared in each embodiment are shown.

[0021] Figure 3 For a current density of 1 mA cm -2 The lithium plating amount is 1 mAh cm⁻¹ -2 The coulombic efficiency diagrams of lithium plating / stripping for half-cells assembled with copper current collectors modified with different materials prepared in each embodiment are shown. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following content is merely illustrative and explanatory of the concept of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined by the claims, all of which should fall within the protection scope of the present invention.

[0023] Example 1: Preparation of SiO2-modified copper current collector Step 1: Preparation of SiO2 nanospheres: Measure 16.5 mL of ethanol, 25 mL of deionized water and 5 mL of ammonia water respectively, pour them into a beaker and stir at room temperature until they are mixed evenly to form a stable reaction base solution; quickly add 2.5 mL of tetraethyl orthosilicate and 45.5 mL of ethanol premixed solution, and stir continuously at 30 °C for 2 h; after the reaction is completed, centrifuge the suspension at 8000 rpm for 5 min, collect the precipitate, wash it three times alternately with ethanol and deionized water, and dry it at 60 °C for 12 h to obtain SiO2 nanospheres.

[0024] Step 2: Preparation of mixed slurry: Take 50 mg of the above SiO2 nanospheres and add them to 0.75 mL of DMF, and stir evenly; add 25 mg of polyacrylonitrile (PAN) to the dispersion and stir magnetically for 12 h to obtain a mixed slurry with no agglomeration and good flowability.

[0025] Step 3, Coating and Drying: The above mixed slurry is uniformly coated onto the surface of a 10 μm thick copper current collector using a 50 μm scraper; the coated copper current collector is then placed in an 80℃ oven and dried for 12 h to obtain a SiO2 modified copper current collector.

[0026] Example 2: Preparation of thiolized SiO2 modified copper current collector Step 1: Preparation of SiO2 nanospheres: SiO2 nanospheres were prepared according to the process parameters of Step 1 in Example 1.

[0027] Step 2: Preparation of thiolized SiO2 nanospheres: 90 mg of SiO2 nanospheres were added to 20 mL of methanol and stirred until evenly dispersed; 1.8 mL of 3-mercaptopropyltrimethoxysilane was added, and the functionalization reaction was carried out by heating and stirring at 50 °C for 24 h under nitrogen protection; after the reaction was completed, the mixture was cooled to room temperature, centrifuged at 8000 rpm for 5 min to collect the product, washed 3 times with methanol, and dried at 60 °C for 12 h to obtain thiolized SiO2 nanospheres.

[0028] Step 3: Preparation of mixed slurry: Take 50 mg of the above-mentioned mercapto-modified SiO2 nanospheres, add them to 0.75 mL of DMF, and stir evenly; add 25 mg of polyacrylonitrile (PAN) to the dispersion, and stir continuously with magnetic force for 12 h to obtain a mixed slurry with no agglomeration and good flowability.

[0029] Step 4, Coating and Drying: Use a 50 μm scraper to uniformly coat the above mixed slurry onto the surface of a 10 μm thick copper current collector; place the coated copper current collector in an 80℃ oven and dry for 12 h to obtain a mercapto-modified SiO2 copper current collector.

[0030] Example 3: Preparation of Ag / SiO2 modified copper current collector Step 1: Preparation of SiO2 nanospheres: SiO2 nanospheres were prepared according to the process parameters of Step 1 in Example 1.

[0031] Step 2: Preparation of Ag / SiO2 nanosphere composite material: Take 0.1 g SiO2 nanospheres, add 50 mL ethylene glycol and stir until uniformly dispersed; add 0.3 g polyvinylpyrrolidone and 0.2 g silver nitrate sequentially and stir until uniform; heat the mixture to 130℃, and slowly add 135 μL of 7.5 mg / mL KCl solution under continuous magnetic stirring. After the addition is complete, keep the reaction temperature for 5 h; after the reaction is complete, cool to room temperature, centrifuge at 8000 rpm for 5 min to collect the product, wash with deionized water and ethanol alternately 3 times, and dry at 60℃ for 12 h to obtain Ag / SiO2 nanosphere composite material.

[0032] Step 3: Preparation of mixed slurry: Take 50 mg of Ag / SiO2 nanosphere composite material and add it to 0.75 mL of DMF, and stir evenly; add 25 mg of polyacrylonitrile (PAN) to the dispersion and stir magnetically for 12 h to obtain a mixed slurry with no agglomeration and good flowability.

[0033] Step 4, Coating and Drying: Use a 50 μm doctor blade to uniformly coat the above mixed slurry onto the surface of a 10 μm thick copper current collector; place the coated copper current collector in an 80℃ oven and dry for 12 h to obtain Ag / SiO2 modified copper current collector.

[0034] Example 4: Preparation of Ag / thiolized SiO2 modified copper current collector Step 1: Preparation of SiO2 nanospheres: SiO2 nanospheres were prepared according to the process parameters of Step 1 in Example 1.

[0035] Step 2: Preparation of thiolized SiO2 nanospheres: Thiolized SiO2 nanospheres were prepared according to the process parameters in Step 2 of Example 2.

[0036] Step 3: Preparation of Ag / Mercaptolated SiO2 nanosphere composite material: Take 0.1 g of mercaptolated SiO2 nanospheres, add 50 mL of ethylene glycol and stir until uniformly dispersed; add 0.3 g of polyvinylpyrrolidone and 0.2 g of silver nitrate in sequence and stir evenly; heat the mixture to 130℃, and slowly add 135 μL of KCl solution with a concentration of 7.5 mg / mL under continuous magnetic stirring. After the addition is completed, keep the reaction temperature for 5 h; after the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 5 min to collect the product, wash with deionized water and ethanol alternately 3 times, and dry at 60℃ for 12 h to obtain Ag / mercaptolated SiO2 nanosphere composite material.

[0037] Step 3: Preparation of mixed slurry: Take 50 mg of Ag / thiolized SiO2 nanosphere composite material, add it to 0.75 mL of DMF, and stir evenly; add 25 mg of polyacrylonitrile (PAN) to the dispersion, and stir continuously with magnetic force for 12 h to obtain a mixed slurry with no agglomeration and good flowability.

[0038] Step 4, Coating and Drying: The above mixed slurry is uniformly coated onto the surface of a 10 μm thick copper current collector using a 50 μm scraper; the coated copper current collector is then placed in an 80℃ oven and dried for 12 h to obtain the Ag / thiolized SiO2 modified copper current collector.

[0039] The prepared SiO2 nanospheres were subjected to Fourier transform infrared spectroscopy (FT-IR) testing, and the results are as follows: Figure 1 As shown: 1073 cm -1 The characteristic absorption peak at 3376 cm⁻¹ corresponds to the stretching vibration of the Si-O-Si bond. -1 The broad peak at this point corresponds to the stretching vibration of the -OH groups on the SiO2 surface. This indicates that the surface of the SiO2 nanospheres is rich in polar functional groups, which can capture lithium ions through electrostatic adsorption, accelerate lithium ion transport at the electrode / electrolyte interface, provide additional migration paths for lithium ions, and thus achieve uniform control of lithium deposition.

[0040] In an argon (Ar)-filled glove box, half-cells were assembled in the following order: negative electrode shell → lithium sheet → electrolyte → separator → Ag / thiolized SiO2 modified copper current collector → positive electrode shell. The separator used was Celgard, and the electrolyte was 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dissolved in a 1:1 volume ratio of 1,3-dioxolane / ethylene glycol dimethyl ether mixed solvent, with 2 wt% lithium nitrate added as a functional additive.

[0041] like Figure 2 As shown, at a current density of 1 mA cm⁻¹ -2 The lithium plating amount is 0.5 mAh cm⁻¹ -2 Under the test conditions: Pure Cu foil current collector: After only 50 cycles, the coulombic efficiency (CE) fluctuated drastically and then rapidly declined, indicating that the uneven nucleation sites on the pure copper surface easily induce lithium dendrites, leading to aggravated side reactions and a large loss of active lithium.

[0042] SiO2-modified copper current collectors exhibit better cycling stability than pure Cu, but their efficiency begins to fluctuate after about 100 cycles. This is because SiO2 can only adsorb lithium ions through surface -OH groups and lacks lithiophilic sites and interface regulation capabilities, thus failing to completely suppress lithium dendrite growth.

[0043] Thiol-modified SiO2-modified copper current collector: Cyclic stability was slightly better than the SiO2-modified sample, but efficiency declined after 150 cycles, indicating that although thiol can promote Li... + They can migrate, but lack lithium-friendly nucleation sites, making nucleation difficult.

[0044] Ag / SiO2 modified copper current collector: Cyclic stability is slightly better than the SiO2 modified sample, but efficiency begins to fluctuate after 120 cycles. This indicates that Ag's lithiophilicity can lower the nucleation energy barrier, but the lack of thiol groups in Li... + Transport-guided processes still have limitations in achieving uniform lithium deposition.

[0045] Ag / thiolized SiO2 modified copper current collector: The initial coulombic efficiency reached 87.44% (higher than 80.72% of pure Cu), and remained stable after 200 cycles, with an average CE > 98.25%. This is the result of the synergistic effect of Ag, thiol, and SiO2: Ag provides lithophilic nucleation sites, and thiol guides Li... + Through migration, SiO2 constructs a rigid framework and adsorbs lithium ions, which together achieve uniform lithium deposition and interface stability.

[0046] like Figure 3 As shown, at a current density of 1 mA cm⁻¹ -2 The lithium plating amount is 1 mAh cm⁻¹ -2 Under test conditions (higher lithium load): Pure Cu foil current collector: After only 35 cycles, the CE fluctuated drastically. The increased lithium load further amplified the nucleation inhomogeneity on the pure copper surface, and the lithium dendrite growth and side reactions became more severe.

[0047] SiO2-modified copper current collector: efficiency begins to decline after about 40 cycles, higher lithium deposition exceeds the adsorption regulation capacity of SiO2, and interface stability deteriorates rapidly.

[0048] Thiolized SiO2 modified copper current collector: efficiency significantly decreases after 80 cycles; thiol-modified Li + The transport mechanism could not match the deposition requirements under high lithium load, and lithium dendrites gradually got out of control.

[0049] Ag / SiO2 modified copper current collector: efficiency fluctuates after 100 cycles. Although the lithophile of Ag can reduce the nucleation energy barrier, it lacks the synergistic guidance of thiol groups, resulting in insufficient uniformity of lithium deposition under high lithium load.

[0050] Ag / thiolized SiO2 modified copper current collector: initial coulombic efficiency reached 92.60% (higher than 91% for pure Cu), and remained stable after 120 cycles, with an average CE > 97.98%. Even under higher lithium loading, the synergistic system of the three components can still effectively regulate Li... +Its excellent adaptability to various operating conditions is demonstrated by its ability to transport and deposit lithium, suppress lithium dendrites and side reactions, and control lithium deposition morphology.

[0051] The above description is merely a preferred embodiment of the present invention, and while it is quite specific and detailed, it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and equivalent substitutions without departing from the principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing Ag / thiolized SiO2 nanosphere-modified anode current collector for use in electrodeless lithium metal batteries, characterized in that, Follow these steps: Step 1: Add ethanol, deionized water and ammonia to the reaction vessel and stir at room temperature until the system is uniformly mixed. Then, quickly add the premixed solution of silicon source and ethanol and stir the reaction thoroughly. Collect the product by centrifugation, wash and dry to obtain SiO2 nanospheres. Step 2: The SiO2 nanospheres obtained in Step 1 are uniformly dispersed in methanol, and a functionalizing reagent containing thiol groups is added. Under the protection of an inert gas, the functionalization reaction is carried out by heating and stirring. After the reaction is completed, the system is cooled to room temperature, the product is collected by centrifugation, washed and dried to obtain thiolized SiO2 nanospheres. Step 3: The thiolized SiO2 nanospheres obtained in Step 2 are uniformly dispersed in ethylene glycol. Polyvinylpyrrolidone and silver nitrate are then added to the resulting dispersion in sequence and stirred until homogeneous. The resulting mixture is heated to the reaction temperature. Under continuous magnetic stirring, KCl solution is slowly added dropwise. After the addition is complete, the reaction is continued at the temperature. After the reaction is completed, the product is collected by centrifugation, washed, and dried to obtain the Ag / thiolized SiO2 nanosphere composite material. Step 4: Disperse the Ag / thiolized SiO2 nanosphere composite material obtained in Step 3 uniformly in a solvent, add polyacrylonitrile, and stir magnetically until uniform to obtain a mixed slurry; coat the mixed slurry uniformly on the surface of the copper current collector and dry it to obtain the Ag / thiolized SiO2 nanosphere modified negative electrode current collector.

2. The preparation method according to claim 1, characterized in that: In step 1, the silicon source is selected from at least one of tetraethyl orthosilicate, methyl orthosilicate, and sodium silicate.

3. The preparation method according to claim 1, characterized in that: In step 2, the functionalizing reagent containing a thiol group is selected from at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropylmethyldimethoxysilane. The functionalization reaction temperature is 40~60℃ and the reaction time is 20~24 h.

4. The preparation method according to claim 1, characterized in that: In step 3, the mass ratio of silver nitrate to mercapto-SiO2 nanospheres is 2-6:1; the amount of polyvinylpyrrolidone added is 1-2 times the mass of silver nitrate.

5. The preparation method according to claim 1, characterized in that: In step 3, the reaction temperature is 120~140℃, the total reaction time is 4~6 h, and the concentration of KCl solution is 5~10 mg / mL.

6. The preparation method according to claim 1, characterized in that: In step 4, the solvent is selected from at least one of water, ethanol, methanol, N,N-dimethylformamide, N-methylpyrrolidone, ethylene glycol, aqueous acetone solution, aqueous ethanol solution, and aqueous methanol solution.

7. The preparation method according to claim 1, characterized in that: In step 4, the mass ratio of the Ag / mercaptolated SiO2 nanosphere composite material to polyacrylonitrile is 2~8:

1.

8. The preparation method according to claim 1, characterized in that: In step 4, the coating thickness of the mixed slurry is 50~100 μm; the drying temperature is 80~100℃, and the drying time is 8~10 h.

9. An Ag / thiolized SiO2 nanosphere modified negative electrode current collector prepared by the preparation method according to any one of claims 1 to 8.

10. A cathodeless lithium metal battery using the Ag / thiolized SiO2 nanosphere modified cathode current collector as described in claim 9 as the cathode.

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