Surface modification method of lithium metal negative electrode copper-based current collector

Abstract

The invention discloses a surface modification method of a lithium metal negative electrode copper-based current collector, and relates to a modification method of a lithium metal negative electrode current collector. The problems that an existing lithium metal negative electrode copper-based current collector is poor in cycling stability, and an interface coating is prone to peeling off are solved. According to the invention, surface property regulation and control of the copper-based current collector are realized by virtue of coordination between the xanthic acid heavy metal capturing agent and metal ions, the morphological characteristics and chemical composition of the lithium-loving modification layer on the surface of the copper-based current collector are flexibly changed, and the electrochemical cycle stability is improved. The surface modification of the copper-based current collector is beneficial to the improvement of the rate capability, the circulating coulombic efficiency under high current density is obviously improved, and the lithium utilization rate is improved. In the surface modification process of the copper-based current collector, the adopted xanthic acid heavy metal capturing agent belongs to an industrial raw material with low value, the use amount of the introduced metal salt is low, the cost is controllable, complex treatment is not needed, the operation process is simple, convenient and stable, and the method is relatively trace and efficient, so that the method is also suitable for mass production.

Description

Technical Field

[0001] The present invention relates to a method for surface modification of a copper-based current collector for a lithium metal anode. Background Art

[0002] Fossil energy, as the main global energy source, has long promoted the industrialization process and economic growth. However, with the increasingly severe climate and environmental problems, the traditional energy system is gradually transitioning to clean energy, and secondary batteries, as a key technology for energy storage and flexible dispatching, have attracted much attention. The booming development in fields such as electric vehicles and grid energy storage has put forward higher requirements for the performance of secondary batteries. At present, the performance improvement of the graphite anode of widely used lithium-ion batteries has faced bottlenecks, and the development of new anode materials with higher energy density has become the key to achieving breakthroughs in next-generation battery technologies. As a potential anode material for secondary batteries, lithium metal anodes have a theoretical capacity (3860 mAh / g) far exceeding that of traditional graphite anodes and a lower potential (-3.04 V vs. SHE), bringing new hope for battery technology transformation. However, lithium metal anodes face many technical challenges in practical applications, and the most prominent problem is uncontrolled dendritic lithium deposition, which seriously threatens the actual cycle life and use safety of batteries.

[0003] Copper-based current collectors have become the preferred current collector materials for lithium metal anodes due to their high conductivity, low price, and good processability. In response to the emergence of lithium dendrites, adjusting the surface state of the current collector is one of the effective improvement strategies, which brings the following positive effects: 1. The modification of surface lithiumophilic components promotes the reduction of deposition overpotential and induces uniform lithium nucleation; 2. The introduction of surface heteroelements affects the solid electrolyte interphase, which can improve interface stability and ion transport; 3. The emergence of surface pores has a positive effect on buffering volume changes during charge and discharge processes and reducing interface fluctuations. Surface modification of copper-based current collectors can improve the cycling performance of corresponding lithium metal batteries.

[0004] However, the following problems still need to be considered urgently in the design process of lithium metal anode current collectors: (1) Complex processing steps. This not only increases costs but also is not conducive to subsequent practical applications. (2) Interface instability. The compatibility problem between the newly introduced surface structure and the Cu substrate cannot be ignored. For example, problems such as coating peeling and separation will cause premature failure of active components and affect the actual application effect. (3) Influence on energy density. The introduction of excessive hetero-components causes additional mass increase, which is not conducive to maintaining high energy density.

[0005] Therefore, it is very necessary to explore simple, stable, and microscale-highly efficient current collector surface treatment strategies to further improve the cycling performance of lithium metal anodes. Summary of the Invention

[0006] In order to solve the problems of poor cycle stability and easy peeling of the interfacial coating existing in the existing copper-based current collector for lithium metal anodes, the present invention proposes a surface modification method for a copper-based current collector for lithium metal anodes.

[0007] The surface modification method of the copper-based current collector for lithium metal anodes of the present invention is carried out according to the following steps:

[0008] First, the copper-based current collector material is placed in a solvent for cleaning and dried at room temperature;

[0009] Second, dilute hydrochloric acid solution and ammonium persulfate solution are mixed, and the copper-based current collector material obtained in the first step is immersed in the mixed solution and allowed to stand. After standing, it is taken out, washed and dried;

[0010] The concentration of the ammonium persulfate solution is 0.002 - 0.02 mol / L; the concentration of the dilute hydrochloric acid solution is 1 mol / L; the volume ratio of the dilute hydrochloric acid solution to the ammonium persulfate solution is 1:1;

[0011] Third, a metal salt is dissolved in a solvent to obtain a metal salt solution; a zinc salt is dissolved in deionized water to obtain a zinc salt solution;

[0012] The metal salt is one or two of silver nitrate, magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, manganese nitrate tetrahydrate, manganese acetate tetrahydrate, cobalt nitrate hexahydrate, cobalt acetate tetrahydrate, copper nitrate trihydrate, copper acetate, zinc nitrate hexahydrate; the use of different metal ions in combination helps to control costs, and at the same time effectively adjusts the surface morphology of the current collector, promotes the more uniform dispersion of lithiumophilic components and subsequent adsorption precipitation. The open porous surface structure combined with a larger atomic utilization efficiency promotes the further improvement of electrochemical performance.

[0013] The zinc salt is zinc nitrate hexahydrate, zinc acetate or zinc chloride;

[0014] The concentration of the metal salt solution is 0.0003 - 0.01 mol / L;

[0015] The concentration of the used zinc salt solution is: 0.0003 - 0.01 mol / L;

[0016] Fourth, a xanthate-based heavy metal scavenger is placed in a solvent to obtain a xanthate-based heavy metal scavenger solution;

[0017] The chemical formula of the xanthate-based heavy metal scavenger is R - O - CS 2 -M, where R is an alkyl group or an aryl group, and M is Na + or K + ; the alkyl group is ethyl, isopropyl or butyl;

[0018] The concentration of the xanthate-based heavy metal scavenger solution is 0.001 - 0.05 mol / L;

[0019] V. Dropwise add a metal salt solution to a xanthate-based heavy metal scavenger solution and mix. Let it stand for 5 - 15 min to obtain a mixed solution; immerse the copper-based current collector material obtained in step two into a zinc salt solution, and then take it out and immerse it into the mixed solution; the immersion time is 3 - 30 min; the volume ratio of the metal salt solution to the xanthate-based heavy metal scavenger solution is 0.02 - 10:80;

[0020] Or dropwise add a metal salt solution to a zinc salt solution and mix. Let it stand for 5 - 15 min to obtain a mixed solution; immerse the copper-based current collector material obtained in step two into the mixed solution, and then take it out and immerse it into a xanthate-based heavy metal scavenger solution; the immersion time is 3 - 30 min; the volume ratio of the metal salt solution to the zinc salt solution is 0.02 - 10:80;

[0021] VI. Wash and dry the copper-based current collector material obtained in step five to complete.

[0022] The present invention has the following beneficial effects:

[0023] 1. The present invention utilizes the coordination between a xanthate-based heavy metal scavenger and metal ions such as Ag + , Zn 2+ , Cu 2+ , Mn 2+ , Co 2+ , Mg 2+ to regulate the surface properties of the copper-based current collector. After the participation of silver, cobalt, copper and other ions, the surface of the copper-based current collector matrix presents a nano-sheet or nano-particle morphology, and the formed open porous structure is conducive to the rapid transmission of lithium ions.

[0024] 2. The copper-based current collector surface modification method proposed by the present invention reduces the irreversible consumption of active lithium and significantly improves the cycle stability of the corresponding lithium metal battery. The modified current collector corresponding to the half-cell with silver ions participating has a coulombic efficiency of up to 98.4% in the 100th cycle at a high current density of 3 mA / cm 2 . The coulombic efficiency is significantly increased, the lithium utilization rate is improved, and at the same time, improved electrochemical reaction kinetics is demonstrated.

[0025] 3. The copper-based current collector surface modification method proposed by the present invention introduces a lithiophilic modification layer that can firmly adhere to the substrate surface, reducing the risk of coating peeling during the cycle. Good interface stability is beneficial to the improvement of the cycle life.

[0026] 4. The present invention introduces a lithiophilic modification on the surface of a copper-based current collector through the coordination of metal zinc ions and alkyl xanthate ions, thereby improving the cycle and rate performance of lithium batteries. The surface-modified copper-based current collector is used in a lithium iron phosphate full cell, and the initial discharge specific capacity at 2C is 137.6 mAh / g. After cycling 500 times, the discharge specific capacity is 132.5 mAh / g, and the average Coulombic efficiency reaches 99.8%.

[0027] 5. During the surface modification process of the copper-based current collector in the present invention, the xanthate-based heavy metal scavenger used belongs to industrial raw materials with relatively low value and is commonly used in mineral flotation and environmental protection treatment. At the same time, the amount of metal salt introduced is relatively low, and the cost is controllable. The present invention does not require complex treatment, has a simple and stable operation process, and is relatively trace and efficient, so it is also suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the Coulombic efficiency diagram of the surface-modified copper-based current collector in Example 1 used in a lithium metal half cell at a current density of 3 mA / cm 2 for different cycle numbers;

[0029] Figure 2 It is the discharge specific capacity diagram of the surface-modified copper-based current collector in Example 1 used in a lithium iron phosphate full cell at 2C for different cycle numbers;

[0030] Figure 3 It is the scanning electron microscope photograph of the surface-modified copper-based current collector in Example 2;

[0031] Figure 4 It is the Raman spectrum of the surface-modified copper-based current collector in Example 2 after ultrasonic treatment;

[0032] Figure 5 It is the Coulombic efficiency diagram of the surface-modified copper-based current collector in Example 2 used in a lithium metal half cell at a current density of 3 mA / cm 2 for different cycle numbers;

[0033] Figure 6 It is the discharge specific capacity diagram of the surface-modified copper-based current collector in Example 2 used in a lithium iron phosphate full cell at 2C for different cycle numbers; DETAILED DESCRIPTION OF THE INVENTION

[0034] The technical solution of the present invention is not limited to the following specific embodiments listed, but also includes any reasonable combination between the specific embodiments.

[0035] Specific Embodiment 1: The surface modification method of the copper-based current collector of the lithium metal negative electrode in this embodiment is carried out according to the following steps:

[0036] I. The copper-based current collector material is placed in a solvent for cleaning and dried at room temperature;

[0037] II. Mix the dilute hydrochloric acid solution and the ammonium persulfate solution, immerse the copper-based current collector material obtained in Step I into the mixed solution, let it stand, take it out after standing, and wash and dry it;

[0038] The concentration of the ammonium persulfate solution is 0.002 - 0.02 mol / L; the concentration of the dilute hydrochloric acid solution is 1 mol / L; the volume ratio of the dilute hydrochloric acid solution to the ammonium persulfate solution is 1:1;

[0039] III. Dissolve the metal salt in a solvent to obtain a metal salt solution; dissolve the zinc salt in deionized water to obtain a zinc salt solution;

[0040] The metal salt is one or two of silver nitrate, magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, manganese nitrate tetrahydrate, manganese acetate tetrahydrate, cobalt nitrate hexahydrate, cobalt acetate tetrahydrate, copper nitrate trihydrate, copper acetate, zinc nitrate hexahydrate; the combined use of different metal ions helps to control costs, and at the same time effectively adjusts the surface morphology of the current collector, promotes more uniform dispersion of the lithiumophilic component and subsequent adsorption precipitation. The open porous surface structure combined with a large atomic utilization efficiency promotes further improvement of the electrochemical performance.

[0041] The zinc salt is zinc nitrate hexahydrate, zinc acetate or zinc chloride;

[0042] The concentration of the metal salt solution is 0.0003 - 0.01 mol / L;

[0043] The concentration of the used zinc salt solution is: 0.0003 - 0.01 mol / L;

[0044] IV. Place the xanthate heavy metal scavenger in a solvent to obtain a xanthate heavy metal scavenger solution;

[0045] The chemical formula of the xanthate heavy metal scavenger is R - O - CS 2 -M, where R is an alkyl group or an aryl group, and M is Na + or K + ; the alkyl group is ethyl, isopropyl or butyl;

[0046] The concentration of the xanthate heavy metal scavenger solution is 0.001 - 0.05 mol / L;

[0047] V. Dropwise add the metal salt solution to the xanthate heavy metal scavenger solution and mix, let it stand for 5 - 15 min to obtain a mixed solution; immerse the copper-based current collector material obtained in Step II into the zinc salt solution, and then take it out and immerse it into the mixed solution; the immersion time is 3 - 30 min; the volume ratio of the metal salt solution to the xanthate heavy metal scavenger solution is 0.02 - 10:80;

[0048] Alternatively, the metal salt solution is added dropwise to the zinc salt solution and mixed, and left standing for 5 - 15 min to obtain a mixed solution; the copper-based current collector material obtained in the second step is immersed in the mixed solution, and then taken out and immersed in the xanthate-based heavy metal scavenger solution; the immersion time is 3 - 30 min; the volume ratio of the metal salt solution to the zinc salt solution is 0.02 - 10:80;

[0049] VI. Wash and dry the copper-based current collector material obtained in the fifth step, and it is completed.

[0050] This embodiment has the following beneficial effects:

[0051] 1. In the present invention, the surface properties of the copper-based current collector are regulated by the coordination between the xanthate-based heavy metal scavenger and metal ions such as Ag + , Zn 2+ , Cu 2+ , Mn 2+ , Co 2+ , Mg 2+ . After the participation of silver, cobalt, copper and other ions, the surface of the copper-based current collector matrix presents a nano-sheet or nano-particle morphology, and the formed open porous structure is conducive to the rapid transmission of lithium ions.

[0052] 2. The surface modification method of the copper-based current collector proposed in the present invention reduces the irreversible consumption of active lithium, and significantly improves the cycle stability of the corresponding lithium metal battery. The modified current collector with the participation of silver ions has a coulombic efficiency of up to 98.4% in the 100th cycle at a high current density of 3 mA / cm 2 . The coulombic efficiency is significantly increased, and the lithium utilization rate is improved. At the same time, improved electrochemical reaction kinetics is demonstrated.

[0053] 3. The surface modification method of the copper-based current collector proposed in the present invention can firmly attach the introduced lithiophilic modification layer to the substrate surface, reducing the risk of coating peeling during the cycle. Good interface stability is beneficial to the improvement of the cycle life.

[0054] 4. In the present invention, a lithiophilic modification is introduced on the surface of the copper-based current collector through the coordination of metal zinc ions and alkyl xanthate ions, thereby improving the cycle and rate performance of the lithium battery. The surface-modified copper-based current collector is used in a lithium iron phosphate full battery, and the initial discharge specific capacity at 2C is 137.6 mAh / g. After cycling to 500 cycles, the discharge specific capacity is 132.5 mAh / g, and the average coulombic efficiency reaches 99.8%.

[0055] 5. During the surface modification of the copper-based current collector in the present invention, the xanthate-based heavy metal scavenger used belongs to industrial raw materials with relatively low value and is commonly used in mineral flotation and environmental protection treatment. Meanwhile, the dosage of the introduced metal salt is relatively low, and the cost is controllable. The present invention does not require complex treatment, has a simple and stable operation process, and is relatively trace and efficient, so it is also suitable for mass production.

[0056] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: the copper-based current collector material in Step 1 is copper foil, electrolytic copper mesh, brass mesh or copper foam.

[0057] Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 or 2 is that: the solvent in Step 1 is one or a combination of deionized water, absolute ethanol, acetone, and 0.05 - 2 mol / L dilute hydrochloric acid solution.

[0058] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that: the mixing method of the hydrochloric acid solution and ammonium persulfate solution in Step 2 is magnetic stirring, and the magnetic stirring time is 5 - 30 min.

[0059] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that: the environmental temperature for standing after immersing the copper-based current collector material obtained in Step 1 into the mixed solution in Step 2 is 0 - 50 °C, and the standing time is 0.5 - 2 h.

[0060] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that: the drying in Step 2 is blast drying or vacuum drying, the drying temperature is 40 - 100 °C, and the drying time is 15 - 25 h.

[0061] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that: the solvent in Step 3 is deionized water, absolute ethanol or methanol.

[0062] Specific Embodiment 8: The difference between this embodiment and any one of Specific Embodiments 1 to 7 is that: the solvent in Step 4 is deionized water, absolute ethanol or methanol.

[0063] Specific Embodiment 9: The difference between this embodiment and any one of Specific Embodiments 1 to 8 is that: the reagents used for cleaning in Step 6 are deionized water and absolute ethanol.

[0064] Specific Embodiment 10: The difference between this embodiment and any one of Specific Embodiments 1 to 9 is that: the drying method in Step 6 is vacuum drying, blast drying or freeze drying, and the time is 5 - 24 h.

[0065] Example 1:

[0066] The surface modification method for the copper-based current collector of lithium metal anode in this embodiment is carried out according to the following steps:

[0067] First, the copper-based current collector material is placed in a solvent for cleaning and dried at room temperature;

[0068] The copper-based current collector material is a purple copper mesh, cut into a size of 13 - 15 cm; 2 size;

[0069] The solvent is deionized water and absolute ethanol;

[0070] Second, mix a 1 mol / L dilute hydrochloric acid solution and a 0.008 mol / L ammonium persulfate solution, immerse the copper-based current collector material obtained in the first step into the mixed solution and let it stand, then take it out after standing, and clean and dry it; the volume ratio of the dilute hydrochloric acid solution to the ammonium persulfate solution is 1:1;

[0071] The mixing method of the hydrochloric acid solution and the ammonium persulfate solution is magnetic stirring, and the magnetic stirring time is 20 min;

[0072] The environmental temperature for immersing the copper-based current collector material obtained in the first step into the mixed solution and letting it stand is 4 °C, and the standing time is 1 h;

[0073] The drying is blast drying, the drying temperature is 60 °C, and the drying time is 19 h;

[0074] Third, dissolve zinc salt in deionized water to obtain a zinc salt solution;

[0075] The zinc salt is zinc nitrate hexahydrate;

[0076] The concentration of the used zinc salt solution is: 0.0015 mol / L;

[0077] The solvent is deionized water;

[0078] Fourth, place the xanthate-based heavy metal scavenger in a solvent to obtain a xanthate-based heavy metal scavenger solution;

[0079] The chemical formula of the xanthate-based heavy metal scavenger is R - O - CS 2 -M, where R is ethyl; M is K + ;

[0080] The concentration of the xanthate-based heavy metal scavenger solution is 0.003 mol / L;

[0081] The solvent is deionized water;

[0082] Fifth, immerse the copper-based current collector material obtained in the second step into the zinc salt solution, and then take it out and immerse it into the xanthate-based heavy metal scavenger solution; the immersion time is 5 min;

[0083] VI. Clean and dry the copper-based current collector material obtained in Step V to complete the process;

[0084] The reagents used for cleaning are deionized water and absolute ethanol;

[0085] The drying method is vacuum drying, the temperature is 60 °C, and the time is 12 h.

[0086] Figure 1 Coulomb efficiency graph of the surface-modified copper-based current collector for the lithium metal half-cell at different cycle numbers under a current density of 3 mA / cm 2 At a high current density of 3 mA / cm 2 During the stable cycling of the corresponding half-cell, the average Coulomb efficiency reaches 97.3%. Figure 2 Discharge specific capacity graph of the surface-modified copper-based current collector for the LiFePO₄ full-cell at different cycle numbers under 2C; At 2C, the discharge specific capacity in the first cycle is 137.6 mAh / g. After cycling to 500 cycles, the discharge specific capacity is 132.5 mAh / g, and the average Coulomb efficiency reaches 99.8%. After using the surface-modified copper-based current collector, the cycling stability of the full-cell is significantly improved.

[0087] Example 2:

[0088] The surface modification method of the copper-based current collector for the lithium metal negative electrode in this example is carried out according to the following steps:

[0089] I. Place the copper-based current collector material in a solvent for cleaning and dry it at room temperature;

[0090] The copper-based current collector material is a purple copper mesh, cut into a size of 13 - 15 cm 2 in size;

[0091] The solvent is deionized water and absolute ethanol;

[0092] II. Mix a 1 mol / L dilute hydrochloric acid solution and a 0.008 mol / L ammonium persulfate solution, immerse the copper-based current collector material obtained in Step I into the mixed solution and let it stand, then take it out after standing, and clean and dry it; The volume ratio of the dilute hydrochloric acid solution to the ammonium persulfate solution is 1:1;

[0093] The mixing method of the hydrochloric acid solution and the ammonium persulfate solution is magnetic stirring, and the magnetic stirring time is 20 min;

[0094] The environmental temperature for immersing the copper-based current collector material obtained in Step I into the mixed solution and letting it stand is 4 °C, and the standing time is 1 h;

[0095] The drying is blast drying, the drying temperature is 60°C, and the drying time is 19 h;

[0096] Third, dissolve silver nitrate and zinc nitrate hexahydrate in a solvent to obtain a metal salt solution; dissolve the zinc salt in deionized water to obtain a zinc salt solution;

[0097] The concentration of silver nitrate in the metal salt solution is 0.00125 mol / L, and the concentration of zinc nitrate hexahydrate is 0.0003 mol / L;

[0098] The zinc salt is zinc nitrate hexahydrate;

[0099] The concentration of the zinc salt solution used is: 0.0015 mol / L;

[0100] The solvent is deionized water;

[0101] Fourth, place the xanthate-based heavy metal scavenger in a solvent to obtain a xanthate-based heavy metal scavenger solution;

[0102] The chemical formula of the xanthate-based heavy metal scavenger is R-O-CS 2 -M, where R is ethyl; M is K + ;

[0103] The concentration of the xanthate-based heavy metal scavenger solution is 0.003 mol / L;

[0104] The solvent is deionized water;

[0105] Fifth, add 1.2 mL of the metal salt solution dropwise to 80 mL of the xanthate-based heavy metal scavenger solution and mix, then let it stand for 5 min to obtain a mixed solution; immerse the copper-based current collector material obtained in step two into 80 mL of the zinc salt solution, and then take it out and immerse it into the mixed solution;

[0106] The immersion time is 5 min;

[0107] Sixth, wash and dry the copper-based current collector material obtained in step five, and it is completed;

[0108] The reagents used for the washing are deionized water and absolute ethanol;

[0109] The drying method is vacuum drying, the temperature is 60°C, and the time is 12 h.

[0110] Perform physical and chemical characterization and electrochemical performance testing on the samples.

[0111] Figure 3 It is the scanning electron microscope photograph of the surface-modified copper-based current collector in Example 2; from Figure 3It can be observed that after the introduction of silver ions into the ethyl xanthate solution, the morphology of the attachments on the surface of the copper mesh changed significantly, showing a uniform coverage of nanosheets. Figure 4 The Raman spectrum of the surface-modified copper-based current collector in Example 2 after ultrasonic treatment; the surface-modified copper-based current collector was subjected to ultrasonic treatment, and the Raman spectrum measured was 250-650cm -1 The appearance of interval-related vibration peaks indicates that the ethylxanthate coordination compound on the copper mesh surface still exists after ultrasonic treatment, confirming the firm adhesion of the lithiophilic modification layer on the substrate surface. Figure 5 The surface-modified copper-based current collector in Example 2 is used for lithium metal half-cells at 3 mA / cm 2 Coulombic efficiency diagram for different cycle numbers under current density; at 3mA / cm 2 At a current density of , the corresponding half-cell can cycle 100 times and the Coulomb efficiency can reach 98.4%. Figure 6 The graph shows the discharge capacity of the surface-modified copper-based current collector in Example 2 for a lithium iron phosphate full battery at different cycle numbers at 2C. After 500 cycles at a rate of 2C, the discharge capacity is 142.9 mAh / g, the capacity retention rate reaches 98%, and the cycle stability is excellent.

[0112] In the lithium copper half-cell test, at 3mA / cm 2 After 100 cycles at a current density of , the coulombic efficiency of Example 2 was improved by 0.9% compared with Example 1, revealing less active lithium loss during the cycle and significantly improved cycle stability. After being assembled into a full lithium iron phosphate battery, at a 2C rate, the discharge specific capacity of Example 2 at the 500th cycle was improved by 7.8% compared with Example 1, and the capacity retention rate of Example 2 reached 98% after 500 cycles.

[0113] In the surface modification treatment of the copper-based current collector in this embodiment, the market price of the alkyl xanthate used is about 8-20 yuan / kg (as of February 2025), which is a widely available and low-cost industrial raw material. The amount of the introduced coordinated silver ions, zinc ions, etc. is small, which reduces the cost and is conducive to the improvement of energy density. The stable adhesion of the lithium-philic modification layer in the embodiment helps to continuously improve the lithium deposition behavior and promote the improvement of the battery cycle life. The overall process does not involve complex operations and is suitable for mass production.

Claims

1. A surface modification method for a lithium metal negative electrode copper-based current collector, characterized in that: The surface modification method of the copper-based current collector of the lithium metal negative electrode is carried out in the following steps:

1. The copper-based current collector material is placed in a solvent for cleaning and dried at room temperature; 2. Mixing a dilute hydrochloric acid solution and an ammonium persulfate solution, immersing the copper-based current collector material obtained in step 1 into the mixed solution and letting it stand, taking it out after standing, and washing and drying it; The concentration of the ammonium persulfate solution is 0.002-0.02 mol / L; the concentration of the dilute hydrochloric acid solution is 1 mol / L; the volume ratio of the dilute hydrochloric acid solution to the ammonium persulfate solution is 1:1; 3. dissolving a metal salt in a solvent to obtain a metal salt solution; dissolving a zinc salt in deionized water to obtain a zinc salt solution; The metal salt is one or two of silver nitrate, magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, manganese nitrate tetrahydrate, manganese acetate tetrahydrate, cobalt nitrate hexahydrate, cobalt acetate tetrahydrate, copper nitrate trihydrate, copper acetate, and zinc nitrate hexahydrate; The zinc salt is zinc nitrate hexahydrate, zinc acetate or zinc chloride; The concentration of the metal salt solution is 0.0003-0.01 mol / L; The concentration of the zinc salt solution used is: 0.0003-0.01 mol / L; 4. placing a xanthogenic acid-based heavy metal scavenger in a solvent to obtain a xanthogenic acid-based heavy metal scavenger solution; The chemical formula of the xanthate-based heavy metal scavenger is RO-CS2-M, wherein R is an alkyl or aryl group, and M is Na + or K + ; The alkyl group is ethyl, isopropyl or butyl; The concentration of the xanthogenic acid heavy metal scavenger solution is 0.001-0.05 mol / L; 5. Add the metal salt solution dropwise to the xanthogenic acid-based heavy metal scavenger solution, and let it stand for 5-15 minutes to obtain a mixed solution; immerse the copper-based current collector material obtained in step 2 into the zinc salt solution, and then take it out and immerse it in the mixed solution; the immersion time is 3-30 minutes; the volume ratio of the metal salt solution to the xanthogenic acid-based heavy metal scavenger solution is 0.02-10:80; Or the metal salt solution is added dropwise to the zinc salt solution, and the mixture is allowed to stand for 5-15 minutes to obtain a mixed solution; the copper-based current collector material obtained in step 2 is immersed in the mixed solution, and then taken out and immersed in a xanthogenic acid-based heavy metal scavenger solution; the immersion time is 3-30 minutes; the volume ratio of the metal salt solution to the zinc salt solution is 0.02-10:80; 6. Clean and dry the copper-based current collector material obtained in step 5.

2. The surface modification method of the lithium metal negative electrode copper-based current collector according to claim 1, characterized in that: The copper-based current collector material in step 1 is copper foil, red copper mesh, brass mesh or foam copper.

3. The surface modification method of the lithium metal negative electrode copper-based current collector according to claim 1, characterized in that: In step 1, the solvent is one or a combination of deionized water, anhydrous ethanol, acetone, and 0.05-2 mol / L dilute hydrochloric acid solution.

4. The surface modification method of the copper-based current collector of the lithium metal negative electrode according to claim 1, characterized in that: In step 2, the hydrochloric acid solution and the ammonium persulfate solution are mixed by magnetic stirring for 5-30 minutes.

5. The surface modification method of the lithium metal negative electrode copper-based current collector according to claim 1, characterized in that: In step 2, the copper-based current collector material obtained in step 1 is immersed in the mixed solution and allowed to stand at an ambient temperature of 0-50° C. for a standing time of 0.5-2 h.

6. The surface modification method of the lithium metal negative electrode copper-based current collector according to claim 1, characterized in that: The drying in step 2 is air drying or vacuum drying, the drying temperature is 40-100° C., and the drying time is 15-25 hours.

7. The surface modification method of the lithium metal negative electrode copper-based current collector according to claim 1, characterized in that: The solvent in step 3 is deionized water, anhydrous ethanol or methanol.

8. The surface modification method of the copper-based current collector of the lithium metal negative electrode according to claim 1, characterized in that: The solvent in step 4 is deionized water, anhydrous ethanol or methanol.

9. The surface modification method of the copper-based current collector of the lithium metal negative electrode according to claim 1, characterized in that: The cleaning reagents used in step six are deionized water and anhydrous ethanol.

10. The surface modification method of the copper-based current collector for lithium metal negative electrode according to claim 1, characterized in that: The drying method in step six is ​​vacuum drying, forced air drying or freeze drying, and the drying time is 5-24 hours.

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