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

Abstract

A surface modification method of lithium metal negative electrode copper-based current collector relates to a modification method of lithium metal negative electrode current collector. In order to solve the problems of poor cycle stability, interface coating easy to peel off and the like existing in the existing lithium metal negative electrode copper-based current collector, the surface property regulation of the copper-based current collector is realized by means of coordination between xanthic acid heavy metal capture agent and metal ions, the morphology characteristics and chemical composition of the lithium-friendly 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 in the application is helpful to the improvement of the rate performance, the cycle coulombic efficiency is significantly increased at high current density, and the lithium utilization rate is improved. In the surface modification process of the copper-based current collector, the xanthic acid heavy metal capture agent used in the application belongs to low-value industrial raw materials, the dosage of the introduced metal salt is low, the cost is controllable, no complex treatment is needed, the operation process is simple, stable, and relatively micro-efficient, and therefore it is also suitable for mass production.

Description

TECHNICAL FIELD

[0001] The present application relates to a surface modification method of a lithium metal negative electrode copper-based current collector. BACKGROUND

[0002] Fossil energy, as the main energy source in the world, has long driven the industrialization process and economic growth. However, with the increasing severity of climate, environmental and other problems, the traditional energy system is gradually transitioning to clean energy, and secondary batteries, as a key technology to achieve energy storage and flexible scheduling, have attracted much attention. The booming development of electric vehicles, grid energy storage and other fields has put forward higher requirements for the performance of secondary batteries. The performance improvement of the widely used graphite negative electrode of lithium-ion batteries has faced a bottleneck, and the development of new negative electrode materials with higher energy density has become the key to realizing breakthroughs in next-generation battery technology. Lithium metal negative electrode, as a potential negative electrode material in secondary batteries, has a theoretical capacity (3860 mAh / g) far exceeding that of traditional graphite negative electrodes and a lower potential (-3.04 V vs. SHE), bringing new hope for battery technology revolution. However, lithium metal negative electrode faces many technical challenges in practical application, the most important of which is uncontrolled dendritic lithium deposition, which seriously threatens the actual cycle life and safety of the battery.

[0003] Copper-based current collectors are the preferred current collector materials for lithium metal negative electrodes due to their high electrical conductivity, low price, and good processability. In response to the emergence of lithium dendrites, surface state adjustment of the current collector is one of the effective improvement strategies, which brings the following positive effects: 1. Modification of surface lithiumophilic components promotes the reduction of deposition overpotential and induces uniform lithium nucleation; 2. The introduction of surface hetero-elements affects the solid-state electrolyte film, which can improve the interface stability and ion transport; 3. The presence of surface pores has a positive effect on buffering the volume change during charging and discharging and reducing interface fluctuations. Surface modification of copper-based current collectors can improve the cycle performance of the corresponding lithium metal batteries.

[0004] However, there are still some problems to be considered in the design of lithium metal negative electrode current collectors: (1) Complex processing steps not only increase the cost but also are not conducive to subsequent practical application. (2) Interface instability. The compatibility problem between the newly introduced surface structure and the Cu substrate cannot be ignored, such as coating peeling, separation, etc., which can cause premature failure of active components and affect the actual application effect. (3) Effect on energy density. The introduction of too many hetero-elements causes additional mass increase, which is not conducive to maintaining high energy density.

[0005] Therefore, it is necessary to explore simple, stable, and micro-efficient current collector surface treatment strategies to further improve the cycle performance of lithium metal negative electrodes. SUMMARY

[0006] The present application proposes a surface modification method of a lithium metal negative electrode copper-based current collector to solve the problems of poor cycle stability, easy peeling of the interface coating and the like of the existing lithium metal negative electrode copper-based current collector.

[0007] The surface modification method of the lithium metal negative electrode copper-based current collector is performed in the following steps:

[0008] I. The copper-based current collector material is cleaned in a solvent and dried at room temperature;

[0009] II. The dilute hydrochloric acid solution and the ammonium persulfate solution are mixed, the copper-based current collector material obtained in step I is immersed in the mixed solution and left to stand, and then taken out, cleaned 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; and the volume ratio of the dilute hydrochloric acid solution to the ammonium persulfate solution is 1:1;

[0011] III. The metal salt is dissolved in a solvent to obtain a metal salt solution; and the 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 helps to control the cost, effectively adjusts the surface morphology of the current collector, promotes more uniform dispersion of the lithiumophilic component and subsequent adsorption and precipitation; the open porous surface structure combined with high atomic utilization efficiency promotes further improvement of the 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 zinc salt solution used is 0.0003-0.01 mol / L;

[0016] IV. A xanthic acid heavy metal capturing agent is placed in a solvent to obtain a xanthic acid heavy metal capturing agent solution;

[0017] The chemical formula of the xanthic acid heavy metal capturing agent is R-O-CS2-M, wherein R is an alkyl group or an aryl group, and M is Na + or K + ; the alkyl group is an ethyl group, an isopropyl group or a butyl group;

[0018] The concentration of the xanthic acid heavy metal capturing agent solution is 0.001-0.05 mol / L;

[0019] Five, the metal salt solution is added dropwise into the xanthic acid heavy metal capture agent solution mixture, and a mixed solution is obtained after standing for 5-15 min; the copper-based current collector material obtained in step two is immersed in the zinc salt solution, and then taken out and immersed in the mixed solution; the immersion time is 3-30 min; the volume ratio of the metal salt solution and the xanthic acid heavy metal capture agent solution is 0.02-10:80;

[0020] Or the metal salt solution is added dropwise into the zinc salt solution mixture, and a mixed solution is obtained after standing for 5-15 min; the copper-based current collector material obtained in step two is immersed in the mixed solution, and then taken out and immersed in the xanthic acid heavy metal capture agent solution; the immersion time is 3-30 min; the volume ratio of the metal salt solution and the zinc salt solution is 0.02-10:80;

[0021] Six, the copper-based current collector material obtained in step five is cleaned and dried, and the process is completed.

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

[0023] 1. The present application utilizes the coordination between the xanthic acid heavy metal capture agent and Ag + , Zn 2+ , Cu 2+ , Mn 2+ , Co 2+ , Mg 2+ metal ions to realize the surface property regulation of the copper-based current collector. After the participation of silver, cobalt, copper and other ions, the copper-based current collector substrate surface presents a nanosheet or nanoparticle morphology, and the open porous structure formed is beneficial to the rapid transmission of lithium ions.

[0024] 2. The copper-based current collector surface modification method proposed in the present application reduces the irreversible active lithium consumption and promotes the significant improvement of the cycle stability of the corresponding lithium metal battery. The modified current collector corresponding to the silver ion participation has a cycle coulombic efficiency of 98.4% at 3mA / cm 2 under high current density, the coulombic efficiency is significantly increased, the lithium utilization rate is improved, and the electrochemical reaction kinetics is also improved.

[0025] 3. The copper-based current collector surface modification method proposed in the present application can firmly adhere to the substrate surface through the introduction of the lithiumophilic modification layer, reduces the risk of coating peeling during the cycle process, and the good interface stability is beneficial to the improvement of the cycle life.

[0026] 4、The present application introduces the modification of lithium affinity on the surface of copper-based current collector by the coordination of zinc ions and alkyl xanthate ions, thereby improving the cycle and rate performance of lithium batteries. The copper-based current collector after surface modification is used for lithium iron phosphate full battery, and the first circle discharge specific capacity is 137.6 mAh / g at 2C, and the discharge specific capacity is 132.5 mAh / g after 500 cycles, and the average coulombic efficiency reaches 99.8%.

[0027] 5、In the surface modification process of the copper-based current collector, the heavy metal capture agent of xanthate series used in the present application belongs to low-value industrial raw materials, which is commonly used in mineral flotation and environmental protection treatment. At the same time, the dosage of the introduced metal salt is low, and the cost is controllable. The present application does not need complex treatment, and the operation process is simple, stable, and relatively trace efficient, so it is also suitable for mass production. BRIEF DESCRIPTION OF DRAWINGS

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

[0029] Figure 2 The copper-based current collector surface modified in Example 1 is used for lithium iron phosphate full battery at 2C, and the discharge specific capacity diagram of different cycle numbers is shown in the figure;

[0030] Figure 3 The scanning electron microscope photo of the copper-based current collector surface modified in Example 2 is shown in the figure;

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

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

[0033] Figure 6 The copper-based current collector surface modified in Example 2 is used for lithium iron phosphate full battery at 2C, and the discharge specific capacity diagram of different cycle numbers is shown in the figure; DETAILED DESCRIPTION

[0034] The technical scheme of the present application is not limited to the following specific embodiments, and also includes any reasonable combination between the specific embodiments.

[0035] Specific embodiment one: the surface modification method of the lithium metal negative electrode copper-based current collector in the present 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. mixing a dilute hydrochloric acid solution and an ammonium persulfate solution, immersing the copper-based current collector material obtained in step I into the mixed solution, taking out after standing, and cleaning and drying;

[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. 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;

[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, and zinc nitrate hexahydrate; the use of different metal ions helps to control the cost, effectively adjusts the surface morphology of the current collector, promotes more uniform dispersion of the lithiumophilic component, and subsequent adsorption and precipitation. The open porous surface structure combined with high 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 zinc salt solution used is 0.0003-0.01 mol / L;

[0044] IV. placing a xanthate heavy metal capture agent in a solvent to obtain a xanthate heavy metal capture agent solution;

[0045] The chemical formula of the xanthate heavy metal capture agent is R-O-CS2-M, wherein R is an alkyl group or an aryl group, and M is Na + or K + ; the alkyl group is an ethyl group, an isopropyl group, or a butyl group;

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

[0047] V. dropwise adding the metal salt solution to the xanthate heavy metal capture agent solution to mix, standing for 5-15 min to obtain a mixed solution; immersing the copper-based current collector material obtained in step II into the zinc salt solution, then taking out and immersing into the mixed solution; the immersion time is 3-30 min; the volume ratio of the metal salt solution to the xanthate heavy metal capture agent solution is 0.02-10:80;

[0048] or the metal salt solution is added dropwise into the zinc salt solution to mix, and a mixed solution is obtained by standing for 5-15 min; the copper-based current collector material obtained in step two is immersed into the mixed solution, and then taken out and immersed into the xanthate heavy metal capturing agent 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] Six, the copper-based current collector material obtained in step five is cleaned and dried, and the process is completed.

[0050] The present embodiment has the following beneficial effects:

[0051] 1. The present application utilizes the coordination between the xanthate heavy metal capturing agent and Ag + , Zn 2+ , Cu 2+ , Mn 2+ , Co 2+ , Mg 2+ metal ions to realize the surface property regulation of the copper-based current collector. After the participation of silver, cobalt, copper and other ions, the copper-based current collector substrate surface presents a nanosheet or nanoparticle morphology, and the open porous structure formed is beneficial to the rapid transmission of lithium ions.

[0052] 2. The copper-based current collector surface modification method proposed in the present application reduces the irreversible active lithium consumption and promotes the significant improvement of the cycle stability of the corresponding lithium metal battery. The modified current collector corresponding to the silver ion participation has a cycle coulombic efficiency of 98.4% at 3mA / cm 2 under a high current density, the coulombic efficiency is obviously increased, and the lithium utilization rate is improved. At the same time, the electrochemical reaction kinetics is improved.

[0053] 3. The copper-based current collector surface modification method proposed in the present application can firmly adhere to the substrate surface through the introduction of the lithiumophilic modification layer, reduces the risk of coating peeling during the cycle process, and the good interface stability is beneficial to the improvement of the cycle life.

[0054] 4. The present application introduces a lithiumophilic modification on the copper-based current collector surface through the coordination between the metal zinc ion and the alkyl xanthate ion, and then improves the lithium battery cycle and rate performance. The copper-based current collector after surface modification is used for a lithium iron phosphate full battery, and the first cycle discharge specific capacity is 137.6 mAh / g at 2C, the discharge specific capacity is 132.5 mAh / g after 500 cycles, and the average coulombic efficiency is 99.8%.

[0055] 5. In the surface modification process of copper-based current collectors, the xanthic acid-based heavy metal scavenging agent used in this invention is a low-value industrial raw material, commonly used in mineral flotation and environmental treatment. Simultaneously, the amount of metal salt introduced is low, and the cost is controllable. This invention requires no complex processing, has a simple and stable operation process, and is relatively efficient with small-scale operations, thus it is also suitable for mass production.

[0056] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the copper-based current collector material mentioned in step one is copper foil, copper mesh, brass mesh, or copper foam.

[0057] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the solvent mentioned in step 1 is one or a combination of several of the following: deionized water, anhydrous ethanol, acetone, and 0.05-2 mol / L dilute hydrochloric acid solution.

[0058] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the mixing method for the hydrochloric acid solution and ammonium persulfate solution in step two is magnetic stirring, and the magnetic stirring time is 5-30 minutes.

[0059] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that: in step 2, the copper-based current collector material obtained in step 1 is immersed in the mixed solution at an ambient temperature of 0-50°C for a standing time of 0.5-2 hours.

[0060] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the drying described in step two is blower drying or vacuum drying, with a drying temperature of 40-100℃ and a drying time of 15-25 hours.

[0061] Specific Implementation Method Seven: This implementation method differs from one of Specific Implementation Methods One to Six in that the solvent mentioned in step three is deionized water, anhydrous ethanol, or methanol.

[0062] Specific Implementation Method Eight: This implementation method differs from one of Specific Implementation Methods One to Seven in that the solvent mentioned in step four is deionized water, anhydrous ethanol, or methanol.

[0063] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the reagents used for cleaning in step six are deionized water and anhydrous ethanol.

[0064] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that the drying method described in step 6 is vacuum drying, forced air drying, or freeze drying, and the time is 5-24 hours.

[0065] Example 1:

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

[0067] I. 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 red copper mesh, which is cut into 13-15 cm 2 in size;

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

[0070] II. A 1 mol / L dilute hydrochloric acid solution and a 0.008 mol / L ammonium persulfate solution are mixed, and the copper-based current collector material obtained in step I is immersed in the mixed solution and left to stand, then taken out, cleaned and dried; the volume ratio of the dilute hydrochloric acid solution to the ammonium persulfate solution is 1:1;

[0071] The mixing method of the mixed hydrochloric acid solution and 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 step I into the mixed solution and standing is 4°C, and the standing time is 1 h;

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

[0074] III. A zinc salt is dissolved in deionized water to obtain a zinc salt solution;

[0075] The zinc salt is zinc nitrate hexahydrate;

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

[0077] The solvent is deionized water;

[0078] IV. A xanthic acid heavy metal capturing agent is placed in a solvent to obtain a xanthic acid heavy metal capturing agent solution;

[0079] The chemical formula of the xanthic acid heavy metal capturing agent is R-O-CS2-M, wherein R is ethyl; M is K + ;

[0080] The concentration of the xanthic acid heavy metal capturing agent solution is 0.003 mol / L;

[0081] The solvent is deionized water;

[0082] V. The copper-based current collector material obtained in step II is immersed in the zinc salt solution, and then taken out and immersed in the xanthic acid heavy metal capturing agent solution; the immersion time is 5 min;

[0083] Six, the copper-based current collector material obtained in step five is cleaned and dried, i.e. finished;

[0084] The reagent used in the cleaning is deionized water and anhydrous ethanol;

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

[0086] Figure 1 The surface-modified copper-based current collector in Example 1 is used for lithium metal half-batteries, and the coulombic efficiency diagram of different cycle numbers at a current density of 3mA / cm 2 The average coulombic efficiency during the stable cycle of the corresponding half-battery reaches 97.3% at a high current density of 3mA / cm 2 Figure 2 The surface-modified copper-based current collector in Example 1 is used for lithium iron phosphate full batteries, and the discharge specific capacity diagram of different cycle numbers at 2C; the first cycle discharge specific capacity is 137.6mAh / g at 2C, and the discharge specific capacity is 132.5mAh / g after cycling to 500 cycles, and the average coulombic efficiency reaches 99.8%. The cycle stability of the full battery is significantly improved after using the surface-modified copper-based current collector.

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

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

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

[0092] II. Mix 1mol / L of dilute hydrochloric acid solution and 0.008mol / L of ammonium persulfate solution, immerse the copper-based current collector material obtained in step I in the mixed solution, stand for 1h, then take it out, 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 mixed hydrochloric acid solution and ammonium persulfate solution is magnetic stirring, and the magnetic stirring time is 20min;

[0094] The standing environment temperature of the copper-based current collector material obtained in step I in the mixed solution is 4°C, and the standing time is 1h;

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

[0096] III. 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] IV. Place the xanthate heavy metal capture agent in a solvent to obtain a xanthate heavy metal capture agent solution;

[0102] The chemical formula of the xanthate heavy metal capture agent is R-O-CS2-M, wherein R is ethyl; M is K + ;

[0103] The concentration of the xanthate heavy metal capture agent solution is 0.003 mol / L;

[0104] The solvent is deionized water;

[0105] V. Add 1.2 mL of the metal salt solution dropwise to 80 mL of the xanthate heavy metal capture agent solution, mix, and stand for 5 min to obtain a mixed solution; immerse the copper-based current collector material obtained in step II in 80 mL of the zinc salt solution, then take it out and immerse it in the mixed solution;

[0106] The immersion time is 5 min;

[0107] VI. Clean and dry the copper-based current collector material obtained in step V, and the process is complete;

[0108] The cleaning reagents used are deionized water and anhydrous ethanol;

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

[0110] Physicochemical characterization and electrochemical performance testing were performed on the sample.

[0111] Figure 3 The scanning electron microscope photograph of the surface-modified copper-based current collector in Example 2; from Figure 3 It can be observed that after introducing silver ions into the ethyl xanthate solution, the morphology of the copper mesh surface attachments changes significantly, showing uniform coverage of nanosheets. Figure 4Raman spectrum of the surface-modified copper-based current collector in Example 2 after ultrasonic treatment; the Raman spectrum measured after ultrasonic treatment of the surface-modified copper-based current collector is 250-650 cm -1 The appearance of the interval-related vibration peak indicates that the ethyl xanthate coordination compound on the surface of the copper mesh still exists after ultrasonic treatment, confirming the firm attachment of the lithiumophilic modification layer on the surface of the substrate. Figure 5 Coulombic efficiency diagram of the lithium metal half-battery using the surface-modified copper-based current collector in Example 2 at different cycle numbers under a current density of 3 mA / cm 2 The corresponding half-battery was cycled for 100 cycles at a current density of 3 mA / cm 2 , and the coulombic efficiency reached 98.4%. Figure 6 Discharge specific capacity diagram of the lithium iron phosphate full battery using the surface-modified copper-based current collector in Example 2 at different cycle numbers under a rate of 2C; the discharge specific capacity was 142.9 mAh / g after cycling for 500 cycles at a rate of 2C, and the capacity retention rate reached 98%, indicating excellent cycle stability.

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

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

Claims

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

1. The copper-based current collector material is cleaned in a solvent and then dried at room temperature; 2. Mix dilute hydrochloric acid solution and ammonium persulfate solution, immerse the copper-based current collector material obtained in step 1 into the mixed solution and let it stand. After standing, take it out, clean and dry 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; and the volume ratio of the dilute hydrochloric acid solution to the ammonium persulfate solution is 1:

1.

3. 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; The metal salt is one or two of the following: 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 was 0.0003-0.01 mol / L; IV. Place the xanthic acid-based heavy metal scavenging agent in a solvent to obtain a xanthic acid-based heavy metal scavenging agent solution; The xanthic acid-based heavy metal scavenger has the chemical formula RO-CS2-M, where 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 xanthic acid-based heavy metal scavenging agent solution is 0.001-0.05 mol / L; 5. Add the metal salt solution dropwise to the xanthic acid-based heavy metal scavenging agent solution and mix. Let 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 into the mixed solution. The immersion time is 3-30 minutes. The volume ratio of the metal salt solution to the xanthic acid-based heavy metal scavenging agent solution is 0.02-10:

80. Alternatively, the metal salt solution can be added dropwise to the zinc salt solution and mixed, then allowed to stand for 5-15 minutes to obtain a mixed solution; the copper-based current collector material obtained in step two can be immersed in the mixed solution, and then removed and immersed in a xanthic acid-based heavy metal scavenging agent 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 to complete the process.

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

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

4. The surface modification method for the copper-based current collector of lithium metal anode according to claim 1, characterized in that: The mixing method for the hydrochloric acid solution and ammonium persulfate solution in step two is magnetic stirring, and the magnetic stirring time is 5-30 minutes.

5. The surface modification method for the copper-based current collector of lithium metal anode according to claim 1, characterized in that: In step two, the copper-based current collector material obtained in step one is immersed in the mixed solution and left to stand at an ambient temperature of 0-50℃ for 0.5-2 hours.

6. The surface modification method for the copper-based current collector of lithium metal anode according to claim 1, characterized in that: The drying process described in step two is either forced air drying or vacuum drying, with a drying temperature of 40-100℃ and a drying time of 15-25 hours.

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

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

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

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