A method for preparing an ultrathin nickel-silver bimetallic coating for the negative electrode of a long-cycle metal battery

Abstract

This invention provides a method for preparing an ultrathin nickel-silver bimetallic coating for a long-cycle metal battery anode, comprising: 1) cleaning the chamber, loading zinc foil onto the sample stage, adjusting the angle between the target and the substrate, and evacuating the chamber using a mechanical pump and a molecular pump; introducing argon gas and using ion source cleaning technology to remove impurities from the zinc foil surface; 2) introducing argon gas, sputtering a nickel-silver alloy target, or co-sputtering a nickel and silver metal target, adjusting the power of the two targets to change the nickel and silver content in the bimetallic coating, and simultaneously depositing the nickel-silver bimetal onto the zinc foil surface after ion source cleaning; 3) allowing the zinc foil modified with the obtained nickel-silver bimetallic coating to stand for a period of time to obtain a nickel-silver bimetallic coating with adjustable composition for a zinc battery anode; this invention guides the uniform deposition of zinc on its surface and uses magnetron co-sputtering technology to adjust the sputtering power of the two metal targets, precisely controlling the nickel and silver content of the nickel-silver bimetallic coating, thereby achieving the preparation of an ultra-long-cycle stable metal battery anode.

Description

Technical Field

[0001] This invention relates to the field of secondary metal battery technology, and specifically to a method for preparing an ultrathin nickel-silver bimetallic coating for the negative electrode of a long-cycle metal battery. Background Technology

[0002] Batteries are a crucial component of modern energy storage systems, converting electrical energy into chemical energy and storing it for release when needed. High-energy-density, long-life, and lightweight rechargeable lithium-ion batteries suffer from drawbacks such as resource scarcity, high cost, demanding manufacturing conditions, and the flammability of organic electrolytes. Therefore, there is an urgent need for a more environmentally friendly and sustainable energy storage device to replace lithium-ion batteries.

[0003] Aqueous zinc-ion batteries offer advantages such as being environmentally friendly, safe, stable, and inexpensive, making them a promising next-generation energy storage technology. Metal batteries, which can utilize aqueous electrolytes, hold great promise for applications in portable electronic devices and large-scale energy storage systems.

[0004] However, in practical applications, some reactions in the aqueous electrolyte solution can affect the metal deposition process, leading to a decrease in the coulombic efficiency of zinc deposition / stripping and causing incomplete metal dissolution. As a result, metal ions gradually deposit unevenly on the metal anode surface, forming needle-like dendrites. As the dendrites continue to form and grow, their mechanical rigidity and uneven structure cause them to detach from the anode surface, resulting in a reduction in battery active material and capacity decay. Dendrites may also puncture the separator, causing internal short circuits. Furthermore, the coexistence of active metals and water is thermodynamically unstable. During electrochemical cycling, hydrogen evolution reaction frequently occurs. Along with hydrogen evolution, side reactions such as corrosion pits and passivation also appear on the anode surface, causing a decrease in battery coulombic efficiency, battery swelling, and reduced cycle stability.

[0005] The aforementioned adverse side reactions on the negative electrode surface do not occur independently but rather influence and promote each other. Therefore, it is necessary to construct an artificial modification layer on the negative electrode surface to improve the cycle life of aqueous metal-ion batteries by suppressing dendrite growth and side reactions; at the same time, the construction of the negative electrode modification layer makes the electrochemical performance of the whole cell, such as cycle life and capacity retention, more stable.

[0006] To address these formidable challenges, metal-based coatings have been employed to modulate the performance of the negative electrode in metal batteries. The affinity and conductivity of specific metal-based coatings on the negative electrode surface contribute to a more uniform deposition distribution during charge / discharge cycles. This modification not only facilitates dendrite-free deposition but also suppresses side reactions, thereby improving the safety and stability of the metal battery. Among various metal-based coatings, alloy negative electrodes have been extensively explored and implemented. Zhang et al. constructed a three-dimensional Ni-Zn negative electrode with a multi-channel lattice structure and a superhydrophilic surface, which effectively improved the electric field distribution, induced uniform metal deposition, and suppressed dendrite growth. Meanwhile, Zheng et al. found that modification with Ag metal coatings, particularly in the form of in-situ generated AgZn3 alloys, is significant for promoting uniform surface deposition and suppressing side reactions such as hydrogen evolution.

[0007] Currently, research on electrode modification using alloy materials has made some progress. However, due to limitations in conductive materials, thin film structures, and preparation processes, the reliability and stability of existing alloy materials still cannot meet the requirements: 1) Due to the numerous steps and complex composition of alloy preparation, it is difficult to precisely control the process and obtain the target sample in one go, thus hindering large-scale production; 2) Some binary alloy modification layers have limited optimization effects, poor chemical stability in alkaline environments, and cannot produce good results in suppressing side reactions such as hydrogen evolution and corrosion, thus failing to obtain batteries with long-cycle stability. Summary of the Invention

[0008] To address the aforementioned issues, this invention employs a one-step magnetron sputtering method to prepare coatings, overcoming the problems of cumbersome preparation methods and uncontrollable composition in existing alloy coating preparation methods. Simultaneously, it proposes a bimetallic synergistic strategy, utilizing the properties of different metals to simultaneously enhance the adsorption and corrosion resistance of the negative electrode surface and suppress hydrogen evolution reaction, thereby achieving the preparation of an ultra-long-cycle stable metal battery negative electrode.

[0009] The present invention adopts the following technical solution:

[0010] A method for preparing an ultrathin nickel-silver bimetallic coating for the negative electrode of a long-cycle metal battery includes: 1) cleaning the chamber, loading zinc foil onto the sample stage, adjusting the angle between the target and the substrate, evacuating the chamber using a mechanical pump and a molecular pump, introducing argon gas, and removing impurities from the surface of the zinc foil using ion source cleaning technology;

[0011] 2) Introduce argon gas and sputter magnetic metal and B11 group metal bimetallic alloy targets by single target sputtering; or co-sputter magnetic metal and B11 group metal targets by adjusting the power of the two targets to change the content of nickel and silver elements in the bimetallic coating, and simultaneously deposit the bimetal onto the zinc foil surface after it has been cleaned by the ion source.

[0012] 3) The obtained bimetallic coating modified zinc foil is left to stand for a period of time to obtain a bimetallic coating with adjustable composition for zinc battery negative electrode.

[0013] Furthermore, the magnetic metal is one of Fe, Co, and Ni.

[0014] Furthermore, the B11 group metal is one of Cu, Ag, and Au.

[0015] Furthermore, in step 1), the angle between the target and the substrate is 60-90°.

[0016] Furthermore, in step 1), the specific conditions for introducing argon gas and using ion source cleaning technology can be as follows: the argon gas flow rate is set to 115 sccm, the pressure in the chamber is adjusted to 15 Pa, and the ion source cleaning time is 10 to 20 minutes.

[0017] Furthermore, in step 2), the specific conditions for single-target sputtering of the nickel-silver bimetallic alloy target are as follows: argon gas is introduced, the alloy target power is adjusted to 20-80W, the sputtering pressure is maintained at 0.4Pa, and the sputtering time is 10min; or the specific conditions for co-sputtering of nickel and silver metal targets are as follows: argon gas is introduced, the total gas flow rate is 120sccm; the nickel metal target power is adjusted to 20-80W, the silver target power is adjusted to 20-80W, the sputtering pressure is maintained at 0.4Pa, and the sputtering time is 10min.

[0018] Furthermore, the thickness of the nickel-silver bimetallic coating is 0.1–1 μm;

[0019] Furthermore, the nickel:silver content ratio is 1:15 to 1:4.

[0020] Furthermore, in step 3), the specific time for allowing the obtained nickel-silver bimetallic coated modified zinc foil to stand is 20 to 60 minutes.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention prepares a coating with controllable structure and adjustable composition. Silver has a strong adsorption capacity for hydrogen, which can effectively inhibit the surface hydrogen evolution reaction. Adding a small amount of nickel to silver can improve the oxidation resistance of the coating metal, reduce the amount of silver used and save costs. By using a bimetallic synergistic strategy, a long-life zinc-ion battery with stronger electrochemical performance can be achieved.

[0023] 2. This invention is the first to utilize magnetron co-sputtering to prepare an ultrathin nickel-silver bimetallic coating with a thickness of approximately 200 nm on zinc foil. This facilitates further optimization of the electrochemical interface, promotes stable electrode / electrolyte interactions, and suppresses harmful side reactions, enabling symmetrical cells to operate at a current density of 1 mA cm⁻¹.-2 It exhibits an excellent cycle life of over 6800 hours, while maintaining a coulombic efficiency of up to 99.7%. For cycle life at various current densities, the nickel-silver-zinc based symmetric cell outperforms most reported binary / ternary alloy based symmetric cells.

[0024] 3. The one-step preparation method in this invention eliminates the need for pretreatment such as grinding, polishing, and chemical treatment of the negative electrode substrate foil, as well as post-treatment such as annealing. While reducing steps and improving efficiency, it also saves material resources. It can handle different substrates and coatings in a simple and quick manner, making it suitable for large-scale production and manufacturing, and beneficial for industrial applications. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0026] Figure 1 XRD patterns of the comparative example and the nickel-silver coated negative electrode;

[0027] Figure 2 For comparative and example purposes, zinc foil was used as the negative electrode of a half-cell at 1 mA cm⁻¹. -2 Coulomb efficiency plot at current density;

[0028] Figure 3 For comparative and example cases, zinc foil was used as the negative electrode of a symmetrical battery at 1 mA cm. -2 Cycle lifetime diagram at current density;

[0029] Figure 4 SEM images of zinc foil used in symmetrical batteries for comparative and Example 4 after 20h and 50h cycling;

[0030] Figure 5 For comparison with Example 4, zinc foil was used in full cells at 1 A·g -1 Charge-discharge cycle diagram at current density; Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] As shown in the figure, this invention provides a technical solution: a method for preparing an ultrathin nickel-silver bimetallic coating for the negative electrode of a long-cycle metal battery, comprising:

[0033] Comparative Example 1

[0034] 1. Preparation of blank zinc anode

[0035] Wipe the 0.08mm thick commercial zinc foil with ethanol and then place it in a vacuum drying oven.

[0036] 2. Preparation of activated carbon electrodes

[0037] Activated carbon (AC), polyvinylidene fluoride (PVDF), and acetylene black were mixed and ground in a ratio of 8:1:1. One drop of N-methylpyrrolidone (NMP) was added and dispersed evenly before coating the mixture onto a stainless steel mesh. After drying at 80°C overnight, AC / / stainless steel mesh was obtained.

[0038] 3. XRD was used to characterize the phase structure of the zinc foil.

[0039] Figure 1 The lower curve is the XRD pattern of a blank zinc foil.

[0040] 4. Zinc-copper half-cell cycle test

[0041] Figure 2 Cyclic testing of a zinc-copper half-cell was conducted. Blank zinc foil and copper foil were used as the negative and positive electrodes, respectively. The voltage was measured at 1 mA cm⁻¹. -2 1mAh cm -2 Cyclic tests were conducted under the conditions of 2 mol / L ZnSO4. The graph shows that the half-cell with blank zinc foil as the negative electrode only completed about 75 cycles, indicating poor stability during cycling.

[0042] 5. Performance testing of zinc-zinc symmetric cells

[0043] Blank zinc foil was assembled into a CR-2032 symmetrical battery for cycle stability testing. Glass fiber was used as the separator for the negative electrode in the CR-2032 battery. The electrolyte used was 100 μL of a 2 mol / L ZnSO4 solution. The test parameters were set as constant current charging and discharging, with a current density of 1 mA cm⁻¹. -2 . Figure 5 The effective cycling time of the blank zinc foil at the above current density is approximately 200 hours. It is evident that the blank sample without coating protection fails in a relatively short time and has poor stability.

[0044] 6. SEM was used to observe the zinc foil structure.

[0045] Blank zinc foil was assembled into a symmetrical cell at 1 mA cm⁻¹. -2 After cycling at current densities for 20 hours and 50 hours, from Figure 4 It is evident that a large number of byproducts and protruding lamellar dendrites are formed.

[0046] 7. Zn-AC Battery Performance Testing

[0047] A CR-2032 coin cell was assembled using blank zinc foil as the negative electrode and the AC electrode as the positive electrode for full-cell cycle performance testing. Glass fiber was used as the separator for both the positive and negative electrodes in the CR-2032 cell. The electrolyte used was ZnSO4 containing 2 mol / L. The test parameters were set to 1 A·g. -1 Constant current charging and constant current discharging. Figure 5 The charge-discharge curves of a full cell cycle with blank zinc foil as the negative electrode show that the capacity is lower and there is a decay trend when blank zinc foil is used as the negative electrode.

[0048] Example 1

[0049] 1. Matrix pretreatment

[0050] (1) Wipe the 0.08mm thick zinc foil with ethanol and then place it in a vacuum drying oven.

[0051] (2) Cut the electrode substrate obtained in step (1) into 5x5cm pieces and place them on the sample stage in the magnetron sputtering chamber. Clean them by bombardment with an ion source. The chamber pressure is 1.5Pa, the argon flow rate is 112sccm, and the cleaning time is 10min.

[0052] 2. Preparation of Nickel-Silver Bimetallic Coating

[0053] After confirming that the angle between the nickel target base and the plane is 75°, the chamber vacuum is evacuated to ≤1.0×10⁻⁶ using a mechanical pump and a molecular pump. - 3 Pa; Ar gas was introduced, with a flow rate set to 120 sccm, and the deposition pressure in the chamber was adjusted to 0.4 Pa; the power of the nickel and silver metal targets was adjusted to 40 W, and pre-sputtering was performed for 5 min; after pre-sputtering, the baffle was opened, the sample stage was rotated, and the power and gas pressure were kept constant for 10 min to obtain a coating with a thickness of about 200 nm, in which the nickel-silver content ratio was about 1:10.

[0054] 3. Zinc-copper half-cell cycle test

[0055] Figure 2 Cyclic testing of a zinc-copper half-cell was conducted. Zinc foil and copper foil coated with the coating prepared in step 2 were used as the negative and positive electrodes, respectively. The test was conducted at 1 mA cm⁻¹. -2 1mAh cm -2 Cyclic tests were conducted under the conditions of 2 mol / L ZnSO4. The figure shows that the zinc-copper battery using the zinc foil prepared in step 2 as the negative electrode can stably achieve more than 300 cycles.

[0056] 4. Performance testing of zinc-zinc symmetric cells

[0057] Blank zinc foil was assembled into a CR-2032 symmetrical battery for cycle stability testing. Glass fiber was used as the separator for the negative electrode in the CR-2032 battery. The electrolyte used was 100 μL of a 2 mol / L ZnSO4 solution. The test parameters were set as constant current charging and discharging, with a current density of 1 mA cm⁻¹. -2 . Figure 5 The results showed that the effective cycle time of the blank zinc foil at the above current density reached 6800 hours, demonstrating that the nickel-silver bimetallic coating greatly improved the cycle stability of the battery.

[0058] Example 2

[0059] 5. Matrix pretreatment

[0060] (3) Wipe the 0.08mm thick zinc foil with ethanol and then place it in a vacuum drying oven.

[0061] (4) Cut the electrode substrate obtained in step (1) into 5x5cm pieces and place them on the sample stage in the magnetron sputtering chamber. Clean them by bombardment with an ion source. The chamber pressure is 1.5Pa, the argon flow rate is 112sccm, and the cleaning time is 10min.

[0062] 6. Preparation of Nickel-Silver Bimetallic Coating

[0063] After confirming that the angle between the nickel target base and the plane is 65°, the chamber vacuum is evacuated to ≤1.0×10⁻⁶ using a mechanical pump and a molecular pump. - 3 Pa; Ar gas was introduced, with a flow rate set to 120 sccm, and the deposition pressure in the chamber was adjusted to 0.4 Pa; the power of the nickel and silver metal targets was adjusted to 40 W, and pre-sputtering was performed for 5 min; after pre-sputtering, the baffle was opened, the sample stage was rotated, and the power and gas pressure were kept constant for 10 min to obtain a coating with a thickness of about 200 nm, in which the nickel-silver content ratio was about 1:4.

[0064] 7. Zinc-copper half-cell cycle test

[0065] Figure 2 Cyclic testing of a zinc-copper half-cell was conducted. Zinc foil and copper foil coated with the coating prepared in step 2 were used as the negative and positive electrodes, respectively. The test was conducted at 1 mA cm⁻¹. -2 1mAh cm -2 Cyclic tests were conducted under the conditions of 2 mol / L ZnSO4. The figure shows that the zinc-copper battery using the zinc foil prepared in step 2 as the negative electrode can stably achieve more than 300 cycles.

[0066] 8. Performance testing of zinc-zinc symmetric cells

[0067] Blank zinc foil was assembled into a CR-2032 symmetrical battery for cycle stability testing. Glass fiber was used as the separator for the negative electrode in the CR-2032 battery. The electrolyte used was 100 μL of a 2 mol / L ZnSO4 solution. The test parameters were set as constant current charging and discharging, with a current density of 1 mA cm⁻¹. -2 . Figure 5 The results showed that the effective cycle time of the blank zinc foil at the above current density reached 6800 hours, demonstrating that the nickel-silver bimetallic coating greatly improved the cycle stability of the battery.

[0068] Example 3

[0069] 1. Matrix pretreatment

[0070] (1) Wipe the 0.08mm thick zinc foil with ethanol and then place it in a vacuum drying oven.

[0071] (2) Cut the electrode substrate obtained in step (1) into 5x5cm pieces and place them on the sample stage in the magnetron sputtering chamber. Clean them by bombardment with an ion source. The chamber pressure is 1.5Pa, the argon flow rate is 112sccm, and the cleaning time is 10min.

[0072] 2. Preparation of activated carbon electrodes

[0073] Activated carbon (AC), polyvinylidene fluoride (PVDF), and acetylene black were mixed and ground in a ratio of 8:1:1. One drop of N-methylpyrrolidone (NMP) was added and dispersed evenly before coating the mixture onto a stainless steel mesh. After drying at 80°C overnight, AC / / stainless steel mesh was obtained.

[0074] 3. Preparation of Nickel-Silver Bimetallic Coating

[0075] After confirming that the angle between the target base and the plane is 85°, use a mechanical pump and a molecular pump to evacuate the chamber to a vacuum level of ≤1.0 × 10⁻⁶. -3 Pa; Ar gas was introduced, with a flow rate set to 120 sccm, and the deposition pressure in the chamber was adjusted to 0.4 Pa; the power of the nickel and silver metal targets was adjusted to 40 W, and pre-sputtering was performed for 5 min; after pre-sputtering, the baffle was opened, the sample stage was rotated, and the power and gas pressure were kept constant for 10 min to obtain a coating with a thickness of about 200 nm, in which the nickel-silver content ratio was about 1:14.

[0076] 4. XRD characterization of the nickel-silver-zinc anode phase structure.

[0077] Figure 1 The upper middle curve is the XRD pattern of the nickel-silver-zinc anode.

[0078] 5. Zinc-copper half-cell cycle test

[0079] Figure 2Cyclic testing of a zinc-copper half-cell was conducted. Zinc foil and copper foil coated with the coating prepared in step 3 were used as the negative and positive electrodes, respectively. The test was conducted at 1 mA cm⁻¹. -2 1mAh cm -2 Cyclic tests were conducted under the conditions of 2 mol / L ZnSO4. As shown in the figure, the zinc-copper battery with the zinc foil prepared in step 2 as the negative electrode can stably achieve more than 300 cycles, with a coulombic efficiency as high as 99.7%.

[0080] 6. Performance testing of zinc-zinc symmetric cells

[0081] Blank zinc foil was assembled into a CR-2032 symmetrical battery for cycle stability testing. Glass fiber was used as the separator for the negative electrode in the CR-2032 battery. The electrolyte used was 100 μL of a 2 mol / L ZnSO4 solution. The test parameters were set as constant current charging and discharging, with a current density of 1 mA cm⁻¹. -2 . Figure 5 The results showed that the effective cycle time of the blank zinc foil at the above current density reached 6800 h, indicating that the coating prepared with a nickel-silver bimetallic ratio of 1:14 greatly improved the cycle stability of the battery.

[0082] 7. Observe the zinc foil structure using SEM.

[0083] Figure 4 The SEM images of the zinc foil prepared in step 2 after cyclic charging and discharging in a symmetric battery are shown in Comparative Example 1, which shows the blank zinc foil reacted under the same conditions. Zinc is deposited uniformly on the nickel-silver surface without obvious dendrites or corrosion pits.

[0084] 8. Performance Testing of Nickel-Silver-Zinc-AC Batteries

[0085] A CR-2032 coin cell was assembled using a nickel-silver coated zinc foil as the negative electrode and an AC electrode as the positive electrode for full-cell cycle performance testing. Glass fiber was used as the separator for both the positive and negative electrodes in the CR-2032 cell. The electrolyte used was ZnSO4 containing 2 mol / L. The test parameters were set to 1 A·g. -1 Constant current charging and constant current discharging. Figure 5 The charge-discharge curves of a full cell cycle with zinc foil modified with nickel-silver coating as the negative electrode are shown. The capacity is higher when blank zinc foil is used as the negative electrode and does not decay after 20,000 cycles.

[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an ultrathin nickel-silver bimetallic coating on the negative electrode of a long-cycle metal battery, characterized in that, The process includes: 1) cleaning the chamber, loading zinc foil onto the sample stage, adjusting the angle between the target and the substrate to 60–90°, and evacuating the chamber using a mechanical pump and a molecular pump; introducing argon gas and using ion source cleaning technology to remove impurities from the surface of the zinc foil; 2) introducing argon gas; adjusting the power of the nickel metal target to 20–80W and the silver target to 20–80W, maintaining the sputtering pressure at 0.4Pa, and the sputtering time at 10min, simultaneously depositing nickel-silver bimetal onto the surface of the zinc foil after ion source cleaning, wherein the ratio of deposited nickel to silver elements is 1:15–1:4; 3) allowing the zinc foil modified with the obtained nickel-silver bimetallic coating to stand for a period of time to obtain a nickel-silver bimetallic coating with adjustable composition for zinc battery anodes.

2. The method for preparing an ultrathin nickel-silver bimetallic coating for the negative electrode of a long-cycle metal battery according to claim 1, characterized in that, In step 1), argon gas is introduced, and the specific conditions for using ion source cleaning technology are as follows: the argon gas flow rate is set to 115 sccm, the pressure in the chamber is adjusted to 15 Pa, and the ion source cleaning time is 10 to 20 minutes.

3. The method for preparing an ultrathin nickel-silver bimetallic coating for the negative electrode of a long-cycle metal battery according to claim 1, characterized in that, The thickness of the nickel-silver bimetallic coating is 0.1–1 μm.

4. The method for preparing an ultrathin nickel-silver bimetallic coating for the negative electrode of a long-cycle metal battery according to claim 1, characterized in that, In step 3), the specific time for allowing the obtained nickel-silver bimetallic coated modified zinc foil to stand is 20 to 60 minutes.

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