Zinc negative electrode and preparation method and application thereof

Abstract

The invention discloses a zinc negative electrode and a preparation method and application thereof.The preparation method comprises the steps that zinc salt, aluminum salt, manganese salt, a complexing agent and water are mixed, an electroplating solution is obtained, and the complexing agent is formamide; and carrying out electro-deposition on the electroplating liquid on the surface of a base material to obtain a zinc metal coating, namely the zinc negative electrode. The preferred orientation of the zinc metal (002) crystal face is realized through a simple electro-deposition process, and the monocrystal-like zinc negative electrode with the highly-oriented (002) crystal face is obtained in one step, is used as a reaction surface of an aqueous zinc metal battery and has excellent electrochemical performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of aqueous zinc metal batteries, and in particular relates to a highly oriented single-crystal-like zinc negative electrode and a preparation method and application thereof. Background Art

[0002] Chemical energy storage is the link between new energy and traditional energy, and is of great significance to solving the large-scale consumption of renewable energy and promoting the green transformation of energy. For lead-acid batteries, which currently dominate the large-scale energy storage market, their energy density is low, their safety is low, and the harmful substances such as lead and sulfuric acid they contain are very likely to pollute the environment; the cost of lithium-ion batteries in the field of large-scale energy storage is extremely high, which hinders their large-scale use in chemical energy storage. Rechargeable aqueous zinc metal batteries are a strong competitor for the next generation of large-scale energy storage technology due to their high safety, low cost, simple production environment and excellent recyclability, and are increasingly valued and favored by countries around the world. Metallic zinc has the advantages of high conductivity, easy processing, abundant reserves (second only to iron, aluminum and copper), environmental friendliness, good chemical stability in the air, and higher cost-effectiveness (US$65kWh -1 The lower redox overpotential of the zinc negative electrode (-0.76V vs. standard hydrogen electrode) is conducive to increasing the battery operating voltage and is an ideal metal negative electrode choice.

[0003] However, there are still many key issues with zinc anodes: uncontrolled zinc dendrites may pierce the glass fiber separator, eventually causing a short circuit in the battery; preferential dissolution of the dendrite root may cause the dendrite to separate from the host, and the resulting "dead zinc" loses its activity, accelerating zinc consumption. In addition, due to the inherent host-free nature of the zinc anode, it is easy to become unstable after repeated cycles. These structural damages are irreparable and greatly increase the risk of battery failure. Therefore, the development of anode materials with uniform zinc deposition behavior is of great significance to improving the overall performance of zinc-ion batteries.

[0004] In recent years, many researchers have proposed a variety of solutions from the negative electrode side, including constructing an interfacial protective layer, designing three-dimensional structure electrolyte additive optimization, etc. Although these strategies can improve the performance of zinc metal anodes to a certain extent, they are difficult to continue to work during long-term cycling. Specifically, in-situ and ex-situ coatings are only effective on the surface and it is difficult to ensure the integrity of the interface during the cycle. The three-dimensional structure requires a complex preparation process and the structural network is prone to deformation or even collapse. Zinc deposition / stripping is a dynamic process, and due to the volume change of zinc deposition, the current rigid coating technology cannot maintain conformal contact with zinc, which easily leads to irreversible fracture during cycling. Such an interfacial coating is not sufficient to adapt to electrode changes and provide continuous protection. Only when zinc deposition and stripping are controlled in a balanced state, the interfacial stability of the zinc anode is sufficient to provide a long-lasting battery life. At present, there is an urgent need to explore substantial modification measures to fundamentally solve the challenges faced by zinc anodes in thermodynamics and kinetics.

[0005] Metallic zinc has a hexagonal close-packed (hcp) structure, and the atomic structures of different crystal planes are very different. Compared with the (100) and (101) crystal planes, the smoother surface atomic arrangement and more uniform charge density of the interface (002) crystal plane favor Zn 2+ Uniform deposition. For the (101) and (100) crystal planes, the risk of dendrite growth will increase due to the uneven atomic arrangement and uneven interfacial charge distribution. In addition, due to the large atomic density, low surface energy and high interatomic binding energy of the (002) crystal plane, its corrosion resistance and anti-dendrite ability are stronger than those of the (100) and (101) crystal planes. Therefore, adjusting the state of electroplated Zn crystals is expected to fundamentally obtain a highly stable and reversible metal negative electrode. At present, most researchers use electrolyte additives to regulate the preferred orientation of the Zn (002) crystal plane, but the strength of the (002) crystal plane is less improved, and it is too one-sided and does not consider the effect of additives on the positive electrode material and the battery as a whole. In addition, specific conductive substrates (e.g., graphene-coated stainless steel and (100) plane-textured Cu foil) have been developed to guide the (002)-oriented Zn electrodeposition, which is achieved by appropriate lattice mismatch between the substrate and Zn. However, when the zinc coating completely covers the substrate, its guiding effect will be weakened or even disappear, which is not suitable for large-scale production. Electrodeposition is the process in which ions in the electrolyte migrate to the electrode under the action of an external electric field, gain and lose electrons for electrochemical reactions, and deposit metals, alloys, hydroxides, oxides and other products on the electrode surface. Electrodeposition can directly load active substances on a conductive substrate, avoiding the use of binders in powder-made electrodes. However, electrodeposition preparation has problems such as poor material versatility, difficulty in interface control, and low deposition load. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a zinc negative electrode and a preparation method and application thereof. Through a simple electrodeposition process, the preferential orientation of the (002) crystal plane of zinc metal is achieved, and a quasi-single crystal zinc negative electrode with a highly oriented (002) crystal plane is obtained in one step, which is used as the reaction surface of an aqueous zinc metal battery and has excellent electrochemical properties.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] A method for preparing a zinc negative electrode comprises mixing zinc salt, aluminum salt, manganese salt, a complexing agent and water to obtain an electroplating solution, wherein the complexing agent is formamide; and electroplating the electroplating solution on the surface of a substrate to obtain a zinc metal coating, namely the zinc negative electrode.

[0009] Preferably, the zinc salt is ZnSO4, ZnCl2 or Zn(CF3SO3)2, the aluminum salt is Al2(SO4)3 or AlCl3, and the manganese salt is MnSO4 or MnCl2; the molar ratio of the zinc salt, the aluminum salt and the manganese salt is 40-20:2-3:1; the concentration of the zinc salt in the electroplating solution is 0.5-3 mol / L; the volume ratio of the complexing agent to water in the electroplating solution is 0.5-1:1.

[0010] Preferably, the substrate is copper foil, zinc foil, titanium foil or a carbon-based material.

[0011] Preferably, the electrodeposition process is as follows: using the zinc sheet as the negative electrode and the substrate as the positive electrode, constant current electrodeposition is performed in an electrolytic cell to deposit a zinc metal coating on the substrate.

[0012] Preferably, the current density of the electrodeposition is 5 to 30 mA / cm 2 .

[0013] The present invention also provides a zinc negative electrode prepared by the above preparation method, wherein the (002) crystal plane of the zinc metal coating is the main orientation, and the relative texture coefficient of the (002) plane is not less than 99%.

[0014] The present invention also provides an application of the zinc negative electrode, which is used to prepare an aqueous zinc metal battery.

[0015] The advantages of the present invention are:

[0016] The present invention innovatively proposes a method for preparing a strong (002) oriented zinc negative electrode material in one step based on electrodeposition. With the help of the coordinated control of aluminum and manganese cations and a complexing agent in the electroplating solution, a single-crystal zinc coating with high structural stability, ionic conductivity and good matrix bonding can be formed on the surface of the substrate. It can be used as the reaction surface of an aqueous zinc metal battery and has excellent electrochemical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The XRD spectra of Zn(002)-1 of Example 1, Zn-Al of Comparative Example 1 and Bare Zn of Comparative Example 3 are shown.

[0018] Figure 2 The XRD spectra of Zn(002)-1 of Example 1, Zn-Mn of Comparative Example 2, and Bare Zn of Comparative Example 3 are shown.

[0019] Figure 3 These are the XRD spectra of Zn(002)-1 of Example 1, Zn(002)-2 of Example 2, and Zn(002)-3 of Example 3.

[0020] Figure 4 These are the XRD spectra of Zn(002)-1 of Example 1, Zn(002)-4 of Example 4, Zn(002)-5 of Example 5, and Zn(002)-6 of Example 6.

[0021] Figure 5 The electron probe images of Zn(002)-1 of Example 1, Zn-Al of Comparative Example 1, and Zn-Mn of Comparative Example 2 are shown.

[0022] Figure 6 The graphs are the cycle performance of zinc symmetric batteries of Example 1 (Zn(002)-1), Comparative Example 1 (Zn-Al) and Comparative Example 2 (Zn-Mn).

[0023] Figure 7 The figure is a comparison chart of the battery cycle performance of the coulombic efficiency of zinc-copper batteries of Zn(002)-1 of Example 1 and Bare Zn of Comparative Example 3.

[0024] Figure 8 This is a comparison chart of the zinc / zinc symmetric battery cycle performance of Zn(002)-1 of Example 1 and Bare Zn of Comparative Example 3.

[0025] Fig. 9 This is the XRD spectrum of the symmetrical battery of Zn(002)-1 in Example 1 after the corresponding number of cycles (a); the SEM image of the negative electrode side after 500 cycles (500 cycles) (b); the SEM image of the negative electrode side after 50 cycles (50 cycles) (c).

[0026] Fig.10 This is a comparison chart of the electrochemical performance of Zn(002)-1 of Example 1 and Bare Zn of Comparative Example 3 using ammonium vanadate positive electrode. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and examples. The raw materials described in the present invention are all obtained through commercial channels. The preparation methods described in the present invention are all conventional preparation methods in the art unless otherwise specified. The following examples are intended to illustrate the present invention rather than to further limit the present invention.

[0028] Example 1

[0029] A method for preparing a zinc metal negative electrode having a (002) orientation by electrodeposition on a copper substrate comprises the following steps:

[0030] Step 1: Weigh 51.3625 g of zinc chloride ZnCl2, 7.5684 g of aluminum chloride AlCl3·6H2O, 3.65489 g of manganese chloride MnCl2·4H2O and 150 ml of formamide solution, add them into 150 ml of deionized water, stir and dissolve at room temperature to obtain an electroplating solution;

[0031] Step 2: Cut the initial copper foil and zinc foil to obtain copper sheets (8cm*8cm) and zinc sheets (8cm*8cm) of fixed size that can be loaded into the electrolytic cell, then perform surface treatment on the copper sheets and zinc sheets, use alcohol to remove possible dust, oil, oxides, etc., and place them in the plating tank after rinsing with deionized water;

[0032] Step 3: Select a constant current of 20mAcm -2 , the electroplating time is 30min, and the electrodeposition process is carried out;

[0033] Step 4: After the electrodeposition is completed, the positive electrode deposition side is taken out, rinsed with deionized water, placed in a drying oven for drying, and then taken out to obtain Zn(002)-1 with a deposition surface capacity of 10 mAh cm -2 ;

[0034] Step 5: Use a tablet press to punch the electroplated layer together with the copper substrate into a disc with a diameter of 15 mm for use as the negative electrode of the zinc ion battery, wherein the deposited layer is used as the reaction surface of the battery.

[0035] Example 2

[0036] A method for preparing a zinc metal negative electrode having a (002) orientation by electrodeposition on a copper substrate comprises the following steps:

[0037] Step 1: Weigh 51.3625 g of zinc chloride ZnCl2, 7.5684 g of aluminum chloride AlCl3·6H2O, 3.65489 g of manganese chloride MnCl2·4H2O and 150 ml of formamide solution, add them into 150 ml of deionized water, stir and dissolve at room temperature to obtain an electroplating solution;

[0038] Step 2: Cut the initial copper foil and zinc foil to obtain copper sheets (8cm*8cm) and zinc sheets (8cm*8cm) of fixed size that can be loaded into the electrolytic cell, then perform surface treatment on the copper sheets and zinc sheets, use alcohol to remove possible dust, oil, oxides, etc., and place them in the plating tank after rinsing with deionized water;

[0039] Step 3: Select constant current 10mAcm -2 , the electroplating time is 60min, and the electrodeposition process is carried out;

[0040] Step 4: After the electrodeposition is completed, the positive electrode deposition side is taken out, rinsed with deionized water, placed in a drying oven for drying, and then taken out to obtain Zn(002)-2 with a deposition surface capacity of 10 mAh cm -2 ;

[0041] Step 5: Use a tablet press to punch the electroplated layer together with the copper substrate into a disc with a diameter of 15 mm for use as the negative electrode of the zinc ion battery, wherein the deposited layer is used as the reaction surface of the battery.

[0042] Example 3

[0043] A method for preparing a zinc metal negative electrode having a (002) orientation by electrodeposition on a copper substrate comprises the following steps:

[0044] Step 1: Weigh 51.3625 g of zinc chloride ZnCl2, 7.5684 g of aluminum chloride AlCl3·6H2O, 3.65489 g of manganese chloride MnCl2·4H2O and 150 ml of formamide solution, add them into 150 ml of deionized water, stir and dissolve at room temperature to obtain an electroplating solution;

[0045] Step 2: Cut the initial copper foil and zinc foil to obtain copper sheets (8cm*8cm) and zinc sheets (8cm*8cm) of fixed size that can be loaded into the electrolytic cell, then perform surface treatment on the copper sheets and zinc sheets, use alcohol to remove possible dust, oil, oxides, etc., and place them in the plating tank after rinsing with deionized water;

[0046] Step 3: Select constant current 15mAcm -2 , the electroplating time is 45min, and the electrodeposition process is carried out;

[0047] Step 4: After the electrodeposition is completed, the positive electrode deposition side is taken out, rinsed with deionized water, placed in a drying oven for drying, and then taken out to obtain Zn(002)-3 with a deposition surface capacity of 10 mAh cm -2 ;

[0048] Step 5: Use a tablet press to punch the electroplated layer together with the copper substrate into a disc with a diameter of 15 mm for use as the negative electrode of the zinc ion battery, wherein the deposited layer is used as the reaction surface of the battery.

[0049] Example 4

[0050] A method for preparing a zinc metal negative electrode having a (002) orientation by electrodeposition on a copper substrate comprises the following steps:

[0051] Step 1: Weigh 51.3625 g of zinc chloride ZnCl2, 7.5684 g of aluminum chloride AlCl3·6H2O, 2.5698 g of manganese chloride MnCl2·4H2O and 150 ml of formamide solution, add them into 150 ml of deionized water, stir and dissolve at room temperature to obtain an electroplating solution;

[0052] Step 2: Cut the initial copper foil and zinc foil to obtain copper sheets (8cm*8cm) and zinc sheets (8cm*8cm) of fixed size that can be loaded into the electrolytic cell, then perform surface treatment on the copper sheets and zinc sheets, use alcohol to remove possible dust, oil, oxides, etc., and place them in the plating tank after rinsing with deionized water;

[0053] Step 3: Select a constant current of 20mAcm -2 , the electroplating time is 30min, and the electrodeposition process is carried out;

[0054] Step 4: After the electrodeposition is completed, the positive electrode deposition side is taken out, rinsed with deionized water, placed in a drying oven for drying, and then taken out to obtain Zn(002)-4 with a deposition surface capacity of 10 mAh cm -2 ;

[0055] Step 5: Use a tablet press to punch the electroplated layer together with the copper substrate into a disc with a diameter of 15 mm for use as the negative electrode of the zinc ion battery, wherein the deposited layer is used as the reaction surface of the battery.

[0056] Example 5

[0057] A method for preparing a zinc metal negative electrode having a (002) orientation by electrodeposition on a copper substrate comprises the following steps:

[0058] Step 1: Weigh 51.3625 g of zinc chloride ZnCl2, 7.5684 g of aluminum chloride AlCl3·6H2O, 4.2345 g of manganese chloride MnCl2·4H2O and 150 ml of formamide solution, add them into 150 ml of deionized water, stir and dissolve at room temperature to obtain an electroplating solution;

[0059] Step 2: Cut the initial copper foil and zinc foil to obtain copper sheets (8cm*8cm) and zinc sheets (8cm*8cm) of fixed size that can be loaded into the electrolytic cell, then perform surface treatment on the copper sheets and zinc sheets, use alcohol to remove possible dust, oil, oxides, etc., and place them in the plating tank after rinsing with deionized water;

[0060] Step 3: Select a constant current of 20mAcm-2 , the electroplating time is 30min, and the electrodeposition process is carried out;

[0061] Step 4: After the electrodeposition is completed, the positive electrode deposition side is taken out, rinsed with deionized water, placed in a drying oven for drying, and then taken out to obtain Zn(002)-5 with a deposition surface capacity of 10 mAh cm -2 ;

[0062] Step 5: Use a tablet press to punch the electroplated layer together with the copper substrate into a disc with a diameter of 15 mm for use as the negative electrode of the zinc ion battery, wherein the deposited layer is used as the reaction surface of the battery.

[0063] Example 6

[0064] A method for preparing a zinc metal negative electrode by electrodeposition on a copper substrate comprises the following steps:

[0065] Step 1: Weigh 51.3625 g of zinc chloride ZnCl2, 7.5684 g of aluminum chloride AlCl3·6H2O, 5.6421 g of manganese chloride MnCl2·4H2O and 150 ml of formamide solution, add them into 150 ml of deionized water, stir and dissolve at room temperature to obtain an electroplating solution;

[0066] Step 2: Cut the initial copper foil and zinc foil to obtain copper sheets (8cm*8cm) and zinc sheets (8cm*8cm) of fixed size that can be loaded into the electrolytic cell, then perform surface treatment on the copper sheets and zinc sheets, use alcohol to remove possible dust, oil, oxides, etc., and place them in the plating tank after rinsing with deionized water;

[0067] Step 3: Select a constant current of 20mAcm -2 , the electroplating time is 30min, and the electrodeposition process is carried out;

[0068] Step 4: After the electrodeposition is completed, the positive electrode deposition side is taken out, rinsed with deionized water, placed in a drying oven for drying, and then taken out to obtain Zn(002)-6 with a deposition surface capacity of 10 mAh cm -2 ;

[0069] Step 5: Use a tablet press to punch the electroplated layer together with the copper substrate into a disc with a diameter of 15 mm for use as the negative electrode of the zinc ion battery, wherein the deposited layer is used as the reaction surface of the battery.

[0070] Comparative Example 1

[0071] A method for preparing a zinc metal negative electrode by electrodeposition on a copper substrate comprises the following steps:

[0072] Step 1: Weigh 51.3625 g of zinc chloride ZnCl2, 7.5684 g of aluminum chloride AlCl3·6H2O and 150 ml of formamide solution, add them into 150 ml of deionized water, stir and dissolve at room temperature to obtain an electroplating solution;

[0073] Step 2: Cut the initial copper foil and zinc foil to obtain copper and zinc sheets of fixed size that can be loaded into the electrolytic cell, then perform surface treatment on the copper and zinc sheets, use alcohol to remove possible dust, oil, grease, oxides, etc., and place them in the plating tank after rinsing with deionized water;

[0074] Step 3: Select a constant current of 20mAcm -2 , the electroplating time is 30min, and the electrodeposition process is carried out;

[0075] Step 4: After the electrodeposition is completed, take out the positive electrode deposition side, rinse it with deionized water, put it into a drying oven for drying, and then take it out to obtain Zn-Al with a deposition surface capacity of 10 mAh cm -2 ;

[0076] Step 5: Use a tablet press to punch the electroplated layer together with the copper substrate into a disc with a diameter of 15 mm for use as the negative electrode of the zinc ion battery, wherein the deposited layer is used as the reaction surface of the battery.

[0077] Comparative Example 2

[0078] A method for preparing a zinc metal negative electrode by electrodeposition on a copper substrate comprises the following steps:

[0079] Step 1: Weigh 51.3625 g of zinc chloride ZnCl2, 3.65489 g of manganese chloride MnCl2·4H2O and 150 ml of formamide solution, add them into 150 ml of deionized water, stir and dissolve at room temperature to obtain an electroplating solution;

[0080] Step 2: Cut the initial copper foil and zinc foil to obtain copper and zinc sheets of fixed size that can be loaded into the electrolytic cell, then perform surface treatment on the copper and zinc sheets, use alcohol to remove possible dust, oil, grease, oxides, etc., and place them in the plating tank after rinsing with deionized water;

[0081] Step 3: Select a constant current of 20mAcm -2 , the electroplating time is 30min, and the electrodeposition process is carried out;

[0082] Step 4: After the electrodeposition is completed, the positive electrode deposition side is taken out, rinsed with deionized water, placed in a drying oven for drying, and then taken out to obtain Zn-Mn with a deposition surface capacity of 10 mAh cm -2 ;

[0083] Step 5: Use a tablet press to punch the electroplated layer together with the copper substrate into a disc with a diameter of 15 mm for use as the negative electrode of the zinc ion battery, wherein the deposited layer is used as the reaction surface of the battery.

[0084] Comparative Example 3

[0085] The common zinc sheet (Bare Zn) with a thickness of 10 μm was purchased from Weifang Purun Co., Ltd. The zinc content was more than 99.9%, and the surface capacity of the zinc sheet was about 5 mAh cm -2 The pellets were punched into 15 mm diameter pellets using a pellet press and used as negative electrodes for zinc ion batteries.

[0086] like Figure 1 As shown, the XRD spectra of Example 1 (Zn(002)-1), Comparative Example 1, (Zn-Al) and Comparative Example 3 (Bare Zn) are shown. Comparative Example 1 (Zn-Al) deposits zinc metal, and relative to ordinary commercially available zinc sheets (Bare Zn), the (002) orientation of the deposited zinc metal is improved, while in Example 1 (Zn(002)-1), the orientation of the zinc metal (002) is significantly and rapidly enhanced. After calculation, the relative texture coefficient of the (002) plane reaches 99%, which is very close to that of zinc single crystal.

[0087] like Figure 2 As shown, the XRD spectra of Example 1 (Zn(002)-1), Comparative Example 2 (Zn-Mn) and Comparative Example 3 (Bare Zn) are shown. Comparative Example 2 (Zn-Mn) deposits zinc metal, and relative to ordinary commercially available zinc flakes (Bare Zn), the deposited zinc metal (002) orientation is improved, while in Example 1 (Zn(002)-1), the orientation of zinc metal (002) is significantly and rapidly enhanced. After calculation, the relative texture coefficient of the (002) plane reaches 99%, which is very close to zinc single crystal.

[0088] like Figure 3 As shown, the XRD spectra of Example 1 (Zn (002-1), Example 2 (Zn (002-2)) and Example 3 (Zn (002)-3) can all obtain zinc metal with high (002) orientation.

[0089] like Figure 4 As shown, (a) is the XRD spectra of Example 1 (Zn (002-1), Example 4 (Zn (002-4), Example 5 (Zn (002)-5) and Example 6 (Zn (002)-6), all of which can obtain zinc metal with high (002) orientation.

[0090] like Figure 5As shown in the figure, the chemical composition of the zinc metal (Zn(002)-1) obtained in Example 1, Example 1 (Zn-Al) and Example 2 (Zn-Mn) measured by electron probe (EPMA) is shown. Analysis shows that with the addition of aluminum and manganese cations, the amount of zinc ion deposition on the copper foil substrate is significantly enhanced (the zinc content in Zn(002)-1 is 77.72%, the zinc content in Zn|Al is 58.01%, and the zinc content in Zn|Mn is 54.75%). The simultaneous addition of the two cations into the plating solution has a significant promoting effect on the zinc deposition process.

[0091] like Figure 6 The figure shows the cycle performance of zinc symmetric batteries of Example 1 (Zn(002)-1), Comparative Example 1 (Zn-Al) and Comparative Example 2 (Zn-Mn). It can be seen that the symmetric batteries assembled by Comparative Example 1 (Zn-Al) and Comparative Example 2 (Zn-Mn) experienced severe voltage fluctuations after running for 200 and 400 hours, respectively, indicating that dendrites were formed on the electrode. However, since Example 1 (Zn(002)-1) is close to the orientation of a single crystal, zinc can be uniformly deposited on the electrode surface, and the symmetric battery can operate stably for more than 1400 hours.

[0092] like Figure 7 The following are the coulombic efficiency diagrams of zinc-copper batteries of Example 1 (Zn(002)-1) and Comparative Example 3 (Bare Zn). Coulombic efficiency (CE) is one of the important indicators for evaluating the reversibility of zinc negative electrodes. In Example 1, at a current density of 5 mA cm –2 Under the condition of (negative electrode utilization rate reaches 10%), the coulombic efficiency can still maintain 99.9% after more than 6000 cycles, surpassing the zinc negative electrode in most literatures. In contrast, the coulombic efficiency of comparative example 3 (Bare Zn) fluctuated after 200 cycles and then quickly dropped to 20% until the battery failed, which can be attributed to its serious side reactions and zinc dendrite growth.

[0093] like Figure 8As shown, the cycle performance diagram of zinc symmetric batteries of Example 1 (Zn (002) -1) and Comparative Example 3 (Bare Zn) is shown. The symmetric battery verifies the advantages of the zinc negative electrode of the present invention in reversible zinc migration: it has a lower nucleation barrier and faster charge transfer. After cycling for more than 120 hours, the voltage curve of the comparative example showed obvious fluctuations, which is usually a typical feature of a violent hydrogen evolution reaction. Its voltage curve is similar to a square wave, which indicates that a short circuit has occurred inside the battery, most likely due to dendrite growth. In contrast, the symmetric battery with Zn (002) -1 as the electrode has accumulated deposition / stripping for more than 1400 hours during a long cycle, and its voltage curve remains stable without obvious polarization. In addition, when evaluating the stability of zinc batteries, an indispensable parameter to consider is to achieve a high depth of discharge (DOD). This is because the process of high-capacity zinc electrodeposition provides a large number of regions and sites where the zinc negative electrode can produce side reactions. Therefore, evaluating the DOD in zinc batteries becomes a key aspect of understanding their long-term stability and performance. This change will produce reliable and meaningful results and promote the development of high-capacity zinc batteries. In terms of cycle performance at 10% depth of discharge, even under such harsh test conditions, Zn(002)-1 can still cycle for more than 1400 hours, which is almost 10 times the cycle life of Bare Zn.

[0094] like Fig. 9 As shown, a is the XRD spectrum of the negative electrode stripping side of the symmetrical battery of Example 1 (Zn(002)-1) after 50 cycles (50Cycle), 200 cycles (200Cycle), and 500 cycles (500Cycle); b is the SEM image of the negative electrode side after 500 cycles; c is the SEM image of the negative electrode side after 100 cycles. From the XRD spectrum analysis, it can be seen that even for a symmetrical battery matched with a 2M ZnSO4 electrolyte, the Zn(002)-1 negative electrode can still maintain the (002) orientation well. According to Figures b and c, it can be seen that the planar structure can be maintained after the cycle, reflecting the stability of the structure. The Zn(002)-1 negative electrode maintains a flat and dense morphology throughout the deposition / stripping process, which indicates that its nucleation and growth process are more stable. The initial nucleation layer of the Zn(002)-1 negative electrode forms a horizontally oriented Zn(002) deposition during the nucleation and growth stages, thus providing a flat deposition site for the subsequently deposited metal. It avoids the disordered growth of dendrites, thus cutting off one of the three cycles of the vicious cycle, and also inhibits the generation of irreversible byproducts and parasitic side reactions.

[0095] like Fig.10 The full cell performance diagram of Example 1 (Zn(002)-1) and Comparative Example 3 (Bare Zn) is shown in Figure 2. -1At a low current density of , the full cell matching the deposited Zn(002)-1 can still be stably cycled for nearly 2000 cycles. However, when bare zinc is used, the full cell is cycled only 80 times and its capacity retention rate drops below 80%. The excellent long-cycle stability can be attributed to the stable interface on the alloy negative electrode side. Even after 2000 cycles in the full cell, Zn(002)-1 still shows a flat and dense surface morphology. In contrast, bare zinc exhibits uncontrollable zinc deposition / stripping, increasing the interfacial impedance, leading to battery capacity decay.

Claims

1. A method for preparing a zinc negative electrode, characterized in that: Zinc salt, aluminum salt, manganese salt, complexing agent and water are mixed to obtain an electroplating solution, wherein the complexing agent is formamide; the electroplating solution is electro-deposited on the surface of the substrate to obtain a zinc metal coating, which is the zinc negative electrode.

2. The preparation method according to claim 1, characterized in that: The zinc salt is ZnSO4, ZnCl2 or Zn(CF3SO3)2, the aluminum salt is Al2(SO4)3 or AlCl3, and the manganese salt is MnSO4 or MnCl2; the molar ratio of the zinc salt, the aluminum salt and the manganese salt is 40-20:2-3:1; the concentration of the zinc salt in the electroplating solution is 0.5-3 mol / L; the volume ratio of the complexing agent to water in the electroplating solution is 0.5-1:

1.

3. The preparation method according to claim 1, characterized in that: The substrate is copper foil, zinc foil, titanium foil or carbon-based material.

4. The preparation method according to claim 1, characterized in that: The electroplating process is as follows: using the zinc sheet as the negative electrode and the substrate as the positive electrode, constant current electroplating is performed in an electrolytic cell to deposit a zinc metal coating on the substrate.

5. The preparation method according to claim 1, characterized in that: The current density of the electrodeposition is 5 to 30 mA / cm 2 .

6. The zinc negative electrode prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The (002) crystal plane of the zinc metal coating is the main orientation, and the relative texture coefficient of the (002) plane is not less than 99%.

7. The use of the zinc negative electrode according to claim 6, characterized in that: It is used to prepare aqueous zinc metal batteries.

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