Preparation method of Cu-HKUST-1 coating for inhibiting growth of zinc dendrites

Abstract

The invention relates to the technical field of aqueous zinc ion batteries, in particular to a preparation method of a Cu-HKUST-1 coating for inhibiting zinc dendritic crystal growth, which comprises the following steps: coating a Cu-MOF (Cu-HKUST-1) coating on the surface of a zinc anode, so that H2O molecules in a solution are not easy to directly contact with Zn, a series of side reactions such as hydrogen evolution and by-product Zn4 (OH) 6SO4. XH2O caused by H2O erosion are greatly reduced, and the service life of the Cu-HKUST-1 coating is prolonged. And on the other hand, the uniformly distributed Cu-HKUST-1 provides more sites for Zn < 2 + > nucleation, so that Zn < 2 + > is uniformly deposited on the surface of the negative electrode in the deposition process, the'point effect 'caused by non-uniform deposition of Zn < 2 + > is effectively reduced, a cavity in the Cu-HKUST-1 structure can capture hydrogen generated in the battery charging process, battery expansion caused by hydrogen is reduced, and the service life of the battery is prolonged. The symmetrical cell, the half cell and the full cell prepared by the invention have longer service life.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical energy, and particularly relates to a preparation method of a Cu-HKUST-1 coating for inhibiting zinc dendrite growth. BACKGROUND

[0002] Chargable zinc ion batteries have great potential in renewable energy storage due to their abundant resources, good safety, environmental friendliness, high theoretical capacity (820 Ah kg-1), and low redox potential (-0.762 V (vs. SHE)). However, the poor cycle life of the batteries hinders their commercial development due to the zinc dendrite growth and a series of side reactions such as hydrogen evolution during the battery cycling. Therefore, reducing the occurrence of dendrites and side reactions is a crucial factor for the large-scale application of zinc ion batteries.

[0003] In view of these side reactions, there are currently many improvement schemes, such as plating Sn on the Zn surface to form an alloy, or forming an alloy with Cu, Bi, and Al to provide more nucleation sites while reducing dendrite growth, which greatly prolongs the service life of the battery. Constructing an artificial solid electrolyte interface layer (ASEI) on Zn is also an important way to regulate Zn2+ electroplating chemistry, such as constructing an inorganic salt SEI film NaZnPO4, CaSO4·2H2O, NaTi2(PO4)3, TiO2, BaTiO3, and an organic SEI layer polyacrylonitrile, ZIF-8, covalent organic framework on the surface of the Zn electrode to inhibit the growth of Zn dendrites and achieve the purpose of prolonging the service life of the battery. Or use separator modification, such as fixing copper nanowires on the glass fiber separator by suction filtration, which is beneficial to the uniform distribution of Zn2+ flux. At the same time, the nanoscale size makes the Cu nanowires have a large specific surface area, which is beneficial to reducing the local current density and homogenizing the Zn2+ concentration field, thereby inhibiting the growth of zinc dendrites. As a convenient and quick method, electrolyte additives are also widely studied at present, such as inorganic salt additives NH4F, LiCl, Sc3+, and PbO, which can shield the surface of the Zn sheet by adsorbing cations, thereby inhibiting the growth of dendrites. Organic electrolyte additives, such as 6-bromo-1H-benzimidazole, histidine, trimethyl phosphate, and dodecyltrimethylammonium chloride, can reduce the number of water molecules in the solvation sheath by adjusting the solvation structure of Zn2+, thereby inhibiting side products and reducing hydrogen evolution to prolong the service life of the battery. Some of these additives are heavy metal salts, which can have some impact on the environment, and some organic additives can have some harm to the human body.

[0004] To improve the stability of zinc metal anode, researchers have developed a variety of strategies to synergistically inhibit dendrite growth and side reactions. Alloying treatment (such as plating Sn, Cu, Bi or Al on the surface of Zn) can provide abundant zincophilic sites, reduce the nucleation energy barrier, promote uniform Zn2+ deposition, thereby reducing dendrites and prolonging the cycle life. Another key approach is to construct an artificial solid electrolyte interface (ASEI), which can effectively isolate the electrolyte from the zinc anode by introducing inorganic layers (such as NaZnPO4, TiO2) or organic layers (such as polyacrylonitrile, polyvinylpyrrolidone). Porous structure can regulate ion transport and inhibit side reactions. Membrane modification (such as copper nanowire modified glass fiber) can optimize the distribution of Zn2+ flux, reduce local current density, and inhibit the tip effect. In addition, electrolyte additives (such as inorganic salts LiCl, NH4F or organic molecules histidine) can reduce water molecule activity by adsorbing electrostatic shielding and adjusting solvation structure, thereby inhibiting dendrites and hydrogen evolution. However, some heavy metal salts or organic additives pose environmental and health risks, and the performance and safety need to be balanced.

[0005] Interface modification is an effective method to inhibit side reactions and reduce dendrite growth, which can effectively isolate direct contact with electrolyte and effectively reduce the occurrence of side reactions, but most of the current interface reactions are complex and cumbersome, so there is an urgent need for a method for preparing Cu-HKUST-1 coating for inhibiting zinc dendrite growth to solve the above problems. SUMMARY

[0006] In order to overcome the above technical problems, the purpose of the present application is to provide a method for preparing Cu-HKUST-1 coating for inhibiting zinc dendrite growth to solve the problem that most of the current interface reactions are complex and cumbersome in the background art.

[0007] To achieve the above purpose, the present application provides the following technical scheme: a method for preparing Cu-HKUST-1 coating for inhibiting zinc dendrite growth, comprising the following steps: S1: dispersing trimesic acid and a copper salt in a mixed solvent of DMF (dimethylformamide) and ethanol, stirring at room temperature for 6h, then incubating the obtained solution at a certain temperature for a certain time; taking out and cooling to room temperature, then centrifuging, washing and drying to obtain a light blue sample Cu-HKUST-1 powder; S2: mixing the obtained Cu-HKUST-1 powder with polyvinylidene fluoride (PVDF) in a certain proportion with N-methyl pyrrolidone (NMP) as the solvent, grinding in a mortar, and coating on the surface of Zn foil with a certain thickness, drying at 40-80℃ for 6-24h to obtain Cu-HKUST-1@Zn anode.

[0008] Preferably, the copper salt used in S1 is any one of copper chloride, copper acetate, copper nitrate and copper sulfate.

[0009] Preferably, the ratio of the mixed solvent in S1 is DMF: ethanol (20-30):(10-20).

[0010] Preferably, the temperature in S1 is 90-120℃ and the holding time is 24-48h.

[0011] Preferably, the coating thickness in S2 is 5-20μm.

[0012] Preferably, the Cu-HKUST-1 coating for inhibiting zinc dendrite growth in S2 is used as the positive electrode sheet and the negative electrode sheet of the symmetric battery.

[0013] Preferably, the Cu-HKUST-1 coating for inhibiting zinc dendrite growth in S2 is used as the negative electrode sheet of the half battery.

[0014] Preferably, the Cu-HKUST-1 coating for inhibiting zinc dendrite growth in S2 is used as the negative electrode sheet of the full battery.

[0015] Compared with the prior art, the present application has the following beneficial effects: 1. The raw material cost used in the preparation method of the Cu-HKUST-1 coating for inhibiting zinc dendrite growth is low, and the hydrothermal and coating methods are simple to operate.

[0016] 2. In the preparation method of the Cu-HKUST-1 coating for inhibiting zinc dendrite growth, the Cu-HKUST-1 negative electrode provides abundant zinc-philic sites by introducing the poorly soluble porous Cu-HKUST-1 into the surface of the zinc electrode, which allows uniform deposition of Zn2+ and reduces the generation of zinc dendrites, so that the assembled symmetric battery can have a cycle life of 2800h.

[0017] 3. In the preparation method of the Cu-HKUST-1 coating for inhibiting zinc dendrite growth, the Cu-HKUST-1 negative electrode reduces the direct contact between the electrolyte and the zinc sheet, effectively reduces the cavities in the Cu-HKUST-1 structure for hydrogen evolution, can capture the hydrogen gas generated at the negative electrode during the charging process, reduces the battery expansion, and at the same time reduces the corrosion and the formation of Zn4(OH)6SO4·xH2O by-products, so that the full battery assembled with Al-MnO2 can be stably cycled for more than 1800 cycles. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 X-ray diffraction pattern of Cu-HKUST-1 powder and coated Cu-HKUST-1@Zn prepared in Example 1 of the present application; Figure 2 Scanning electron microscope image of Cu-HKUST-1@Zn prepared in Example 1 of the present application; Figure 3 The charge-discharge performance curve of the symmetrical battery when Cu-HKUST-1@Zn prepared for Example 1 of the present application is used as the negative electrode of the aqueous zinc ion battery at a current density of 1 mA / cm2and a surface capacity of 0.5 mAh / cm2; Figure 4 The charge-discharge performance curve of the symmetrical battery when Cu-HKUST-1@Zn prepared for Example 1 of the present application is used as the negative electrode of the aqueous zinc ion battery at a current density of 5 mA / cm2and a surface capacity of 1 mAh / cm2; Figure 5 The coulombic efficiency graph of the half-cell assembled with Cu-HKUST-1@Zn prepared for Example 1 of the present application as the negative electrode material and Cu foil as the positive electrode material at a current density of 2 mA / cm2and a surface capacity of 1 mAh / cm2; Figure 6 The charge-discharge performance curve of the full battery assembled with Cu-HKUST-1@Zn prepared for Example 1 as the negative electrode material and Al-MnO2positive electrode at a current density of 1 A / g. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0020] Please refer to Figures 1-6 The present application provides an embodiment: a preparation method of Cu-HKUST-1 coating for inhibiting zinc dendrite growth, comprising the following steps: S1: dispersing uniform triphenylmethane acid and a copper salt in a mixed solvent of DMF (dimethylformamide) and ethanol, stirring at room temperature for 6 h, then incubating the obtained solution at a certain temperature for a certain time, taking out, cooling to room temperature, then centrifuging, washing, and drying to obtain a light blue sample Cu-HKUST-1 powder; S2: mixing the obtained Cu-HKUST-1 powder with polyvinylidene fluoride (PVDF) in a certain proportion with N-methyl pyrrolidone (NMP) as the solvent, grinding in a mortar, then coating on the surface of Zn foil at a certain thickness, and drying at 40-80℃ for 6-24 h to obtain Cu-HKUST-1@Zn negative electrode.

[0021] Further, the copper salt used in S1 is any one of copper chloride, copper acetate, copper nitrate and copper sulfate.

[0022] Further, the ratio of the mixed solvent in S1 is DMF: ethanol (20-30):(10-20).

[0023] Further, the temperature in S1 is 90-120℃ and the holding time is 24-48h.

[0024] Further, the coating thickness in S2 is 5-20μm.

[0025] Further, the Cu-HKUST-1 coating for inhibiting zinc dendrite growth in S2 is used as the positive electrode sheet and the negative electrode sheet of a symmetric battery.

[0026] Further, the Cu-HKUST-1 coating for inhibiting zinc dendrite growth in S2 is used as the negative electrode sheet of a half battery.

[0027] Further, the Cu-HKUST-1 coating for inhibiting zinc dendrite growth in S2 is used as the negative electrode sheet of a full battery. Embodiment

[0028] The Cu-HKUST-1 coating for inhibiting zinc dendrite growth provided by the application has the following preparation process: (1) A mixture of molar ratio 7:24 of trimesic acid and copper nitrate trihydrate is dissolved in a mixed solvent of DMF: ethanol in a volume ratio of 25:13, stirred at room temperature for 6h, then put into a reaction kettle and kept at 100℃ for 36h, and then centrifuged, washed and dried to obtain Cu-HKUST-1 powder.

[0029] (2) The obtained Cu-HKUST-1 powder is mixed with polyvinylidene fluoride (PVDF) in a mass ratio of 9:1 with N-methyl pyrrolidone (NMP) as the solvent, and then ground in a mortar to obtain a Cu-HKUST-1@Zn negative electrode with a thickness of 10μm coated on the surface of a Zn foil and dried at 60℃ for 10h.

[0030] The Cu-HKUST-1@Zn prepared in this example is used as the positive and negative electrode sheets of a button cell, a glass fiber separator (GF / A) is used, 2mol / L ZnSO4 is used as the electrolyte, and a button cell is assembled under normal environment, which is recorded as Cu-HKUST-1@Zn / / Cu-HKUST-1@Zn symmetric battery.

[0031] The Cu-HKUST-1@Zn prepared in this example is used as the negative electrode sheet of a button cell, a copper foil is used as the positive electrode sheet, a glass fiber separator (GF / A) is used, 2mol / L ZnSO4 is used as the electrolyte, and a button cell is assembled under normal environment, which is recorded as Cu-HKUST-1@Zn / / Cu half battery.

[0032] Cu-HKUST-1@Zn prepared in this example was used as the negative electrode of the button cell, Al-MnO2 was used as the positive electrode, glass fiber separator (GF / A) was used, 2 mol / L ZnSO4 and 0.2 mol / L MnSO4 were used as the electrolyte, and a button cell was assembled under normal environment, which was recorded as Cu-HKUST-1@Zn / / Al-MnO2 full cell.

[0033] Comparative Example 1 Zinc foil was used as the positive and negative electrode of the button cell, glass fiber separator (GF / A) was used, 2 mol / L ZnSO4 was used as the electrolyte, and a button cell was assembled under normal environment, which was recorded as Zn / / Zn symmetric cell.

[0034] Zinc foil was used as the negative electrode of the button cell, copper foil was used as the positive electrode, glass fiber separator (GF / A) was used, 2 mol / L ZnSO4 was used as the electrolyte, and a button cell was assembled under normal environment, which was recorded as Zn / / Cu half cell.

[0035] Zinc foil was used as the negative electrode of the button cell, Al-MnO2 was used as the positive electrode, glass fiber separator (GF / A) was used, 2 mol / L ZnSO4 and 0.2 mol / L MnSO4 were used as the electrolyte, and a button cell was assembled under normal environment, which was recorded as Zn / / Al-MnO2 full cell.

[0036] The prepared Cu-HKUST-1 coating was subjected to X-ray diffraction analysis, scanning electron microscope analysis, symmetric cell cycle life test, half cell coulomb efficiency test, full cell life and retention rate test, and the results are shown in Figures 1-6 .

[0037] Figure 1 The X-ray diffraction of Cu-HKUST-1 and Cu-HKUST-1@Zn samples prepared in Example 1 is shown. From the figure, it can be seen that the diffraction peaks of Cu-HKUST-1 can be well observed, indicating that the sample of Cu-HKUST-1 is successfully prepared. Figure 2 The scanning electron microscope image of the sample is shown. In the figure, the octahedral structure of Cu-HKUST-1 can be seen distributed on the surface of the zinc foil.

[0038] Figure 3 The symmetric cell constant current charge-discharge test graph of Example 1 and Comparative Example 1 under small current and large current density is shown. Figure 4 The symmetric cell constant current charge-discharge test graph of Example 1 and Comparative Example 1 under small current and large current density is shown. Figure 3It can be seen that the symmetric battery at a current density of 1 mA / cm2and a surface capacity of 0.5 mAh / cm2, the overpotential of Cu-HKUST-1@Zn is significantly smaller than that of pure Zn electrode symmetric battery, which indicates that the existence of Cu-HKUST-1 coating reduces the nucleation energy barrier of Zn, and also reduces the polarization, promotes the relatively uniform zinc deposition / dissolution process, so that the 48h cycle life of the symmetric battery relative to the pure zinc symmetric battery, the cycle life of the symmetric battery with Cu-HKUST-1 coating is 2800h. Figure 4 This rule also applies to a large current density of 5 mA / cm2and a surface capacity of 1 mAh / cm2, and has a longer cycle life than pure Zn electrode, which indicates that the presence of Cu-HKUST-1 can effectively reduce the occurrence of side reactions and prolong the battery life.

[0039] Figure 5 As the negative electrode of the button cell in Example 1 and Comparative Example 1 respectively, the Cu foil is the positive electrode of the button cell. The half-cell assembled is tested at a current density of 2 mA / cm2. From the figure, it can be seen that the pure Zn electrode has a large fluctuation in coulomb efficiency after 180 cycles due to a series of side reactions, resulting in battery damage. While the half-cell of Cu-HKUST-1@Zn prepared in Example 1 still maintains a coulomb efficiency of 99.8% after 800 cycles due to the excellent side reaction inhibition ability of Cu-HKUST-1, which is significantly better than Comparative Example 1.

[0040] Figure 6 As the negative electrode of the button cell in Example 1 and Comparative Example 1 respectively, the Al-MnO2 is the positive electrode of the button cell. The full battery assembled is tested at a current density of 1 A / g. From the figure, it can be seen that the initial capacity of Zn / / Al-MnO2 battery is the same as that of Cu-HKUST-1@Zn / / Al-MnO2, while the pure Zn electrode has a rapid capacity decay after 300 cycles due to various side reactions. The Cu-HKUST-1@Zn / / Al-MnO2 full battery of Example 1 has a higher capacity after 1800 cycles due to the reduction of side reactions, which is significantly better than Comparative Example 1.

[0041] It is apparent for those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and this application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and it is intended that all changes and modifications which come within the meaning and range of equivalency of the claims are reserving to the application. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

Claims

1. A method for preparing a Cu-HKUST-1 coating that inhibits zinc dendrite growth, characterized in that: Includes the following steps: S1: Tris(tribenzoic acid) and a copper salt were fully dispersed in a mixed solvent of DMF (dimethylformamide) and ethanol, stirred at room temperature for 6 hours, and then the resulting solution was kept at a certain temperature for a certain time. The solution was then removed, cooled to room temperature, centrifuged, washed, and dried to obtain a light blue sample Cu-HKUST-1 powder. S2: The obtained Cu-HKUST-1 powder is mixed with polyvinylidene fluoride (PVDF) in a certain proportion and ground thoroughly in a mortar with N-methylpyrrolidone (NMP) as solvent. The mixture is then coated onto the surface of Zn foil with a certain thickness and dried at 40-80℃ for 6-24h to obtain Cu-HKUST-1@Zn anode.

2. The method for preparing a Cu-HKUST-1 coating for inhibiting zinc dendrite growth according to claim 1, characterized in that: The copper salt used in S1 is any one of copper chloride, copper acetate, copper nitrate, and copper sulfate.

3. The method for preparing a Cu-HKUST-1 coating for inhibiting zinc dendrite growth according to claim 1, characterized in that: The ratio of the mixed solvent in S1 is DMF:ethanol (20-30):(10-20).

4. The method for preparing a Cu-HKUST-1 coating for inhibiting zinc dendrite growth according to claim 1, characterized in that: The temperature in S1 is 90-120℃ and the heat preservation time is 24-48h.

5. The method for preparing a Cu-HKUST-1 coating for inhibiting zinc dendrite growth according to claim 1, characterized in that: The coating thickness in S2 is 5-20 μm.

6. The method for preparing a Cu-HKUST-1 coating for inhibiting zinc dendrite growth according to claim 1, characterized in that: The Cu-HKUST-1 coating in S2, which inhibits the growth of zinc dendrites, serves as the positive and negative electrode plates of the symmetrical battery.

7. The method for preparing a Cu-HKUST-1 coating for inhibiting zinc dendrite growth according to claim 1, characterized in that: The Cu-HKUST-1 coating in S2, which inhibits the growth of zinc dendrites, serves as the negative electrode of the half-cell.

8. The method for preparing a Cu-HKUST-1 coating for inhibiting zinc dendrite growth according to claim 1, characterized in that: The Cu-HKUST-1 coating in S2, which inhibits the growth of zinc dendrites, serves as the negative electrode of the full cell.

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