Surface-modified composite zinc-based anode, method of preparation and battery

Abstract

The application discloses a surface-modified composite zinc-based negative electrode, a preparation method and a battery. The composite zinc-based negative electrode comprises a zinc matrix material, a nano inorganic metal / alloy modification layer and an organic polymer protective layer. The nano inorganic metal / alloy modification layer can improve the hydrogen evolution overpotential of the composite zinc-based negative electrode, inhibit the generation of hydrogen on the negative electrode surface and the occurrence of a side reaction. The organic polymer protective layer can enhance the zinc ion concentration and deposition uniformity at the electrode interface, and improve the dendrite problem caused by uneven zinc deposition-dissolution in the charging and discharging process. The modified composite zinc-based negative electrode applied to a water-based zinc-based battery can improve the cycle stability of the battery under the conditions of a large current and high utilization rate, and exhibits good rate performance and cycle life. The surface modification method of the composite zinc-based negative electrode provided by the application has the advantages of simple preparation process, low cost and suitability for large-scale production, and can promote the practicalization process of high specific energy and long cycle life water-based zinc-based batteries.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous zinc-based batteries, and particularly relates to a surface-modified composite zinc-based negative electrode, a preparation method and a battery. BACKGROUND

[0002] At present, lithium ion batteries dominate the electrochemical energy storage technology. However, commercial lithium ion batteries mainly use organic electrolyte systems, which have safety hazards such as high toxicity and flammability. In recent years, aqueous zinc-based batteries have received extensive attention due to their low cost, high energy density, good safety and environmental friendliness. However, improving the electrochemical performance of zinc negative electrodes is still a great challenge in practical applications.

[0003] The metal zinc negative electrode has problems such as low coulombic efficiency, insufficient utilization rate and zinc dendrite growth. Among them, the low coulombic efficiency and insufficient utilization rate are mainly related to the hydrogen evolution reaction and the generation of irreversible by-products of the zinc negative electrode, and the zinc dendrite is mainly caused by the inhomogeneous zinc deposition-dissolution process. In view of the above problems, domestic and foreign researchers have proposed many effective measures, including three-dimensional electrode or current collector structure design (CN113782702A, CN114171726A), electrolyte additives (CN114725536A, CN114843626A), surface protective layer construction (CN114725336A, CN114335447A), etc., which have solved the interface instability between the electrode and the electrolyte to some extent and improved the cycle life of the aqueous battery. However, the complex preparation process, high cost and limited cycle life under the conditions of large current and high surface capacity limit the practical application of many methods. Therefore, it is of great significance to develop a zinc negative electrode material with excellent cycle stability under the conditions of large current and high surface capacity, high specific capacity, simple preparation method and low cost to promote the practical application of aqueous zinc-based batteries. SUMMARY

[0004] The application proposes a surface-modified composite zinc-based negative electrode with a simple preparation process and suitable for large-scale production. The composite zinc-based negative electrode comprises a zinc matrix material, a nano-inorganic metal / alloy modification layer and an organic polymer protective layer. Through the synergistic effect of the nano-inorganic metal / alloy layer and the organic polymer protective layer, the problems of hydrogen evolution on the negative electrode surface, by-product accumulation and dendrite caused by inhomogeneous zinc deposition / detachment are simultaneously relieved, the cycle stability and discharge specific capacity of the aqueous zinc-based battery under the conditions of large current and high zinc utilization rate are improved, and the cycle life of the battery is prolonged.

[0005] The technical scheme adopted by the application is as follows:

[0006] A surface modified composite zinc-based negative electrode, the composite zinc-based negative electrode comprises a zinc-based matrix material, a nano inorganic metal / alloy modification layer and an organic polymer protective layer. The zinc-based matrix material can be at least one of metal zinc foil, zinc powder and zinc-based alloy.

[0007] Further, the nano inorganic metal / alloy modification layer is generated in situ on the zinc-based matrix material by chemical displacement reaction by placing the zinc-based matrix material in an aqueous reaction solution containing inorganic salt and buffer. The inorganic salt in the reaction solution is at least one of indium chloride, indium nitrate, indium sulfate, antimony chloride, antimony fluoride, tin chloride, tin fluoride, lead nitrate, lead acetate, and lead chloride. The buffer is at least one of thiourea, sodium citrate, citric acid, and boric acid.

[0008] Further, the concentration of inorganic salt in the reaction solution is 1 g / L -1 ~50 g / L -1 , the concentration of the buffer is 0.1-3 times the concentration of the inorganic salt, and the reaction time is 1 s-1 h, and the specific reaction time is adjusted according to the concentration of the reaction solution.

[0009] Further, the organic polymer protective layer is obtained by coating the polymer modification layer slurry on the substrate and drying, and the modification layer slurry is a mixture of the following components and solvents, and the mass fraction of each component in the slurry is: 1-95 wt% polymer powder, 0-20 wt% binder, 0-20 wt% functional electrolyte salt, 0-5 wt% functional filler, and the balance is solvent, and the sum of the proportions of each component is 100%.

[0010] Further, the solvent in the polymer modification layer slurry is at least one of deionized water, acetonitrile, and N-methyl pyrrolidone or a mixed solution thereof, the polymer powder is at least one of polyacrylamide, polypyrrole, polyvinylidene fluoride, and 2-methyl imidazole zinc salt, the binder is at least one of polyvinylidene fluoride, carboxymethyl cellulose, butadiene rubber, polyvinyl alcohol, and polyvinyl butyral, the functional electrolyte salt is at least one of LiTFSI, LiFSI, LiTfO, ZnSO4, Zn(TFSI)2, Zn(TfO)2, NaTFSI, NaFSI, and NaTfO, the functional filler in the polymer modification layer slurry is at least one of aluminum oxide, zinc oxide, magnesium oxide, titanium oxide, silicon oxide, and zirconium oxide, and the polymer modification layer slurry is prepared by mixing the components with the solvent, the mixing time is 0.1-12 hours, and the reaction temperature is 25-100°C.

[0011] Further, the thickness of the organic polymer protective layer is 2 nm-200 μm, and preferably the thickness of the organic polymer protective layer is 200 nm-2 μm.

[0012] A battery employs the above-mentioned surface-modified composite zinc-based negative electrode as a negative electrode, and the battery is a water-based zinc-based battery, a zinc-air battery, or a zinc-based flow battery.

[0013] According to an embodiment of the present application, the preparation process of the surface-modified composite zinc-based negative electrode comprises the following steps:

[0014] 1) The zinc-based substrate material is a zinc foil or a sheet-shaped zinc alloy material. The sheet-shaped zinc-based substrate material is scrubbed several times with ethanol to remove impurities on the surface of the zinc-based substrate material. Inorganic salts and buffers are weighed according to the concentration ratio, stirred and dissolved in a deionized water solvent. The cleaned sheet-shaped zinc-based substrate material is immersed in a reaction solution containing inorganic salts and buffers. After a uniform inorganic metal / alloy layer is generated in situ on the surface of the zinc-based substrate material, it is taken out, washed several times with deionized water, and dried in a vacuum oven at room temperature to 60°C.

[0015] 2) The polymer powder, binder, functional electrolyte salt, and functional filler are weighed according to the mass ratio, stirred in an oil bath at 25-100°C for 0.1-12 hours to dissolve them in the solvent. The polymer slurry is coated on the sheet-shaped substrate prepared in step 1), and dried in a vacuum oven at room temperature to 60°C to remove the solvent, thereby preparing a sheet-shaped organic / inorganic surface-modified composite zinc-based negative electrode.

[0016] According to another embodiment of the present application, the preparation process of the surface-modified composite zinc-based negative electrode comprises the following steps:

[0017] 1) The zinc-based substrate material is a zinc powder or a powder-shaped zinc alloy material. Inorganic salts and buffers are weighed according to the concentration ratio, stirred and dissolved in a deionized water solvent. The powder-shaped zinc-based substrate material is added to the water-based reaction solution under a protective atmosphere and slowly stirred to react. After a uniform inorganic metal / alloy layer is generated in situ on the surface of the zinc-based substrate material, it is filtered or suction-filtered to obtain the reacted powder-shaped substrate. The powder-shaped substrate modified with the inorganic metal / alloy layer is washed several times with deionized water and dried in a vacuum oven at room temperature to 60°C. The powder-shaped substrate modified with the inorganic metal / alloy layer, a binder, and a conductive agent are weighed according to a certain mass ratio, dissolved in a solvent, and coated on the surface of a stainless steel mesh or carbon paper to prepare a sheet-shaped substrate modified with the inorganic metal / alloy layer. Alternatively, the powder-shaped zinc-based substrate material, a binder, and a conductive agent are weighed according to a certain mass ratio, dissolved in a solvent, and coated on the surface of a stainless steel mesh or carbon paper to prepare a sheet-shaped zinc-based substrate material. Then, the sheet-shaped zinc-based substrate material is immersed in a reaction solution containing inorganic salts and buffers. After a certain period of reaction, the sheet-shaped zinc-based substrate material is washed several times with deionized water and dried in a vacuum oven at room temperature to 60°C to prepare a sheet-shaped substrate modified with the inorganic metal / alloy layer.

[0018] 2) According to the mass ratio, the polymer powder, the binder, the functional electrolyte salt and the functional filler are weighed and stirred in an oil bath at 25-100℃ for 0.1-12 hours to dissolve them in the solvent. The polymer slurry is coated on the substrate in the form of the electrode sheet prepared in step 1), and then dried in a vacuum oven at room temperature-60℃ to remove the solvent, thereby preparing the organic / inorganic surface modified composite zinc-based negative electrode.

[0019] Compared with the prior art, the modified composite zinc-based negative electrode has the following main advantages:

[0020] The inorganic metal / alloy modification layer on the surface of the composite zinc-based negative electrode can greatly improve the hydrogen evolution overpotential of the composite zinc-based negative electrode, reduce the generation of hydrogen and the occurrence of side reactions at the interface during the battery cycle process, and the nanoporous structure of the inorganic modification layer is beneficial to the uniform and rapid zinc ion transmission at the negative electrode interface. On the other hand, the organic polymer protective layer has a strong interaction with zinc ions, which can enhance the zinc ion concentration and deposition uniformity at the electrode interface, improve the ion migration rate and inhibit the growth of zinc dendrites. The synergistic effect between the organic / inorganic composite modification layer can solve the main problems existing in the metal zinc negative electrode, and significantly improve the long cycle stability of the aqueous zinc-based battery under high current density and high utilization conditions. In addition, the preparation method provided by the present application is simple in operation, mild and fast in reaction conditions, low in raw material cost and suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the composite zinc-based negative electrode in the present application;

[0022] Figure 2 It is a surface scanning electron microscope (SEM) photo and element distribution diagram (EDS) of the composite zinc-based negative electrode prepared in Example 1 of the present application;

[0023] Figure 3 It is a surface scanning electron microscope (SEM) photo and element distribution diagram (EDS) of the composite zinc-based negative electrode prepared in Example 3 of the present application;

[0024] Figure 4 It is a linear sweep curve (LSV) of the composite zinc-based negative electrode prepared in Example 1 and the pure zinc negative electrode in Comparative Example 1 in Example 2 of the present application;

[0025] Figure 5 It is a voltage-time curve of the symmetrical battery of the composite zinc-based negative electrode prepared in Example 1 and the composite zinc-based negative electrodes in Comparative Examples 1-6 in Example 2 of the present application under the test conditions of 5mA cm -2 , 5mAh cm -2 (zinc utilization rate: 28.5%);

[0026] Figure 6 Voltage-time curves of the symmetrical battery of the composite zinc-based negative electrode prepared in Example 2 of the present application and the pure zinc negative electrode in Comparative Example 1 under the test conditions of 10 mA cm -2 , 10 mAh cm -2 (zinc utilization rate: 57%) were tested.

[0027] Figure 7 Voltage-time curves of the symmetrical battery of the composite zinc-based negative electrode prepared in Example 3 of the present application and the pure zinc powder negative electrode in Comparative Example 7 under the test conditions of 1 mA cm -2 , 1 mAh cm -2 (zinc utilization rate: 11.4%) were tested.

[0028] Figure 8 Voltage-time curves of the symmetrical battery of the composite zinc-based negative electrode prepared in Example 5 of the present application under the test conditions of 10 mA cm -2 , 10 mAh cm -2 (zinc utilization rate: 57%) were tested.

[0029] Figure 9 Voltage-time curves of the symmetrical battery of the composite zinc-based negative electrode prepared in Example 6 of the present application under the test conditions of 10 mA cm -2 , 10 mAh cm -2 (zinc utilization rate: 57%) were tested.

[0030] Figure 10 Coulomb efficiency, specific capacity and cycle number curves of the full battery of the composite zinc-based negative electrode prepared in Example 2 of the present application and the pure zinc negative electrode in Comparative Example 1 and the electrolytic manganese dioxide positive electrode under the 5C rate were tested.

[0031] Figure 11 Coulomb efficiency, specific capacity and cycle number curves of the full battery of the composite zinc-based negative electrode prepared in Example 2 of the present application and the electrolytic manganese dioxide positive electrode under the negative electrode / positive electrode capacity ratio (N / P ratio) of 3.8 and the 0.1C rate were tested. DETAILED DESCRIPTION

[0032] The present application will be further described in detail with reference to the accompanying drawings and specific examples, but the embodiments of the present application are not limited thereto.

[0033] Example 1

[0034] A surface-modified foil-shaped composite zinc-based negative electrode, the preparation process of which comprises the following steps:

[0035] 1) Take 0.4 g of indium chloride (InCl3) and 1.2 g of thiourea to be dissolved in 20 mL of deionized water. Commercial zinc foil is scrubbed several times with ethanol to remove impurities on the surface of the zinc foil. The scrubbed zinc foil is immersed in the above indium-containing reaction solution, taken out after 10 s of reaction, washed several times with deionized water, and dried in a vacuum oven at 40°C for about 3 hours;

[0036] 2) Take 0.25 g of polyacrylamide (PAM, Mw: 2-14 million g mol -1 ) and 0.1 g of zinc sulfate (ZnSO4) electrolyte salt to be added to 10 mL of deionized water, and stirred in an oil bath at 50°C for 3 hours to form a uniform transparent polymer slurry;

[0037] 3) The polymer slurry is uniformly dispersed on the surface of the foil-shaped zinc-indium substrate obtained in step 1) by using a doctor blade method or a spin coating method, and dried in a vacuum oven at 50°C for about 5 hours to remove solvent water, forming a thin and uniform polymer film on the surface of the zinc-indium substrate, obtaining an organic / inorganic surface-modified composite zinc-based negative electrode. The surface-modified electrode sheet is cut into a circular electrode sheet with a diameter of 15 mm, and is denoted as ZnIn-PAM.

[0038] 4) The surface of the ZnIn-PAM negative electrode prepared in step 3) is observed for morphology and element analysis by using a scanning electron microscope, as shown in FIG. 1, wherein the organic polymer modification layer and the inorganic metal indium layer are uniformly distributed on the surface of the zinc foil substrate. Figure 2

[0039] Comparative Example 1 uses ethanol to scrub commercial zinc foil several times to remove impurities on the surface of the zinc foil. The treated zinc foil is cut into a circular electrode sheet with a diameter of 15 mm as a pure zinc metal negative electrode.

[0040] Comparative Example 2 uses the same method as step 1) in Example 1 to prepare an inorganic metal indium layer modified zinc foil, and the treated composite zinc negative electrode is cut into a circular electrode sheet with a diameter of 15 mm as a composite zinc-based negative electrode modified only with a nano inorganic metal indium layer.

[0041] Comparative Example 3 uses the same method as steps 2) and 3) in Example 1 to prepare a zinc foil coated with a PAM polymer protective layer, and the treated composite zinc negative electrode is cut into a circular electrode sheet with a diameter of 15 mm as a composite zinc-based negative electrode modified only with an organic polymer protective layer.

[0042] ​Comparative Example 4 The composite zinc-based negative electrode was prepared by the same method as in Example 1, except that in step 1) the aqueous reaction solution for preparing the nano-inorganic modification layer was prepared by dissolving 0.4 g of antimony fluoride (SbF3) and 1.2 g of sodium citrate in 20 mL of deionized water. The treated composite zinc negative electrode was cut into a circular electrode with a diameter of 15 mm as an inorganic metal antimony / organic polymer surface-modified composite zinc-based negative electrode.

[0043] Comparative Example 5 The composite zinc-based negative electrode was prepared by the same method as in Example 1, except that in step 1) the aqueous reaction solution for preparing the nano-inorganic modification layer was prepared by dissolving 0.4 g of tin chloride (SnCl2) and 1.2 g of sodium citrate in 20 mL of deionized water. The treated composite zinc negative electrode was cut into a circular electrode with a diameter of 15 mm as an inorganic metal tin / organic polymer surface-modified composite zinc-based negative electrode.

[0044] Comparative Example 6 The composite zinc-based negative electrode was prepared by the same method as in Example 1, except that in step 1) a nano-inorganic metal indium modification layer was deposited on the surface of the zinc foil by magnetron sputtering, and the deposition time was 10 s to 5 min. The treated composite zinc negative electrode was cut into a circular electrode with a diameter of 15 mm as an inorganic metal indium / organic polymer surface-modified composite zinc-based negative electrode.

[0045] Example 2

[0046] Performance test, specifically including the following steps:

[0047] 1) The surface-modified composite zinc-based negative electrode prepared in Example 1 and the pure zinc foil negative electrode in Comparative Example 1 were used as the working electrode, a stainless steel mesh was used as the counter electrode, and Ag / AgCl was used as the reference electrode. Linear sweep voltammetry was performed in 1 mol L -1 of sodium sulfate (Na2SO4) electrolyte, and the scan rate was 5 mV s -1 . As shown in Figure 4 , the hydrogen evolution potential of the surface-modified composite zinc-based negative electrode was much higher than that of the pure zinc negative electrode;

[0048] 2) The composite zinc-based negative electrodes prepared in Examples 1 and Comparative Examples 1 to 6 were assembled into symmetric batteries, 1 mol L -1 of zinc sulfate (ZnSO4) electrolyte and a glass fiber separator were used to assemble CR2032 button cells for cyclic charge-discharge test. The long cycle performance of the symmetric batteries was tested at a current density of 5 mA cm -2 , 5 mAh cm -2 , 10 mA cm -2 , and 10 mAh cm -2 , and the surface capacity, respectively, as shown in Figure 5 and Figure 6As shown, the surface modification method of the composite zinc-based negative electrode in Example 1 can more effectively improve the cycle life of the zinc negative electrode under large current and high zinc utilization than the composite zinc-based negative electrodes prepared by using different components and modification methods in Comparative Examples 1-6.

[0049] 3) The surface-modified composite zinc-based negative electrode prepared in Example 1 and the pure zinc negative electrode in Comparative Example 1 were assembled into full cells with electrolytic manganese dioxide as the positive electrode, 2 mol L -1 ZnSO4+0.1 mol L -1 MnSO4 electrolyte and glass fiber separator to assemble CR2032 button cells for cyclic charge-discharge tests. The long cycle stability of the two full cells at 5C rate was tested, as shown in FIG. 2. Figure 10 As shown, the surface-modified composite zinc-based negative electrode exhibits higher discharge specific capacity than the pure zinc negative electrode, and can maintain a high capacity retention rate after 10,000 cycles. In addition, the discharge specific capacity and cycle stability of the full cell with the composite zinc-based negative electrode as the negative electrode under positive and negative capacity matching (negative electrode / positive electrode capacity ratio: 3.8) were tested. As shown in FIG. 3. Figure 11 As shown, the modified full cell can achieve a specific capacity of 250 mAh g -1 at 0.1C rate, and can be stably cycled for about 50 cycles, showing high practical value.

[0050] Example 3

[0051] A surface-modified powder-like composite zinc-based negative electrode, the preparation process of which comprises the following steps:

[0052] 1) 0.2 g of InCl3 and 0.4 g of thiourea were dissolved in 20 mL of deionized water, and 2 g of pure zinc powder was added to the above reaction solution. The mixture was slowly stirred under a protective atmosphere for 30 s, and then poured into a vacuum filtration device to obtain an inorganic metal indium layer-modified composite zinc-based powder. The powder was washed several times with deionized water, dried in a vacuum oven at 40°C for about 3 hours, and then ground to obtain a powder-like zinc-indium matrix.

[0053] 2) The powder-like zinc-indium matrix, conductive agent, and polyvinylidene fluoride binder prepared in step 1) were weighed according to a mass ratio of 7:2:1 and added to an N-methyl pyrrolidone solvent. The mixture was uniformly mixed using a mechanical mixing stirrer, coated on the surface of a stainless steel mesh or titanium mesh, and then placed in a forced air drying oven at 60°C for about 5 hours to remove the solvent and obtain an electrode sheet-like zinc-indium matrix.

[0054] 3) Weigh 0.2g of polyvinylidene fluoride binder and 0.1g of ZnSO4 electrolyte salt and add them to 10g of N-methylpyrrolidone solvent. Stir at room temperature for about 10 hours to mix evenly. Weigh 5g of polypyrrole and add it to the above mixed solution. Grind the mixture to obtain a uniform polymer slurry.

[0055] 4) Coat the zinc-indium substrate in the electrode shape obtained in step 2) with polymer slurry, dry it in a vacuum oven at 60°C for about 5 hours to remove the solvent, and form a thin and uniform polymer film to obtain an organic / inorganic surface-modified composite zinc-based anode in the electrode shape. Cut the treated composite zinc-based anode in the electrode shape into a circular electrode with a diameter of 15 mm.

[0056] 5) The morphology and elemental analysis of the powdered zinc-indium substrate obtained in step 1) were performed using a scanning electron microscope, such as... Figure 3 As shown, the inorganic indium layer is uniformly distributed on the surface of the zinc powder particles;

[0057] 6) Assemble symmetrical cells and test the electrochemical performance of composite zinc-based anodes with organic / inorganic surface modifications, such as... Figure 7 As shown, the surface-modified composite zinc-based anode can achieve a current of 1 mA cm⁻¹. -2 1mAh cm -2 Under stable cycling conditions, it can cycle for more than 2700 hours, which is more than 9 times that of pure zinc powder anode. The surface modification method of powdered metallic zinc anode in Example 3 can also effectively improve the long-term cycling stability of zinc anode.

[0058] Example 4

[0059] A powdered composite zinc-based negative electrode was prepared using the same method as in Example 3, except that pure zinc powder, activated carbon conductive agent, and polyvinylidene fluoride binder were first weighed in a mass ratio of 7:2:1 and added to N-methylpyrrolidone solvent. The solution was then mixed evenly using a mechanical mixer and coated onto the surface of a stainless steel or titanium mesh. The mixture was then dried in a forced-air drying oven at 60°C for approximately 5 hours to obtain a sheet-like pure zinc powder negative electrode. Next, the sheet-like pure zinc powder negative electrode was immersed in a reaction solution containing indium salt and a buffer. After reacting for a period of time, it was washed several times with deionized water and dried in a vacuum oven at 40°C for approximately 3 hours to obtain a sheet-like zinc-indium matrix. A polymer slurry is coated onto an electrode-shaped zinc-indium substrate, and the solvent is removed by drying at 60°C for about 5 hours in a vacuum oven to form a thin and uniform polymer film, resulting in an electrode-shaped organic / inorganic surface-modified composite zinc-based anode. The treated electrode-shaped composite zinc-based anode is then cut into circular electrodes with a diameter of 15 mm.

[0060] Comparative Example 7 Zinc powder, activated carbon conductive agent and polyvinylidene fluoride binder were weighed in a mass ratio of 7:2:1, respectively, and added to N-methyl pyrrolidone solvent. A mechanical mixing stirrer was used to mix the above solution uniformly. The solution was coated on the surface of a stainless steel mesh or titanium mesh and placed in a forced air drying oven at 60°C for about 5 hours to remove the solvent. A slicer was used to cut the treated zinc into a circular electrode with a diameter of 15 mm as a pure zinc powder negative electrode.

[0061] Example 5

[0062] The same method as in Example 1 was used to prepare a composite zinc-based negative electrode, except that the polymer slurry used to prepare the composite zinc-based negative electrode was mixed in a mass ratio of N-methyl pyrrolidone (NMP) : polyvinylidene fluoride (PVDF) : lithium bis-trifluoromethanesulfonimide (LiTFSI) = 10:5:1 to form an inorganic / organic surface modified composite zinc-based negative electrode, which was denoted as ZnIn-PVDF. The treated composite zinc negative electrode was cut into a circular electrode with a diameter of 15 mm, and a symmetrical battery was assembled and subjected to electrochemical testing, as shown in Figure 8 The surface modified composite zinc-based negative electrode with different organic polymer components can also prolong the cycle life of the zinc negative electrode under high current density and high specific capacity conditions.

[0063] Example 6

[0064] The same method as in Example 1 was used to prepare a composite zinc-based negative electrode, except that the polymer slurry used to prepare the composite zinc-based negative electrode was mixed in a mass ratio of N-methyl pyrrolidone (NMP) : 2-methyl imidazole zinc salt (ZIF8) : polyvinylidene fluoride (PVDF) = 20:4:1 to form an inorganic / organic surface modified composite zinc-based negative electrode, which was denoted as ZnIn-ZIF8. The treated composite zinc negative electrode was cut into a circular electrode with a diameter of 15 mm, and a symmetrical battery was assembled and subjected to electrochemical testing, as shown in Figure 9 The surface modified composite zinc-based negative electrode with different organic polymer components can also prolong the cycle life of the zinc negative electrode under high current density and high specific capacity conditions.

Claims

1. A surface-modified composite zinc-based anode, characterized in that, The composite zinc-based anode comprises a matrix and an organic polymer protective layer disposed outside the matrix. The matrix includes a zinc matrix material and a nano-inorganic metal / alloy modification layer. The nano-inorganic metal / alloy modification layer is generated in situ on the zinc matrix material by placing it in an aqueous reaction solution containing inorganic salts and a buffer, through a chemical displacement reaction. The inorganic salt is at least one of indium chloride, indium nitrate, and indium sulfate, and the buffer is at least one of thiourea, sodium citrate, citric acid, and boric acid. The concentration of the inorganic salt in the aqueous reaction solution is 1 g / L. -1 ~50 g L -1 The buffer concentration is 0.1 to 3 times the inorganic salt concentration. The organic polymer protective layer is obtained by coating the substrate with a polymer modification layer slurry and then drying it. The modification layer slurry is a mixture of the following components and solvents, with each component having the following mass percentage in the slurry: 1 to 95 wt% polymer powder, 0 to 20 wt% binder, 0 to 20 wt% functional electrolyte salt, 0 to 5 wt% functional filler, and the balance being solvent. The total proportion of each component is 100%.

2. The surface-modified composite zinc-based anode according to claim 1, characterized in that, The zinc matrix material is at least one of zinc foil, zinc powder, and zinc-based alloy.

3. The surface-modified composite zinc-based anode according to claim 1, characterized in that, When the zinc substrate material is zinc foil or sheet-like zinc alloy material, the preparation method of the substrate is as follows: immerse the sheet-like zinc substrate material in an aqueous reaction solution, and after a uniform inorganic metal / alloy layer is formed in situ on the surface of the zinc substrate material, remove it, wash it several times with deionized water, and dry it; when the zinc substrate material is zinc powder or powdered zinc alloy material, the preparation method of the substrate is as follows: under a protective atmosphere, add the powdered zinc substrate material to an aqueous reaction solution and stir slowly to react. After a period of time, filter or vacuum filter to obtain the reacted powdered substrate, wash it several times with deionized water, dry it, grind it, and make it into an electrode sheet for later use; or: first mix the powdered zinc substrate material with binder and conductive agent to form a slurry, coat it on the surface of stainless steel mesh or carbon paper to prepare an electrode sheet, then immerse the prepared electrode sheet in an aqueous reaction solution, react for a period of time, remove it, wash it several times with deionized water, and dry it to obtain the electrode sheet-like substrate.

4. The surface-modified composite zinc-based anode according to claim 1, characterized in that, The reaction time is 1 second to 1 hour, and the specific reaction time is adjusted according to the concentration of the reaction solution.

5. The surface-modified composite zinc-based anode according to claim 1, characterized in that, The mixing time of the polymer-modified slurry is 0.1 to 12 hours, and the reaction temperature is 25 to 100 ℃; the coating method of the polymer-modified slurry includes blade coating, spin coating, spray drying, and impregnation; the thickness of the organic polymer protective layer is 2 nm to 200 μm.

6. The surface-modified composite zinc-based anode according to claim 1, characterized in that, The solvent in the polymer-modified slurry is at least one of deionized water, acetonitrile, and N-methylpyrrolidone, or a mixture thereof; the polymer powder is at least one of polyacrylamide, polypyrrole, polyvinylidene fluoride, and 2-methylimidazolium zinc salt; the binder is at least one of polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, and polyvinyl butyral; the functional electrolyte salt is at least one of LiTFSI, LiFSI, LiTfO, ZnSO4, Zn(TFSI)2, Zn(TfO)2, NaTFSI, NaFSI, and NaTfO; and the functional filler is at least one of alumina, zinc oxide, magnesium oxide, titanium oxide, silicon oxide, and zirconium oxide.

7. A battery, characterized in that, The battery uses a surface-modified composite zinc-based negative electrode as described in any one of claims 1 to 6, and the battery is an aqueous zinc-based battery, a zinc-air battery, or a zinc-based flow battery.

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