High-performance anode-free aqueous zinc metal batteries based on composite layered negative current collector

Abstract

The application relates to a high-performance anode-free aqueous zinc metal battery based on a composite layered negative electrode current collector, comprising the steps of: coating a conductive layer on the surface of a zinc metal deposition base; configuring a guide layer solvent and coating the guide layer on the conductive layer by a coating method, and then drying in an oven. The application has the beneficial effects that: the application is provided with the conductive layer, which provides uniform deposition sites for zinc ions during the charging process; the guide layer skeleton is arranged, so that the zinc ions are uniformly deposited on the surface of the conductive layer, the growth of zinc dendrites is inhibited, and the risk of battery short circuit is effectively reduced; the guide layer adopts a hydrophobic adhesive, so that the side reaction between active zinc and electrolyte on the negative electrode can be effectively avoided, and the capacity retention rate can be prevented from being reduced with the increase of the cycle number; the anode-free system is adopted, so that the energy density of the battery is greatly improved; the material cost is low, the preparation method is simple in process and good in repeatability, and the application can be mass-produced under the existing production conditions.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, and particularly relates to a high-performance, electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector. Background Technology

[0002] With the continuous development of society, the demand for energy storage is increasing. Lithium-ion batteries, due to their relatively mature technology and rapid commercialization, have become the main product in the energy storage field. However, their organic electrolytes pose uncontrollable risks of combustion and explosion. Aqueous zinc metal batteries, as a new type of battery, not only offer high energy density and high safety but also boast low material costs and environmental friendliness, making them a promising candidate to become the next generation of mainstream products in the energy storage field.

[0003] Currently, zinc metal batteries commonly use zinc foil or zinc powder as the active material, coated onto a metal substrate with an aqueous slurry. This type of zinc metal battery has the following problems: 1) Due to the side reaction between metallic zinc and the aqueous slurry during the preparation process, the utilization rate is reduced. Therefore, an excess of zinc anode is needed to meet battery performance requirements, resulting in a lower overall energy density of the battery; 2) During charging, zinc ions cannot be uniformly deposited in the traditional zinc anode, leading to the growth of zinc dendrites and short-circuit problems; 3) During cycling, some active zinc undergoes side reactions with the electrolyte, and cannot be compensated by zinc metal on the anode side. The lack of active zinc leads to overall battery capacity decay and reduces the battery's cycle performance.

[0004] Therefore, while achieving high energy density, suppressing dendrite growth and improving cycle performance have become pressing problems to be solved. Chinese invention patent CN113036152A discloses a method for preparing and applying a high-energy-density, high-safety negative-electrode zinc metal battery. This invention uses a zinc-loving metal as a coating to suppress dendrites, but the metal used is expensive and the process is complex, making it difficult to use on a large scale. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-performance, electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector.

[0006] This high-performance, electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector includes: a composite layered current collector, a separator, an electrolyte, a positive electrode, and a positive electrode current collector; the composite layered negative electrode current collector includes a zinc metal deposition substrate, a conductive layer, and a guiding layer, which are sequentially bonded together; the electrolyte contains zinc salts.

[0007] Preferably, the zinc metal deposition substrate includes one or more of the following: stainless steel foil, stainless steel mesh, titanium foil, titanium mesh, copper foil, copper mesh, tin-plated copper foil, tin-plated copper mesh, tin foil, carbon paper, carbon cloth, carbon felt, and carbon.

[0008] The preparation method of this high-performance electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector includes the following steps:

[0009] S1. A conductive layer is coated on the surface of a zinc metal deposition substrate using a conductive agent and a binder, wherein the mass ratio of the conductive agent to the binder is 60:40 to 99:1.

[0010] S2. The guiding agent and hydrophobic adhesive are mixed in a mass ratio of 50:50 to 99.9:0.1 and dispersed in a solvent. The mixture is then coated onto the conductive layer using a coating method and dried in an oven.

[0011] Preferably, in step S1: the conductive agent is one or more of artificial graphite, natural graphite, conductive carbon black, Ketjen black, graphene, acetylene black, and carbon fiber; the binder is one or more of polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene, polyvinyl chloride, polystyrene, polyurethane, and styrene-butadiene rubber.

[0012] Preferably, in step S1, the coating method for the conductive layer includes one or more of the following: coating method, spraying method, spin coating method, sputtering method and deposition method; the coating thickness of the conductive layer is 0.5 to 50 μm.

[0013] Preferably, in step S2: the guiding agent is poorly soluble or insoluble in water, and the guiding agent is one or more of zinc-containing inorganic or organic substances; the hydrophobic adhesive includes one or more of polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene, polyvinyl chloride, polystyrene, polyurethane, and styrene-butadiene rubber; the guiding layer coating thickness is 1-200 μm.

[0014] Preferably, in step S2, the oven temperature is 50–150°C and the drying time is 0.5–24 h.

[0015] The beneficial effects of this invention are:

[0016] 1) The present invention is provided with a conductive layer, which provides uniform deposition sites for zinc ions during the charging process.

[0017] 2) This invention includes a guiding layer framework. The guiding layer framework itself does not participate in the reaction, but the functional groups therein interact with Zn. 2+ The interaction guides zinc ions to pass uniformly through the guide layer and then deposits uniformly on the surface of the conductive layer, inhibiting the growth of zinc dendrites and effectively reducing the risk of battery short circuit.

[0018] 3) The guide layer uses a hydrophobic binder, which can effectively avoid side reactions between the active zinc on the negative electrode side and the electrolyte, and prevent the capacity retention rate from decreasing with the increase of the number of cycles.

[0019] 4) The negative electrode-free system enables lighter and thinner cells and effectively solves the problem of low zinc utilization, thereby significantly improving battery energy density.

[0020] 5) The material described in this invention has low cost and a simple preparation process with good repeatability, and can be commercially produced on a large scale under existing production conditions. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a composite layered negative electrode current collector structure;

[0022] Figure 2 This is a cycle capacity curve of the zinc metal battery prepared in Example 1;

[0023] Figure 3 This is a cycle capacity curve of the zinc metal battery prepared in Example 2;

[0024] Figure 4 This is a cycle capacity curve of the zinc metal battery prepared in Comparative Example 3.

[0025] Figure labeling: 1. Zinc metal deposition substrate; 2. Conductive layer; 3. Guide layer. Detailed Implementation

[0026] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0027] Example 1

[0028] As one embodiment, copper foil is used as zinc metal deposition substrate 1; artificial graphite is used as conductive agent and polytetrafluoroethylene emulsion is used as binder, and they are mixed at a mass ratio of 80:20 and dispersed in a solvent to obtain a precursor solution; the precursor solution is loaded into a spray gun and sprayed onto the surface of copper foil to form a conductive layer 2, with a spraying time of 10 min, a spraying rate of 2 mL / min, and a coating thickness of 10 μm.

[0029] Zinc ions-kaolin and zinc phosphate were used as guiding agents, and styrene-butadiene rubber latex was used as a hydrophobic adhesive. The zinc ions-kaolin, zinc phosphate, and styrene-butadiene rubber latex were mixed in a mass ratio of 85:5:10 and dispersed in a solvent. The mixture was then coated onto conductive layer 2 using a coating machine to obtain guiding layer 3, with a coating thickness of 20 μm. The coating was then dried in an oven at 80 °C for 4 hours to obtain a composite layered current collector. Figure 1 As shown.

[0030] The positive electrode used was LiMn₂O₄, the separator was a cellulose membrane, and the electrolyte was a 2M ZnSO₄ + 0.5M Li₂SO₄ aqueous electrolyte. A negative electrode-free zinc metal battery was assembled using the aforementioned composite current collector and tested. The electrolyte was activated by charging before use. After 100 cycles, the capacity retention was 79.28%. Figure 2 As shown.

[0031] Example 2

[0032] In another embodiment, titanium foil is used as zinc metal deposition substrate 1; acetylene black is used as a conductive agent and polytetrafluoroethylene emulsion is used as a binder, which are mixed at a mass ratio of 60:40 and dispersed in a solvent to obtain a precursor solution; the precursor solution is loaded into a spray gun and a conductive layer 2 is sprayed onto the surface of the titanium foil for a spraying time of 10 min, a spraying rate of 4 mL / min, and a coating thickness of 10 μm.

[0033] Zinc ion-resin and zinc fluoride were used as guiding agents, and polyurethane emulsion was used as a hydrophobic adhesive. Zinc ion-resin, zinc fluoride and polyurethane emulsion were mixed in a mass ratio of 80:5:15 and dispersed in a solvent. The mixture was coated onto conductive layer 2 to form guiding layer 3. Then it was placed in an oven and dried at 80°C for 4 hours. The coating thickness was 20 μm, resulting in a composite layered current collector.

[0034] The positive electrode uses LiMn2O4, the separator uses a cellulose membrane, and the electrolyte uses a 2M ZnSO4 + 0.5M LiSO4 aqueous electrolyte. These are combined with the aforementioned composite current collector to assemble a negative electrode-free zinc metal battery. The electrolyte is then charged and activated before testing. Figure 3 As shown, the capacity retention rate is 82.33% after 100 cycles.

[0035] Comparative Example 1

[0036] As a comparative example, an aqueous zinc metal battery was constructed with LiMn2O4 as the positive electrode, a cellulose membrane as the separator, and a 2M ZnSO4 + 0.5M Li2SO4 aqueous electrolyte as the electrolyte. Zinc foil was used as the negative electrode, and the battery was assembled. After the electrolyte was charged and activated, the battery was tested.

[0037] Comparative Example 2

[0038] As another comparative example, zinc powder, conductive carbon black, sodium carboxymethyl cellulose, and styrene-butadiene rubber latex were mixed in a mass ratio of 80:10:5:5 and dispersed in a solvent. The mixture was then coated onto the surface of copper foil using a coating machine and dried in an oven at 80°C for 4 hours. After rolling and cutting, the negative electrode sheet of zinc powder was obtained.

[0039] The positive electrode is LiMn2O4, the separator is a cellulose membrane, and the electrolyte is a 2M ZnSO4 + 0.5M Li2SO4 aqueous electrolyte. The battery is assembled with the above negative electrode, and the electrolyte is activated by charging before testing.

[0040] Comparative Example 3

[0041] The positive electrode used was LiMn₂O₄, the separator was a cellulose membrane, and the electrolyte was a 2M ZnSO₄ + 0.5M Li₂SO₄ aqueous electrolyte. A negative electrode-free battery was assembled with copper foil. After charging and activation of the electrolyte, testing was conducted. After 100 cycles, the capacity retention was 28.85%. Figure 4 As shown.

[0042] The energy densities of the batteries in Examples 1 to 2 and Comparative Examples 1 to 3 were compared. The energy density of the batteries was expressed as the discharge energy of the battery / the mass of the battery. The measurement results are shown in the table below.

[0043] negative electrode Battery energy density Example 1 Composite current collector 1 (without negative electrode) 104Wh / kg Example 2 Composite current collector 2 (without negative electrode) 106Wh / kg Comparative Example 1 Zinc foil 56Wh / kg Comparative Example 2 Zinc powder anode 50Wh / kg Comparative Example 3 Copper foil current collector (without negative electrode) 116Wh / kg

[0044] It can be seen that the negative electrode-free aqueous zinc metal batteries of Examples 1, 2 and Comparative Example 3 have significantly higher energy densities than those of Comparative Examples 1 and 2. This shows that the negative electrode-free system in this invention can significantly improve the energy density of the battery compared to the traditional zinc foil and zinc powder as negative electrodes.

[0045] In contrast Figures 2 to 4 The capacity retention of different electrodeless aqueous zinc metal batteries varies with the number of cycles. It can be seen that in Examples 1 and 2, the electrodeless systems using composite current collectors initially decrease in capacity retention before gradually remaining constant with increasing cycle count. However, in Comparative Example 3, the electrodeless system using copper foil current collectors exhibits a significant decrease in battery capacity retention with increasing cycle count. Therefore, although Comparative Example 3, with its copper foil current collectors, shows the greatest improvement in battery energy density, the electrodeless aqueous zinc metal battery using composite current collectors demonstrates a significant improvement in capacity retention. This is because the hydrophobic binder effectively prevents side reactions between the active zinc on the negative electrode side and the electrolyte.

Claims

1. A method for preparing a high-performance, electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector, characterized in that, The high-performance electrodeless aqueous zinc metal battery based on the composite layered negative electrode current collector includes: a separator, an electrolyte, a positive electrode, a positive electrode current collector, and a composite layered negative electrode current collector. The composite layered negative electrode current collector includes a zinc metal deposition substrate (1), a conductive layer (2), and a guiding layer (3), which are sequentially bonded together. The electrolyte contains zinc salt. The preparation method includes the following steps: S1. A precursor solution is prepared using a conductive agent and a binder, and the precursor solution is coated onto the upper surface of a zinc metal deposition substrate (1) to form a conductive layer (2); the mass ratio of the conductive agent to the binder in the precursor solution is 60:40 to 99:1; the coating thickness of the conductive layer (2) is 0.5 to 50 μm. S2. The guiding agent and the hydrophobic adhesive are mixed in a mass ratio of 50:50 to 99.9:0.1 and dispersed in a solvent. The mixture is then coated onto the conductive layer (2) to obtain the guiding layer (3), which is then dried in an oven. The guiding agent is either poorly soluble or insoluble in water and is one or more of zinc ion-kaolin and zinc phosphate or zinc ion-resin and zinc fluoride. The hydrophobic adhesive includes one or more of polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene, polyvinyl chloride, polystyrene, polyurethane and styrene-butadiene rubber. The coating thickness of the guiding layer is 1 to 200 μm.

2. The method for preparing a high-performance, electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector according to claim 1, characterized in that: The zinc metal deposition substrate (1) includes one or more of the following: stainless steel foil, stainless steel mesh, titanium foil, titanium mesh, copper foil, copper mesh, tin-plated copper foil, tin-plated copper mesh, tin foil, carbon paper, carbon cloth, and carbon felt.

3. The method for preparing a high-performance, electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector according to claim 1, characterized in that, In step S1: the conductive agent is one or more of artificial graphite, natural graphite, conductive carbon black, Ketjen black, graphene, acetylene black and carbon fiber; the binder is one or more of polyvinylidene fluoride, epoxy resin, polytetrafluoroethylene, polyvinyl chloride, polystyrene, polyurethane and styrene-butadiene rubber.

4. The method for preparing a high-performance electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector according to claim 1, characterized in that, In step S1: the coating method of the conductive layer (2) includes one or more of the following: spraying, spin coating, sputtering and deposition.

5. The method for preparing a high-performance, electrodeless aqueous zinc metal battery based on a composite layered negative electrode current collector according to claim 1, characterized in that, In step S2: the oven temperature is 50-150℃, and the drying time is 0.5-24h.

Images