Plastic soft solid zinc powder composite negative electrode material and preparation method and application thereof

Abstract

The application belongs to the technical field of zinc metal negative electrode, and discloses a plastic soft solid zinc powder composite negative electrode material and a preparation method and application thereof. The negative electrode material is composed of zinc powder, carbon and liquid polymer oligomer with a mass ratio of (6-8):(1-2):(1-3). The pre-composite of carbon and zinc powder is uniformly mixed with a polymer oligomer solution, and then the solvent in the mixture is removed. The obtained dry substance is kneaded into a group to obtain the plastic soft solid zinc powder composite negative electrode material. The material has excellent electrochemical performance and plasticity, can be processed into electrodes with different shapes, and shows good electrodeposition / peeling performance, cycle stability and coulomb efficiency, and can be used as a self-supporting zinc powder composite negative electrode. The method is simple, and the polymer oligomer matrix in the composite has moderate rheological property, which not only plays a bonding role, but also significantly improves the electrochemical performance and diversified processing performance of the zinc powder composite negative electrode.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of zinc metal negative electrode, and more particularly relates to a plastic soft solid zinc powder composite negative electrode material and a preparation method and application thereof. BACKGROUND

[0002] Zinc-based energy storage devices such as zinc-based batteries have a long history and broad market prospects, however, current zinc-based batteries are basically primary batteries and cannot be used as effective secondary batteries. After more than ten years of continuous exploration by domestic and foreign researchers, the electrochemical performance of zinc-based battery related positive electrode materials and negative electrode materials such as aqueous zinc ion batteries (ZIBs) has been significantly improved, and the key performances such as the cycle life of the device and the overall battery energy density have also been gradually improved. It can be said that zinc-based batteries are expected to become a zinc-based electrochemical energy storage system with high safety, low cost and scalable application in the future.

[0003] At present, one of the important research directions in the field of zinc-based battery research is zinc metal negative electrode. Because zinc metal has the advantages of high theoretical energy density, low redox potential, low cost and non-toxicity, it is considered to be an ideal negative electrode material for zinc-based batteries. However, the commonly used zinc foil or zinc sheet negative electrode has obvious dendrite growth, low utilization rate and limited processing modification technology (Energy Environ. Sci., 2020, 13, 3330), which has become a major bottleneck for the development of zinc-based battery industry. Zinc powder is considered to be a more practical zinc metal negative electrode. This is because zinc powder has convenient and adjustable dosage and surface area, as well as mature industrial production and diversified processing modification technology.

[0004] However, how to process the particulate zinc powder into a usable zinc powder negative electrode and improve the electrochemical performance of the zinc powder negative electrode is a key technical problem currently faced by the zinc powder negative electrode. It has been found that the zinc powder negative electrode based on the traditional high molecular binder such as PVDF combined with conductive carbon black and zinc powder exhibits significant polarization phenomenon (Energy Storage Materials., 2022, 45, 465), resulting in unsatisfactory electrochemical performance, which is not conducive to promoting the use of zinc-based energy storage devices under high capacity and high rate conditions. This is because the high molecular in the traditional high molecular composite zinc powder negative electrode has a high degree of entanglement and strong intermolecular force, which is not conducive to the transmission of ions and the transfer of electrons between conductive substances. Therefore, by applying low entanglement degree high molecular oligomers as binders to composite particulate zinc powder, it is expected to design zinc powder composite materials with certain rheological properties and controllable viscoelasticity to achieve rapid transmission of electric charge, thereby constructing high-performance zinc powder negative electrode. Based on this, starting from the idea of soft matter, a simple and effective method is designed to improve the processing and electrochemical performance of the zinc powder negative electrode, which is of great significance for preparing practical high-performance zinc metal negative electrode. SUMMARY

[0005] In order to solve the above-mentioned problems of the prior art, the present application aims to provide a soft solid zinc powder composite negative material with plasticity. The material has excellent electrochemical performance and plasticity, and can be processed into electrodes with different shapes, showing good electrodeposition / detachment performance, cycle stability and coulombic efficiency, and can be used as a self-supporting zinc powder composite negative electrode.

[0006] Another object of the present application is to provide a method for preparing the soft solid zinc powder composite negative material with plasticity. The method can overcome the problems of the prior art, and can realize the preparation of zinc powder composite negative electrodes with different topological structures, providing the possibility for various needs of zinc powder negative electrodes in practical applications.

[0007] Still another object of the present application is to provide the application of the soft solid zinc powder composite negative material with plasticity in zinc-based energy storage devices.

[0008] The object of the present application is achieved by the following technical solutions:

[0009] A soft solid zinc powder composite negative material with plasticity, which is composed of zinc powder, carbon and a liquid high molecular oligomer. The mass ratio of zinc powder, carbon and the liquid high molecular oligomer is (6-8):(1-2):(1-3).

[0010] Preferably, the mass ratio of zinc powder, carbon and the liquid high molecular oligomer is (13-15):(1-3):(3-5).

[0011] More preferably, the mass ratio of zinc powder, carbon and the liquid high molecular oligomer is (13-14):(2-3):(4-5).

[0012] Preferably, the carbon is one or more of carbon black, carbon nanotubes, graphene, graphyne or carbon spheres.

[0013] Preferably, the liquid high molecular oligomer is a high molecular substance in liquid state at room temperature, such as an oily liquid or a viscous liquid.

[0014] More preferably, the liquid high molecular oligomer is one or more of epoxy resin oligomer E44, polyamide-amine dendrimer PAMAM, polyoxypropylene glycerol ether, polybutylene glycol, polytetrahydrofuran, polypropylene glycol, alkylphenol polyoxyethylene ether and polyoxyethylene.

[0015] The preparation method of the soft solid zinc powder composite negative material with plasticity comprises the following specific steps:

[0016] Carbon and zinc powder are added into a solvent and uniformly mixed by wet grinding, then the pre-composite of carbon and zinc powder and a liquid polymeric oligomer solution are mixed, stirred and ultrasonicated, the solvent in the mixture is removed at 60-120 DEG C, the obtained dry product is kneaded into a lump to obtain a soft solid zinc powder composite negative electrode material.

[0017] Preferably, the solvent is one or more of ethanol, acetone or isopropanol.

[0018] Preferably, the grinding time is 5-20 min, the stirring speed is 200-1000 rpm, the stirring time is 0.2-1 h, the ultrasonic power is 50-100 W, and the ultrasonic time is 5-40 min.

[0019] The soft solid zinc powder composite negative electrode material can be used in the field of zinc-based energy storage devices.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] 1. The present application adopts a method of rheological polymeric oligomer adhesion, skillfully controls the amount of polymeric oligomer and carbon material filler, realizes the adhesion of loose zinc powder particles into available zinc powder electrode material, and the material has the elasticity of solid material and moderate liquid rheological property, forming a composite material with self-supporting and convenient plasticity.

[0022] 2. The soft solid zinc powder composite of the present application has excellent electrochemical performance and plasticity, can be processed into electrodes of different shapes, shows good electrodeposition / detachment performance, cycle stability and coulombic efficiency, and can be used as a self-supporting electrode to prepare a patterned zinc metal negative electrode for micro devices.

[0023] 3. In the composite system prepared by the present application, the zinc powder has a very high relative mass fraction (65-80%), which provides the possibility for high utilization rate of zinc metal. DETAILED DESCRIPTION

[0024] Figure 1 A physical photo of the zinc powder-graphene-epoxy resin composite prepared in Example 1.

[0025] Figure 2 A scanning electron microscope image of the zinc powder-graphene-epoxy resin composite prepared in Example 1.

[0026] Figure 3 Electrochemical performance of the zinc powder-graphene-epoxy resin composite prepared in Example 1 in a zinc ion capacitor.

[0027] Figure 4The electrochemical performance of the zinc powder-graphene-epoxy resin composite prepared in Example 1 was tested in a water-based zinc ion battery. DETAILED DESCRIPTION

[0028] The present application is further described in conjunction with the following examples, which should not be construed as limiting. The techniques used in the examples, unless otherwise specified, are routine techniques commonly used in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present application are conventional reagents, methods, and equipment in the art.

[0029] Example 1

[0030] 1. Directly use commercially available carbon materials (purchased from Shenzhen Nanotech Port Co. Ltd.), or laboratory-made carbon materials, such as defect-free two-dimensional graphene sheets (PG, thickness of 1-10 nm, lateral size of 0.05-5 μm) obtained by ultrasonic-assisted solvent exfoliation of graphite, then collect the PG by suction filtration and wash with water and ethanol, and dry the purified PG for use.

[0031] 2. Add 700 mg of zinc powder to 100 mg of PG in a mortar, grind with 1 mL of ethanol, and collect the mixture to obtain a pre-composite of carbon and zinc powder.

[0032] 3. Add 1 mL of a 200 mg / mL ethanol solution of epoxy resin E-44 to the pre-composite of carbon and zinc powder, stir the mixture at a speed of 1000 rpm for 10 min, and then ultrasonicate at a power of 100 W for 30 min to obtain a mixed dispersion of the carbon-zinc powder pre-composite-epoxy resin E-44.

[0033] 4. Place the mixed dispersion in a glass culture dish, heat in an oven at 80°C to volatilize the ethanol, and weigh the mixture every 1 h until the weight no longer decreases, then collect the dried material and knead into a mass to obtain a plastically soft solid zinc powder composite negative electrode material, i.e., a zinc powder-graphene-epoxy resin composite. The zinc powder is an active electrode material, the PG is a conductive additive and filler, and the epoxy resin is a rheological binder. This zinc powder-graphene-epoxy resin composite is a plastically soft solid zinc powder composite negative electrode material.

[0034] Figure 1 A photograph of the zinc powder-graphene-epoxy resin composite prepared in Example 1. From Figure 1 It can be seen that the obtained zinc powder-graphene-epoxy resin composite has excellent plasticity and can be processed into electrodes of different shapes. Figure 2 A scanning electron microscope image of the zinc powder-graphene-epoxy resin composite prepared in Example 1. From Figure 2As can be seen from the figure, the graphene and zinc powder are uniformly dispersed in the epoxy resin E44 matrix. Figure 3 The charge-discharge performance of the zinc powder-graphene-epoxy resin composite prepared in Example 1 in a zinc ion capacitor is shown in Table 2. Figure 3 As can be seen from the table, the pliable soft solid zinc powder composite anode (zinc powder-graphene-epoxy resin composite anode) has a longer charge-discharge time than the conventional high polymer (such as solid epoxy resin E12) bonded zinc powder and PG (conventional zinc powder composite anode), and the results show that the pliable soft solid zinc powder composite anode has significantly enhanced electrochemical performance compared to the conventional high polymer binder bonded zinc powder anode system, exhibiting lower polarization and higher capacity. Figure 4 The charge-discharge performance of the zinc powder-graphene-epoxy resin composite prepared in Example 1 in a zinc ion battery is shown in Table 3. Figure 4 As can be seen from the table, the pliable soft solid zinc powder composite anode has higher discharge capacity and lower polarization voltage than the conventional zinc powder composite anode, indicating that the pliable soft solid zinc powder composite anode has significantly enhanced deposition kinetics in the aqueous zinc ion battery.

[0035] Example 2

[0036] 1. Commercial carbon nanotubes (CNT, diameter 40-60 nm, length 5-15 μm) were added to an ethanol solvent and ultrasonicated to disperse the CNT and prevent aggregation, then the CNT was collected by suction filtration and washed with water and ethanol, and the purified CNT was dried for use.

[0037] 2. 700 mg of zinc powder was added to 100 mg of CNT in a mortar, ground with 1 mL of ethanol, and the mixture was collected to obtain a pre-composite of carbon and zinc powder.

[0038] 3. 1 mL of a 200 mg / mL polyoxypropylene glycol ether solution was added to the above-mentioned pre-composite of carbon and zinc powder, and the mixture was stirred at a speed of 1000 rpm for 10 min, then ultrasonicated at a power of 100 W for 30 min to obtain a mixed dispersion of carbon-zinc powder pre-composite-polyoxypropylene glycol ether.

[0039] 4. The above-mentioned mixed dispersion was placed in a glass culture dish and heated in an oven at 80°C to evaporate the ethanol, and the mass of the mixture was measured every 1 h until the mass no longer decreased, then the dried material was collected and kneaded into a mass to obtain a zinc powder-carbon nanotube-polyoxypropylene glycol ether composite, which is a pliable soft solid zinc powder composite anode material. The zinc powder is an active electrode material, the CNT is a conductive additive and a filler, and the polyoxypropylene glycol ether is a rheological binder, and this zinc powder-CNT-polyoxypropylene glycol ether composite is also a pliable soft solid zinc powder composite anode material.

[0040] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are included in the protection scope of the present application.

Claims

1. A ductile, soft-solid zinc powder composite anode material, characterized in that, The composite anode material is composed of zinc powder, carbon, and liquid oligomers, with a mass ratio of zinc powder, carbon, and liquid oligomers of (6~8):(1~2):(1~3). The carbon is one or more of carbon black, carbon nanotubes, graphene, graphyne, or carbon spheres. The liquid oligomers are epoxy resin oligomer E44 and / or polyoxypropylene glycerol ether. The mass ratio of zinc powder, carbon, and liquid oligomers of (13~15):(1~3):(3~5). Carbon and zinc powder are added to a solvent and wet-milled to mix evenly. Then, the pre-composite of carbon and zinc powder and the liquid oligomer solution are mixed and stirred, followed by ultrasonication. The solvent in the mixture is removed at 60~120℃. The resulting dried material is kneaded into a ball to obtain a plastic soft solid zinc powder composite anode material.

2. The ductile soft-solid zinc powder composite anode material according to claim 1, characterized in that, The mass ratio of the zinc powder, carbon and liquid oligomer is (13~14):(2~3):(4~5).

3. A method for preparing a ductile soft-solid zinc powder composite anode material according to claim 1 or 2, characterized in that, The specific steps include the following: Carbon and zinc powder are added to a solvent and wet-milled to mix evenly. Then, the pre-composite of carbon and zinc powder is mixed and stirred with a liquid polymer oligomer solution and ultrasonicated. The solvent in the mixture is removed at 60~120℃. The resulting dried material is kneaded into a ball to obtain a plastic soft solid zinc powder composite anode material.

4. The method for preparing the plastic soft solid zinc powder composite anode material according to claim 3, characterized in that, The solvent is one or more of ethanol, acetone or isopropanol.

5. The method for preparing the plastic soft solid zinc powder composite anode material according to claim 3, characterized in that, The grinding time is 5-20 min, the stirring speed is 200-1000 rpm, the stirring time is 0.2-1 h, the ultrasonic power is 50-100 W, and the ultrasonic time is 5-40 min.

6. The application of the ductile soft solid zinc powder composite anode material according to claim 1 or 2 in the field of zinc-based energy storage devices.

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