Preparation of a ferrite positive electrode for aqueous zinc ion battery and application thereof

Abstract

The present application relates to the field of aqueous zinc-ion batteries, and particularly relates to a method for preparing a ferrite positive electrode for a zinc-ion battery, wherein the ferrate is a kind of ferrite that realizes reversible storage of zinc ions through oxidation and reduction of trivalent iron, and metal cations coordinated with ferrite can be zinc, cobalt, nickel, copper and the like; the positive electrode does not have problems such as metal dissolution and environmental pollution. The preparation method involves low-temperature hydrothermal synthesis combined with calcination in an air atmosphere. The ferrite as a positive electrode material for a zinc-ion battery can effectively improve the cycle stability of the zinc-ion battery, and has a very broad application prospect in large-scale green energy storage.

Description

Technical Field

[0001] This invention relates to the field of aqueous zinc-ion battery technology, specifically to a ferrite cathode for aqueous zinc-ion batteries, its preparation method, and its application. Background Technology

[0002] Compared to lithium batteries that use flammable and toxic organic electrolytes, aqueous zinc-ion batteries have attracted widespread research attention due to their advantages such as safer, greener materials, lower cost, and simpler manufacturing processes, making them a promising alternative to existing energy storage technologies. Currently, the main challenge facing zinc-ion batteries is to explore high-capacity cathode materials that can reversibly store zinc ions while maintaining structural stability.

[0003] However, the available cathode materials for aqueous zinc-ion batteries are currently limited, mainly focusing on manganese-based and vanadium-based compounds. While manganese-based cathodes are abundant and inexpensive, manganese is easily soluble, has poor stability, and a short cycle life, hindering its further application. Vanadium-based cathodes, although having very high capacity, cause severe environmental pollution, are not green or environmentally friendly, and do not conform to the concept of sustainable development. Therefore, this invention proposes a ferrite cathode, which utilizes the redox properties of iron to reversibly store zinc ions, while avoiding problems such as metal dissolution and environmental pollution. Summary of the Invention

[0004] The purpose of this invention is to address the problems of manganese metal dissolution and vanadium metal environmental pollution in current aqueous zinc-ion battery cathode materials, and to provide an aqueous zinc-ion battery ferrite cathode material and its application.

[0005] Specifically, the inventive solution disclosed herein is as follows:

[0006] (1) Prepare a mixed solution of a weak reducing agent and a salt containing cation A, and add an iron salt to the solution to form a mixed system.

[0007] (2) Place the solution obtained in step (1) in a reaction vessel and heat it at 120-180℃ for 8-12 hours. Then cool it to room temperature and centrifuge to clean it.

[0008] (3) Place the precursor obtained in step (2) in a muffle furnace and heat it at 150-240℃ for 8-12 hours to obtain ferrate.

[0009] Preferably, in step (1), the weak reducing agent can be at least one of citric acid, oxalic acid, ascorbic acid, and formaldehyde. The solvent is at least one of glycerol, ethanol, and isopropanol.

[0010] Preferably, in step (1), the salt of cation A can be any one of cobalt, nickel, zinc, or copper, with a concentration of 2-3 mol / L.

[0011] Preferably, in step (1), the iron salt can be either ferric nitrate or ferric chloride. The molar ratio with cation A is approximately 1:2 to 1:2.8.

[0012] Preferably, in step (2), the solvothermal temperature is 150°C and the holding time is 10h;

[0013] Preferably, in step (3), the calcination temperature is 200°C and the holding time is 8 hours.

[0014] The obtained ferrate, PTFE, and carbon black were coated onto titanium foil in a mass ratio of 8:1:1 to form a positive electrode, and an aqueous zinc-ion battery was assembled.

[0015] The electrolyte in the ordinary zinc-ion battery electrolyte can be one or more of zinc sulfate, zinc chloride, or zinc trifluoromethanesulfonate.

[0016] The zinc-ion battery negative electrode used in this invention is metallic zinc.

[0017] This invention provides an aqueous zinc-ion battery based on a ferrite cathode. The active center of the ferrite cathode is trivalent iron, and zinc ions can be stored through the redox reaction of iron, thereby achieving the corresponding specific capacity. The metal cation A involved can be of various types. Furthermore, this green and pollution-free cathode avoids dissolution issues, which is beneficial for improving the stability of the zinc-ion battery. The advantages of this invention are that it expands the selectivity of aqueous zinc-ion batteries, achieving a specific capacity exceeding 150 mAh / g, and holds promise as a next-generation, long-cycle, environmentally friendly, and sustainable electrode material. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 To use the cyclic voltammetry provided in Embodiment 1 of this application;

[0020] Figure 2 The cycle life diagram of the zinc-ion full battery provided in Example 1 of this application is shown. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0022] Example 1

[0023] 0.3 g of zinc acetate was dissolved in 20 mL of glycerol and 75 mL of isopropanol, and then 1.1 g of ferric nitrate nonahydrate was added to form a mixed solution. The solution was placed in a 100 mL reaction vessel and hydrothermally heated at 180 °C for 12 h. After centrifugation, the precursor was obtained and dried in an oven at 80 °C for 12 h. The precursor was then calcined in a muffle furnace at 400 °C for 2 h to obtain zinc ferrite.

[0024] The obtained zinc ferrite, PTFE and conductive carbon black were mixed in a mass ratio of 8:1:1, then coated onto a Ti mesh and dried under vacuum at 80°C for 12 hours to form a positive electrode. A battery was assembled using 2M zinc sulfate as the electrolyte and zinc foil as the negative electrode for electrochemical performance testing.

[0025] Figure 1 The cyclic voltammogram of the full cell is shown, and a pair of obvious redox peaks can be observed. The second and third CV curves are basically overlapping, demonstrating the stability of the zinc ferrite cathode.

[0026] This example also underwent charge-discharge cycle testing. After 500 cycles at a current density of 100 mA / g, the cathode still had a specific capacity of 105 mAh / g.

[0027] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0028] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0029] The same or similar parts between the various embodiments in this specification can be referred to mutually. In particular, the terminal embodiments are basically similar to the method embodiments, so the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

[0030] The embodiments described above do not constitute a limitation on the scope of protection of this application.

Claims

1. A method for preparing a zinc ferrite cathode for aqueous zinc-ion batteries, characterized in that, Includes the following steps: (1) Prepare a solution with glycerol as solvent and oxalic acid as weak reducing agent, and add a salt containing zinc ions to the solution to make the concentration of the salt containing zinc ions 2-3 mol / L to obtain a mixed solution containing zinc ions; then add an iron salt to the mixed solution to form a mixed system, wherein the molar ratio of the iron salt to the salt containing zinc ions is 1:2-1:2.8; (2) Place the mixture obtained in step (1) in a reactor, heat it at 150°C and keep it at that temperature for 10 hours, then cool it to room temperature and centrifuge and wash it to obtain the precursor. (3) The precursor obtained in step (2) is placed in a muffle furnace, heated at 200°C and kept at that temperature for 8 hours to obtain zinc ferrite powder; (4) The zinc ferrate powder obtained in step (3) is mixed with conductive agent and binder at a mass ratio of 8:1:1, isopropanol is added to make a slurry, which is then coated on the current collector and dried under vacuum to obtain an electrode sheet, wherein the current collector is selected from titanium mesh, carbon cloth and titanium foil.

2. The preparation method according to claim 1, characterized in that, The iron salt is ferric nitrate or ferric chloride.

3. A zinc ferrate cathode material, characterized in that, It is prepared by the preparation method described in claim 1 or 2.

4. The application of the zinc ferrite cathode material according to claim 3 in an aqueous zinc-ion battery.

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