CN116031359A

CN116031359A - Preparation of self-supporting zinc anode

Info

Publication number: CN116031359A
Application number: CN202211727994.8A
Authority: CN
Inventors: 陈人杰; 胡正强
Original assignee: Beijing Institute of Technology BIT
Current assignee: Beijing Institute of Technology BIT
Priority date: 2022-12-29
Filing date: 2022-12-29
Publication date: 2023-04-28

Abstract

The invention relates to the field of water-based zinc ion batteries, in particular to a preparation method and application of an N-doped conductive carbon film self-supporting zinc anode. The preparation method comprises the following steps: the commercial conductive carbon film is calcined in an ammonia environment at low temperature to achieve N doping. And performing induced zinc ion uniform deposition. The self-supporting zinc cathode provided by the invention can quantitatively control zinc content, reduce N/P ratio of a full battery and improve energy density. Meanwhile, the conductive substrate can enable zinc ion deposition to be more uniform, inhibit zinc dendrite growth, improve the circulation stability of the zinc ion battery, and has very wide application prospects in the field of water-based zinc ion batteries.

Description

Preparation of self-supporting zinc anode

Technical Field

The invention relates to the technical field of water-based zinc ion batteries, in particular to a preparation method and application of an N-doped conductive carbon film self-supporting zinc anode.

Background

The exploitation and utilization of traditional fossil fuels such as petroleum coal and the like have caused serious pollution to our environment, and greatly improve the concentration of carbon dioxide in the atmosphere. In order to achieve the aim of reducing carbon, the development and utilization of renewable energy sources such as solar energy, wind energy and the like are proposed. However, the intermittent nature of these renewable energy sources can only be intermittently utilized, requiring the development of suitable energy storage devices. Rechargeable batteries are considered to be the preferred option for the next generation of sustainable energy storage.

The secondary battery can realize the high-efficiency conversion of chemical energy and electric energy, has the advantages of convenient use and the like, and has been widely applied to various fields such as electric automobiles, mobile electronic equipment, power grids and the like. Among the existing secondary batteries, lithium batteries are currently the most widely studied rechargeable batteries having very high energy density (200-350 Wh/kg), however, shortage of lithium resources and inflammability of organic electrolyte bring about serious safety hazards, and moreover, the assembly environment requirements of lithium batteries are extremely strict. Thus, the search for new and safe alternative battery systems is becoming a pressing need.

The metallic zinc can be stably present in an air environment and can be directly used as a zinc anode compared with other alkali metals (lithium, sodium and potassium), and the zinc anode also has higher theoretical capacity (820 mAh/g) and low oxidation-reduction potential (-0.76vvs. She). However, the aqueous zinc battery is also particularly inherently problematic in that the stability is poor during cycling, dendrite growth occurs near the metallic zinc negative electrode, resulting in increased polarization of the negative electrode, capacity decay, and short circuit caused by puncturing the separator; the occurrence of hydrogen evolution side reaction leads to lower coulomb efficiency and battery failure, and in addition, excessive ineffective zinc is often caused by directly using metallic zinc, so that the energy density of the battery is lower, and the market competitiveness of the zinc battery is reduced.

Therefore, a cheap, green and efficient zinc cathode treatment method is needed, side reactions such as zinc dendrites can be restrained for a long time, and the zinc cathode utilization rate is effectively improved.

Disclosure of Invention

The invention aims to provide the N-doped conductive carbon film self-supporting zinc cathode prepared by combining heat treatment and electroplating aiming at the problems of the metallic zinc, the process is safe and pollution-free, the operation is simple, the zinc content of the cathode can be quantitatively controlled, and the stability and the energy density of a battery are improved.

In order to solve the technical problems, the invention adopts the following technical scheme:

in a first aspect of the present disclosure, an embodiment of the present application provides a method for preparing an N-doped conductive carbon film self-supporting zinc anode by heat treatment in combination with electroplating, comprising the steps of:

(1) The commercial conductive carbon film is washed clean by deionized water and ethanol and is placed in an oxygen atmosphere for calcination at 300-450 ℃ for 2-5h.

(2) And (3) placing the precursor obtained in the step (1) in a tube furnace, performing heat treatment for 2-3 hours in an ammonia gas atmosphere at 400-500 ℃, and naturally cooling to room temperature to obtain the N-doped conductive carbon film.

(3) And (3) placing the N-doped conductive carbon film obtained in the step (2) into an electroplating pool, using a metal zinc foil as a counter electrode, using 2-5mol/L zinc salt solution as electroplating solution, and applying current to the conductive carbon film under a stirring environment to perform zinc quantitative deposition to obtain a self-supporting zinc cathode. And assembling the water-based zinc ion battery for electrochemical performance test.

Preferably, in the step (1), the heating rate of the heat treatment is 5 ℃/min, the heating temperature is 350 ℃, and the calcination time is 2 hours.

Preferably, in the step (2), the heating rate of the heat treatment is 2 ℃/min, the heating temperature is 400 ℃, and the calcination time is 2h.

Preferably, in the step (3), the stirring speed is 220 r/min, and the current density is 1mA/cm ² Zinc salt is used as zinc sulfate.

The electrolyte of the common zinc ion battery electrolyte can be one or more of zinc sulfate, zinc chloride or zinc triflate.

In a preferred scheme, the volume molar concentration of the zinc salt in the electrolyte is 1 mol/L-3 mol/L.

The negative electrode of the zinc-based battery is metallic zinc, and the positive electrode is one of manganese dioxide, lithium iron phosphate, prussian blue, vanadium pentoxide and lithium manganate.

Through tests, the self-supporting negative electrode of the water-based zinc ion battery can effectively improve the cycling stability of the zinc negative electrode; based on the test data, the electrolyte can be used in an aqueous zinc ion battery energy storage device.

The invention has the advantages and beneficial effects that:

1. according to the scheme, the commercial carbon film is used as a substrate, the adsorption active sites of zinc ions are increased by using a nitrogen doping method, uniform deposition of zinc is realized, and dendrite growth is inhibited.

2. The N-doped conductive carbon film self-supporting zinc cathode prepared by electroplating can quantitatively control the quality of negative metal zinc, reduce invalid zinc cathodes and reduce the waste of zinc metal materials.

3. The preparation method provided by the invention has the advantages of simple process, great superiority in time cost and great application prospect in the field of practical application of zinc ion batteries.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the description of the embodiments or the prior art will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.

FIG. 1 is a scanning electron microscope image of a self-supporting zinc anode employing an N-doped conductive carbon film provided in example 1 of the present application;

fig. 2 is a view of a zinc foil negative electrode scanning electron microscope provided in example 1 of the present application;

FIG. 3 is a graph of the time voltage of a self-supporting zinc anode using the N-doped conductive carbon film provided in example 1 of the present application;

Detailed Description

In order to better understand the technical solutions in the present application, the following description will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application.

Example 1

The commercial conductive carbon film was rinsed clean with deionized water and ethanol and placed in an oxygen atmosphere at 350 ℃ for 2h. And then placing the obtained precursor in a tube furnace, performing heat treatment for 2 hours in an ammonia gas atmosphere at 400 ℃, and naturally cooling to room temperature to obtain the N-doped conductive carbon film. Placing the obtained N-doped conductive carbon film in an electroplating pool, using metal zinc foil as a counter electrode, and using 4 mol/L zinc sulfate aqueous solution as electroplating solution, wherein the concentration of the zinc sulfate aqueous solution is 1mA/cm ² And (5) electroplating for 20 hours to obtain the N-doped conductive carbon film self-supporting zinc cathode.

The zinc cathode obtained in this example was subjected to scanning electron microscopy and x-ray diffraction test, respectively, and applied to a zinc-zinc symmetrical cell using 5mA/cm ^-2 And (3) carrying out charge and discharge at current density, wherein the charge and discharge cycle time is 1 hour, and observing dendrite growth conditions on the surface of the zinc electrode by using a scanning electron microscope after 10 cycles.

The electron microscope observation results are shown in fig. 1 and 2, wherein fig. 1 is a self-supporting zinc cathode scanning electron microscope image, and fig. 2 is a direct zinc foil cathode scanning electron microscope image. The result shows that the surface of the self-supporting zinc anode is smooth and uniform, and no obvious dendrite exists; and the surface of the cathode directly adopting zinc foil in the comparative experiment has a plurality of columnar dendrites.

The self-supporting zinc cathode and the zinc foil cathode obtained in the example are applied to a zinc-zinc battery to perform constant current charge and discharge test, and the current density is 10mA/cm ^-2 The time was 0.5h and the voltage curve was observed. The results are shown in fig. 3, where the zinc-zinc cell with the self-supporting zinc negative electrode had a longer cycle life.

Example 2

The commercial conductive carbon film was rinsed clean with deionized water and ethanol and calcined in an oxygen atmosphere at 300 ℃ for 2 hours. And then placing the obtained precursor in a tube furnace, performing heat treatment for 2 hours in an ammonia gas atmosphere at 420 ℃, and naturally cooling to room temperature to obtain the N-doped conductive carbon film. Placing the obtained N-doped conductive carbon film in an electroplating pool, using metal zinc foil as a counter electrode, using 10 mol/L zinc chloride aqueous solution as electroplating solution, and using 1mA/cm ² And (5) electroplating for 20 hours to obtain the N-doped conductive carbon film self-supporting zinc cathode.

The zinc cathode obtained in this example was subjected to scanning electron microscopy and x-ray diffraction test, respectively, and applied to a zinc-zinc symmetrical cell using 5mA/cm ^-2 And (3) carrying out charge and discharge at current density, wherein the charge and discharge cycle time is 1 hour, and after 5 times of cycle, observing the dendrite growth condition on the surface of the zinc electrode by using a scanning electron microscope.

The result shows that the surface of the self-supporting zinc anode is smooth and uniform, and no obvious dendrite exists; and the surface of the cathode directly adopting zinc foil in the comparative experiment has a plurality of columnar dendrites.

The self-supporting zinc cathode and the zinc foil cathode obtained in the example are applied to a zinc-zinc battery to perform constant-current charge and discharge test, and the battery is poweredThe flow density was 5mA/cm ^-2 The time was 0.5h and the voltage curve was observed. Wherein the zinc-zinc cell containing the self-supporting zinc anode has a longer cycle life.

It should be noted that in this document, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended 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.

The same or similar parts between the various embodiments in this specification are referred to each other. In particular, for the terminal embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and reference should be made to the description in the method embodiment for relevant points.

The above-described embodiments of the present application are not intended to limit the scope of the present application.

Claims

1. A self-supporting zinc cathode design, a water-based zinc ion battery. In particular to a preparation method of an N-doped conductive carbon film self-supporting zinc anode, which is characterized by comprising the following steps:

(2) And (3) placing the precursor obtained in the step (1) in a tube furnace, performing heat treatment for 2-3 hours in an ammonia gas atmosphere at 300-500 ℃, and naturally cooling to room temperature to obtain the N-doped conductive carbon film.

(3) And (3) placing the N-doped conductive carbon film obtained in the step (2) into an electroplating pool, using a metal zinc foil as a counter electrode, using a zinc salt solution of 2-5mol/L as an electroplating solution, and applying current to the conductive carbon film under a stirring environment to perform zinc quantitative deposition to obtain the self-supporting zinc cathode. And assembling the water-based zinc ion battery for electrochemical performance test.

2. The method according to claim 1, wherein in the step (1), the heating rate of the heat treatment is 5 ℃/min, the temperature is raised to 350 ℃ and the temperature is kept for 2 hours.

3. The method according to claim 1, wherein in the step (2), the heating rate of the heat treatment is 2 ℃/min, the temperature is raised to 400 ℃ and the temperature is kept for 2 hours.

4. The method according to claim 1, wherein in the step (3), the stirring speed is 200 to 300r/min and the current density is 1mA/cm ² Zinc salt is one or more of zinc sulfate, zinc chloride or zinc triflate.

5. Use of the N-doped conductive carbon film self-supporting zinc anode prepared by the method according to any one of claims 1-5 in an aqueous zinc ion battery.

6. The application of the N-doped conductive carbon film self-supporting zinc anode in the water-based zinc ion battery, which is characterized in that electrolyte used in the water-based zinc ion battery is zinc sulfate, zinc chloride or zinc triflate aqueous solution with volume molar concentration of 1 mol/L-3 mol/L.