WO2020077652A1

WO2020077652A1 - Rechargeable zinc-air flow single battery

Info

Publication number: WO2020077652A1
Application number: PCT/CN2018/111547
Authority: WO
Inventors: 陈忠伟
Original assignee: 苏州沃泰丰能电池科技有限公司
Priority date: 2018-10-16
Filing date: 2018-10-24
Publication date: 2020-04-23
Also published as: CN209515870U

Abstract

A rechargeable zinc-air flow single battery. A dual-electrode zinc-air flow battery is designed by adopting a dual-function catalyst; a single battery consists of a battery housing, an air inlet cavity (1), an air cathode (2), a metal anode (4), an electrolyte layer (3), and a conductive current collecting sheet (2-1); the battery only uses one kind of electrolyte, and the charging and discharging reaction of the battery is immediately completed in one electrolyte cavity. By improving a liquid flow system and a metal electrode, the formation of a zinc crystal branch is prevented, and by improving an air cathode, the air cathode can normally participate in the reaction without liquid leakage, so that the safety and commercialization of the battery are greatly improved.

Description

Rechargeable zinc air flow single battery

Technical field

The present invention relates to the field of metal-air batteries, in particular to a rechargeable zinc air-flow single cell.

Background technique

In today's energy field, the development and utilization of solar energy, wind energy and other renewable energy sources are getting more and more attention. In order to achieve the stability of power supply, it is necessary to develop efficient large-scale energy storage technology. As an important energy storage technology, the secondary battery has been researched and developed, and it has been gradually introduced to the market. Among them, a redox flow battery has special advantages in large-scale energy storage and storage due to its technical characteristics such as large capacity, deep discharge, and long cycle life. Among these batteries, all-vanadium flow batteries have become a hot spot for development and are entering the market. However, the theoretical voltage of the all-vanadium flow battery is low (1.26V), and it is difficult to obtain higher energy density and power density.

Rechargeable zinc-air batteries are considered to be one of the most promising technologies due to many advantages. For example, zinc-air batteries use oxygen from the air in the atmosphere, which is not costly and inexhaustible, eliminating the need to store a fuel source in the battery. In addition, the catalyst used in the zinc-air battery is not consumed in the actual electrochemical reaction, and theoretically may play a role in an infinite period. In addition, the zinc-air battery uses metallic zinc, which is abundant in the earth's crust and widely distributed, as the active material. Therefore, the zinc-air battery is a low-cost, safe, and environmentally friendly energy storage device.

Currently, zinc-air primary batteries have been mass-produced and are widely used as power sources for hearing aids and the like. In a zinc-air battery, an alkaline aqueous solution such as potassium hydroxide is used as an electrolyte, and a separator (partition) is used to prevent short circuits between the positive and negative electrodes. In the traditional zinc-air battery, as shown in the following reaction formula,

cathode:

anode:

During discharge, O ₂ is reduced on the air electrode (positive electrode) side to generate OH ⁻ , and at the same time, the negative electrode zinc is oxidized to generate ZnO. Therefore, the consumption of metal in the metal-air battery / fuel cell is inevitable, and it is necessary to continuously replenish the metal for long-term operation.

For the commercialization of rechargeable zinc-air batteries, there are currently two main technical issues:

The first problem is the corrosion of the carbon contained in the cathode, which occurs during the charging phase of the battery. In a conventional rechargeable zinc-air battery, the same cathode is used for charging and discharging cycles, and the cathode includes a porous carbon material that supports a desired catalyst. During the charging and discharging process of the battery, the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) occur. During this process, side reactions occur, in which the carbon is corroded during the OER and the carbon is oxidized to CO ₂ . Once the carbon carrier is oxidized and consumed, the catalyst supported on the carbon loses contact with the electrode, making the catalyst ineffective, resulting in a decline in battery performance. Recently, the US patent US9590253 provides a dual-function catalyst for air batteries and fuel cells. The dual-function catalyst has a catalytic activity for both oxygen reduction and oxygen precipitation reactions. Application prospects.

The second problem is the electrode deformation at the anode and the formation of zinc dendrites. In a traditional rechargeable zinc-air battery, during the discharge phase, the metallic zinc of the anode is oxidized to zinc ions and moves into the electrolyte. Then, due to the poor solubility of zinc ions in the alkaline electrolyte, almost at the same time, these ions are deposited as zinc oxide particles. During the charging phase, the zinc oxide particles are transformed into zinc particles. These zinc particles can move down in a long-term cycle due to gravity, and this can cause the shape of the anode to change. The zinc particles can also form zinc dendrites on the anode. Changes in the shape of the anode can cause energy decay, and zinc dendrites can cause sudden failure of the battery.

The zinc-air battery uses oxygen in the air from the atmosphere, which is free and inexhaustible, eliminating the need to store a fuel source in the battery. In addition, the catalyst used in the zinc-air battery is not consumed during the actual charge-discharge electrochemical reaction, which makes it theoretically possible to play a role indefinitely. Chinese patent CN201680000396 provides a rechargeable three-electrode single-flow zinc-air battery with high cycle life. The electrode structure is composed of an anode and two cathodes (one for charging and the other for discharging), one for charging and the other for discharging. Using two cathodes with different functions can solve the problem of cathode carbon corrosion and catalyst loss. Make the battery more long-term operating life.

In general, zinc-air batteries, which use oxygen and zinc as active materials, have been vigorously developed due to their low material cost and high performance, safety and environmental friendliness.

Summary of the invention

The main technical problem solved by the present invention is to provide a rechargeable zinc air-flow single cell, which solves the zinc crystal branch problem, and does not need to supplement metal fuel, can be repeatedly re-discharged, and the structure is more compact and optimized. The flow structure of the battery designed by the present invention, the reaction equation of the battery becomes as follows:

cathode:

anode:

To achieve the above objectives, the technical solutions adopted by the present invention to solve the technical problems are:

A rechargeable zinc air-flow single cell includes a battery casing, an air intake cavity, an air cathode, a metal anode, an electrolyte layer, and a conductive current collecting plate; the air cathode is two pieces and is located outside the single cell The metal anode is located in the middle of the single cell, the cavity between the metal anode and the air cathode is suitable for the flow of electrolyte, the air intake cavity is connected to the air cathode side, and the current collectors are respectively Connected to the air cathode and metal anode.

The metal anode includes an alkali-resistant metal mesh and / or metal foam permeable to electrolyte.

The metal anode is one or more of copper foam, metal copper mesh, nickel foam, and metal nickel mesh.

The air cathode includes a conductive, gas-permeable and water-impermeable alkali-resistant electrolyte membrane.

The outer surface of the air cathode is coated with a catalyst having catalytic activity for both oxygen reduction reaction and oxygen precipitation reaction.

The air intake cavity supplies air to the battery through an external air pump.

The electrolyte is pumped in from the bottom of the electrolyte layer by a pump and flows out from the upper part of the electrolyte layer.

The electrolyte is an alkaline electrolyte, including one of NaOH, KOH, LiOH or any mixture thereof.

The alkali concentration of the electrolyte is 1 mol / L-15 mol / L.

A zinc salt is dissolved in the electrolyte, and the zinc salt is one or more of ZnO, Zn (OH) ₂ , K ₂ Zn (OH) ₄ , and Na ₂ Zn (OH) ₄ .

The concentration of zinc ions in the zinc salt is 0.05 mol / L-1.5 mol / L.

Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art:

A rechargeable zinc air-flow single cell is provided. (1) Oxygen in the air is used as the positive electrode active material, and the inert metal anode is used as the negative electrode, which avoids the consumption of metal fuel and enables metal ions to be charged and discharged during the battery Carry out cyclic oxidation and reduction; (2) If the alkaline solution is used as the electrolyte, a flowing electrolyte is used to wash away the generated zinc oxide and other deposits with the flow of the electrolyte, and the zinc crystal branch problem will not occur; (3) ) The flow direction of the electrolyte from the bottom to the top can also prevent the insoluble matter generated from being precipitated to the bottom and be brought into the storage tank with the flow of the electrolyte, preventing deposition (4) Using a dual-functional catalyst and reasonable The battery structure is designed so that the air cathode can be permeable without water leakage, and the electrolyte ions can oxidize and oxygen evolve well on the surface of the catalyst, which solves the problems of carbon corrosion and low catalytic efficiency; (5) adopts a porous inert metal anode , So that zinc is deposited on the surface when it is redoxed, and the porous structure greatly increases the contact area of the electrolyte, and also makes the cost lower; (6) the zinc-air battery of the present invention does not Any material easily lead to a fire or explosion, high security, low cost, great promotional value.

BRIEF DESCRIPTION

FIG. 1 is a schematic cross-sectional view of a rechargeable zinc air-flow single cell of the present invention.

Fig. 2 is a schematic front view of a rechargeable zinc air flow single cell of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS: 1 intake cavity, 2 air cathode, 3 electrolyte layer, 4 metal anode, 1-1, air intake, 1-2 first battery holder, 2-1 cathode conductive current collector, 2 -2 alkali-resistant electrolyte membrane, 2-3 dual-function catalyst, 3-1 electrolyte outlet, 3-2 second battery holder, 3-3 electrolyte inlet, 4-1, anode conductivity and flow sheet, 4-2 metal Anode sheet.

detailed description

The present invention will be further described below in conjunction with the embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so that the protection scope of the present invention is more clearly defined.

Referring to the drawings, a rechargeable zinc air flow single cell includes: an air intake cavity 1, an air cathode 2, an electrolyte layer 3, a metal anode 4, the metal anode 4 is located in the center of the battery, and inside the electrolyte layer 3, The air cathode 2 is located on both sides of the electrolyte layer 3, and the intake cavity 1 is connected to the outside of the air cathode 2. The single cells are supported by the first battery holder 1-2 and the second battery holder 3-2 at the required positions. The electrolyte flows in from the electrolyte inlet 3-3 and flows out from the electrolyte outlet 3-1. An air inlet 1-1 is connected to the upper edge of the cavity 1, and is connected to the fan through the air pipe to supply air to the battery. First, during the battery charging phase, an oxidation reaction takes place on the surface of the air cathode 2, causing the OH- in the electrolyte to lose electrons to be oxidized to oxygen, and the hydroxide ions come into contact with the bifunctional catalyst 2-3 through the alkali-resistant electrolyte membrane 2-2 to react At the same time, on the surface of the metal anode 4, the zinc oxide in the electrolyte gets a reduction reaction, which reduces the zinc oxide to elemental zinc and deposits on the surface of the metal anode 4. In the discharge phase, the elemental zinc deposited on the surface of the metal anode 4 undergoes an oxidation reaction to produce zinc oxide, which is then dissolved by the alkaline electrolyte and circulated to the outside of the battery as the electrolyte flows. On the surface of the air cathode 2, the oxygen in the air cavity, Through the alkali-resistant electrolyte membrane 2-2, the reduction reaction is carried out under the action of the dual-function catalyst 2-3, and it is reduced to OH ^- ions into the electrolyte, thus completing a charge-discharge cycle.

Metal anode 4 The anode consists of an alkali-permeable metal mesh and / or metal foam that is permeable to the electrolyte. The metal mesh can be made of copper foam, metal copper mesh, nickel foam, or metal nickel mesh. As the material, when zinc oxidation-reduction reaction occurs, zinc can react on the metal anode network structure, so that the metal zinc is not consumed during the charge and discharge cycle, and no additional metal fuel is needed.

The alkaline electrolyte is one of potassium hydroxide, sodium hydroxide or lithium hydroxide, and the solubility of the zinc ion is better when the concentration of the alkali is in the range of 1-15 mol / L. The electrolyte in the electrolyte layer 3 includes a saturated zinc salt, which is one or more of ZnO, Zn (OH) ₂ , K ₂ Zn (OH) ₄ , Na ₂ Zn (OH) ₄ , zinc The concentration of ions is 0.05-1.5mol / L.

When a single cell is working, an electromotive force is generated between the cathode and anode. By embedding a current collector on the cathode and anode, electrical energy can be gathered and exported.

The above are only the embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by the description and drawings of the present invention, or directly or indirectly used in other related technical fields, The same reason is included in the patent protection scope of the present invention.

Claims

A rechargeable zinc air-flow single cell includes a battery casing, an air intake cavity, an air cathode, a metal anode, an electrolyte layer, and a conductive current collecting plate; the air cathode is two pieces and is located outside the single cell The metal anode is located in the middle of the single cell, the cavity between the metal anode and the air cathode is suitable for the flow of electrolyte, the air intake cavity is connected to the air cathode side, and the current collectors are respectively Connected to the air cathode and metal anode.
The rechargeable zinc air-flow single cell according to claim 1, characterized in that the metal anode comprises an alkali-resistant metal mesh and / or metal foam permeable to electrolyte.
The rechargeable zinc air-flow single cell according to claim 1 or 2, wherein the metal anode is one or more of copper foam, metal copper mesh, nickel foam, and metal nickel mesh.
The rechargeable zinc air-flow single cell according to claim 1, wherein the air cathode includes a conductive, gas-permeable and water-impermeable alkali-resistant electrolyte membrane.
The rechargeable zinc air-flow single cell according to claim 1, wherein the outer surface of the air cathode is coated with a catalyst having catalytic activity for both oxygen reduction reaction and oxygen precipitation reaction.
The rechargeable zinc air-flow single battery according to claim 1, wherein the air intake cavity supplies the battery with an external air pump.
The rechargeable zinc air flow single cell according to claim 1, wherein the electrolyte is pumped in from the bottom of the electrolyte layer by a pump and flows out from the upper part of the electrolyte layer.
The rechargeable zinc air-flow single cell according to claim 1, wherein the electrolyte is a strong alkaline electrolyte, including one of NaOH, KOH, LiOH or any mixture thereof.
The rechargeable zinc air-flow single cell according to claim 1 or 8, wherein the alkaline concentration of the electrolyte is 1mol / L-15mol / L
The rechargeable zinc air-flow single cell according to claim 8, characterized in that: zinc salt is dissolved in the electrolyte, and the zinc salt is ZnO, Zn (OH) 2 and K 2 Zn (OH ) 4 , one or more of Na 2 Zn (OH) 4 .
The rechargeable zinc air-flow single cell according to claim 10, wherein the concentration of zinc ions in the zinc salt is 0.05mol / L-1.5mol / L.