CN109786761B

CN109786761B - Positive electrode material for zinc-bromine flow battery, preparation and application

Info

Publication number: CN109786761B
Application number: CN201711111243.2A
Authority: CN
Inventors: 赖勤志; 李先锋; 张华民; 许鹏程; 宋杨
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2017-11-10
Filing date: 2017-11-10
Publication date: 2022-07-05
Anticipated expiration: 2037-11-10
Also published as: CN109786761A

Abstract

The invention relates to a positive electrode for a zinc-bromine flow battery, which takes a conductive current collector as a matrix, a catalytic material is supported on the matrix, the catalytic material is carbon-coated metal titanium disulfide, and the conductive current collector is foamed nickel or carbon felt. Starting with the electrode, the electrode in the flow battery provides a reaction field for electrochemical reaction, and if the generated bromine can be completely reacted in the discharging process, the concentration of bromine in the electrolyte solution in the subsequent circulating process can be greatly reduced, and the permeation pollution of the bromine is reduced.

Description

Positive electrode material for zinc-bromine flow battery, preparation and application

Technical Field

The invention relates to the technical field of electrodes for zinc-bromine flow batteries, in particular to a zinc-bromine flow battery anode material and a preparation technology thereof.

Background

Compared with the all-vanadium redox flow battery, the zinc-bromine redox flow battery has the advantages of high energy density and low cost. The theoretical open-circuit voltage of the zinc-bromine flow energy storage battery is about 1.80V, and the theoretical energy density is 430 Wh/kg. The positive electrode and the negative electrode of the zinc-bromine flow battery are separated by a diaphragm, and electrolyte solutions on both sides are ZnBr₂And (3) solution. Under the action of the power pump, the electrolyte solution circulates in a closed loop formed by the liquid storage tank and the battery. The potential difference between the positive electrode pair and the negative electrode pair is the power for reaction, and the electrode reaction of the zinc-bromine flow battery is as follows:

and (3) positive electrode:

negative electrode:

the study of zinc-bromine flow batteries began in the late 70 s and early 80 s of the 20 th century. The zinc bromine flow battery is developed faster in the united states, and the united states ZBB company provides potential customers with various commercial modules such as 50kWh and 500kWh for application demonstration in 2008, and positions the zinc bromine flow energy storage battery in the fields of electric vehicle power supplies, wind energy and solar energy storage batteries, emergency power supplies and the like.

Nevertheless, there are still many problems and challenges to be solved for the zinc-bromine flow battery to be used in industrialization.

The bromine environmental pollution and the penetration of the positive electrode of the zinc bromine battery are key problems which restrict the practicability and the industrialization of the zinc bromine flow battery. Bromine generated during battery charging can not be completely changed into bromide ions in a discharging stage, so that on one hand, the coulomb efficiency of the battery in subsequent circulation is reduced, and on the other hand, the concentration of the bromine in the positive electrode is easily too high, and the bromine permeates into the environment to cause pollution. In order to reduce such self-discharge and environmental pollution, the existing solutions mainly include: 1) and adding a bromine simple substance complexing agent into the electrolyte solution to reduce the concentration of the free bromine simple substance. The commonly used bromine simple substance complexing agent is mainly a brominated water-soluble organic compound, and reduces the content of free bromine simple substance in the electrolyte solution by the characteristic that the complexing agent is used for complexing the bromine simple substance to form a phase independently, thereby solving the problem of bromine simple substance permeation; 2) by developing the cheap bromine-resistant diaphragm, on the basis of ensuring the ion conduction, the thickness and the pore size distribution of the bromine-resistant diaphragm are regulated and controlled to realize the isolation of the electrolyte solution of the positive electrode and the negative electrode and reduce the permeation of bromine.

As the main body of the battery, the anode material mainly uses a carbon material as a catalytic material of the anode bromine at present, and the effect is poor.

Disclosure of Invention

In order to solve the technical problems, the invention starts with the electrode, and the electrode in the flow battery provides a reaction field for electrochemical reaction, for example, the generated bromine can be completely reacted in the discharging process, so that the concentration of bromine in the electrolyte solution in the subsequent circulating process can be greatly reduced, and the permeation pollution of the bromine is reduced. Therefore, the development of efficient elemental bromine redox catalytic materials is the key to solve the problems.

In order to achieve the purpose of the invention, the specific technical scheme is as follows:

the metal sulfide is a better photocatalyst and is mainly used for catalyzing the oxidation-reduction reaction of halogen ions, wherein the function of the titanium disulfide is particularly obvious.

The positive electrode for the zinc-bromine flow battery takes a conductive current collector as a matrix, and a catalytic material is supported on the matrix and is carbon-coated metal titanium disulfide. The conductive current collector is a nickel foam or carbon felt.

The preparation method of the positive electrode comprises the following steps of,

sintering an organic compound containing sulfur, titanium and carbon elements under the protection of inert atmosphere,

synthesizing carbon-coated metal titanium disulfide;

coating the synthesized carbon-coated metal titanium disulfide on a conductive current collector substrate, wherein the loading capacity is 1-4mg/cm²。

The organic compound is alkyl thiourethane titanium salt.

The number of carbon atoms in the titanium alkyl thiocarbamate salt is between 4 and 10.

The inert atmosphere gas is nitrogen or/and argon.

The sintering temperature is 500-1000 ℃, and the heating rate is 1-10 ℃ per minute.

The sintering temperature is 1-4 h.

The prepared carbon-coated titanium disulfide material and the binder are coated on the conductive current collector according to the mass ratio of 9:1-8:2, and the loading capacity is 1-4mg/cm²(ii) a The binder is one or more of Nafion, PVDF or PTFE.

The carbon-coated metal titanium disulfide is used as a positive electrode catalytic material to be applied to a zinc-bromine flow battery.

Drawings

Figure 1, SEM image of carbon coated metal titanium disulfide synthesized in example 1.

Fig. 2, SEM image of the positive electrode prepared from carbon-coated metal titanium disulfide synthesized in example 1.

Figure 3, graph comparing cycle performance.

Figure 4 SEM image of carbon coated metal titanium disulfide synthesized in example 2.

Figure 5, SEM image of carbon coated metal titanium disulfide synthesized in example 3.

Detailed Description

Example 1

2g of titanium dimethyldithiocarbamate is placed under nitrogen, and the temperature is increased from room temperature to the sintering temperature of 500 ℃, wherein the temperature increase rate is 1 ℃ per minute. And sintering at 500 ℃ for 1h, and taking out to obtain the carbon-coated metal titanium sulfide. The material was agglomerated in granular form as shown in fig. 1, wherein the white particles were uncoated titanium sulfide. The prepared carbon-coated titanium disulfide material and the adhesive nafion are coated on 36cm in a ratio of 9:1²The loading amount on the carbon felt (5mm thickness) is 2mg/cm²As a positive electrode;

the cathode is 36cm²Carbon felt (5mm thickness) with nafion membrane in the middle as the membrane. The electrolyte of the positive electrode and the negative electrode is 60ml of 2mol/L zinc bromide solution. And circularly flows between the liquid storage tank and the positive and negative electrodes of the battery through a circulating pipeline. The battery adopts 40mA/cm²Charging and discharging at current density for 1 h; the discharge cut-off voltage was 1.0V. The cycle performance is shown in figure 3.

Comparative example 1

The positive and negative electrodes are 36cm²Carbon felt (5mm thickness) with nafion membrane in the middle as the membrane. The electrolyte of the positive electrode and the negative electrode is 60ml of 2mol/L zinc bromide solution. And circularly flows between the liquid storage tank and the positive and negative electrodes of the battery through a circulating pipeline. The battery adopts 40mA/cm²Charging and discharging at current density for 1 h; the discharge cut-off voltage was 1.0V. The cycle performance is shown in figure 3.

As can be seen from fig. 3, the coulombic efficiency of the cell of example 1 is significantly higher than that of comparative example 1. Illustrating the efficient use of elemental bromine. Also, the cycle stability of example 1 was significantly improved.

Example 2

2g of titanium diethyldithiocarbamate was placed under nitrogen and the temperature was raised from room temperature to a sintering temperature of 700 ℃ at a rate of 10 ℃ per minute. And sintering at 700 ℃ for 2h, and taking out to obtain the carbon-coated metal titanium sulfide. The material was agglomerated in granular form, see fig. 4.

Example 3

2g of titanium diethyldithiocarbamate was placed under nitrogen gas and the temperature was raised from room temperature to a sintering temperature of 1000 ℃ at a rate of 5 ℃ per minute. And sintering at 1000 ℃ for 4h, and taking out to obtain the carbon-coated metal titanium sulfide. The material is agglomerated in a granular form as shown in fig. 5, from which it is apparent that the bright white is titanium sulfide embedded in the carbon skeleton.

Claims

1. The application of the positive electrode in the zinc-bromine flow battery is characterized in that: the anode takes a conductive current collector as a matrix, a catalytic material is loaded on the matrix, the catalytic material is carbon-coated titanium disulfide, and the conductive current collector is foamed nickel or a carbon felt; the carbon-coated titanium disulfide is used as a positive electrode catalytic material and applied to a zinc-bromine flow battery;

the carbon-coated titanium disulfide is synthesized by sintering an organic compound containing sulfur, titanium and carbon elements under the protection of inert atmosphere, wherein the organic compound is alkyl thiourethane titanium salt.

2. Use according to claim 1, characterized in that: the sintering temperature is 500-1000 ℃, and the sintering temperature time is 1-4 h.

3. Use according to any of claims 1-2, wherein:

1) sintering an organic compound simultaneously containing sulfur, titanium and carbon elements under the protection of inert atmosphere to synthesize carbon-coated titanium disulfide;

2) the synthesized carbon-coated titanium disulfide is coated on a conductive current collector substrate, and the loading is 1-4mg/cm 2.

4. Use according to claim 1, characterized in that: the number of carbon atoms of the alkyl group in the titanium alkyl thiocarbamate is between 4 and 10.

5. Use according to claim 1, characterized in that: in the sintering process, the organic compound is heated from room temperature to the sintering temperature, and the heating rate is 1-10 ℃ per minute.

6. Use according to claim 1, characterized in that: the prepared carbon-coated titanium disulfide and the binder are coated on a conductive current collector according to the mass ratio of 9:1-8:2, and the loading capacity is 1-4mg/cm 2; the binder is one or more of Nafion, PVDF or PTFE.