CN113036156B

CN113036156B - Gel electrolyte and zinc-bromine or zinc-iodine single flow battery

Info

Publication number: CN113036156B
Application number: CN201911250755.6A
Authority: CN
Inventors: 李先锋; 王胜男; 尹彦斌; 张华民
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2019-12-09
Filing date: 2019-12-09
Publication date: 2022-05-31
Anticipated expiration: 2039-12-09
Also published as: CN113036156A

Abstract

A hydrogel electrolyte is used for a zinc halogen (bromine, iodine) single flow battery. The electrolyte is an aqueous solution of iodide, zinc salt and supporting electrolyte, and the battery membrane material is a macromolecule without ion exchange groups. Stirring and mixing polyvinyl alcohol and electrolyte, taking glutaraldehyde as a cross-linking agent, immersing a carbon felt into the obtained solution, and preparing the zinc halogen single flow battery anode under the weak acid condition of the electrolyte. The hydrogel structure can obviously inhibit the mutual connection of halogen ions from the positive electrode to the negative electrode, thereby reducing the self-discharge of the battery and improving the performance of the battery. The gel electrolyte has the advantages of simple operation, stable process and low cost. The gel electrolyte prepared by the invention can effectively improve the coulombic efficiency and prolong the service life of the battery when operating the zinc halogen single flow battery.

Description

Gel electrolyte and zinc-bromine or zinc-iodine single flow battery

Technical Field

The invention relates to the field of flow batteries, in particular to the field of zinc bromine/iodine single flow batteries.

Background

The large use of fossil energy raises energy crisis and environmental issues. The development and utilization of non-renewable energy sources become the focus of attention of all countries in the world. However, the discontinuity and instability of renewable energy sources such as wind energy and solar energy make their direct utilization difficult, so that the continuous supply of renewable energy sources by using energy storage technology becomes the key to solve the above problems. The flow battery has good safety and long design life due to flexible design (energy and power separated design), and has become one of the technologies with the best prospect in the large-scale energy storage market.

In many flow battery systems, the zinc bromine and zinc iodine flow batteries attract attention due to the advantages of simple working principle, safe operation, easy maintenance and low cost, but the development of the batteries is restricted by the self-discharge phenomenon of the batteries. Br produced at the positive electrode during charging of the battery₃ ^-、I₃ ^-The zinc oxide can diffuse to the negative electrode through the diaphragm micropores and further has an oxidation-reduction reaction with the simple substance zinc of the negative electrode, so that the coulomb efficiency of the battery is reduced, and the capacity is reduced.

Disclosure of Invention

The positive gel structure electrolyte of zinc bromine/iodine single flow battery is prepared by crosslinking polyvinyl alcohol with glutaraldehyde to fix the electrolyte in the micropores of gel structure. Br in charging process after electrolyte is fixed₃ ^-、I₃ ^-Can be fixed in the pore structure of the gel, effectively improves the Br blocking₃ ^-、I₃ ^-The diffusion of the lithium ion battery is inhibited, the self-discharge reaction of the lithium ion battery after the lithium ion battery is diffused to the cathode of the lithium ion battery is relieved, the coulomb efficiency of the lithium ion battery is improved, and the capacity of the lithium ion battery is improved.

The crosslinking process of the gel electrolyte is simple and easy to implement, and the carbon felt current collector with the three-dimensional porous structure can be crosslinked in vivo, so that the side reaction of the battery is slowed down, and the conductivity of the electrolyte is not reduced. The manufacturing process comprises the following steps: dissolving polyvinyl alcohol in electrolyte, fully mixing, adding glutaraldehyde, putting into a three-dimensional porous carbon felt current collector, standing and crosslinking at room temperature for 24 hours without external initiation of crosslinking reaction. And soaking the gel carbon felt electrolyte electrode integrated structure obtained after crosslinking in electrolyte for later use.

When the zinc bromine/iodine single flow battery is assembled, the anode uses a gel carbon felt electrolyte electrode integrated structure, the cathode uses a carbon felt, the diaphragm is a porous membrane, a pump on the anode side does not flow, and the electrolyte on the cathode side circularly flows.

The gel carbon felt integrated electrode manufactured by the method is 40mA/cm²And 80mA/cm²When the zinc-iodine and zinc-bromine single flow batteries are operated, the coulombic efficiency is respectively 9-10% and 5-6%.

The hydrogel structure can obviously inhibit the mutual connection of halogen ions from the positive electrode to the negative electrode, thereby reducing the self-discharge of the battery and improving the performance of the battery. The gel electrolyte has the advantages of simple operation, stable process and low cost. The gel electrolyte prepared by the invention can be used for operating the zinc halogen single flow battery, thereby effectively improving the coulomb efficiency and prolonging the service life of the battery.

Drawings

FIG. 1 is a schematic diagram of a single flow battery assembly according to the present invention;

FIG. 2 is a graph of battery performance data for example 1;

FIG. 3 is a graph of example 2 cell performance data;

FIG. 4 is a graph of comparative example 1 cell performance data;

fig. 5 is a graph of comparative example 2 cell performance data.

Detailed Description

The performance of the gel electrolyte was tested using a single flow cell, an embodiment of which is assembled as follows. Wherein 1 is a positive and a negative terminal plate; 2 is a positive and negative current collector; 3 liquid flow frames of positive and negative electrodes; 4 is a membrane of the battery; 5 is a positive electrolyte inlet and outlet valve; 6 is an electrolyte storage tank; 7 electrolyte circulation pump. The positive electrode is the gel carbon felt integrated electrode or the carbon felt dipped with electrolyte, the negative electrode is the carbon felt electrode, the electrolyte is the conventional electrolyte corresponding to zinc bromide/iodine, and the film is a commercial polyethylene porous film.

Example 1

A gel electrolyte is prepared by the following steps:

100ml of zinc-iodine electrolyte is taken, and the electrolyte comprises 2mol/L of zinc bromide, 4mol/L of potassium iodide and 2mol/L of potassium chloride. Dissolving 4g of polyvinyl alcohol in the electrolyte, stirring for 12h at 40 ℃, fully mixing, and adding 1ml of glutaraldehyde to form a steeping liquor; and (3) placing the carbon felt in the impregnation liquid, standing and crosslinking for 20 hours at room temperature, and scraping the crosslinked substances on the surface of the carbon felt by using a blade to obtain the zinc-iodine gel electrolyte anode.

Zinc-iodine single flow battery was assembled using a gel carbon felt integrated electrode, and a membrane using a commercial polyethylene porous membrane at 40mA/cm²Battery performance data under the conditions. The result shows that the coulombic efficiency of the battery is 92.22%, the mutual connection of iodine three negative ions is effectively inhibited, and the battery performance is improved.

Example 2

100ml of zinc-bromine electrolyte is taken, and the electrolyte comprises 2mol/L of zinc bromide, 0.8mol/L of 1-methyl-1-ethyl pyrrolidine bromide and 3mol/L of potassium chloride. Dissolving 4g of polyvinyl alcohol in the electrolyte, stirring for 12h at 40 ℃, fully mixing, and adding 1ml of glutaraldehyde to form a steeping liquor; and (3) placing the carbon felt in the impregnation liquid, standing and crosslinking for 20 hours at room temperature, and removing the crosslinking substances on the surface of the carbon felt to obtain the zinc-bromine gel electrolyte anode.

The zinc-bromine single flow battery is assembled by using the gel carbon felt integrated electrode, and the membrane uses a commercial polyethylene porous membrane at 80mA/cm²Battery performance data under the conditions. The result shows that the coulombic efficiency of the battery is 96.54 percent, the mutual connection of three negative ions of bromine is effectively inhibited, and the performance of the battery is improved.

Comparative example 1

The anode uses carbon felt electrode soaked in electrolyte to assemble zinc-iodine single flow battery at 40mA/cm²Battery performance data under the conditions. The result shows that the coulombic efficiency of the battery is 83.74%, and the mutual series of iodine three anions causes the self-discharge of the battery, so that the performance of the battery is poor.

The electrolyte was the same as in example 1.

Comparative example 2

The anode uses carbon felt electrode soaked in electrolyte to assemble the zinc-bromine single flow battery at 80mA/cm²Battery performance data under the conditions. The result shows that the coulombic efficiency of the battery is 92.46%, and the mutual series of bromine triple negative ions causes the self-discharge of the battery, so that the performance of the battery is poor.

The electrolyte was the same as in example 2.

Comparative example 3

100ml of zinc-iodine electrolyte and 4g of polyvinyl alcohol are evenly stirred at 40 ℃, 1ml of glutaraldehyde is added to form impregnation liquid, the impregnation liquid is scraped on the surface of a polyethylene porous membrane, and the polyethylene porous membrane is kept stand at room temperature for crosslinking to form a layer of gel with the thickness of 200 mu m. The zinc-iodine single flow battery was formed using the membrane with the gel layer, and the other conditions were the same as in comparative example 1. Compared with the battery using the integrated gel electrolyte anode, the voltage efficiency and the energy efficiency of the battery are reduced, and the internal resistance of the battery is increased; the coulombic efficiency of the battery is also reduced, and the effect of blocking iodine three negative ions/bromine three negative ions is weakened.

Claims

1. The application of the gel electrolyte anode in a zinc bromine or zinc iodine single flow battery is characterized in that: the preparation process of the gel electrolyte anode is as follows:

dissolving polyvinyl alcohol in electrolyte, fully mixing, and adding glutaraldehyde to form impregnation liquid; placing the carbon felt in the impregnation liquid, standing and crosslinking for 12-24h at room temperature, and removing a crosslinking substance on the surface of the carbon felt to obtain a gel electrolyte anode;

the gel electrolyte positive electrode is used as a positive electrode on the non-flowing side of the electrolyte;

when the single flow battery is assembled, the positive electrode adopts a gel carbon felt electrolyte electrode integrated structure, the negative electrode adopts a carbon felt, the diaphragm is a porous membrane, the electrolyte on the positive electrode side does not flow, and the electrolyte on the negative electrode side circularly flows.

2. Use according to claim 1, characterized in that:

the electrolyte is as follows: an aqueous solution containing an electrode active material;

in the zinc-bromine flow battery, the electrode active substances are zinc bromide with the molar concentration of 1-3 mol/L and 1-methyl-1-ethyl pyrrolidine bromide with the molar concentration of 0.1-1 mol/L;

or, in the case of a zinc-iodine flow battery, the electrode active material contains zinc bromide with a molar concentration of 1-4 mol/L and potassium iodide with a molar concentration of 2-8 mol/L.

3. Use according to claim 2, characterized in that:

the electrolyte also contains a supporting electrolyte with the molar concentration of 1-3 mol/L, and the supporting electrolyte is one or two of sodium chloride or potassium chloride.

4. Use according to claim 1, characterized in that:

the degree of polymerization of the polyvinyl alcohol is selected from the group consisting of a low degree of polymerization: 1000-20000.

5. Use according to claim 1 or 4, characterized in that: 4-10g of polyvinyl alcohol and 1-3ml of glutaraldehyde are added to each 100ml of electrolyte.

6. Use according to claim 1 or 4, characterized in that: and soaking the gel carbon felt electrolyte electrode integrated structure obtained after crosslinking in electrolyte for later use.

7. Use according to claim 1, characterized in that:

in the case of a zinc-bromine flow battery, the electrode active substances are zinc bromide with the molar concentration of 2mol/L and 1-methyl-1-ethyl pyrrolidine bromide with the molar concentration of 0.8 mol/L;

or, in the case of a zinc-iodine flow battery, the electrode active material is zinc bromide with a molar concentration of 2mol/L and potassium iodide with a molar concentration of 4 mol/L.

8. Use according to claim 2, characterized in that:

the electrolyte also contains a supporting electrolyte with the molar concentration of 2 mol/L.

9. Use according to claim 1, characterized in that:

the degree of polymerization of the polyvinyl alcohol is selected from the group consisting of a low degree of polymerization: 1700-1800.

10. Use according to claim 1 or 4, characterized in that: 4-6g of polyvinyl alcohol and 1-2ml of glutaraldehyde are added to each 100ml of electrolyte.