CN102856573A - Zinc-vanadium redox flow energy storage battery - Google Patents

Abstract

A zinc-vanadium flow energy storage battery, which is composed of a battery module, an electrolyte storage tank, a liquid pump and pipelines. The battery is composed of a positive electrode, a negative electrode, a positive and negative terminal plate, and a battery diaphragm, and the positive electrode is composed of a positive electrode current collector and carbon felt. Composition, the negative electrode is a deposition type electrode, the positive electrode electrolyte is a sulfuric acid solution of V ⁴⁺ , and the negative electrode electrolyte is an acidic solution of Zn ²⁺ . The liquid flow energy storage battery has the advantages of low cost, environmental friendliness, high energy density, strong temperature adaptability, and high cycle life.

Description

A zinc-vanadium redox flow energy storage battery

technical field

The invention relates to a novel flow energy storage battery, in particular to a zinc vanadium flow energy storage battery.

Background technique

The concept of liquid flow energy storage battery was first proposed as an electrochemical energy storage concept by Thaller, L.H. (NASA Lewis Research Center, Cleveland, US) in 1974. The core of the flow battery is that the active substances that carry out redox reactions and realize the charging and discharging process exist in the electrolyte, and the single-cell or half-cell electrodes are only used as the place for the reaction, not the place where the active substances are stored. Since the active material is stored in the electrolyte, the flow battery has the advantages of separation of power and capacity and long life. Flow batteries have been developed for more than 30 years. Researchers from various countries have obtained a variety of available flow battery systems by changing two oxidation/reduction pairs. Liquid phase energy storage chemical systems include early CrlFe and TilFe systems, and In recent years, the all-vanadium and zinc-bromine flow battery systems have developed well.

The all-vanadium flow energy storage battery was developed by the University of New South Wales in Australia in the late 1980s. The positive/negative electrode electrolyte of the all-vanadium redox flow energy storage battery is vanadium sulfate in different valence states, and the supporting electrolyte is H ₂ SO ₄ . The battery response is:

The negative electrode reaction is: V ²⁺ →V ³⁺ +e

The positive reaction is: V ⁵⁺ +e→V ⁴⁺

The two reactions are reversible on the carbon felt without supporting catalysts, and the migration of H ⁺ maintains the electroneutrality on both sides. Since the active material of this system is the same element with variable valence, the problem of cross-contamination of the reactants at the two poles is alleviated to a certain extent, and the regeneration of the mixed solution of the positive and negative electrodes is facilitated.

However, due to the high price of vanadium in the all-vanadium redox flow energy storage battery, the cost of the battery is too high, and the solubility of the negative electrodes V ²⁺ and V ³⁺ of the all-vanadium redox flow battery is easily reduced when the temperature is high. Precipitation, and the battery will inevitably increase the system temperature during operation, which affects the stable operation performance of the battery. In addition, due to the low solubility of vanadium, the actual energy density of the all-vanadium redox flow battery is only about 15Wh/kg.

Zinc-bromine flow battery: A zinc-bromine flow battery is an electrochemical system that stores energy in a solution. The positive and negative half cells are separated by a separator, and the electrolyte on both sides is a ZnBr _solution . Under the action of the power pump, the electrolyte circulates in the closed circuit formed by the liquid storage tank and the battery. The potential difference between the redox reaction electrode pair is the driving force for the reaction to occur. The electrode reaction of the zinc-bromine flow battery is:

The negative electrode reaction is: Zn ²⁺ +2e→Zn

The positive reaction is: 3Br ^- → Br ₃ ^- +2e

Zinc-bromine flow battery has a higher actual energy density of 65Wh/kg because the negative electrode zinc is the metal with the highest specific energy density among the metal elements that can exist stably in aqueous solution. However, due to the high toxicity of the positive bromine of the battery, its further development is restricted.

Contents of the invention

The purpose of the present invention is to solve the problems of high cost, low energy density, high-temperature negative electrode electrolyte easy crystallization of the all-vanadium redox flow energy storage battery and the poor high-temperature operation performance of the negative electrode and the toxicity of bromine in the zinc-bromine redox flow battery. Based on the advantages of the battery, a zinc-vanadium flow energy storage battery is proposed.

To achieve the above object, the technical scheme of the present invention is as follows:

A zinc-vanadium flow energy storage battery, which is composed of a battery module, an electrolyte storage tank filled with positive and negative electrolytes, a liquid pump and pipelines, wherein the battery module is composed of a positive electrode, a negative electrode, and a battery diaphragm. The electrolyte storage tank of the negative electrolyte is respectively connected to the positive and negative raw material inlet and outlet of the battery module through the liquid pump through the pipeline; the positive electrolyte is an acid solution of tetravalent vanadium, and the negative electrolyte is an acid solution containing Zn ²⁺ ; The actual energy density of vanadium redox flow battery is 35wh/kg.

The electrode reaction is as follows:

The negative electrode reaction is: Zn ²⁺ +2e→Zn

The positive reaction is: V ⁵⁺ +e→V ⁴⁺

The positive electrode electrolyte V ⁴⁺ concentration is 0.5-2.0mol/L; the negative electrode electrolyte Zn ²⁺ concentration is 1.0-5.0mol/L.

The positive electrode of the battery is composed of positive current collector and carbon felt; the negative electrode is a deposited electrode of carbon material, metal foil, metal plate or foam metal. The battery diaphragm adopts anion exchange membrane.

During the charge and discharge process, the electrolyte is continuously flowing between the electrolyte storage tank and the stack through the pipeline driven by the liquid pump. When charging, zinc is deposited from the electrolyte onto the negative electrode current collector to become the negative electrode active material, V ⁴⁺ is oxidized to V ⁵⁺ as the positive electrode active material, and zinc is dissolved from the negative electrode current collector into the electrolyte during discharge. V ⁵⁺ is reduced to V ⁴⁺ . Since the active materials of the battery are all cations, and the anion membrane has the characteristics of a small cation passing rate, the problem of mixing positive and negative active materials is solved.

Beneficial effects of the present invention:

1. The actual energy density of the zinc-vanadium flow energy storage battery is 35wh/kg, which is much higher than the actual energy density of the vanadium flow energy storage battery of 15wh/kg;

2. Zinc-vanadium flow energy storage battery has strong temperature adaptability and can work normally at -10°C to 50°C;

3. Since the active materials of the battery are all cations, and the anion membrane has the characteristics of a small cation pass rate, the problem of mixing positive and negative active materials is solved;

4. Zinc-vanadium flow energy storage battery has less environmental pollution and no volatile substance overflow problem;

5. The battery has the advantages of low cost and high cycle life.

Description of drawings

Fig. 1 is the structural representation of zinc-vanadium redox flow energy storage battery of the present invention;

1-battery module; 2-negative terminal plate; 3-positive terminal plate; 4-negative pole; 5-positive pole; 6-battery separator; 7-negative pole storage tank; 8-positive pole storage tank; 9-pump;

Fig. 2 is the charging and discharging curve diagram of embodiment 1 assembled battery;

FIG. 3 is a charge-discharge curve diagram of the battery assembled in Example 2. FIG.

Detailed ways

A zinc-vanadium flow energy storage battery, which is composed of a battery module, an electrolyte storage tank filled with positive and negative electrolytes, a liquid pump and pipelines, wherein the battery module is composed of a positive electrode, a negative electrode, and a battery diaphragm. The electrolyte storage tank of the negative electrolyte is respectively connected to the positive and negative raw material inlet and outlet of the battery module through the liquid pump through the pipeline; flow continuously.

Example 1

Add 40ml, 1.5mol/L vanadyl sulfate dissolved in 3mol/L sulfuric acid solution to the positive electrode electrolyte storage tank of the battery as the positive electrode electrolyte, add 40ml, 2.0mol/L zinc sulfate solution to the negative electrode electrolyte storage tank as the negative electrode electrolyte. The positive electrode is composed of a current collector graphite plate and a 9cm2 carbon felt, the negative electrode current collector is a ^9cm2 graphite plate, and the battery separator is an imidazole-type anion exchange membrane. The battery is charged and discharged at 50°C at 20mA/ ^cm2 . It can be seen from Fig. 2 that the coulombic efficiency of the obtained battery is 97%, and the energy efficiency is 69%.

Example 2

Add 40ml, 1.0mol/L vanadyl sulfate solution and 3mol/L sulfuric acid solution to the positive electrode electrolyte storage tank of the battery as the positive electrode electrolyte, add 40ml, 3.0mol/L zinc sulfate solution to the negative electrode electrolyte storage tank as the negative electrode electrolyte. The positive electrode is composed of current collector graphite plate and 9cm ² carbon felt, the negative electrode current collector is 9cm ² zinc foam, and the battery separator is an imidazole-type anion exchange membrane. The battery is charged and discharged at -10°C at 20mA/cm ² . It can be seen from Fig. 3 that the coulombic efficiency of the obtained battery is 96%, and the energy efficiency is 70%.

Claims (7)

1. A zinc-vanadium redox flow energy storage battery, characterized in that: The negative electrode reaction of the battery system is: Zn ²⁺ +2e→Zn; the positive electrode reaction is: V ⁵⁺ +e→V ⁴⁺ . 2. The zinc vanadium flow energy storage battery according to claim 1, characterized in that: The battery system consists of a battery module, an electrolyte storage tank filled with positive and negative electrolytes, a liquid pump and pipelines, wherein the battery module includes a positive terminal plate, a negative terminal plate, a positive pole, a negative pole, a battery diaphragm, and a positive electrolytic The liquid is an acidic solution of tetravalent vanadium, the negative electrode electrolyte is an acidic solution of zinc ions, and the electrolyte storage tanks of the positive and negative electrolytes are respectively connected to the positive and negative raw material inlets and outlets of the battery module through liquid pumps and pipelines. 3. The zinc-vanadium redox flow energy storage battery according to claim 2, characterized in that: the positive electrode of the battery is composed of positive electrode current collector and carbon felt; the negative electrode is a deposited electrode of carbon material, metal foil, metal plate or foam metal . 4. The zinc-vanadium flow energy storage battery according to claim 2, characterized in that: the positive electrode electrolyte V ⁴⁺ concentration is 0.5-2.0 mol/L. 5. The zinc-vanadium flow energy storage battery according to claim 2, characterized in that the concentration of Zn ²⁺ in the negative electrode electrolyte is 1.0-5.0 mol/L. 6. The zinc-vanadium flow energy storage battery according to claim 2, characterized in that: the battery separator is an anion exchange membrane. 7. The zinc-vanadium flow energy storage battery according to claim 2, characterized in that: during the charging and discharging process of the battery, the electrolyte is continuously flowing between the electrolyte storage tank and the battery through the pipeline under the push of the liquid pump When charging, zinc ions are deposited from the electrolyte to the negative electrode to become the negative active material, and V ⁴⁺ is oxidized to V ⁵⁺ as the positive active material. When discharging, zinc dissolves from the negative electrode into the electrolyte, and V ⁵⁺ is reduced to V ^{4 +} .

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