CN104852074A

CN104852074A - Method for preparing all-vanadium redox flow battery positive electrolyte via electrolytic synthesis method

Info

Publication number: CN104852074A
Application number: CN201510165077.9A
Authority: CN
Inventors: 陈殿磊; 吴艳民; 任凤
Original assignee: New Energy Technology Co Ltd Is Got Over By Shenzhen Ten Thousand
Current assignee: New Energy Technology Co Ltd Is Got Over By Shenzhen Ten Thousand
Priority date: 2015-04-09
Filing date: 2015-04-09
Publication date: 2015-08-19

Abstract

The invention discloses a method for preparing an all-vanadium redox flow battery positive electrolyte via an electrolytic synthesis method, comprising the steps as follows: using V2O5 or metavanadate (NH4VO3) as raw material, adding H2SO4 solution with the V2O5 or the metavanadate (NH4VO3) in a negative pole area of an electrolytic tank with a diaphragm; adding H2SO4 with the same concentration in a positive pole area; adding appropriate direct current at the two poles of the electrolytic tank, enabling the V2O5 or the metavanadate powder to be reduced on a negative pole surface after being contacted with a negative pole, and simultaneously enabling the V2O5 or the metavanadate powder to be reduced with V(II), V(III), V(IV) generated in the electrolyte so as to achieve dissolving. The method of the invention is suitable for preparing vanadium battery electrolyte with high concentration, and the maximum concentration can reach 5mol/L. The method for preparing the all-vanadium redox flow battery positive electrolyte via the electrolytic synthesis method of the invention is suitable for mass production and facilitates practicality of a vanadium battery.

Description

A kind of method being prepared positive electrolyte for all-vanadiumredox flow battery by electrolytic synthesis

Technical field

The present invention relates to a kind of method being prepared positive electrolyte for all-vanadiumredox flow battery by electrolytic synthesis.

Background technology

Vanadium redox battery (VRB) receives much attention because having stored energy capacitance and power adjustable, big current and can't harm the advantages such as deep discharge, long service life, Operation and Maintenance are simple, environmental protection, obtain very large development in recent years, progressively moving towards practical.

Vanadium cell forms primarily of 3 parts: electrode material section, battery diaphragm, electrolyte, and therefore its development is also mainly by the restriction of these 3 aspects.Wherein electrolyte is the core of vanadium cell, and it is the multivalent state system of a vanadium, realizes storage and the release of vanadium cell energy.Electrolyte and the conventional batteries of vanadium cell are not quite alike, it comprises the ion (active material as vanadium cell) of the different valence state of sulfuric acid (as supporting electrolyte) and vanadium, therefore the storage performance of vanadium cell more depends on its electrolyte than other battery, require that electrolyte will have high concentration, to realize the high-energy-density of battery, there is high stability again.

Anode electrolyte of vanadium battery is V (V)/V (IV) mixed solution using sulfuric acid as supporting electrolyte, and when fully charged state, vanadium ion is pentavalent, is tetravalence completely during electric discharge.In strong acidic environment, pentavalent vanadium is often considered to flaxen VO2+ form existence, and tetravalence vanadium then exists with the VO2+ form of sapphirine.

The initial electrolysis liquid of vanadium cell generally using the sulfuric acid solution of tetravalent vanadium ion as both positive and negative polarity.After primary charging activation, positive pole is oxidized to V (V) ion.Negative pole is reduced into V (II) ion.When initial electrolysis liquid concentration is identical, the volume of anode electrolyte is 2 times of negative pole.Because in activation process, negative pole also exists the transfer of two electronics, and positive pole only has one.Although VOSO4 directly can be used as the initial electrolysis liquid of vanadium cell, its price is very expensive, is unfavorable for the large-scale promotion of vanadium cell.Because the solubility of V2O5 is very little, directly can not be dissolved in acid solution by V2O5 and produce battery electrolyte.Therefore a kind of method better preparing electrolyte must separately be sought.In the preparation process of electrolyte of vanadium redox battery, factors such as improving its concentration, stability, conductivity, electro-chemical activity and economy must be considered.

Summary of the invention

The object of the invention is to improve positive electrolyte for all-vanadiumredox flow battery concentration, stability, conductivity, electro-chemical activity and economy.

For achieving the above object, the present invention adopts following technical scheme: a kind of method being prepared positive electrolyte for all-vanadiumredox flow battery by electrolytic synthesis, with V2O5 or metavanadate (NH4VO3) for raw material, the H2SO4 solution that people contains V2O5 or metavanadate is added in septate electrolytic cell negative pole district, positive polar region adds the H2SO4 of same concentrations, suitable direct current is added at electrolytic cell the two poles of the earth, be reduced in negative terminal surface after V2O5 or metavanadate powder and cathode contact, the V (II) simultaneously generated in electrolyte, V (III), V2O5 or metavanadate powder reduction also can make it dissolve by V (IV), the reaction that negative pole half-cell occurs is:

(1)V(V)+3e→V(Ⅱ)

(2)V(V)+2e→V(Ⅲ)

(3)V(V)+e→V(Ⅳ)

(4)V(Ⅱ)+V(Ⅳ)→2v(Ⅲ)

(5)V(II)+1/2V2O5→V(Ⅲ)／V(Ⅳ)

(6)V(Ⅲ)+1/2V2O5→2V(Ⅳ)。

Because electrolysis relates to the reduction at electrode surface of V2O5 or metavanadate, therefore higher to the requirement of electrode, the preparation of electrode is very important.Use electrolysis can obtain the electrolyte of vanadium redox battery of 5mol/L VOSO4+5mol/L H2SO4.The electrolyte of high concentration is an effectively approach for the energy density improving vanadium cell.

The present invention is simple to operate, is suitable for large-scale production, is conducive to the practical of vanadium cell.Another advantage of electrolysis is the electrolyte of vanadium redox battery being suitable for producing high concentration, and maximum concentration can reach 5mol/L.In vanadium cell, the energy content of battery stores with the chemical energy form of electrolyte, and the liquid stream electrolyte of development high concentration is the effective way improving vanadium cell energy density, and therefore producing electrolyte of vanadium redox battery by electrolysis is a kind of proper method.

Embodiment

A kind of method being prepared positive electrolyte for all-vanadiumredox flow battery by electrolytic synthesis, take V2O5 as raw material, the H2SO4 solution of people containing V2O5 is added in septate electrolytic cell negative pole district, positive polar region adds the H2SO4 solution of same concentrations, suitable direct current is added at electrolytic cell the two poles of the earth, be reduced in negative terminal surface after V2O5 and cathode contact, V2O5 reduction also can make it dissolve by the V (II), the V (III) that generate in electrolyte, V (IV) simultaneously.

Active material and supporting electrolyte need Optimization.By studying the stability of anode electrolyte of vanadium battery under different solution compositions, different solution charged states and different temperatures further, find that 3 ~ 4mol/L is more suitable for than usual 2mol/L, not only stability improves, and the conductivity of electrolyte increases, this is by the voltage efficiency of raising battery in charge and discharge cycles.In addition, at higher temperature or when not needing often to carry out charge and discharge cycles, optimum electrolyte composition is the sulfuric acid of 1.5mol/L V (V) and 3 ~ 4mol/L; There is no long term high temperature, and the electrolyte solution continuing to carry out 2mol/L V (V) and 3 ~ 4 mol/L sulfuric acid composition in the system of charge and discharge cycles can be used safely.Consider energy density two factor of electrode reaction dynamics and battery, the optium concentration of V (IV) solution is the concentration of 1.5 ~ 2.0mol/L, H2SO4 is 3mol/L.

For the technical staff in field of the present invention, according to technical scheme described above and design, other various corresponding change can be made, all should belong within the protection range of application claims these all changes.

Claims

1. prepared the method for positive electrolyte for all-vanadiumredox flow battery by electrolytic synthesis for one kind, it is characterized in that: with V2O5 or metavanadate (NH4VO3) for raw material, the H2SO4 solution that people contains V2O5 or metavanadate is added in septate electrolytic cell negative pole district, positive polar region adds the H2SO4 of same concentrations, suitable direct current is added at electrolytic cell the two poles of the earth, be reduced in negative terminal surface after V2O5 or metavanadate powder and cathode contact, the V (II) simultaneously generated in electrolyte, V (III), V2O5 or metavanadate powder reduction also can make it dissolve by V (IV).