Stability of highly supersaturated vanadium electrolyte solution and characterization of precipitated phases for vanadium redox flow battery  

作　　者：Waldemir M.Carvalho Jr Laurent Cassayre Delphine Quaranta Fabien Chauvet Ranine El-Hage Theodore Tzedakis Béatrice Biscans 

机构地区：[1]Laboratoire de Génie Chimique,Universitéde Toulouse,CNRS,INP,UPS,Toulouse,France

出　　处：《Journal of Energy Chemistry》2021年第10期436-445,I0012,共11页能源化学（英文版）

基　　金：financial support from the French National Research Agency(project ANR-17-CE05-0023)。

摘　　要：The vanadium redox flow battery(VRFB)has been receiving great attention in recent years as one of the most viable energy storage technologies for large-scale applications.However,higher concentrations of vanadium species are required in the H_(2)O-H_(2)SO_(4) electrolyte in order to improve the VRFB energy density.This might lead to unwanted precipitation of vanadium compounds,whose nature has not been accurately characterized yet.For this purpose,this study reports the preparation ofⅤ^((Ⅱ)),ⅤV^((Ⅲ)),Ⅴ^((Ⅳ))andⅤ^((Ⅴ))supersaturated solutions in a 5 M H_(2)SO_(4)-H_(2)O electrolyte by an electrolytic method,from the only vanadium sulfate compound commercially available(VOSO_(4)).The precipitates obtained by ageing of the stirred solutions are representative of the solids that may form in a VRFB operated with such supersaturated solutions.The solid phases are identified using thermogravimetric analysis,X-ray diffraction and SEM.We report that dissolvedⅤ^((Ⅱ)),Ⅴ^((Ⅲ))andⅤ^((Ⅳ))species precipitate as crystals of VSO_(4),V_(2)(SO_(4))3 and VOSO_(4) hydrates and not in their anhydrous form;conversely V^((Ⅴ))precipitates as an amorphous V_(2) O_(5) oxide partially hydrated.The measured hydration degrees(respectively 1.5,9,3 and 0.26 mol of H_(2)O per mol of compound)might significantly affect the overall engineering of VRFB operating with high vanadium concentrations.

关 键 词：Vanadium Redox Flow Batteries Supersaturated electrolyte PRECIPITATION Vanadium sulfate Vanadium hydrates 

分 类 号：TM912[电气工程—电力电子与电力传动] O646.1[理学—物理化学]