Influence of Several Phosphate-Containing Additives on the Stability and Electrochemical Behavior of Positive Electrolytes for Vanadium Redox Flow Battery

The poor operational stability of electrolytes is a persistent impediment in building redox flow battery technology; choosing suitable additives usually the research direction to solve this problem. effects five phosphate containing (including 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), hexamethylene diamine tetramethylene phosphonic (HDTMPA), amino trimethylene (ATMPA), sodium ethylenediamine phosphonate (EDTMPS), and diethyl triamine pentamethylene (DTPMP)) on thermal electrochemical performance positive electrolyte vanadium were investigated. With 0.5 wt% addition, most selected able improve electrolyte. HEDP HDTMPA extended time pentavalent at 50 °C from 5 days (blank sample) 30 15 days, respectively. was further investigated by cyclic voltammetry, steady state polarization, impedance spectroscopy tests. It found that enhanced activity electrolyte, diffusion coefficients, exchange current densities, reaction rate constants V(IV) species became larger with addition these additives. verified are significantly improved combination ATMPA + or HDTMPA. This study provides new approach for battery.