Effect of l-glutamic acid on the positive electrolyte for all-vanadium redox flow battery

l-Glutamic acid is used as an additive for the positive electrolyte of all-vanadium redox flow battery (VRFB), and its effect on the thermal stability and electrochemical activity is investigated. It is found that the addition of l-glutamic can significantly alleviate the precipitation of V2O5 from positive electrolyte. The conservation rate of V(V) ion can be as high as 58% after 2 M V(V) solution being kept in 40 °C for 89 h. Besides, l-glutamic can also improve the mass transport and electrochemical performance of anolyte. A high coulombic efficiency of over 95% and energy efficiency of 74% are obtained. XPS spectra illustrate that l-glutamic can react with the surface of carbon felt electrode and introduce more oxygen-containing and nitrogen-containing groups, which should be responsible for the improvement of electrochemical performance.

► Amino acid is used as additive for all-vanadium redox flow battery. ► The additive can significantly improve performance of positive electrolyte. ► Mechanism for the improvement is investigated.