Towards sustainable redox flow battery (RFB) with lignin-based electrolyte
Monalisa Chakraborty
Division of Applied Electrochemistry, Department of Chemical Engineering, KTH Royal Institute of Technology
RFBs are attracting choice for grid-scale energy storage applications thanks to their unique feature of independent scaling of energy and power. Low-cost and non-toxic organic electrolytes are the potential alternative to the present metal-based RFB chemistries. Lignin, the most naturally occuring biopolymer on Earth, features the advantages of high carbon content, rich in aromatic groups, a potential electrolyte for RFBs. In this work, lignosulfonate is considered as redox species modified in optimum oxidative conditions. CV analysis confirmed its electrochemical activity, later for RFB tests, modified lignosulfonate was used on the negative side versus ferrocyanide in the counterpart in alkaline media. From RFB cycling, a substantial improvement was achieved in the charge/discharge capacities and coulombic efficiency using modified lignosulfonate compared to pristine. Further study on higher concentration of lignin is under way towards boosting the RFB capacity thus energy density.