Conversion of Spent Coffee Beans to Electrode Material for Vanadium Redox Flow Batteries

This study presents the application of pyrolyzed spent coffee beans as a potential electrode material to replace commercial bipolar graphite plate in vanadium redox flow batteries (VRB). The results indicate that the biochar obtained from spent coffee beans shows relatively good electrochemical charge transfer kinetics of vanadium redox reactions as well as generates higher energy and voltage efficiency in a static cell test when compared to TF6 bipolar graphite plate. Additionally, the biochar was activated via steam at various activation times to increase its surface area, and their effect on the kinetics of the electrochemical reactions was investigated. The activated carbon did not exhibit any improvement neither in electron transfer kinetics nor in the battery efficiency, despite their increased surface area. The performed studies demonstrate that the biochar obtained from spent coffee beans can be a low-cost electrode material for VRB with improved performance characteristics.