Flexible Graphite–Poly(Lactic Acid) Composite Films as Large-Area Conductive Electrodes for Energy Applications

For industrial-scale electrochemical applications of renewable energy routes such as electrochemical water splitting or supercapacitors, there is a huge need for flexible, durable, and large-area electrodes. In this study, flexible and conductive poly(lactic acid)/graphite composite films, with a high mass percentage (∼64%) of conductive graphitic material, are prepared without specialized equipment and can be used as stable electrodes in aqueous solutions. These films can be used as a substrate for the hydrogen evolution reaction, which is demonstrated in this study by spray coating with molybdenum(IV) sulfide. Finally, the films are manipulated to construct a flexible solid-state supercapacitor device that can withstand a bending angle of 120° without any change in performance. The geometric characteristics of the electrodes can be manipulated to any shape and size, and as such, they are scalable to large areas.