Recent advances in the design of bacteria-based supercapacitors: Current limitations and future opportunities

A rapid technological advancement observed in recent decades has indicated the urgent need for the development of robust and efficient energy storage devices. An interesting concept that has just emerged in the literature describes the use of biologically-derived materials, particularly living electroactive bacterial biofilms, for the development of supercapacitors. The aim of this paper is to present a recent state-of-the art in the field of bacteria-based supercapacitors, indicating current limitations and future opportunities of this microbial electrotechnology. Starting from a brief characterization of electrochemically active bacteria, we describe the mechanism of electron transfer in biofilms, identify structural units responsible for electron transfer, characterize supercapacitive properties of bacteria as confirmed by different measuring techniques, and provide a summary of recent literature studies employing bacteria, either in a living or in a mineralized form, in the design of novel supercapacitors. In the last section, we indicate the most important issues that need to be resolved to allow for the practical implementation of bacteria-based supercapacitors in energy storage applications.