Flexible and Stretchable Electrodes in Biofuel Cells for Sustainable Power

Abstract

Electrochemical devices, especially biofuel cells (BFCs), aim to extend wearable devices by using the electrode under compressive force with a maximized output current density and open-circuit voltage. The high deformability of a stretchable electrode offers (1) a higher active area and wider actual contacting area between the electrode and the dielectric, (2) enhanced charge inducement from the electrostatic effect, and (3) enhanced charge generation and improved electrical output. Even with flexibility and deformability in elastomeric electrodes with metal-like electrical conductivity, a high surface area featuring nanocomposite film acts as the active layer at an electric field. The highly flexible and stretchable electronics of an ultrathin range of energy enhance the areal capacities by assembling film electrolytes and a metal anode. In this work, we discuss the most significant strategies of flexible and stretchable electrode fabrication through (1) the island−bridge method and (2) the wrapping structure to access flexible electrodes. We emphasize the logic behind attaining flexibility and stretchability and their origin in an electrode material. Furthermore, we discuss features of stretchable BFCs with major potential associated with mechanical strength and extended capability. An interlink between electrode fabrication and electrochemical performance emphasizes our discussion to enable an understanding of flexibility in the context of BFCs and their corresponding electrochemical performance and durability. We extend the review with a range of flexible and stretchable material-based polymers (PU, PDMS) for the growth of electrodes on a substrate. We include conclusive remarks with future models and achievements for stretchable BFCs.