Highly efficient unitized regenerative hydrogen peroxide cycle cell with ultralow overpotential for renewable energy storage

Abstract

The potential large-scale applications of intermittent renewable energy sources require inexpensive, efficient, and less-resource-demanding energy storage systems to achieve grid balancing. Conventional unitized regenerative fuel cells (URFCs) based on the H2–H2O cycle are promising but suffer from high overpotential and low energy efficiency. Here we demonstrate a highly efficient unitized regenerative hydrogen peroxide cycle cell (UR-HPCC) for the renewable energy storage. The prototype utilizes a carbon-based platinum group metal-free catalyst containing atomically dispersed Co and N dopants (Co–N–C) as the bifunctional oxygen electrode catalyst for the hydrogen peroxide oxidation reaction (HPOR) and two-electron oxygen reduction reaction (2e-ORR) in H2O2 electrolyzer and fuel cell modes, respectively. Further, this prototype exhibits a close-to-zero overpotential with remarkably high round-trip efficiency of over 90%, which is attributed to the ideal catalytic properties of Co–N–C toward HPOR and 2e-ORR. The thermodynamic analysis of these single-intermediate reactions indicates the intrinsic superiority of UR-HPCC in energy efficiency and reversibility over conventional URFCs, thus facilitating the development of future sustainable distributed generation and energy storage systems.