A Triple Strategy to Enhance Energy Storage and Power Generation Performances of a Rechargeable Zn-H2O Fuel Cell.

Abstract

Aqueous rechargeable Zn-organic batteries at discharged state can self-charge through the spontaneous O2-oxidation of organic cathode, and the self-charged energy originates from the consumption of Zn anode, as the stripped Zn is converted into complex compounds on cathode surface. These byproducts block ion diffusion and shorten cycle life. Additional drawbacks include the semi-open battery case for air uptake, which leads to electrolyte evaporation, and the low discharge voltage plateau. To address these challenges, herein a triple strategy is presented: (i) The fabrication of a bicomponent organic cathode comprising a polymer and small molecules, achieving a synergistic effect by the regulation of molecular orbital levels; (ii) The incorporation of Pt nanoparticles into the organic blend to modulate redox reactions, thereby enhancing capacity and enabling self-charging capability based on proton chemistry, without the O2-oxidation mechanism; (iii) The implementation of an electrolyte decoupling strategy, which not only elevates the self-charged voltage to 2.1 V but also prevents byproduct formation on cathode surface. The hermetically sealed cell can self-charge to generate power by consuming the Zn anode. The role of Pt nanocatalyst in augmenting capacity and self-charging performance is investigated both experimentally and theoretically. Furthermore, practical applications of this self-charging battery are vividly demonstrated.