Thermally driven phase transition of manganese oxide on carbon cloth for enhancing the performance of flexible all-solid-state zinc-air batteries

Flexible and rechargeable zinc-air batteries with high energy density and stable output voltage are promising energy sources for wearable electronics and implantable medical devices. The development of efficient bi-functional catalysts with low-cost and environmentally friendly properties has become the focus of research on rechargeable zinc-air batteries. Herein, we present the in situ growth of manganese oxide (MnOx) on carbon cloth (MnOx-CC) by incorporating a simple chemical bath deposition method with the phase transformation of MnOx driven by thermal treatment for improving the bifunctional catalytic activities for the ORR and OER. With bifunctional catalytic activities, the carbon cloth supported MnOx electrode without an additional nonconductive binder has been used to assemble an all-solid-state rechargeable zinc-air battery. The solid-state battery shows a high open circuit voltage (1.47 V), superior round-trip efficiency (62.4% after 120 cycles), long cycling life (45 h over an operating voltage of 1.2 V), and high capacity (728 mA h g(-1)), which is superior to those of the Pt/C and RuO2 based battery. The battery also demonstrated excellent mechanical flexibility and cycling stability without obvious performance degradation. The present work provides an efficient approach to prepare advanced bifunctional electrocatalysts for the fabrication of all-solid-state zinc-air batteries, which would meet the demand for flexible and wearable devices.