Dominant Pseudocapacitance Filling Charge-Discharge Voltage Gap of Flexible Hybrid Zinc-Based Batteries.

Abstract

The high charge-discharge voltage gap is one of the main bottlenecks of zinc-air batteries (ZABs) because of kinetically sluggish rate of oxygen reduction/evolution reaction (ORR/OER) on the oxygen electrode side, and thus an efficient bifunctional catalyst for ORR and OER is highly pursued. Here, a honeycomb-like MnCo2O4.5 spheres, as an efficient bifunctional electrocatalyst, has been demonstrated that both ORR and OER catalytic activity are promoted by the Mn (IV) induced oxygen vacancy defects and multi-active sites. Importantly, the rich multivalent ion and defect structure endow stable pseudocapacitance within the inactive-region of ORR and OER, thus affording a low charge-discharge voltage gap (0.43 V at 10 mA cm-2) when it is employed in the flexible hybrid Zn-base battery. This mechanism provides unprecedented and valuable insights in the development of next-generation metal-air batteries.