The design of flower-like C–MnO2 nanosheets on carbon cloth toward high-performance flexible zinc-ion batteries

With the increased development of wearable electronics, flexible zinc ion batteries (ZIBs) have attracted widespread attention owing to their low cost, superior safety, and simple fabrication process. Nevertheless, the limited active mass loading and low specific capacity remain challenges to be overcome. Herein, an effective in situ growth strategy is used to boost the mass loading and specific capacity of flexible ZIBs. We employed a mussel-derived polydopamine layer as an inductive catalyst to prompt the growth of flower-like δ-MnO2 on carbon cloth, which demonstrated strong adhesion to the surface, high mass loading, and excellent flexibility. In addition, the formed 3D conductive and supporting networks contribute to the realization of superior long cycle life, as well as a high specific capacity. As a result, the as-obtained flexible cathode can achieve a high initial discharge capacity of 1.3 mA h cm−2 at a current density of 1 mA cm−2 and a reversible capacity of 0.25 mA h cm−2 at 10 mA cm−2 for 10 000 cycles. Moreover, its reaction mechanism in ZIBs was analyzed via a series of ex situ characterization techniques, and the results suggest that the charge–discharge behavior is determined based on the Zn2+ (de-)intercalation in the δ-MnO2 interlayer. Remarkably, the as-developed flexible cathode is assembled into a flexible quasi-solid-state device, which shows excellent flexibility and can easily power one LED-based device, which has significant application prospects in wearable electronics. This work provides a novel tactic for the design of flexible batteries with high active mass loading and excellent electrochemical performance via employing polydopamine as an inductive catalyst.