Flexible Zn-ion batteries based on manganese oxides: Progress and prospect

The ever-growing market of wearable electronic devices has greatly stimulated the rapid development of flexible Zn-ion batteries (ZIBs). Manganese oxides are one of the most commonly used hosts for zinc ion accommodation and thus receive particular research interest for high-performance flexible ZIB constructions. In this review, a comprehensive summary of the recent development of flexible ZIBs with manganese oxides as cathode materials is presented. Apart from the brief introduction of flexible electronic devices and ZIBs, the charge storage mechanisms and crystal structures of various manganese oxides are summarized. Modifications of the cathode materials in terms of morphology, conductivity, structures, and flexibilities are illustrated in detail, together with the demonstration of structure-performance relationships and applications in flexible ZIBs. Finally, limitations to be overcome are indicated and the future work directions are proposed.