Rational Design of Layered MnO2@Graphene with Hierarchical Structure for Flexible Quasisolid‐State Aqueous Zinc‐Ion Battery via Laser Activation

Abstract

AbstractAqueous zinc‐ion battery (AZIB) based on Zn//MnO2 is considered as one of the most promising energy storage devices. However, the poor Zn2+ storage kinetics and structural integrity of MnO2 affect its electrochemical performance. In this work, the vertically aligned multilayer graphene sheets (VGS) are in situ formed on the graphite paper via laser activation, and then MnO2 nanoflakes are coated on the VGS by electrochemical deposition, leading to the layered MnO2@graphene with hierarchical structure. The MnO2 nanoflakes coated on the VGS not only have improved charges transfer and structural integrity owing to the conductive skeleton, but also expose more accessible area to the electrolyte. In addition, the inner layer of graphite paper maintains its original structure, which can serve as current collector and endow the composite materials with good flexibility. In light of this rational design, the coin‐type AZIB assembled with layered MnO2@graphene as cathode shows a maximum capacity of 363.6 mAh g−1. Furthermore, a flexible quasisolid‐state AZIB is fabricated, which also exhibits superior electrochemical performance and flexibility (97.0% capacity retention after 1000 bending cycles). This work provides a feasible and effective strategy to develop flexible MnO2@graphene as cathode for high‐performance rechargeable Zn//MnO2 AZIB by rational design of the structure.