Suppressed Layered‐to‐Spinel Phase Transition in δ‐MnO<sub>2</sub> via van der Waals Interaction for Highly Stable Zn/MnO<sub>2</sub> Batteries
Ce Qiu, Jia Liu, Hanghui Liu, Xiaohui Zhu, Liang Xue, Shuang Li, Mingzhu Ni, Yang Zhao, Tong Wang, Serguei V. Savilov, С. М. Алдошин, Hui Xia
Abstract
Abstract Although birnessite‐type manganese dioxide (δ‐MnO 2 ) with a large interlayer spacing (≈7 Å) is a promising cathode candidate for aqueous Zn/MnO 2 batteries, the poor structural stability associated with Zn 2+ intercalation/deintercalation limits its further practical application. Herein, δ‐MnO 2 ultrathin nanosheets are coupled with reduced graphene oxide (rGO) via van der Waals (vdW) self‐assembly in a vacuum freeze‐drying process. It is interesting to find that the presence of vdW interaction between δ‐MnO 2 and rGO can effectively suppress the layered‐to‐spinel phase transition in δ‐MnO 2 during cycling. As a result, the coupled δ‐MnO 2 /rGO hybrid cathode with a sandwich‐like heterostructure exhibits remarkable cycle performance with 80.1% capacity retained after 3000 cycles at 2.0 A g −1 . The first principle calculations demonstrate that the strong interfacial interaction between δ‐MnO 2 and rGO results in improved electron transfer and strengthened layered structure for δ‐MnO 2 . This work establishes a viable strategy to mitigate the adverse layered‐to‐spinel phase transition in layered manganese oxide in aqueous energy storage systems.