Aerogel-structured MnO2 cathode assembled by defect-rich ultrathin nanosheets for zinc-ion batteries

Rechargeable MnO2//Zn zinc-ion batteries (ZIBs) gain increasing attention as prospective candidates for large-scale energy storage applications, but MnO2 cathode materials are afflicted by intrinsic low electrical conductivity, sluggish Zn2+ diffusion kinetics and unstable crystal structure during Zn2+ insertion/extraction. Herein, we report the scalable synthesis of an aerogel-structured MnO2 (A-MnO2) assembled by defect-rich ultrathin nanosheets for ZIBs. For the A-MnO2, V doping and its induced oxygen vacancies manipulate electronic structure to enhance electrical conductivity and decrease Zn2+ diffusion energy barrier, and meanwhile, the ultrathin nanosheets-assembled aerogel structure favors the exposure of more electrochemically active sites and the shortening of ion diffusion distance. As a consequence, the A-MnO2 is endowed with markedly boosted electrochemical kinetics and thus superior electrochemical performance than defect-free MnO2 nanorod counterpart. Furthermore, flexible ZIB devices with both impressive flexibility and outstanding electrochemical properties can be realized using the A-MnO2 cathode material. This work is expected to promote the practical application of MnO2//Zn ZIBs.