Vacancy-rich Al-doped MnO cathodes break the trade-off between kinetics and stability for high-performance aqueous Zn-ion batteries

Rechargeable aqueous zinc ion batteries (RAZIBs) have the potential for large scale energy storage due to their environmental friendliness, high safety and low cost. The trade-off between charging/discharging kinetics and stability has been the bottleneck of most cathode materials, which impedes the rate performance and cycle life of RAZIBs. Here we break the trade-off by designing vacancy-rich and Al-doped birnessite-type MnO 2 nanosheet (Al x -MnO 2 ) electrodes, which are synthesized by electrochemically oxidizing manganese based layered double hydroxides (MnAl-LDHs). Rich Al cation vacancies formed during the process of electrochemical oxidation provide three-dimensional diffusion channels for the storage of Zn ions, and the remaining Al atoms benefit the structural stability by suppressing the Jahn-Teller distortion of Mn( iii )O 6 polyhedra during battery cycling. As a result, by employing the optimized cathode (Al 0.1 -MnO 2 ), the rate capability and stability of the RAZIBs are spontaneously enhanced. Specifically, the battery exhibits a large specific capacity (327.9 mA h g −1 at 0.2 A g −1 ), superior rate performance (135.8 mA h g −1 at 8 A g −1 ) and high capacity retention (87% after 1000 cycles at 1 A g −1 ) that exceeds that of most of the reported manganese and vanadium based cathode materials. A novel vacancy-rich, Al-doped MnO 2 cathode is proposed for AZIBs, showcasing 3D ion diffusion channels and excellent structural stability. It overcomes the trade-off between electrode kinetics and stability, delivering impressive rate performance and outstanding capacity retention.