Dual cation doping enabling simultaneously boosted capacity and rate capability of MnO2 cathodes for Zn//MnO2 batteries

Aqueous rechargeable Zn//MnO 2 batteries show promising prospects for grid-scale energy storage due to their intrinsic safety, abundant resource, and potential high performance. Unfortunately, the real capability of these devices is far from satisfactory thanks to the low capacity and sluggish kinetics of the MnO 2 cathode. Herein, we report a dual cation doping strategy by synthesis of MnO 2 in the presence of Ti 3 C 2 X MXenes and Ni 2+ ions to essentially address these drawbacks. Such a process contributes to a Ti,Ni co-doped α-MnO 2 anchored on MXenes. The Ti 3+ ions incorporated in the framework allow a partial multivalent variation for a large capacity while the Ni 2+ ions promote the H + transfer within the MnO 2 matrix via the Grotthuss proton transport manner. As a result, the optimal dual cation doped MnO 2 exhibits a large reversible capacity of 378 mAh·g −1 at 0.1 C and a high rate capability. Moreover, capacity retention as high as 92% is observed after cycling at 4 C for 1000 times, far superior to many of the previously reported results. This facile strategy demonstrated here may shed new insight into the rational design of electrodes based on high-performance Zn//MnO 2 batteries.