A high-energy-density aqueous zinc-manganese battery with a La-Ca co-doped ε-MnO2cathode

Aqueous zinc-manganese dioxide batteries (Zn//MnO2) are gaining considerable research attention for energy storage taking advantage of their low cost and high safety. However, the capacity and cycling stability of the state-of-the-art devices are still utterly disappointing because of the inevitable MnO(2)dissolution and its low conductivity. In this work, to elevate the energy density of Zn//MnO2, a La-Ca co-doping strategy is proposed to boost the electrochemical performance of the epsilon-MnO(2)cathode. Specifically, the introduction of heteroatoms, La(3+)and Ca2+, is achievedviaa facile one-step liquid coprecipitation method. Our experimental results reveal that Ca(2+)significantly improves the stability of epsilon-MnO(2)while Ca(2+)and La(3+)both contribute to the capacity and reversibility enhancement. Therefore, the overall performance of the La-Ca co-doped epsilon-MnO(2)cathode exceeds the pristine sample, as demonstrated by its commendable capacity of 297.3 mA h g(-1)at 0.2 A g(-1), superior cycle stability (up to 76.8% capacity retention after 200 cycles) and excellent rate capability (161 mA h g(-1)when the current density increased to 1.6 A g(-1)). Besides, the assembled Zn//epsilon-MnO(2)device delivers a maximum energy and power density of 401.22 W h kg(-1)and 5.2 kW kg(-1)respectively, outperforming most of the recently reported Zn//MnO(2)counterparts.