Bi<sub>2</sub>O<sub>3</sub> Induced Ultralong Cycle Lifespan and High Capacity of MnO<sub>2</sub> Nanotube Cathodes in Aqueous Zinc-Ion Batteries
Lei Gou, Shao-Pan Zhao, Wenqi Wang, Lei Xu, Wenyan Wang, Jun Wu, Zhefan Ma, Xiaoyong Fan, Lin Li
Abstract
MnO2 is regarded as a promising cathode for aqueous rechargeable zinc-ion batteries (ARZBs) due to its high theoretical capacity and high voltage. However, it still faces unsatisfied long-term cycling durability due to the John–Teller effect and the formation of the irreversible phase during cycling. Herein, this issue is addressed by constructing a hybrid cathode with a facile commercial strategy involving a uniform mixture of Bi2O3 and MnO2 nanotubes. The multiple effects of adding Bi2O3 are deeply revealed by means of the electrochemical kinetics test, charge–discharge mechanism investigation, phase and structural evolution analyses, as well as density functional theory (DFT) calculations. It is found that the in situ-formed Bi3+ can not only enhance the structural stability and alleviate the dissolution of Mn3+ by forming Mn–O bonds with MnO2, but also lead to better transport kinetics of Zn2+ by the competitive formation of Bi2Mn4O10 that can inhibit the irreversible ZnMn2O4 produced during the repeated H+ and Zn2+ coinsertion/extraction process. Moreover, the tunnel-like Bi2Mn4O10 can contribute an additional capacity by the insertion of H+. Benefiting from these, the MnO2/Bi2O3 hybrid cathode delivers high capacities of 120 and 80 mAh g–1 even after 5000 cycles at the current densities of 3000 and 10 000 mA g–1, respectively. This design provides an effective and scalable pathway to enhance the electrochemical performance of the MnO2 cathode and may speed up the commercial application of ARZBs.