Bi2O3 Induced Ultralong Cycle Lifespan and High Capacity of MnO2 Nanotube Cathodes in Aqueous Zinc-Ion Batteries

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.