An approaching-theoretical-capacity anode material for aqueous battery: Hollow hexagonal prism Bi2O3 assembled by nanoparticles

At present, various strategies are utilized to improve the specific capacity of electrode materials to overcome the low energy density problem of aqueous battery, while their specific capacity is still far away from the theoretical value, especially for anode materials. Herein, we designed and synthesized nanoparticles assembled hollow hexagonal prism Bi2O3 (HHP Bi2O3) through template inducing synthesis. When used as an anode material for aqueous battery, it demonstrated a remarkable specific capacity of 327 mAh/g at 1 A/g, which reaches 94.8% of its theoretical capacity and is the highest value of its kind. Besides the high specific capacity, the as-fabricated HHP Bi2O3 also exhibits superior rate capability (220 mAh/g at 20 A/g) and long-term stability (~80%, 3000 cycles). Such high performance originates from high atom utilization and fast reaction kinetics for electrochemical reaction brought by its unique structures. Notably, when the HHP Bi2O3 is paired with the cathode material NixCo1-x (OH)2 to form an aqueous alkaline battery, its high electrochemical property is well exhibited. The designed HHP Bi2O3 with scalable synthesis process provides guidance for the preparation of other high capacity energy-storage materials, and paves the way to promote their practicality.