A space-confined strategy towards stable α/β-Bi₂O₃ heterojunction anode for high-energy aqueous battery

It is very necessary to design a high-capacity and stable Bi₂O₃ anode for nickel-bismuth (Ni//Bi) batteries. In this work, a stable α- and β- phase Bi₂O₃ heterojunction nanocomposite (α/β - Bi₂O₃) was successfully prepared via a simple "space-confined" strategy and it was used as a superior anode for nickel-bismuth (Ni//Bi) battery. The α/β-Bi₂O₃ obtained by using MCM-41 as a space-confined template possesses a stable structure and enhanced charge transfer capability. Such superior traits vest the designed α/β-Bi₂O₃ electrode with high specific capacity (235 mAh g^-1 at 1 A g^-1), extraordinary rate performance (137 mAh g^-1 at 40 A g^-1, and ∼58% capacity retention vs 1 A g^-1), and excellent cyclic durability (75% capacity retention after 5000 cycles). Such performances are far superior to that of mono-phase α-Bi₂O₃ and β-Bi₂O₃ electrodes. Furthermore, an excellent Ni//Bi battery with outstanding energy density (∼155 Wh kg^-1) and long cycle life was assembled using the obtained α/β-Bi₂O₃ electrode and a NiC₂O₄ electrode as anode and cathode, respectively (NiC₂O₄//α/β-Bi₂O₃). This work opens a new alternative strategy for the rational design of efficient electrodes for reliable aqueous rechargeable batteries.