Unleashing high-efficiency mass-charge transfer in BiOBr anodes for aqueous batteries via targeted (110) plane orientation

Bismuth oxybromide (BiOBr) is being actively researched as a promising anode material for aqueous batteries due to its unique layered structure, which theoretically allows for efficient ion diffusion. However, current studies have come across many challenges, e.g. serious capacity degradation and inferior rate capability caused by severe structural collapse and sluggish reaction kinetics, highlighting the need for further improvement in efficient utilization of the layered space. Herein, this study employs a novel crystal orientation regulation to enhance the performance of BiOBr electrode by a facile solvothermal method to efficiently utilize the interlayered structure. The delicate design of BiOBr (BOB) succeeds in maximizing the exposed (110) crystalline plane, providing efficient pathways for ion diffusion and streamlining the mass migration process. Moreover, the optimized band structure and the formation of oxygen vacancies in this designed material have been found, enabling high electrical conductivity, accelerating the charge transfer process and facilitating rapid reaction rate. Owing to the simultaneously enhanced mass transfer at the interlayers and the charge transfer during the phase conversion process, the BOB-110 electrode exhibits exceptional electrochemical performances, boasting impressive charge storage and rate capability (159 mAh g⁻¹ at 4 A g⁻¹), and outstanding cycling stability of capacity retention around 75% (119 mAh g⁻¹) even after 1000 cycles at a high current density of 4 A g⁻¹. These findings underscore the substantial potential of BiOBr electrodes for future energy storage devices such as wearable electronics and power grids where the power output, lifespan, and affordability are simultaneously required.