Dual kinetics-enhanced crystalline BiOF hollow nanorods toward high-capacity and high-rate aqueous alkaline batteries.

Lack of double-high (high energy density and power density) anode materials is the key bottleneck for the application of Aqueous alkaline batteries (AABs). Although the emergence of Bismuth-based materials provides an opportunity to solve this issue, due to their high theoretical capacity via a three-electron redox reaction and suitable operating potential, their restricted ion diffusion kinetics via closed-packed atomic arrangement limit their application performance. Herein, the bismuth oxyfluoride hollow nanorods (BiOF-HNs) with intrinsic layer atom configuration have been constructed by the crystallization optimization and morphology engineering synergistic strategy during MOF etching process. Bi3+ hydrolysis is the key points to achieve the co-precipitating and repining reactions of BiOF at the surface of Bi MOF for hollow nanorods morphology. The BiOF-HNs deliver dramatically increased electron conductivity and ion transport ratio with the work function of 6.42 eV and OH- diffusion value of 2.11 × 10-13 cm2 s-1. Therefore, the optimized BiOF-HNs electrode delivers a remarkable specific capacity of 342.2 mAh g-1 (1232 F g-1) at 1 A g-1 and maintains 86% capacity retention at 20 A g-1. Furthermore, the assembled BCNP (basic cobalt/nickel phosphate)//BiOF-HNs AABs achieve a high energy density of 157.81 Wh kg-1 at 1.28 kW kg-1 and outstanding cycling stability (81% after 9000 cycles). The exploration of BiOF materials with morphology and crystalline optimization in AABs application, may offer new insights of design high performance aqueous anode materials.