3D Micro-Flower Structured BiFeO₃ Constructing High Energy Efficiency/Stability Potassium Ion Batteries Over Wide Temperature Range

The fatty K+ ion calls for suitable host materials to meet the requirement for high safety and long-term stability of potassium-ion batteries (PIBs) to rival lithium-ion batteries, thus anode materials possessing high capacity, high stability, and well-defined plateaus involving favorable working voltage (approximate to 0.5 V) have always been desired. Here, a 3D BiFeO3 with micro-flower structure (BFO-MF) constructed by nanosheets is proposed as an anode for PIBs. Density functional theory calculations evidence that the intrinsically favorable affinity and diffusion for K+ ion render fast electrochemical kinetics and attenuated voltage-hysteresis, and electrochemical measurements indicate that the stable 3D structure of BFO-MF enables to achieve impressive performances including a high capacity of 606 mAh g(-1), flat plateaus at approximate to 0.5 V, stable performances for 5000 cycles at 500 mA g(-1), and 500 cycles at 100 mA g(-1) upon -20 degrees C. In situ and ex situ characterizations definitely elucidate the conversion and alloy/dealloy mechanism. The satisfying features of BFO-MF anode ensure full-cells to achieve excellent cyclic performances, and a high energy efficiency retention rate of approximate to 98.2% for the cathode, with energy density/power density output up to 177.1 Wh kg(-1)/2152.8 W kg(-1), respectively. This work can provide new insights for developing advanced anodes for PIBs.