In‐Built Polaronic States Self‐Regulation for Boosting Potassium‐Ion Diffusion Kinetics

Abstract

Potassium ion batteries (PIBs) have attracted enormous attention due to their low cost and high abundance of potassium resources. Here, self‐hybridized BiOBr0.5I0.5 with a flower‐like structure composed of 2D nanosheets is assembled and used as PIBs anode. According to the systematic theoretical calculations, the unbalanced charge distribution between Br and I atoms induces an intensified internal electric field and a wide van der Waals gap; while the decreasing of electron polarons caused by the hybridized structure improves the stability and electronic conductivity of the system. Moreover, the K+ ion uptake induces an energetic evolution in polaronic states in the BiOBr0.5I0.5 crystal skeleton, whereby the dynamic K+ ion‐halogen atoms correlation in situ forms hole‐like polarons, which substantially promotes K+ ion diffusion kinetics and the corresponding reaction kinetics during charge/discharge processes, imparting significant implications for the design of high‐performance energy storage electrode materials by engineering the interface interaction and electronic structure. Therefore, with this atomic orbital self‐hybridized structure, the K+ ion diffusion kinetics and the corresponding reaction kinetics during the charge/discharge process are both enhanced remarkably, thus enabling a high electrochemical performance of 155 mAh g−1 at 1000 mA g−1 over 4000 cycles in PIBs with the BiOBr0.5I0.5 as the anode.