A Flower-Like Sb4O5Cl2 Cluster-based material as anode for potassium ion batteries

Abstract

Potassium ion batteries (PIBs) have attracted tremendous attentions based on the fact that lithium ion batteries have been increasingly challenged by the uneven distribution and ultralow reserve of lithium sources. Safety concern has raised requirement for acceptable anode materials with high capacity and favorable working-potential. Here, a 3D flower-like antimony oxychloride (Sb4O5Cl2) that is synthesized via a mild hydrothermal method, is firstly employed as anode material for PIBs, where a high reversible capacity of 530 mAh g−1 could be achieved at current density of 50 mA g−1, with decent cycling performance and rate capability. Kinetic analyses based on electrochemical measurements evidence that the Sb4O5Cl2 electrode could deliver high K+ ion diffusion coefficient, and density functional theory calculations are also conducted to probe the migration paths of K+ ion in Sb4O5Cl2 and the electronic structure involved in the electrochemical kinetics behaviors. The K+ ion storage mechanism during potassiation/de-potassiation is investigated via ex-situ X-ray diffraction, high resolution transmission electron microscope and theoretical calculations, and a reversible process involving both conversion-type and alloy/de-alloy reactions is established.