Novel synthesis and electrochemical properties of fluoride cathode with a yolk–shell structure for K-ion battery

K-ion batteries (KIBs) have attracted considerable attention because of their unique advantages. Manganese-containing electrode materials have poor cycle performance due to the dissolution of manganese in the electrolyte. Here, manganese-containing KIB cathode with a yolk–shell structure is synthesised by a homogeneous precipitation method. In addition, large charge–discharge capacity and good cycle stability are obtained. Electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) are used to understand the improvement in the electrochemical performance caused by the developed material. Due to the volume-buffering effect, the yolk–shell structure does not cause particle rupture, which helps form a stable solid–electrolyte interface (SEI) film. This reduces the number of Mn ions exposed to the electrolyte and results in long-term cycle stability. This work provides a universal route to improve the cycling performance of manganese-containing cathode for KIBs applications.