Only few cathode compounds are reported to date for K ion batteries. In this early stage, it is important to design cathode materials that can maintain their crystal structures during de/intercalation of large K ions. We develop a new cathode material for K ion batteries and investigate K storage mechanism in this new cathode compound by in-situdiffraction characterization combined with electrochemical measurements. Lastly, we further demonstrate the practical feasibility of K ion batteries by constructing full cells. We consider that this work can suggest a guideline to open up new research opportunities in the development of K ion batteries.
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