β-FeOOH: A new anode for potassium-ion batteries

Potassium-ion batteries (PIBs) hold great potential in large-scale energy storage system. Here, β-FeOOH is employed as anode for PIBs, exhibiting high capacity and good cycling stability. The study of potassium storage mechanism discloses that β-FeOOH turns into amorphous structure in the first discharge process, and remains stable amorphous state in subsequent cycles.