Dual-effect pre-potassiation unlocks stable and high-energy potassium-ion batteries

An overdischarge strategy is proposed to enable the in situ formation of K x Mn[Fe(CN) 6 ] ( x > 2) and the generation of a robust SEI, significantly improving the cyclability and energy density of K 2 Mn[Fe(CN) 6 ]–graphite potassium-ion batteries.