FeP/C Composites as an Anode Material for K-Ion Batteries.

Owing to their natural abundance, the low potential, and the low cost of potassium, potassium-ion batteries are regarded as one of the alternatives to lithium-ion batteries. In this work, we successfully fabricated a FeP/C composite, a novel electrode material for PIBs, through a simple and productive high-energy ball-milling method. The electrode delivers a reversible capacity of 288.9 mA·h·g-1 (2nd) at a discharge rate of 50 mA g-1, which can meet the future energy storage requirements. Density functional theory calculations suggest a lower diffusion barrier energy of K+ than Na+, which allows faster K+ diffusion in FeP.