Iron phosphate hydroxide hydrate as a novel anode material for advanced aqueous full potassium-ion batteries

Abstract

The development of aqueous potassium-ion batteries is limited by the lack of suitable anode materials. Here, a novel anode material, iron phosphate hydroxide hydrate Fe_1.19PO₄(OH)_0.18(H₂O)_0.3, was introduced and synthesized, which delivers considerable reversible capacities of 80 mA h g⁻¹ at 0.05 A g⁻¹. An aqueous full potassium-ion battery assembled with the K₂Zn₃(Fe(CN)₆)₂ cathode exhibits 80% capacity retention after 1000 cycles.