A potassium-rich iron hexacyanoferrate/dipotassium terephthalate@carbon nanotube composite used for K-ion full-cells with an optimized electrolyte

Abstract

K-ion batteries, as an emerging battery system, have attracted tremendous attention in the research community. Herein, we report a K-ion full-cell based on a nano-sized K_1.92Fe[Fe(CN)₆]_0.94·0.5H₂O cathode, dipotassium terephthalate (K₂TP)@carbon nanotube (CNT) anode and an optimized electrolyte. K_1.92Fe[Fe(CN)₆]_0.94·0.5H₂O delivers a high capacity of 133 mA h g⁻¹ with 92.8% capacity retention after 200 cycles and high coulombic efficiency of 98.5%. The side reactions of K metal with the electrolyte are suppressed in KClO₄/propylene carbonate (PC). The K₂TP nanosheets grown in situ on the CNT show a high reversible capacity of about 250 mA h g⁻¹ and an ultra-high rate capability. The full-cells based on them are well cycled in a DME-based electrolyte and show a great promise for large-scale energy storage.