| 초록 |
We introduce K4Fe3(PO4)2(P2O7) as a novel cathode material with outstanding electrochemical performance for potassium-ion batteries. First-principles calculation is performed to predict the theoretical properties and detailed K+ storage mechanism of K4Fe3(PO4)2(P2O7), which are consistent with experimental results. K4Fe3(PO4)2(P2O7) exhibits a large specific discharge capacity of ~118 mAh g−1 at C/20 (1C = 120 mA g−1) in the voltage range of 2.1–4.1 V (vs. K+/K), allowing ~3 mol of K+ de/intercalation per formula unit. Even at 5C, up to ~70 % of its theoretical specific capacity is maintained, and this remarkable power-capability is related to the low activation barrier energy for K+ diffusion, as verified through first-principles calculations. Furthermore, K4Fe3(PO4)2(P2O7) exhibits excellent cyclability with retention of ~82 % of the initial capacity after 500 cycles at 5 C. The above theoretical and experimental results suggest the feasibility of using K4Fe3(PO4)2(P2O7) as a promising cathode material for rechargeable potassium-ion batteries. |
