Asymmetric K/Li-Ion Battery Based on Intercalation Selectivity

Using ab initio calculations combined with experimental confirmation, we design an asymmetric intercalation battery using K2NiFeII(CN)(6) as the cathode, commercial graphite as the anode, and an organic electrolyte containing mixed lithium and potassium salts. It works by reversible K-ion intercalation at the cathode side and reversible Li-ion intercalation at the anode side simultaneously. The pi-electron coordination environment in K2NiFeII(CN)6 ensures the preferred reversible intercalation of the K-ion, and the small ionic radius ensures the preferred reversible intercalation of the Li-ion in graphite. It also shows a high working voltage (similar to 3.6 V) and an ultralong cycling life with no capacity fading even after 5000 cycles.