Characteristics of potassium iron oxide for high-powered anode materials for lithium-ion batteries

Abstract Here, the electrochemical properties of layered-structure KFeO2 anode material for lithium-ion batteries (LIBs) are reported for the first time in the literature. The even-sized KFeO2 compounds were synthesized by the thermal diffusion of potassium into Fe2O3 nanoparticles produced using high temperature calcination of a graphene substrate. With the help of potassium, unlike typical iron oxide electrodes, the redox conversion between Fe0 and Fe2+/Fe3+ in the KFeO2 electrode became gradually decreased, whereas the interfacial charging/discharging of lithium ions through the layered-structure increased as charge/discharge was repeated. In addition, the continuous cycle led to potassium desertion from KFeO2 phases, forming well-dispersed layered-structure Fe2O3 nanoparticles less than 2 nm throughout the electrode. Such a favorable scenario gave rise to a significant reversible capacity of 2564 mAh g−1 after 1000 cycles at an extremely high current rate of 18.56 A g−1.