Hierarchical Co<sub>3</sub>O<sub>4</sub>@N-Doped Carbon Composite as an Advanced Anode Material for Ultrastable Potassium Storage
David Adekoya, Hao Chen, Hui Ying Hoh, Tim Gould, Muhammad‐Sadeeq Balogun, Chao Lai, Huijun Zhao, Shanqing Zhang
Abstract
Cobalt oxide (Co3O4) delivers a poor capacity when applied in large-sized alkali metal-ion systems such as potassium-ion batteries (KIBs). Our density functional theory calculation suggests that this is due to poor conductivity, high diffusion barrier, and weak potassium interaction. N-doped carbon can effectively attract potassium ions, improve conductivity, and reduce diffusion barriers. Through interface engineering, the properties of Co3O4 can be tuned via composite design. Herein, a Co3O4@N-doped carbon composite was designed as an advanced anode for KIBs. Due to the interfacial design of the composite, K+ were effectively transported through the Co3O4@N–C composite via multiple ionic pathways. The structural design of the composite facilitated increased Co3O4 spacing, a nitrogen-doped carbon layer reduced K-ion diffusion barrier, and improved conductivity and protected the electrode from damage. Based on the entire composite, a superior capacity of 448.7 mAh/g was delivered at 50 mA/g after 40 cycles, and moreover, 213 mAh/g was retained after 740 cycles when cycled at 500 mA/g. This performance exceeds that of most metal-oxide-based KIB anodes reported in literature.