Uniform cobalt nanoparticles-decorated biscuit-like VN nanosheets by in situ segregation for Li-ion batteries and oxygen evolution reaction

Biscuit-like Co-VN@C synthesized by a hydrothermal process and nitriding has outstanding electrochemical properties as anode materials in lithium-ion batteries (LIBs) and catalysts in the oxygen evolution reaction (OER). The metallic Co nanoparticles with abundant exposed active sites are segregated uniformly on VN nanosheets in situ so that they adhere strongly to the VN substrate leading to accelerated charge transfer and enhanced stability. The carbon shell of the composite acts as a buffer layer to alleviate the volume expansion and the battery shows a stable capacity of 335.5 mAh g⁻¹ after500 cycles at 0.5 A g⁻¹. After testing at different rates, the current density reverts back to 0.1 A g⁻¹ and the capacity of the Co-VN@C electrode returns to 588.0 mAh g⁻¹. Besides, Co-VN@C has excellent electrochemical catalytic activity in the oxygen evolution reaction. This work sheds light on the long cycle stability and high rate capacity electrode materials for future development of LIBs and the strategy provides insights into the design of high-performance electrode materials for electrochemical catalysis.