Encapsulating VO Nanoparticles in Hierarchical Porous Carbon Nanosheets via C-O-V Bonds for Fast and Durable Potassium-Ion Storage.

Vanadium oxide (VO) has been considered as a promising anode material for potassium-ion batteries (PIBs), but challenging as well for the low electron/ion conductivity and poor structural stability. To tackle these issues, herein, a novel sheetlike hybrid nanoarchitecture constructed by uniformly encapsulating VO nanoparticles in amorphous carbon nanosheets (VO@C) with the generation of C-O-V bonding is presented. Such a subtle architecture effectively facilitates the infiltration of electrolyte, relieves the mechanical strain, and reduces the potassium-ion diffusion distance during the repetitive charging/discharging processes. The generated C-O-V bonding not only accelerated charge transfer across the carbon-VO interface but also strengthened the structural stability. Benefiting from the synergistic effects, the as-prepared VO@C nanosheets display fast and durable potassium storage behaviors with a reversible capacity of 116.6 mAh g delivered at 5 A g, and a specific capacity of 147.9 mAh g retained after 1800 cycles at a high current density of 2 A g. Moreover, the insertion/extraction mechanism of VO@C nanosheets in potassium-ion storage is systematically demonstrated by electrochemical analysis and ex situ technologies. This study will shed light on the fabricating of other metal oxides anodes for high-performance PIBs and beyond.