Nitrogen/oxygen co-doped mesoporous carbon octahedrons for high-performance potassium-ion batteries

Abstract

Carbonaceous materials as promising anode materials for KIBs have drawn much attention owing to their low price, wide range of sources, fast electron transfer and environmental benignity. However, low capacity and capacity fading during cycles still need to be addressed. Herein, we demonstrate the preparation of nitrogen/oxygen co-doped mesoporous carbon octahedrons (MCOs) through a carbonization–etching process of Cu-BTC. The resulting MCOs possess an enlarged interlayer spacing, large specific surface area, amorphous nature and hierarchical mesoporous structure. When tested as an anode material for KIBs, MCOs deliver a high reversible capacity (364 mA h g⁻¹ at 50 mA g⁻¹ over 50 cycles and 240 mA h g⁻¹ at 100 mA g⁻¹ over 100 cycles), and excellent cyclability (100 mA h g⁻¹ at 1 A g⁻¹ after 1300 cycles and 80 mA h g⁻¹ at 2 A g⁻¹ after 3000 cycles), which exceeds the theoretical capacity of carbon materials and demonstrates one of the best electrochemical performances reported to date.