Construction of mesoporous carbon sphere with local short-range ordered graphitized structure for high-rate potassium storage

Abstract

Mesoporous carbon spheres (MCSs) have emerged as promising high-performance anodes of potassium ion batteries (PIBs) due to their larger layer spacing, randomly distributed amorphous regions, and abundance of defect sites. However, achieving high potassium-storage capacity at high current densities remains a difficult challenge due to its highly disordered structure leading to low conductivity. Herein, we propose a novel synthetic strategy to introduce locally short-range ordered graphitized structure into mesoporous carbon spheres to tunning the morphology and the internal structure, which improves the electrical conductivity, increases the specific surface area, and enriches K⁺ intercalation sites. The optimized locally graphitized mesoporous carbon spheres (LGMCSs-2) exhibit a high-rate performance (210.1 mAh g⁻¹) at 5 A g⁻¹ and delivers a capacity of 214.2 mAh g⁻¹ at 1 A g⁻¹ after 500 cycles. Even after 1000 cycles at 5 A g⁻¹, it can still maintain a capacity of 144.3 mAh g⁻¹. The superior rate capability and excellent cycling stability of LGMCSs-2 electrode are attributed to the well-defined mesoporous structure and locally graphitized structure design, which enhance the potassium-ion reaction kinetics. This work provides a new approach to designing local short-range ordered MCSs and offers valuable insights into the carbon-based anodes with fast charge/discharge capability for PIBs.