Defect engineering of hierarchical porous carbon microspheres for potassium-ion storage

Owing to adjustable microstructure and stable physiochemical properties, carbon-based materials are regarded as promising materials as anodes for potassium-ion batteries (PIBs). Building amorphous structure and introducing defects are favorable methods to generate active sites and improve the electrochemical performances of carbon-based materials. In this work, we develop a facile carbonization method to prepare sulfur-doped amorphous carbon microspheres with hierarchical structure and modulated defects concentration (S-CM-700) for potassium storage. Benefiting from the special microstructure, S-CM-700 exhibits the optimal performance and obtains high reversible capacity of 199.6 mAh·g −1 at 100 mA·g −1 , excellent rate property and prominent durability (0.0055% capacity decay per cycle during 1800 cycles). Kinetics analysis and electrochemical characterization are carried out to reveal that the potassium storage could be boosted by regulating the defect level, layer spacing and the content of sulfur-doping. The work provides a general synthesis approach to prepare sustainable carbon anodes for advanced PIBs. Graphical abstract