High-Capacity Hard Carbon Pyrolyzed from Subbituminous Coal as Anode for Sodium-Ion Batteries

A pyrolyzed subbituminous carbon is synthesized through a simple one-step carbonization process as low-cost and high-capacity anode for sodium-ion batteries (SIB). The pyrolyzed subbituminous carbon, SHC-1300 anode shows high Na storage capacity of 291 mA h g–1 at 20 mA g–1 and high initial Coulombic efficiency of 79.5%, as well as stable cycling performance, exhibiting a promising alternative anode for affordable and high-performance SIB. Furthermore, according to the investigation of the electrochemical performance and structural characterizations, the SHC-1300 pyrolyzed from subbituminous coal with flexible structure demonstrates a better electrochemical performance compared with the BHC-1300 pyrolyzed from bituminous coal with rigid structure. The sodium storage mechanism and structural evolution reported in this work may give a new prospect for the selection of pyrolyzed carbon materials for high-performance sodium-ion batteries.