Improved electrochemical performance of soft carbon derived from coal liquefaction residue coated with expanded graphite for Lithium/Potassium batteries

Abstract

This study investigated the use of asphaltene from coal liquefaction residue (CLRA) as a precursor for creating carbon nanosheets, which were then used to create a unique sandwich structure of soft carbon (SC) coated with expanded graphite (EG) composite (SC@EG) anodes for both lithium-ion and potassium-ion batteries. The SC@EG was formed through a covalent bond between EG and SC, resulting in a porous structure with favorable porosity and copious defects that expedited the migration of both Li+ and K+ ions. The SC@EG showed good electrochemical properties including high reversible capacity (510 mAh/g at 0.5 A/g in LIBs and 268 mAh/g at 0.1 A/g in KIBs), good rate performance (172 mAh/g at 4 A/g in LIBs and 154 mAh/g at 1 A/g in KIBs) and cyclic stability, attributed to the exceptional electronic conductivity and profound porosity of the structure.