Direct conversion of ester bond-rich waste plastics into hard carbon for high-performance sodium storage

Disordered hard carbon (HC) has shown potential as the most promising anode materials for sodium-ion batteries (SIBs). Pyrolyzing waste plastics is a sustainable alternative to obtain HC. However, most plastics will completely decompose without carbon residue or transform into highly graphitic carbon during the carbonation process because of lacking oxygen functional groups. Hence, ester bond-rich waste engineering plastics, polycarbonate (PC), and polyethylene terephthalate (PET) were selected and directly converted into HC by a simple pyrolysis method. The PC and PET-derived carbon anodes (PC-HC and PET-HC) exhibit high reversible capacities of 327 and 342 mAh·g−1 at 20 mA·g−1with remarkable initial coulombic efficiency (ICE) of 84.7% and 86.1%, respectively. Particularly, the carbon samples have no severe capacities decay after 140 cycles at 100 mA g−1. This work provides a cost-effective, easily large-scale, and eco-friendly route to fabricate HC anodes for grid-scale energy storage.