Facile Synthesis of Highly Graphitized Carbon via Reaction of CaC2 with Sulfur and Its Application for Lithium/Sodium-Ion Batteries

In the present work, we report, for the first time, a novel one-step approach to prepare highly graphitized carbon (HGC) material by selectively etching calcium from calcium carbide (CaC2) using a sulfur-based thermo-chemical etching technique. Comprehensive analysis using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and N2 adsorption–desorption isotherms reveals a highly graphitized mesoporous structure for the CaC2-derived carbon with a specific surface area of 159.5 m2 g–1. Microscopic analysis displays micron-scale mesoporous frameworks (4–20 μm) with a distinct layered structure along with agglomerates of highly graphitized nanosheets (about 10 nm in thickness and 1–10 μm lateral size). The as-prepared HGC is investigated for the role of an anode material for lithium- and sodium-ion batteries. We found that HGC exhibits good lithium storage performance in the 0.01–1.5 V range (reversible capacity of 272.4 mA h g–1 at 50 mA g–1 after 100 cycles and 214.2 mA h g–1 at 500 mA g–1 after 500 cycles), whereas, when sodium is considered, we observed a drop in the overall electrochemical performance owing to the high graphitization degree. More importantly, the present study provides a perspective approach to fabricate HGC via a simple, cost-effective, and efficient synthetic route using CaC2 and sulfur as reactants.