High-Purity Graphitic Carbon for Energy Storage: Sustainable Electrochemical Conversion from Petroleum Coke

The petroleum coke (PC) has been widely used as raw materials for the preparation of electrodes in aluminium electrolysis and lithium-ion batteries (LIB), during which massive CO₂ gases are produced. To meet global CO₂ reduction, an environmentally friendly route for utilizing PC is highly required. Here, a simple, scalable, catalyst-free process that can directly convert high-sulfur PC into graphitic nanomaterials under cathodic polarization in molten CaCl₂-LiCl at mild temperatures is proposed. The energy consumption of the proposed process is calculated to be 3 627.08 kWh t⁻¹, half that of the traditional graphitization process (≈7,825.21 kWh t⁻¹ graphite). When applied as a negative electrode for LIBs, the as-converted graphite materials deliver a competitive specific capacity of ≈360 mAh g⁻¹ (0.2 C) compared with commercial graphite. This approach has great potential to scale up for sustainably converting low-value PC into high-quality graphite for energy storage.