Insights into the Carbonization Mechanism of Bituminous Coal-Derived Carbon Materials for Lithium-Ion and Sodium-Ion Batteries

Despite the recent interest in low-temperature carbonization of coal sources to prepare disordered carbon materials for the anode of lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), the carbonization mechanism is still poorly understood. Herein, we select bituminous coal as the raw material and investigate the chemical, microcrystalline, and pore structure evolution from coal to the resulting disordered carbon during the carbonization process. These structural evolutions with temperature show an increasing interlayer spacing (3.69–3.82 Å) and defect concentration (1.26–1.90), as well as the generation of abundant nano-microporous structures. These changes are attributed to the migration of the carbon layer and the release of small molecules. Furthermore, a decrease in interlayer spacing and defect concentration occurs between 1000 °C and 1600 °C. In LIBs, samples carbonized at 1000 °C (CC-1000) showed the best electrochemical performance, with a reversible capacity of 384 mAh g–1 at 0.1C and excellent rate performance, maintaining 170 mAh g–1 at 5C. In SIBs, samples carbonized at 1200 °C (CC-1200) had a reversible capacity of 270.1 mAh g–1 at 0.1C and high initial Coulombic efficiency of 86.8%. These results guide the structural regulation of disordered carbon materials derived from coal for targeted applications.