Preparation of synthetic graphite from bituminous coal as anode materials for high performance lithium-ion batteries

An earth-abundant and low cost bituminous coal was used as precursor to prepare synthetic graphite materials through preliminary carbonization coupled with further high temperature graphitization treatment at 2000–2800 °C. The microstructure characteristics of the obtained synthetic graphite materials were characterized by means of X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman spectroscopy and nitrogen adsorption–desorption. The results show that the microstructures of synthetic graphite materials are strongly dependent on the graphitization temperature. The synthetic graphite graphitized at 2800 °C has perfect ordered layered structure with high graphitization degree and relatively large surface area with well-developed mesopores, which offers a favorable pathway for the electrochemical intercalation-deintercalation of lithium ions in carbon matrix. Such synthetic graphite applied as anode materials for lithium-ion batteries presents a maximum reversible capacity of 310.3 mAh·g^{− 1} at current rate of 0.1C and still remains as high as 143.9 mAh·g^{− 1} at current rate of 5C. Moreover, the synthetic graphite also exhibits superior rate capability and outstanding cycling performance with over 95.3% initial capacity retention after 100 cycles. This study demonstrates a promising feasibility for large-scale production of synthetic graphite materials from bituminous coal for high performance lithium-ion batteries.