Surface structure and electrochemical properties of surface-fluorinated petroleum cokes for lithium ion battery

Surface structure and electrochemical behavior of surface-fluorinated petroleum coke samples (original petroleum coke and those heat-treated at 1860, 2300 and 2800 °C, abbreviated to original PC, PC1860, PC2300 and PC2800, respectively) have been investigated. Surface fluorination of petroleum cokes by elemental fluorine reduced surface oxygen. Surface areas of fluorinated petroleum cokes were nearly the same as those of non-fluorinated ones or only slightly increased by fluorination except original PC fluorinated at 300 °C. Total meso-pore volumes of fluorinated samples showed the same trend. The charge capacity of non-fluorinated petroleum coke was increased by heat-treatment at 2300 and 2800 °C. However, the first coulombic efficiency was the highest, 90–89% in PC1860, decreasing to 72–70 and 65–64% for PC2300 and PC2800, respectively. It is noted that first coulombic efficiencies were increased by 12–18% for PC2300 and PC2800 fluorinated at 300 °C.