Electrochemical behavior of surface-modified petroleum cokes in propylene carbonate containing solvents

Abstract Surface modification of petroleum coke (PC) and those heat-treated at 1860, 2300 and 2800 °C (PC1860, PC2300 and PC2800) has been performed by F 2 , ClF 3 and NF 3 to improve their charge/discharge characteristics in propylene carbonate containing solvents. Surface fluorination by F 2 increased surface disorder of PC1860, PC2300 and PC2800, leading to increase in their first coulombic efficiencies in 1 mol dm −3 LiClO 4 –ethylene carbonate (EC)/diethyl carbonate (DEC)/propylene carbonate (PPC) (1:1:1 in volume) solution. First coulombic efficiencies were the largest in fluorinated PC1860 with the highest surface disorder. However, surface modification by ClF 3 and NF 3 did not increase surface disorder of petroleum cokes, being not as effective as the fluorination with F 2 to increase first coulombic efficiencies of petroleum cokes. The reactions of ClF 3 and NF 3 with carbon materials are radical reactions while the reaction with F 2 is an electrophilic reaction yielding fluorinated layers with high disorder. Surface modification using F 2 , ClF 3 and NF 3 also increased first charge capacities of PC and PC1860.