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

Surface modification of petroleum coke (PC) and those heat-treated at 1860,2300 and 2800 degrees C (PC 1860, PC2300 and PC2800) has been performed by F-2, CIF3 and NF3 to improve their charge/discharge characteristics in propylene carbonate containing solvents. Surface fluorination by F-2 increased surface disorder of PC 1860, PC2300 and PC2800, leading to increase in their first coulombic efficiencies in 1 mol dm(-3) LiClO4-ethylene carbonate (EQ/diethyl carbonate (DEC)/propylene carbonate (PPC (1: 1: 1 in volume) solution. First coulombic efficiencies were the largest in fluorinated PC 1860 with the highest surface disorder. However, surface modification by CIF3 and NF3 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 CIF3 and NF3 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, CIF3 and NF3 also increased first charge capacities of PC and PC1860. (c) 2007 Elsevier B.V. All rights reserved.