Surface structure and electrochemical characteristics of plasma-fluorinated petroleum cokes for lithium ion battery

Tsuyoshi Nakajima (1) , Seiko Shibata (1) , Kazuhisa Naga (1) , Yoshimi Ohzawa (1) , Alain Tressaud (2) , Etienne Durand (2) , Henri Groult (3) , Fabienne Warmont (4)

1 Department of Applied Chemistry
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
3 LCMD - Laboratoire Colloïdes et Matériaux Divisés
4 CRMD - Centre de Recherche sur la Matière Divisée

Plasma-fluorination of petroleum coke and those heat-treated at 1860, 2300 and 2800 °C (abbreviated to PC, PC1860, PC2300 and PC2800) was conducted for 15, 30 and 60 min using CF4 gas at 90 °C. Fluorine contents obtained by elemental analysis were negligible except PC fluorinated for 60 min (0.7 at.%). Fluorine concentration on the surface decreased with increasing heat-treatment temperature of petroleum coke, i.e. from PC to PC2800 when plasma-fluorination was made for 30 and 60 min. Transmission electron microscopic observation revealed that the closed edges of PC2800 were destroyed and opened by plasma-treatment. Plasma-fluorination increased surface disorder of heat-treated petroleum cokes, however, slightly reduced surface areas. These surface structure changes increased first coulombic efficiencies of PC2300 and PC2800 by 6–8 and 8–10% at both 60 and 150 mA g−1, respectively.

Mots clés: Plasma-fluorination; Surface modification; Carbon anode; Lithium ion battery

Domaines: Matériaux

Tsuyoshi Nakajima, Seiko Shibata, Kazuhisa Naga, Yoshimi Ohzawa, Alain Tressaud, et al.. Surface structure and electrochemical characteristics of plasma-fluorinated petroleum cokes for lithium ion battery. Journal of Power Sources, 2007, 168 (1), pp.265-271. ⟨10.1016/j.jpowsour.2007.03.008⟩. ⟨hal-00150404⟩