Surface Modification of Carbonaceous Materials by Fluorinated Gases and Use as Anode in Lithium-Ion Battery

Abstract

The electrochemical performances of raw and surface- fluorinated graphite powders used as anode in Li-ion battery have been studied. The fluorination obtained from F2 gas mainly concerns the surface of the particles for TF2≤300 {degree sign}C. For higher temperature, important modifications of the bulk structure were observed. When they are used as anode in Li-ion battery, fluorinated graphite powders exhibit better electrochemical performances than raw graphite notably due to an increase of the surface area and surface defects which allow the storage of a higher amount of lithium into the host lattice. These results have been confirmed by impedance measurements performed in delithiated state: a drastic decrease of both the charge transfer resistance and the resistance related to the SEI layer was observed for TF2 lower than 300 {degree sign}C.

Hydrophobic Gas-Diffusion Media for Polymer-Electrolyte Fuel Cells by Direct Fluorination

“…Direct fluorination of carbon materials has been investigated for many applications ranging from low friction and durable materials for lubrication to materials for lithium-ion batteries. [18][19][20][21][22][23][24][25][26][27][28][29][30][31] In these studies, carbon powder materials were reacted with fluorine gas from 350 to 600 • C, with the value of x in the compound CF x on the surface of the carbon materials varying from 0.6 up to 1, respectively. Treatment at lower temperatures (<300 • C) was found to result in materials with poorly fluorinated surfaces, and treatment at higher temperatures (<700 • C) resulted in materials with higher x values due to the formation of CF 2 and CF 3 groups on the surface and loss in carbon material due to the formation of gaseous CF 4 product.…”