Surface De-Fluorination and Bond Modification of CF_x by High-Density Hydrogen Plasma Processing

The Li/CFx (lithium/fluorinated carbon) primary battery has attracted worldwide interest from the academic community and industry. However, Li/CFx batteries encounter the issue of poor rate capability because of the poor electronic conductivity of CFx due to the strong covalent C–F bond. Herein, we reported a vapor-phase method, namely, a low-temperature plasma technique, to modify the surface morphology, chemical components, and the microstructure of CFx. High-density hydrogen plasma processing partially de-fluorinated the CFx surface with a gradient fluorine content in the CFx powders and resulted in the increased ionic C–F bond simultaneously on the surface of CFx. As a result, both the specific capacity and rate performance of the Li/CFx primary battery were significantly improved due to the enhanced electron and Li+ transfer evidenced by the electrochemical tests. Different from the commonly used liquid-phase/solid-phase methods, no centrifugation, filtration, or washing processes were involved in this time-saving, eco-friendly, and facile plasma technique of the present plasma method.