The effects of different plasma agent species ( CF4, N2) over the conductivity of CFX cathode material were identified. Both plasma treatments have surface etching effect, while the CF4 plasma treatment has C–F bond modification effect and the N2 plasma treatment has defluorination effect. The changes of surface chemical species and porosity along the plasma agent were elucidated. Moreover, the electrochemical properties of plasma-treated CFX confirmed the effects of plasma treatments. The charge-transfer resistance of plasma-treated CFX was maximum 60.3% reduced than the pristine CFX. The effects of surface chemical modification coupled with etching along the plasma gas agents were compared and identified with their reaction mechanisms.

Plasma treatment of CFX: the effect of surface chemical modification coupled with surface etching
    Abstract
    1 Introduction
    2 Experimental
        2.1 Preparation of plasma-treated CFX
        2.2 Characterization of plasma-treated CFX
        2.3 Electrochemical properties of plasma-treated CFX
    3 Results and discussion
    4 Conclusion
    Acknowledgements 
    References

• Chaehun Lim(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea)
• Seongmin Ha(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea)
• Naeun Ha(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea)
• Seo Gyeong Jeong(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea)
• Young‑Seak Lee(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea, Institute of Carbon Fusion Technology (InCFT), Chungnam National University, Daejeon 34134, Republic of Korea) Corresponding author