The electrochemical properties of a CFX cathode were improved by defluorination of the surface with a N2 plasma and using a silica wafer. Compared to the N2 plasma treatment alone, when the CFX and silica were reacted together, the C-F bonds were modified and the surface was etched efficiently, so defluorination was enhanced. An electrochemical analysis confirmed that Half-cells prepared by treating CFx and silica with nitrogen plasma exhibited a capacity of about 400 mAh/g at 5C. In addition, it was confirmed that the loss of charge transfer was reduced by up to 71% compared to that for pristine CFX. As shown by a GITT analysis, when the CFx and silica were treated with N2 plasma together, the ion conductivity gradually increased due to a decrease in the ion diffusion barriers and the formation of a carbon layer. Therefore, this is a simple and effective way to improve the conductivities of CFX cathode materials with the energy of a N2 plasma and the silica-fluorine reaction.

It was found in this study that fluorinated microporous carbon aerogels with enhanced hydrophobicity could be successfully prepared by direct fluorination to separate water-in-oil emulsions at high flux. The fluorinated carbon aerogel (F-CA) surface treated by the fluorination method had a water contact angle of 151.2° and could immediately absorb oil. In addition, the unique network structure of F-CA and its hydrophobicity allow surfactant-stabilized water-in-oil emulsions to be effectively and simply separated under gravity without requiring external forces such as vacuum or pressurization. The network structure of F-CAs consists of randomly connected spherical particles that form fluorinated permeation channels, which induce high flux during emulsion separation. The F-CA spherical particles have nanosized pores and high hydrophobicity, which repel and trap water droplets to increase the separation purity. Therefore, F-CA exhibited excellent performance, such as high filtrate purity (up to 99.9954%) and flux (up to 11,710 L/m2h). Furthermore, F-CA reusability was demonstrated as it did not lose its hydrophobicity and maintained its performance even after repeated use. This type of aerogel has great potential to be utilized throughout various environmental fields, including oil remediation.

Fluorine heteroatoms were introduced to increase the limited specific capacitances of electric double-layer capacitors (EDLCs), and the effects of the fluorine atoms were analyzed. To introduce the fluorine, a CF4 plasma treatment was used that introduced the fluorine atoms quickly. Among the fluorine functional groups in the F6-ACA framework, the semi-ionic C–F bonds induced rapid charge transfer and imparted pseudocapacitance. Consequently, we achieved a specific capacitance of 325.68 F/g for the F6-CA sample at 0.5 A/g. By analyzing the contributions of the electric double-layer capacitance and the pseudocapacitance, we determined that the contribution from the pseudocapacitance was 37.57%. A remarkable specific capacitance retention rate of 95.87% was obtained over 1000 charge/discharge cycles with a high current density of 3 A/g. Additionally, the semi-ionic C–F bonds reduced the charge transfer resistance ( Rct) by 36.8%. Therefore, the specific capacitance was improved by the fluorine heteroatoms, and the semi-ionic C–F bonds played a pivotal role in this improvement.