Clarify the capacitance contribution of lactone surface functionalities

Determine the relationship between lactone surface functionality and the difference in specific capacitance between oxidized and non-oxidized carbon electrodes in 1 m and 21 m LiTFSI electrolytes.

Background

The study analyzes how six oxygen-containing surface functionalities—carboxylic, anhydride, carbonyl, phenol, ether, and lactone groups—affect the capacitance of graphitic carbon nano-onions and conductive carbon black in LiTFSI electrolytes. The quantity ΔCₛ is defined as the difference in specific capacitance between oxidized and non-oxidized samples, allowing the effect of surface functionalization to be assessed separately from the underlying carbon structure.

The authors identify clear groupings for the effects of carboxylic and anhydride groups, carbonyl and phenol groups, and ether groups. However, they explicitly state that the relationship for lactone groups is unclear. Thus, the quantitative and mechanistic contribution of lactone functionality to capacitance enhancement remains unresolved within the reported analysis.

References

Interestingly, the relationship between surface functionality and ΔCₛ can be categorized into 3 groups (except lactone, whose relation is unclear): (1) carboxylic and anhydride groups, (2) carbonyl and phenol groups, and (3) ether.

— Unveiling the Influence of Graphitic Nanocarbon Structures, Defects, and Surface Functional Groups on Supercapacitive Performance in LiTFSI Electrolyte  (2610.13482 - Sakulaue et al., 9 Oct 2026) in Section 3.4, discussion accompanying Figure 8(c–d)