The Li spectrum revealed the presence of Li-O and Li-C, consistent with the C 1s and O 1s spectra (Fig. ). Upon discharge to 0.005 V (Fig. ), changes were observed in the XPS spectra compared to the initial state: the intensity of the C-C peak increased. In contrast, the C=C peak decreased, accompanied by enhancements in the intensities of the C-Li and C-O/C-N peaks. In the N 1s, O 1s, and Li 1s spectra, the peaks for N-C and Li-C increased, while those for N=C and O-Li decreased. These changes suggested that C=C, C=N, and furan may be involved in lithium-ion storage. Upon charging to 3.0 V (Fig. ), the C 1s and N 1s spectra gradually resembled the initial XPS spectra, confirming the reversible lithium-ion storage properties of C=C and C=N. The peak intensity of O-Li decreased, indicating that furan may also play a role in lithium storage.