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Cui et al. Energy Mater 2023;3:300023 https://dx.doi.org/10.20517/energymater.2022.90 Page 9 of 12

Figure 7. Ex-situ high-resolution XPS spectra of ZVNW-CC electrodes at different charge-discharge states: (A) V 2p. (B) Zn 2p. (C) O 1s.

603.5 (109.1) Ω, respectively, indicating the improved conductivity of the self-supporting electrode. The
above results further proved that both the 1D ZVNW-CC cathode and self-supporting electrode together
2+
fastened the Zn immigration, resulting in high capacity and high cycle stability. Moreover, the energy
-1
density and power density of the ZVNW-CC electrode were calculated to be 273.5 Wh kg and
1,888 W kg , respectively. Compared with the reported AZIBs containing similar cathodes such as
-1
[21]
Ca V O ·nH O , Zn V O , VS , and FeFe(CN) , the ZVNW-CC electrode provided higher energy
[25]
[27]
[36]
2
2
6
2
7
2
0.25
2
5
densities in a wide range of power densities in Ragone plots (as shown in Figure 6F).
Ex situ XPS analyses were used to analyze the valence-state change of the ZVNW-CC electrode and further
revealed the possible Zn storage mechanism during the charge and discharge processes. Figure 7A shows
2+
the Zn 2p spectra of the fully charged and fully discharged states of the ZVNW-CC electrode. In the fully
discharged state, Zn 2p peaks at 1,022.48 and 1,021.58 eV or Zn 2p peaks at 1,045.76 and 1,044.67 eV
3/2
1/2
[37]
were due to the formation of Zn-O and Zn-C bonds . However, in the fully charged state, only the XPS
2+
peak of the Zn-O bond remained and the Zn-C peak disappeared, which suggested that Zn of Zn-C was
2+
more easily de-intercalated and led to an increase in capacitance. Moreover, with the interaction of Zn , the