As
a result of the absence of solid-state diffusion limitation,
intercalation pseudocapacitance behavior is emerging as an attractive
charge-storage mechanism that can greatly facilitate the ion kinetics
to boost the rate capability and cycle stability of batteries; however,
related research in the field of zinc-ion batteries (ZIBs) is still
in the initial stage and only found in limited cathode materials.
In this study, a novel V2O5–x@rGO hybrid aerogel consisting of ultrathin V2O5 nanosheets (∼1.26 nm) with abundant oxygen vacancies
(Vö) and a three-dimensional (3D) graphene conductive network
was specifically designed and used as a freestanding and binder-free
electrode for ZIBs. As expected, the ideal microstructure of both
the material and the electrode enable fast electron/ion diffusion
kinetics of the electrode, which realize a typical intercalation pseudocapacitance
behavior as demonstrated by the simulation calculation of cyclic voltammetry
(CV), ex situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy
(XPS), and first-principles density functional theory (DFT) calculation.
Thanks to the elimination of solid-state diffusion limitation, the
V2O5–x@rGO electrode
delivers a high reversible rate capacity of 153.9 mAh g–1 at 15 A g–1 and 90.6% initial capacity retention
at 0.5 A g–1 after 1050 cycles in ZIBs. The intercalation
pseudocapacitance behavior is also realized in the assembled soft-pack
battery, showing promising practical application prospects.