High-Performance Aqueous Zinc-Ion Batteries Enabled by Binder-Free and Ultrathin V₂O_5–x@Graphene Aerogels with Intercalation Pseudocapacitance

Abstract

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 V 2 O 5−x @rGO hybrid aerogel consisting of ultrathin V 2 O 5 nanosheets (∼1.26 nm) with abundant oxygen vacancies (Vo) 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 V 2 O 5−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.

Poly(3,4-ethylenedioxythiophene) encapsulating hydrated vanadium oxide nanobelts boosts their conductivity and zinc-ion storage properties

“…VOH@PEDOT has a wider conduction band, with the Fermi level moving through it, indicating that more electronic states can be used for the electronic transmission, resulting in higher conductivity than VOH. 35 The C 2p and V 2p orbitals overlap with the O 2p orbital near the Fermi level (Fig. 6d and S8 †), indicating orbital hybridization and stable bonding of C and V with the O atom.…”

“…recognized as promising shell materials to improve both the stability and conductivity. For instance, Chen et al 35 reported a V 2 O 5− x @reduced graphene oxide (rGO) hybrid aerogel with a three-dimensional rGO network used as a freestanding cathode for AZIBs. As expected, the V 2 O 5− x @rGO cathode showed 153.9 mA h g −1 at 15 A g −1 and 90.6% capacity remained after 1050 cycles at 0.5 A g −1 .…”

Ionic Liquid Promotes High Dispersion of V2O5 on 3D Porous g-C3N4 Carrier to Enhance Catalytic Oxidative Desulfurization Performance

“…For the high resolution XPS spectrum of V 2p, the electron binding energies of V 2p1/2 and V 2p3/2 were 524.95 and 517.35 eV, respectively, and the distance of the peak is 7.6 eV, manifesting that the vanadium atom is +5. 4 Moreover, the peaks of 523.7 and 516.1 eV ascribed to +4 valence vanadium V 2p1/2 and V 2p3/2, respectively, 19 were also detected, indicating the presence of defect sites in the supported catalyst, which is helpful to improve the catalytic oxidation desulfurization performance. 20,21 In order to analyze the morphology and structure of 30% V 2 O 5 /3D g-C 3 N 4 , SEM and TEM analyses are shown in Figure 2.…”

Fine valence regulation of hydrated vanadium oxide as a novel cathode for stable potassium-ion storage

“…A special storage mechanism of intercalation pseudo-capacitance is identified for VOH. 7 Although its relatively low average operating potential (2–4 V vs. K + /K) would set a limitation on the energy density, it can deliver a discharge capacity of 110 mA h g −1 at 10 mA g −1 with an excellent capacity retention of 99.2% even after 700 cycles at 500 mA g −1 .…”

“…On the basis of the above results, the intercalation pseudo-capacitance mechanism of the VOH-S cathode is proposed, which emphasizes that ions migrate inside crystal lattices, especially moving between the layers, rather than the surfaces. 7 Intercalation pseudocapacitive electrodes usually contain sufficient interstitial ion pathways and present no phase transformations during the charge and discharge processes. 31 Considering the solid-solution reaction, ultra-large 2D ion diffusion pathways, superior reaction kinetics, and fast capacitive-dominated characteristics, it is rational to deduce an intercalation pseudocapacitive behavior for VOH-S.…”