Customizing Hydrophilic Terminations for V₂CT_x MXene Toward Superior Hybrid‐Ion Storage in Aqueous Zinc Batteries

Abstract

V2CTx MXene is a “rising star” cathode material for aqueous zinc‐based batteries (AZBs) owing to its large/flexible interlayer spacing, rich redox chemistry of V, and high electronic conductivity. Nevertheless, the plentiful F surface terminations generated during the common preparation (fluorine‐containing acid etching process) of V2CTx generally result in high hydrophobicity, poor Zn affinity, and sluggish ion‐diffusion kinetics. Herein, a novel OH‐termination‐rich V2CTx material with interlayer “K+‐pillars” (alk‐V2CTx) is fabricated via a facile one‐step alkalization method, which features excellent hydrophilicity, expanded ion‐transport channels, and robust layered structure. Impressively, the tailored alk‐V2CTx cathode enables highly reversible and rapid Li+/Zn2+ co‐insertion/extraction electrochemistry in the formulated 15 m LiTSFI + 1 m Zn(CF3SO3)2 aqueous electrolyte, meanwhile, the “self‐exfoliation” phenomenon of MXenes upon cycling significantly increases the active sites, rendering the superior rate performance (498.2/195.1 mAh g−1 at 0.1/30 A g−1, respectively) and exceptional cycling life (96.2% capacity retention over 20 000 cycles). Systematic in situ/ex situ analyses and theoretical computations elucidate the above hybrid‐ion storage mechanisms. Finally, flexible quasi‐solid‐state rechargeable Zn batteries employing the alk‐V2CTx cathode exhibit inspiring energy output even under severe deformation conditions and low temperatures. This study provides new perspectives for designing high‐performance MXene‐based cathodes for AZBs by modulating surface terminations.

Synergistic Effect of the V2CTx MXene@V2O5/TiO2 NP Composite for Stimulating Photocatalytic CO2 Reduction through Bireforming of Methanol to Produce CO and CH4

“…Figure (b) shows the XPS spectrum of V 2p with characteristics peaks linked to V 3+ , V 4+ , and V 5+ . The V 4+ species in V 2 C is associated with 516.9 and 425.5 eV, which confirm the existence of V 2 O 5 (V–O) on the surface of V 2 C. The binding energies at 516.1 and 517.9 eV are associated with V 3+ and V 5+ , respectively, confirming the presence of monolayer oxide/V 2 O 5 in the composite. , Comparing the results of V 2 C MXene and the V 2 C@V 2 O 5 /TiO 2 composite, it can be observed that various V 2 O 5 species are present in the composite, which was due to heating the samples at higher temperatures. Figure (c) shows the XPS spectrum of Ti 2p with binding energies of 458.8 and 463.7 eV, associated with Ti 2p 3/2 and Ti 2p 1/2 , respectively, which confirms the existence of Ti 4+ in V 2 C@V 2 O 5 /TiO 2 .…”

Controllable synthesis of electric double-layer capacitance and pseudocapacitance coupled porous carbon cathode material for zinc-ion hybrid capacitors

“…13 SA-3 exhibited the highest specific capacitance among the four samples because of the largest specific surface area and the appropriate amount of oxygen-containing functional groups. In order to explore the role of oxygen-containing functional groups 54,55 in the charge and discharge process (Fig. 5a), ex situ XRD, SEM, and XPS were measured.…”

Confined Mn Ions Enhance Charge Transport for High-Performance Hydrated Vanadium Oxide Cathode

“…Vanadium oxides have attracted extensive attention due to their open-frame crystal structure, which facilitates the mobility of Zn 2+ . − However, certain challenges cannot be disregarded, such as an unstable layered structure and limited electronic conductivity, resulting in inadequate cycle capacity and stability. To overcome these obstacles, extensive efforts have been undertaken, such as the implementation of preintercalation techniques − or defect engineering. − One common approach involves the introduction of metal ions into the interlayer spacing of vanadium-based materials. − This method aims to increase the interlayer spacing, create more diffusion channels, and enhance ionic conductivity.…”