Flexible Free‐Standing VO₂/MXene Conductive Films as Cathodes for Quasi‐Solid‐State Zinc‐Ion Batteries

Abstract

Flexible rechargeable zinc-ion batteries (ZIBs) have aroused tremendous attention owing to the good safety and abundant reserves, making it one of the most promising alternatives for novel energy storage devices. Herein, flexible, free-standing hybrid films with a three-dimensional interlaced network are reported for ZIBs. The flexible and pliable VO 2 /MXene hybrid films deliver a high specific capacity of 228.5 mAh g À 1 at 0.2 A g À 1 and display a reversible capacity over 126.6 mAh g À 1 after 700 cycles at 2 A g À 1. More impressively, the flexible electrode also shows exciting mechanical flexibility and outstanding Zn 2 + storage capability with a moderate capacity retention of 72.1 % after 2500 cycles at 5 A g À 1 in quasi-solidstate ZIBs. The special structure can boost the diffusion pathway of Zn 2 + and effectively stabilize the structure of the electrode upon cycling. This work also evidences that the flexible VO 2 / MXene hybrid films own an immense potential for portable and flexible equipment.

A Composite Material with Internal Hydrophilicity and External Stability as the Cathode of Aqueous Zinc-Ion Batteries Exhibiting Excellent Rate Performance and Energy Density at High Power Density

“…Additionally, the diffusion coefficient of Zn 2+ (D Zn ) in the VO 2 -SDBS@rGO electrode was also identified by the GITT (Figure 4e,f). 42,43 The calculated D Zn values at the process of discharge and charge correspond to the processes of Zn 2+ intercalation and deintercalation, respectively. The results of GITT show that with the progress of the Zn 2+ intercalation and deintercalation process, the diffusion of the zinc ions becomes slower.…”

The Emergence of 2D MXenes Based Zn‐Ion Batteries: Recent Development and Prospects

“…Shi et al. reported [ 231 ] binder‐free, cohesive and flexible VO 2 /MXene hybrid films for rechargeable ZIBs. The VO 2 nanobelts were embedded into the MXene sheets and formed 3D lamination‐like conductive network (Figure 17f).…”

“…f–k) Reproduced with permission. [ 231 ] Copyright 2021, John Wiley & Sons. l) Schematic representation of the fabrication of MnO x @Ti 3 C 2 T x , SEM images of m) multilayered Ti 3 C 2 T x ‐MXene, n) MnO x @Ti 3 C 2 T x assembly, galvanostatic charge–discharge curves of the flexible battery, o) at different bending angles, p) after multiple bending cycles, q) under severe mechanical deformation, r) optical images illustrating energy storage performance.…”

“…Notably, only a very slight capacity fading was observed over 120 cycles, which indicates the strong deformation tolerance of this battery. Shi et al reported [231] binder-free, cohesive and flexible VO 2 /MXene hybrid films for rechargeable ZIBs. The VO 2 nanobelts were embedded into the MXene sheets and formed 3D laminationlike conductive network (Figure 17f).…”

Construction of Hierarchical Flower‐Shaped (NH4)2V3O8/rGO with Enhanced Zinc Storage Performance**

“…Various studies have explored ZIBs cathode materials including manganese‐, [11–13] vanadium‐, [14–16] molybdenum‐, [17] Prussian blue analogues‐based [18–19] inorganic compounds and organic materials [20] . Among them, layered V‐based cathode materials have been reported due to their high specific capacity.…”