Reconstruction Effects of Layered Vanadium Oxides by Nanoengineering and Preintercalation for High Zinc-Ion Storage Performance.

Layered vanadium oxides with preintercalated cations have been recognized to be among the most promising cathode materials for aqueous zinc-ion batteries (AZIBs). However, their underlying structure-property relationships are still poorly understood owing to the lack of systematic comparison. Herein, a series of layered VO nanobelts including single-layer α-VO and bilayer hydrated δ-VO with preintercalation (MVO·HO, M = Mg, Ca, or Ba) with similar morphology are fabricated through a controllable synthesis protocol as models. The side-by-side comparisons of the energy storage performances and related kinetics in these samples decouple the reconstruction effects of nanostructuring and preintercalation. Results demonstrate that nanostructuring tends to improve the capacity and rate retention of α-VO but leaves the rapid capacity decay unsettled, whereas preintercalation can convert α-VO into δ-VO with simultaneously enhanced discharge capacity, rate retention, and cycling stability. Regulation of the cations' species/content and their associated structural water appears to accelerate the electron/ion transport in VO and stabilize the framework of VO, thereby boosting the energy storage properties. The optimized sample with a stoichiometric formula of MgVO·0.809HO exhibits outstanding comprehensive energy storage performance that is comparable to the most advanced vanadium oxide hydrate cathodes reported in the literature. The quantification and understanding of the reconstruction effects of nanostructuring and preintercalation in this work offer insights into the structural engineering of advanced cathodes for AZIBs and beyond.