Hierarchical Vanadium Sulfide Nanosheets with Expanded Interchain Spacings for High Performance Sodium–Ion Batteries

Abstract

Sodium–ion batteries (SIBs) have been intensively researched as potential alternative energy storage devices for lithium–ion batteries (LIBs). Nevertheless, the scarcity of suitable anode materials capable of hosting the large radius of Na+ has hindered the further application of SIBs. Herein, we developed a hierarchical VS4 nanosheet with expanded interchain spacing of 0.98 nm without additive for the first time. Additionally, we found that the porous structure in hierarchical VS4 nanosheet provides sufficient active sites for Na+ storage and alleviates the volume variation during discharge/charge cycles, as supported by finite element simulations (FES) data. More importantly, a dynamic insertion–dominated storage mechanism was revealed through synchrotron X–ray absorption spectra and X–ray photoelectron spectroscopy. Thus, the optimized anode delivered a high capacity of 441 mAh g–1 at 1 A g–1 after 200 cycles. This work provides critical insights into the design of SIBs by correlating storage mechanisms with electrode’s structural composition.