Long-lifespan benzoquinone-intercalated vanadium oxide with vacancies and disorders on the (00l) facets for efficient sodium-ion battery: A facile approach to Na+ capture and pre-sodiation

• It was synthesized ( m -BQ) 0.15 V 2 O 5 ·0.5H 2 O (BQ = benzoquinone) porous microflowers. • Rietveld refinement and HAADF-STEM reveal the intercalation of m -BQ into V 2 O 5 . • The dehydrated sample shows an excellent rate performance and an ultralong cycle life. • DFT calculations reveal a lower Na + migration barrier in the dehydrated sample. • The affinity of m -BQ towards Na + provides a facile routine for pre-sodiation. Via a facile one-step hydrothermal method, it was synthesized ( m -BQ) 0.15 V 2 O 5 ·0.5H 2 O ( m -BQ = m -benzoquinone) (denoted as ( m -BQ)-VO) three-dimensional (3D) porous hierarchical microflowers, which possesses a large (001) lattice spacing of 13.7 Å with crystalline vacancies and disorders on the (00 l ) facets. Rietveld refinement and high-angle annular dark field-scanning transmission election microscopy (HAADF-STEM) of ( m -BQ)-VO unveil that the successful intercalation of m -BQ into layered V 2 O 5 leads to the elongation of V-O bonds. As a result, the V centers of the sample are unsaturated with structural oxygen vacancies, and the V-O-V bilayer is split into two V-O-V monolayers with the (001) facet as the division plane. Consequently, upon lower-temperature annealing, the dehydrated sample can deliver a high initial capacity of 252 mAh g -1 at 0.05 A g -1 with excellent capacity retentions of 90 % over 210 cycles at 0.1 A g -1 , and 87 % over 2100 cycles at 2 A g -1 , respectively, in which no apparent phase change is observed. It is associated with the large interlayer channel with a lower Na + migration barrier of 0.48 eV. And the anchoring effect of layered V-O-V framework can prevent the leaching of m -BQ into electrolyte. Furthermore, the redox-active m -BQ can provide extra capacity, whose affinity towards Na + can induce the partial inclusion of Na + ions in the sample even only immersion in Na + solution undisturbed under room temperature, giving rise to improved electron conductivity and a facile approach to pre-sodiation, as evidenced by density functional theory (DFT) calculations.