Benzoquinone-intercalated vanadium oxide in the electrolyte with Al3+ for zinc-ion storage: dual-pillar effect and reversible disorder–order conversion

Abstract

It was synthesized oxygen-deficient (1, 2, 3-BQ)-VO formulated as (1, 2, 3-BQ)0.25V2O5·0.5H2O (BQ = benzoquinone) via a facile one-step hydrothermal technique. Continuous rotation electron diffraction (cRED), Rietveld refinement and spherical aberration-corrected transmission election microscopy unravel the successful pre-intercalation of the BQ organic species into the layered vanadium oxide, in which two neighboring V-O-V monolayers are observed with the (001) facet as the division plane. (1, 2, 3-BQ)-VO possesses a good electrochemical property in 3 M Zn(CF3SO3)2. And in the electrolyte with Al3+, it shows improved rate capability and remarkably enhanced cycling performance. Its average capacity is up to an unprecedented value of 446/400 mAh/g at 0.2/1 A/g with a capacity retention exceeding 100 % over 550 cycles at 1 A/g (411 mAh/g), which is associated with the dynamic reversible conversion between disorder and order on the (001) facets. The inserted Al3+ into the inner channel of (1, 2, 3-BQ)-VO during the discharge process, not only acts as the interlayer pillar to prevent the collapse of the layered structure, but also can improve the crystallinity of the charged (1, 2, 3-BQ)-VO sample due to the more ordered atomic arrays from the interlayer (00l) facets. And the dual pillars of BQ and Al3+ in the sample can boost the exposure of active sites, thus enhance the storage capacity. In addition, density functional theory (DFT) calculations disclose a small Zn2+ diffusion barrier of 0.85 eV in (1, 2, 3-BQ)-VO. Moreover, it is found that the electrolyte with Al3+ is not only beneficial for the modification of the (1, 2, 3-BQ)-VO cathode, but also can inhibit the Zn dendrite formation at the Zn anode.