Structural and orbital multifunctional intercalation engineering of vanadium oxide for aqueous zinc-ion storage

Aqueous zinc-vanadium batteries constitute a highly promising system within the category of aqueous Zn-ion batteries (AZIBs). However, the low electrical conductivity and the infinite dissolution of V 2 O 5 cathodes in aqueous electrolytes pose significant challenges to the battery system. To address these challenges, a multifunctional interlayer engineering strategy is proposed to enhance the reaction kinetics of V 2 O 5 and enable its stable cycling in AZIBs. The structural and atomic orbital changes in vanadium oxide induced by intercalation agents were investigated using a combination of various spectroscopic and microscopic techniques, complemented by theoretical simulations. Firstly, X-ray absorption fine spectroscopy (XAFS), Mott-Schottky (MS) spectroscopy, Ultraviolet-visible (UV–vis) spectroscopy, and ultraviolet photoelectron (UPS) spectroscopy analyses collectively demonstrate that the intercalation of dodecylamine optimizes the electronic structure of V 2 O 5 . This structural modification facilitates electron transitions to the V 3 d xy state and increases the occupancy of the V t 2g orbitals, thereby enhancing the electrical conductivity of the material. Secondly, dodecylamine has been intercalated into the interlayers of V 2 O 5 to expand the interlayer spacing of V 2 O 5 , thereby ensuring rapid ionic/electron transport. Thirdly, abundant oxygen vacancies generate during the subsequent annealing process, which alleviated the electrostatic interactions between adjacent O atoms and Zn 2+ ions. Fourthly, a flexible graphitic carbon layer derived from the conversion of dodecylamine was encapsulated between the V 2 O 5 layers, effectively alleviating volume expansion throughout the cycling process and further accelerating electron transfer. Leveraging the aforementioned synergistic effect, the as-synthesized electrode demonstrates a high capacity of 403.35 mAh g −1 at 0.1 A g −1 , and retains a stable capacity retention rate of 92.6% after undergoing 1000 cycles at 5 A g −1 . This work offers novel insights into the structural and orbital changes induced by intercalation and highlights the advantages of intercalated vanadium oxide as a high-performance electrode for Zn storage.