Enhancing the Electrochemical Performance of Aqueous Zinc-Ion Batteries Using 1,4-Diazabicyclo[2.2.2] Octane-Intercalated Vanadium Pentoxide Cathode

Vanadium-based cathodes are promising materials for aqueous zinc-ion batteries owing to their high capacity; however, their layered structure tends to collapse, adversely affecting the electrochemical properties and cycling stability. Guest preintercalation has emerged as an effective approach for enhancing the electrochemical behavior of vanadium-based cathodes. Herein, we investigate the effect of introducing the small molecule 1,4-diazabicyclo[2.2.2] octane (C6H12N2) into the interlayer space of vanadium oxide on its electrochemical performance. Using distinct synthesis methods, we obtain vanadium-based oxides (DVO) in either molecular (MDVO) or ionic (IDVO) intercalated forms. Extensive characterizations and investigations reveal that IDVO possesses a stabilized interlayer structure but suffers from a low capacity, potentially due to the strong ionic bonds between layers hindering the transport of Zn2+/H+. Conversely, MDVO exhibits a larger interlayer spacing and weaker interlayer interactions, providing more storage space for Zn2+/H+ for enhanced capacity. Furthermore, the energy storage mechanism of MDVO is discussed. This preintercalation strategy offers valuable insights for future research.