Suppressed Proton Insertion Enhances Zinc-Ion Storage Kinetics and Stability in Hydrated Vanadate
Heng Liu, Menghao Yang, Quan Zong, Min‐Hsin Yeh, Chun‐Chi Chang, Long Yang, Wei‐Hsiang Huang, Chaofeng Liu, Guozhong Cao
Abstract
Preintercalation chemistry is pivotal for tuning the structure of layered hydrated vanadium pentoxide (V 2 O 5 · n H 2 O, VOH) cathodes in aqueous zinc-ion batteries (AZIBs). However, the underlying fundamental impacts on proton insertion accompanied by zinc storage are elusive in the electrochemical process. In this work, 1,3-diaminoguanidine (DG) molecules are preintercalated into the interlayers of VOH. The modified sample (DG-VOH) exhibits enhanced Zn 2+ diffusion and storage despite the reduced interlayer spacing. This improvement stems from the charge shielding effect provided by preintercalated DG molecules. Additionally, distortion of [VO 6 ] octahedra modulates the electronic structure, leading to increased electronic conductivity. More importantly, the modulated electronic structure contributes to the effectively suppressed detrimental H + co-insertion, which alleviates lattice strain, vanadium dissolution, and byproduct formation. As a result, the DG-VOH cathode delivers a high specific capacity of 437.8 mAh/g and outstanding long-term cycling stability, retaining 91% of its capacity after 5000 cycles at 8 A/g. This work elucidates the critical role of organic preintercalants in inhibiting H + co-intercalation, providing valuable insights for the design of high-performance AZIB cathodes.