Fast zinc-ion storage enabled by hydrophobic alkyl chains via reducing dual diffusion barriers

Vanadium-based aqueous zinc-ion batteries (AZIBs) represent a highly promising solution for large-scale energy storage applications. For fast zinc-ion storage within the V₂O₅ cathode and mitigating its structural degradation, hydrophobic alkyl chains are pre-intercalated into V₂O₅. In particular, the synthesized tetraethylammonium pre-intercalated V₂O₅ (TEAVO) delivers a remarkable capacity of 470.9 mA h g^–1 a 0.2 A g^–1, especially excellent rate capability of 307.8 mA h g⁻¹ at 10 A g^–1 over 5,000 cycles (98.3 % capacity retention). Thorough investigations elucidate the multiple roles of the alkyl chains, including the inhibition of H₂O insertion, facilitation of Zn²⁺ desolvation, and suppression of vanadium dissolution fundamentally. The combination of ex/in-situ characterizations and density functional theory (DFT) calculations has also unraveled the dual roles of the alkyl chains in reducing Zn²⁺ diffusion barriers. Notably, the diffusion barriers governing the entire Zn²⁺ insertion process have been determined for the first time at least for TEAVO. This pioneering work presents novel insights into the organic pre-intercalation, and sheds light on the advancement of AZIBs technology.