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 preintercalated 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.