Rechargeable aqueous zinc-ion batteries (ZIB) are emerging as one promising alternative for Li-ion batteries on account of the high energy density, environmental friendliness, rich earth abundance and good safety characteristics. Nevertheless, almost all the ZIBs suffer from sluggish kinetics of Zn 2+ diffusion in electrodes, leading to poor rate capability and inadequate cycle life in practical applications. To tackle this issue, herein we develop an in situ polyaniline (PANI) intercalation strategy to facilitate the Zn 2+ (de)intercalation kinetics in V2O5. In this way, a remarkably enlarged interlayer distance (13.90 Å) can be constructed alternatively between the V-O layers, offering expedite This article is protected by copyright. All rights reserved.3 channels for facile Zn 2+ diffusion. More importantly, the electrostatic interactions between Zn 2+ and host O 2-, which is another key factor in hindering the Zn 2+ diffusion kinetics, can be effectively blocked by the unique π-conjugated structure of PANI. As a result, the PANI-intercalated V2O5 exhibits a stable and highly reversible electrochemical reaction during repetitive Zn 2+ insertion and extraction, as demonstrated by in situ synchrotron X-ray diffraction and Raman studies. Further first-principles calculations clearly reveal a remarkably lowered binding energy between Zn 2+ and host O 2+ , which explains the favorable kinetics in PANI-intercalated V2O5. Moreover, the intercalation of PANI leads to an intermediated energy band lying across the Fermi level, thereby offering a step for electron transport during charging/discharging process. Benefitting from the above, the overall electrochemical performance of PANI-intercalated V2O5 electrode has been remarkable improved, exhibiting excellent high rate capability of 197.1 mAh g −1 at current density of 20 A g −1 with capacity retention of 97.6% over 2000 cycles. Our approach presents a prospective guideline for the electrode design of high performance aqueous ZIBs, which could be also expanded to widespread battery researches.

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Aqueous Zn||vanadium oxide batteries (ZVBs) have recently received considerable attention owing to their high capacity, safety, environmental friendliness, and cost effectiveness. However, the limited cycling stability caused by the irreversible dissolution in traditional aqueous electrolytes still restricts their further application. Herein, a novel 3 m Zn(CF3SO3)2 electrolyte with a mixture solvent of propylene carbonate (PC) and H2O is adopted for aqueous vanadium‐based zinc‐ion batteries. With the manipulation of the electrolyte solvation structure, the optimized P20 (20% PC in volume ratio) electrolyte enables super‐stable cycling performance with high‐capacity retention of 99.5%/97% after 100/1000 cycles at 0.1/5 A g−1 at ambient environment in the Zn||NaV3O8·1.5H2O batteries. Systematical electrochemical testing and characterizations illustrate the addition of PC effectively reduces the active water molecule in Zn2+‐solvent cations and H+ in the electrolyte, thereby suppressing the cathode dissolution caused by the inserted H+ and co‐inserted H2O during the discharge/charge process. Impressively, the PC addition also enabled the Zn||NaV3O8·1.5H2O batteries present high specific capacity of 183/168 mAh g‐1 and high‐capacity retention of 100%/100% over 300/400 cycles at 0.1/0.2 A g‐1 at −40 °C, thus efficiently broadening the practical application for ZVB. This research may provide a promising strategy for designing high‐performance electrolytes for aqueous vanadium‐based batteries.

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