In situ electrochemical activation of commercial V2O5 cathodes enabling high-performance aqueous zinc-ion batteries

Vanadium pentoxide (V 2 O 5 ) has emerged as a compelling cathode candidate for aqueous zinc-ion batteries (AZIBs) owing to its high theoretical capacity (589 mAh g −1 ). Nevertheless, practical implementation faces critical challenges: (1) intrinsic electronic insulating properties, (2) irreversible structural collapse during Zn 2+ intercalation, and (3) vanadium dissolution in aqueous media, collectively resulting in rapid capacity degradation. While existing modification approaches (e.g., pre-intercalation, nano structuring) partially address these issues, their multi-step processing and high energy consumption hinder scalability. Herein, we propose a novel hybrid electrolyte strategy (ZnSO 4  + Na 2 SO 4 ) that enables spontaneous electrochemical reconstruction of commercial V 2 O 5 during initial cycles (∼200 cycles). The dual-anion synergy precisely controls phase evolution, inducing in situ formation of a Zn 3 V 2 O 7 (OH) 2 ·2H 2 O/Na 2 V 6 O 16 ·3H 2 O dual-phase heterostructure. The optimized cathode delivers exceptional cyclability with 206 mAh g −1 residual capacity after 1500 cycles at 1 A g −1 (ultrahigh 78 % retention), outperforming most reported V-based AZIB cathodes. This simple yet effective electrolyte engineering strategy demonstrates high material utilization from raw V 2 O 5 , establishing a paradigm for sustainable battery manufacturing through electrochemically-driven structural optimization.