Strong Lewis electron-pair bonding in vanadium oxide for ultra-fast and long-term stable Zn-ion storage

Vanadium-based oxides typically show low electrical conductivity, high repulsion for Zn2+, and severe structure collapse problems, resulting in unsatisfied cathode performance for aqueous Zn-ion batteries (AZIBs). Herein, we propose an advanced structural optimization strategy to address the above issues by constructing strong Lewis electron-pair bonding in vanadium oxide through initial doping Ca and a subsequent in-situ electrochemical activation process. We prepared the precursor of Ca-doped and amorphous carbon-encapsulated V2O3 material (Ca0.17V2O3-x@C) and verified a phase transition into a layered V2O5-typed cathode during the activation process. Importantly, we find the initial-doped Ca and generated abundant oxygen vacancy defects are well restored in the phase-transformed crystal lattice. We reveal that band and bond structures of the phase-transformed cathode are optimized, exhibiting an improved electrical conductivity, optimal Zn2+ binding energy, ultra-low Zn-ion transport barrier, and considerably strong bonds of Ca-O and V-O, thereby realizing enhanced reaction kinetics and stability. The Ca0.17V2O3-x@C exhibits surprisingly high-rate performance (233 mAh g(-1) at 40 A g(-1)) and excellent cycling stability (10,000 cycles with 82 % retention at 20 A g(-1)). This work offers a novel and simple band and bond structure engineering strategy for preparing high-performance phase transformation typed vanadium oxide cathodes for AZIBs.