Synergistic modification of V2O5 cathodes with Ca2+ and chitosan: Structural regulation and performance enhancement

Vanadium pentoxide (V 2 O 5 ), owing to its high theoretical capacity and layered structure, is considered a promising cathode material for aqueous zinc-ion batteries (AZIBs). However, its practical application is limited by sluggish Zn 2+ diffusion and structural instability during cycling. In this work, Ca 2+ and chitosan co-modified V 2 O 5 (VO-CS-Ca) was synthesized from commercial V 2 O 5 via an alcohol-assisted solvothermal method. XRD analysis revealed that the interlayer spacing of the (200) plane increased from 0.577 to 0.585 nm after co-modification. SEM and BET analyses confirmed the formation of a porous nanoflower-like architecture, with the specific surface area increasing from 14.99 m 2  g −1 for VO to 23.55 m 2  g −1 for VO-CS-Ca. Benefiting from the expanded interlayer spacing and optimized interfacial properties, the VO-CS-Ca electrode delivered an initial specific capacity of 310.5 mAh g −1 at 0.1 A g −1 , maintained 105 mAh g −1 after 1400 cycles at 1.0 A g −1 , and retained 92 mAh g −1 after 4500 cycles at 5.0 A g −1 . EIS and GITT results confirmed reduced charge-transfer resistance and enhanced Zn 2+ diffusion kinetics, while ex-situ XRD/XPS revealed reversible V 5+ /V 4+ redox behavior and structural evolution during Zn 2+ storage. These results indicate that Ca 2+ /chitosan co-modification effectively tailors the interlayer structure and surface/interface environment of V 2 O 5 , offering a feasible route for high-performance V 2 O 5 cathodes in AZIBs.