Vanadium-based oxides have gained significant attention as promising cathode materials for aqueous zinc-ion batteries, owing to their high theoretical capacities, the ability to undergo multi-electron transfer, and varied crystal structures. Despite these advantages, challenges related to structural instability and poor electrical conductivity remain significant barriers to their practical application. In this study, Cr-doped VO 2 (B) nanorods were prepared using a hydrothermal treatment process as a promising candidate for aqueous zinc-ion battery cathodes. The multivalent nature of vanadium promotes a variety of redox reactions, resulting in high specific capacities. Chromium ion doping increases oxygen vacancy defects and provides efficient channels for electron transfer. The nanorod morphology offers an increased specific surface area, thereby promoting a higher density of active sites. Positron annihilation lifetime spectroscopy indicates that the generated defects exist in the form of single vacancies. Thanks to the unique tunnel structure and micro-morphology advantages, the CrVO cathode exhibits rapid electron transfer and superior reaction kinetics. Electrochemical performance is optimized at a chromium ion doping concentration of 6 at.%, achieving a high specific capacity of 312.8 mAh g −1 at 0.1 A g −1 and retaining 188.3 mAh g −1 at 5 A g −1 after 2000 cycles, with a remarkable capacity retention of 90.39 %, indicating exceptional long-term cycling stability. This work optimizes the electrochemical performance by introducing different concentrations of chromium ions into the monoclinic VO 2 , thereby altering the Cr 3+ /Cr 6+ and V 4+ /V 5+ ratio, providing a feasible approach for developing high-performance vanadium-based aqueous zinc-ion battery cathodes.
Han Shen,Xiaorong Meng,An Zhou,Zhifan Zhang,Pan Feng,Haigang Qin
This study employs a synergistic strategy combining La 3+ -doped modified VO 2 (B) (L x VO) with mesoporous hollow carbon spheres (MHCS) to prepare a high-capacity, highly stable MHCS-supported La-doped VO 2 (B) cathode material (HLVO). Optimizes the La 3+ doping ratio of L x VO and the MHCS content in HLVO, and the lattice expansion behavior of VO 2 (B) caused by La 3+ doping and the composite of carbon materials is clarified, which effectively contributes to the improvement of Zn 2+ diffusion kinetics rate and electrochemical performance of HLVO. The dynamic mechanism of LVO and HLVO is explained by density functional theory. The results show that the (110) interplanar spacing of 5 % La-doped L 0.05 VO increases to 0.355 nm. In the optimized H2L 0.05 VO, L 0.05 VO loose nanorods and MHCS are evenly distributed. The diffusion kinetic rate constant of Zn 2+ in HLVO is two orders of magnitude higher than that of VO 2 (B). At 1 A g −1 , the specific capacity of H2L 0.05 VO cathode remains at 403.5 mAh g −1 after 200 cycles, and the capacity retention rate is as high as 81.6 % after 10 A g −1 10000 cycles. The synergistic strategy of rare earth doping and carbon material composite provides a new idea for the development of high-performance aqueous zinc ion batteries (AZIBs) cathode materials.
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