Heteroatom doping hollow vanadium oxide/carbon composites as universal anode materials for efficient alkali-metal ion storage

Abstract

Hollow structure and heteroatom doping strategies are effective approaches to prepare high-performance energy storage materials. Herein, hollow precursors are obtained in a solvothermal reaction based on Ostwald-ripening process, time-tracking and variable-control methods are adopted to explore the formation mechanism and influencing factors of hollow precursors. Selenium-doped V2O3/carbon composites (VOSe) are prepared via the high-temperature selenization process. VOSe manifests abundant internal space and plentiful defects, which provides more adsorption sites for Na+/K+/Li+ and facilitates immersion of the electrolyte. Therefore, VOSe exhibits a higher capacity and excellent cycle stability for sodium storage (201.5 mA h/g after 2700 cycles at 3.0 A/g), potassium storage (162.3 mA h/g after 500 cycles at 0.5 A/g) and lithium storage (305 mA h/g at 5.0 A/g over 1000 cycles), Compared to V2O3/carbon composites (VO), kinetic analysis and DFT calculation indicate that VOSe possesses more rapid Na + diffusion kinetics and lower diffusion barrier. The reversible chemical transformation of Na++V2O3↔ α-NaVO3 and performance evolution are characterized via ex-situ analyses. Finally, full-cells assembled with Na3V2(PO4)3 cathode exhibits superior cycle stability (170.8 mA h/g after 150 cycles at 0.5 A/g).