Synergistically Electronic and Structural Regulation of VO₂ by Ce Doping Toward High-Performance Zinc-Ion Batteries

The unique tunnel-like structure of the monoclinic B phase of VO2 makes it a highly potential option for the cathode material of aqueous zinc-ion batteries (AZIBs), while the poor electronic conductivity and slow Zn2+ diffusion kinetics in VO2 limit its further application. To address these challenges, in this study, Ce ions were intercalated into the tunnel structure of VO2 via a facile one-step hydrothermal method. Density functional theory calculation results indicate that the intercalation of Ce ions not only serves as an interlayer support and expands the interlayer spacing of VO2 from 3.430 to 3.933 Å, but also introduces emerging energy states in proximity to the Fermi level, resulting in a reduction of the band gap. The intercalation of Ce ions also reduces the binding energy between Zn2+ and VO2 and thereby significantly improves the diffusion kinetics of Zn2+ within Ce-VO2. Thanks to these advantages, the as-prepared Ce-VO2 offers a high superior capacity of 371.4 mAh g–1 at 0.1 A g–1 and exceptional rate performance of 111.2 mAh g–1 at 5.0 A g–1. The as-prepared Ce-VO2 also has excellent cyclability and can present remarkable capacity retention of 98.2% is maintained at 0.1 A g–1 after 100 cycles, and an admirable capacity retention of 85% is sustained after 2000 cycles even at an high current density of 5.0 A g–1, far superior to those of pristine VO2 electrode. The proposed rare earth ion doping strategy provides a new direction for achieving high-performance VO2 cathodes toward AZIBs.