Synergistically Electronic and Structural Regulation of VO<sub>2</sub> by Ce Doping Toward High-Performance Zinc-Ion Batteries
Haozhen Li, Xiaocheng Li, Juan Liu, Nengwen Ding, Qian Zhang, Shulai Lei, Sydorov Dmytro
Abstract
The unique tunnel-like structure of the monoclinic B phase of VO 2 makes it a highly potential option for the cathode material of aqueous zinc-ion batteries (AZIBs), while the poor electronic conductivity and slow Zn 2+ diffusion kinetics in VO 2 limit its further application. To address these challenges, in this study, Ce ions were intercalated into the tunnel structure of VO 2 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 VO 2 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 Zn 2+ and VO 2 and thereby significantly improves the diffusion kinetics of Zn 2+ within Ce-VO 2 . Thanks to these advantages, the as-prepared Ce-VO 2 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-VO 2 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 VO 2 electrode. The proposed rare earth ion doping strategy provides a new direction for achieving high-performance VO 2 cathodes toward AZIBs.