Hydrogen Sodium Vanadium Oxide Hydrate with Oxygen Vacancy: A New Layered Cathode Material for Sodium-Ion Battery
Haofei Yang, Wenbin Li, Yangyang Luo, Shuting Jia, Jianhua Zhang, Yitong Yuan, Xifei Li
Abstract
The layered HNaV 6 O 16 ·4H 2 O (hydrogen sodium vanadium oxide hydrate) with large interlayer spacing and interlayer H + has been used as a cathode for the zinc-ion battery. However, it is rarely applied in sodium-ion batteries, and only a report tests its initial discharge capacity of ∼23 mAh g –1 at 50 mAh g –1 . In this regard, we first develop HNa x V 6 O 16– y · n H 2 O with an abundant oxygen vacancy (Vo) by a hydrothermal method and then realize the double modification of Co 2+ preintercalation and further Ti 3 C 2 T x coating (Vo-CHNVOT) by an in situ preintercalating and electrostatic self-assembly method, respectively. Benefiting from the synergistic effect of Vo, Co 2+, and Ti 3 C 2 T x, Co 2+ preintercalation and further Ti 3 C 2 T x coating improve the Na + diffusion kinetics, reinforce the lattice stability, weaken the electrochemical polarization, elevate the charge and discharge stability, and enhance the reaction activity at high voltage. The Vo-CHNVOT cathode shows excellent Na + storage properties with discharge capacities of 85.5 and 82.5 mAh g –1 after 100 cycles at 165 and 660 mA g –1, where the capacity retention rates reach 75.2% and 78.6%, respectively.