title: A new high-energy cathode for a Na-ion battery with ultrahigh stability.
abstract: Large-scale electric energy storage is a key enabler for the use of renewable energy. Recently, the room-temperature Na-ion battery has been rehighlighted as an alternative low-cost technology for this application. However, significant challenges such as energy density and long-term stability must be addressed. Herein, we introduce a novel cathode material, Na1.5VPO4.8F0.7, for Na-ion batteries. This new material provides an energy density of ~600 Wh kg(-1), the highest value among cathodes, originating from both the multielectron redox reaction (1.2 e(-) per formula unit) and the high potential (~3.8 V vs Na(+)/Na) of the tailored vanadium redox couple (V(3.8+)/V(5+)). Furthermore, an outstanding cycle life (~95% capacity retention for 100 cycles and ~84% for extended 500 cycles) could be achieved, which we attribute to the small volume change (2.9%) upon cycling, the smallest volume change among known Na intercalation cathodes. The open crystal framework with two-dimensional Na diffusional pathways leads to low activation barriers for Na diffusion, enabling excellent rate capability. We believe that this new material can bring the low-cost room-temperature Na-ion battery a step closer to a sustainable large-scale energy storage system.
authors: Department of Materials Science and Engineering, ‡Research Institute of Advanced Materials (RIAM), and §Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Korea.
authors: Young-Uk
authors: YU
authors: Park
authors: Dong-Hwa
authors: DH
authors: Seo
authors: Hyung-Soon
authors: HS
authors: Kwon
authors: Byoungkook
authors: B
authors: Kim
authors: Jongsoon
authors: J
authors: Kim
authors: Haegyeom
authors: H
authors: Kim
authors: Inkyung
authors: I
authors: Kim
authors: Han-Ill
authors: HI
authors: Yoo
authors: Kisuk
authors: K
authors: Kang