title: Insights into the Dual-Electrode Characteristics of Layered Na0.5Ni0.25Mn0.75O2Materials for Sodium-Ion Batteries.
abstract: Sodium-ion batteries are now close to replacing lithium-ion batteries because they provide superior alternative energy storage solutions that are in great demand, particularly for large-scale applications. To that end, the present study is focused on the properties of a new type of dual-electrode material, Na0.5Ni0.25Mn0.75O2, synthesized using a mixed hydroxy-carbonate route. Cyclic voltammetry confirms that redox couples, at high and low voltage ranges, are facilitated by the unique features and properties of this dual-electrode, through sodium ion deintercalation/intercalation into the layered Na0.5Ni0.25Mn0.75O2material. This material provides superior performance for Na-ion batteries, as evidenced by the fabricated sodium cell that yielded initial charge-discharge capacities of 125/218 mAh g-1in the voltage range of 1.5-4.4 V at 0.5 C. At a low voltage range (1.5-2.6 V), the anode cell delivered discharge-charge capacities of 100/99 mAh g-1with 99% capacity retention, which corresponds to highly reversible redox reaction of the Mn4+/3+reduction and the Mn3+/4+oxidation observed at 1.85 and 2.06 V, respectively. The symmetric Na-ion cell, fabricated using Na0.5Ni0.25Mn0.75O2, yielded initial charge-discharge capacities of 196/187 μAh at 107 μA. These results encourage the further development of new types of futuristic sodium-ion-battery-based energy storage systems.
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, South Korea.
authors.forename: Manikandan
authors.initials: M
authors.lastname: Palanisamy
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, South Korea.
authors.forename: Hyun Woo
authors.initials: HW
authors.lastname: Kim
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, South Korea.
authors.forename: Seongwoo
authors.initials: S
authors.lastname: Heo
authors.affiliation: Chemical Science and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors.forename: Eungje
authors.initials: E
authors.lastname: Lee
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, South Korea.
authors.forename: Youngsik
authors.identifier: http://orcid.org/0000-0001-7076-9489
authors.initials: Y
authors.lastname: Kim
keywords: charge−discharge cycling; dual-electrode; layered P2-type structure; mixed hydroxy-carbonate; symmetric sodium-ion batteries