title: Hollow Cobalt Selenide Microspheres: Synthesis and Application as Anode Materials for Na-Ion Batteries.
abstract: The electrochemical properties of hollow cobalt oxide and cobalt selenide microspheres are studied for the first time as anode materials for Na-ion batteries. Hollow cobalt oxide microspheres prepared by one-pot spray pyrolysis are transformed into hollow cobalt selenide microspheres by a simple selenization process using hydrogen selenide gas. Ultrafine nanocrystals of Co3O4 microspheres are preserved in the cobalt selenide microspheres selenized at 300 °C. The initial discharge capacities for the Co3O4 and cobalt selenide microspheres selenized at 300 and 400 °C are 727, 595, and 586 mA h g(-1), respectively, at a current density of 500 mA g(-1). The discharge capacities after 40 cycles for the same samples are 348, 467, and 251 mA h g(-1), respectively, and their capacity retentions measured from the second cycle onward are 66, 91, and 50%, respectively. The hollow cobalt selenide microspheres have better rate performances than the hollow cobalt oxide microspheres.
authors.affiliation: Department of Materials Science and Engineering, Korea University , Anam-Dong, Seongbuk-Gu, Seoul 136-713, South Korea.
authors.forename: You Na
authors.initials: YN
authors.lastname: Ko
authors.affiliation: Department of Materials Science and Engineering, Korea University , Anam-Dong, Seongbuk-Gu, Seoul 136-713, South Korea.
authors.forename: Seung Ho
authors.initials: SH
authors.lastname: Choi
authors.affiliation: Department of Materials Science and Engineering, Korea University , Anam-Dong, Seongbuk-Gu, Seoul 136-713, South Korea.
authors.forename: Yun Chan
authors.initials: YC
authors.lastname: Kang
keywords: Na-ion battery; cobalt oxide; cobalt selenide; energy storage; nanostructure