title: Carbon/two-dimensional MoTe2core/shell-structured microspheres as an anode material for Na-ion batteries.
abstract: Unique-structured composite microspheres of carbon and MoTe2were prepared by a two-step process. Precursor C-MoOxcomposite microspheres were prepared by spray pyrolysis, and then the precursor was transformed into C-MoTe2composite microspheres by a tellurization process. C-MoTe2composites with a uniform distribution of MoTe2nanocrystals (C/MoTe2) and core-shell-structured C-MoTe2composites (C@MoTe2) were synthesized at tellurization temperatures of 450 and 600 °C, respectively. At a higher tellurization temperature of 600 °C, all of the MoTe2nanocrystals moved to the surface of the microsphere because of the Ostwald ripening process. The initial discharge capacities of the C/MoTe2, C@MoTe2, and bare MoTe2(i.e., containing no carbonaceous materials) powders for Na-ion storage at a current density of 1.0 A g-1were 328, 388, and 341 mA h g-1, respectively. The discharge capacities of the C/MoTe2, C@MoTe2, and bare MoTe2powders for the 200thcycle were 241, 286, and 104 mA h g-1, respectively, and the corresponding capacity retentions, which were measured from the second cycle were 100%, 99%, and 37%, respectively. The high structural stability and well-developed two-dimensional layer of MoTe2of the C@MoTe2microspheres provide superior Na-ion storage properties compared to those of the C/MoTe2microspheres and bare MoTe2powder.
authors.affiliation: Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713, Republic of Korea. yckang@korea.ac.kr and Department of Engineering Chemistry, Chungbuk National University, Chungbuk 361-763, Republic of Korea.
authors.forename: Jung Sang
authors.initials: JS
authors.lastname: Cho
authors.affiliation: Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713, Republic of Korea. yckang@korea.ac.kr.
authors.forename: Hyeon Seok
authors.initials: HS
authors.lastname: Ju
authors.affiliation: Department of Chemical Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
authors.forename: Jung-Kul
authors.identifier: http://orcid.org/0000-0001-7384-5301
authors.initials: JK
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713, Republic of Korea. yckang@korea.ac.kr.
authors.forename: Yun Chan
authors.identifier: http://orcid.org/0000-0001-5769-5761
authors.initials: YC
authors.lastname: Kang