title: Role of Cu in Mo₆S₈ and Cu mixture cathodes for magnesium ion batteries.
abstract: The reversible capacity of Chevrel Mo6S8 cathode can be increased by the simple addition of the Cu metal to Mo6S8 electrodes. However, the exact reaction mechanism of the additional reversible capacity for the Mo6S8 and Cu mixture cathode has not been clearly understood yet. To clarify this unusual behavior, we synthesize a novel Cu nanoparticle/graphene composite for the preparation of the mixture electrode. We thoroughly investigate the electrochemical behaviors of the Mo6S8 and Cu mixture cathode with the relevant structural verifications during Mg(2+) insertion and extraction. The in situ formation of Cu(x)Mo6S8 is observed, indicating the spontaneous electrochemical insertion of Cu to the Mo6S8 host from the Cu nanoparticle/graphene composite. The reversible electrochemical replacement reaction of Cu in the Mo6S8 structure is clarified with the direct evidence for the solid state Cu deposition/dissolution at the surface of Mo6S8 particles. Moreover, the Mo6S8 and Cu mixture cathode improves the rate capability compared to the pristine. We believe that our finding will contribute to understanding the origin of the additional capacity of the Mo6S8 cathode arising from Cu addition and improve the electrochemical performance of the Mo6S8 cathode for rechargeable Mg batteries.
authors.affiliation: †Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816, Republic of Korea.|∥Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Choi
authors.affiliation: ‡Department of Chemical Engineering, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Jeom-Soo
authors.initials: JS
authors.lastname: Kim
authors.affiliation: †Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816, Republic of Korea.
authors.forename: Sang-Gil
authors.initials: SG
authors.lastname: Woo
authors.affiliation: †Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816, Republic of Korea.
authors.forename: Woosuk
authors.initials: W
authors.lastname: Cho
authors.affiliation: §Cheorwon Plasma Research Institute, Cheorwon, Gangwon 269-802, Republic of Korea.
authors.forename: Sun Yong
authors.initials: SY
authors.lastname: Choi
authors.affiliation: ∥Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea.|⊥Green School, Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Jungkyu
authors.initials: J
authors.lastname: Choi
authors.affiliation: #School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Republic of Korea.
authors.forename: Kyu-Tae
authors.initials: KT
authors.lastname: Lee
authors.affiliation: †Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816, Republic of Korea.
authors.forename: Min-Sik
authors.initials: MS
authors.lastname: Park
authors.affiliation: †Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816, Republic of Korea.
authors.forename: Young-Jun
authors.initials: YJ
authors.lastname: Kim
keywords: Chevrel Mo6S8; Cu nanoparticle/graphene composite; Mg batteries; cathode; electrochemistry