title: Cobalt carbonate/ and cobalt oxide/graphene aerogel composite anodes for high performance Li-ion batteries.
abstract: Nanocomposites consisting of ultrafine, cobalt carbonate nanoneedles and 3D porous graphene aerogel (CoCO3/GA) are in situ synthesized based on a one-step hydrothermal route followed by freeze-drying. A further heat treatment produces cobalt oxide nanoparticles embedded in the conductive GA matrix (Co(3)O(4)/GA). Both the composite anodes deliver excellent specific capacities depending on current density employed: the CoCO(3)/GA anode outperforms the Co(3)O(4)/GA anode at low current densities, and vice versa at current densities higher than 500 mA g(-1). Their electrochemical performances are considered among the best of similar composite anodes consisting of CoCO(3) or Co(3)O(4) active particles embedded in a graphene substrate. The stable multistep electrochemical reactions of the carbonate compound with a unique nanoneedle structure contribute to the excellent cyclic stability of the CoCO(3)/GA electrode, whereas the highly conductive networks along with low charge transfer resistance are responsible for the high rate performance of the Co(3)O(4)/GA electrode.
authors.affiliation: Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Mohammad Akbari
authors.initials: MA
authors.lastname: Garakani
authors.forename: Sara
authors.initials: S
authors.lastname: Abouali
authors.forename: Biao
authors.initials: B
authors.lastname: Zhang
authors.forename: Curtis Alton
authors.initials: CA
authors.lastname: Takagi
authors.forename: Zheng-Long
authors.initials: ZL
authors.lastname: Xu
authors.forename: Jian-qiu
authors.initials: JQ
authors.lastname: Huang
authors.forename: Jiaqiang
authors.initials: J
authors.lastname: Huang
authors.forename: Jang-Kyo
authors.initials: JK
authors.lastname: Kim
keywords: Li-ion battery; anode; cobalt carbonate; cobalt oxide; graphene aerogel; hydrothermal process