title: Synthesis of Ultrathin Si Nanosheets from Natural Clays for Lithium-Ion Battery Anodes.
abstract: Two-dimensional Si nanosheets have been studied as a promising candidate for lithium-ion battery anode materials. However, Si nanosheets reported so far showed poor cycling performances and required further improvements. In this work, we utilize inexpensive natural clays for preparing high quality Si nanosheets via a one-step simultaneous molten salt-induced exfoliation and chemical reduction process. This approach produces high purity mesoporous Si nanosheets in high yield. As a control experiment, two-step process (pre-exfoliated silicate sheets and subsequent chemical reduction) cannot sustain their original two-dimensional structure. In contrast, one-step method results in a production of 5 nm-thick highly porous Si nanosheets. Carbon-coated Si nanosheet anodes exhibit a high reversible capacity of 865 mAh g(-1) at 1.0 A g(-1) with an outstanding capacity retention of 92.3% after 500 cycles. It also delivers high rate capability, corresponding to a capacity of 60% at 20 A g(-1) compared to that of 2.0 A g(-1). Furthermore, the Si nanosheet electrodes show volume expansion of only 42% after 200 cycles.
authors.affiliation: Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, South Korea.
authors.forename: Jaegeon
authors.initials: J
authors.lastname: Ryu
authors.affiliation: Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, South Korea.
authors.forename: Dongki
authors.initials: D
authors.lastname: Hong
authors.affiliation: Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, South Korea.
authors.forename: Sinho
authors.initials: S
authors.lastname: Choi
authors.affiliation: Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, South Korea.
authors.forename: Soojin
authors.initials: S
authors.lastname: Park
keywords: Si nanosheets; lithium-ion battery anode; metallothermic reduction; molten salt induced exfoliation