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Joint Conference
July 17-18, 2017 Chicago, USA
International Conference on
DIAMOND AND CARBON MATERIALS & GRAPHENE AND SEMICONDUCTORS
Volume 6, Issue 6 (Suppl)
J Material Sci Eng, an open access journal
ISSN: 2169-0022
Diamond and Carbon 2017 & Graphene 2017
July 17-18, 2017
Notes:
Elastic nano-graphene-functionalized silicon anode for lithium ion battery with superior cycle
stability and rate capability
Jong-Sung Yu, Tong-Hyun Kang
and
Chunfei Zhang
Daegu Gyeongbuk Institute of Science and Technology, Republic of Korea
S
ilicon (Si), one of the most promising anode materials for next generation high-performance Li-ion batteries (LIB), is
popularly studied recently because of its super high lithium capacity (4200 mAh g-1). However, Si has a dramatic volume
change (~300%) during charge-discharge cycling, leading to severe capacity decay and poor cycle stability originating from
its structural collapse. Carbon or graphene-modified Si is an effective method to improve its performance. Traditional three
models of carbon or graphene/Si-based core-shell, yolk-shell and physical wrapping have been reported recently. However,
they are still insufficient in structure to solve the silicon issues. In our work, a new concept multifunctional nano-graphene
shell is elaborately designed for silicon by a low-temperature chemical vapor deposition (CVD) method on a hierarchical
nickel nano-template. The as-synthesized nano-graphene-functionalized silicon (Si@NG) composite shows unique functions
to challenge the current silicon anode issues in LIB. The new functional nano-graphene shell gives the full consideration of Si
issues such as Si conductivity, Si volume expansion, and mass transfer, which not only can supplement poor conductivity of Si,
but also self-adaptively changes their space to accommodate the lithiated Si with inflated volume by their elastic feature. More
importantly, different with traditional large graphene flakes, the graphene sheets in nano size has less ions barrier effect to
guarantee easy Li+ and electrolyte paths. In addition, the graphene layer provides excellent protection for SEI film to guarantee
high cycle stability. As an anode electrode for LIB, the Si@NG composite exhibits excellent cycling performance with high
reversible specific capacity (2330 mAh g−1 at 250 mA g-1 with an initial CE of 83.4%, and 1385 mAh g−1 at 500 mA g−1
after 510 cycles with a CE of 99.2%). A superior 95% capacity retention is achieved after 510 cycles. More notably, remarkable
cycling performances were obtained over harsh testing conditions of high current density and high Si@NG loading, where
the Si@NG still shows several times higher capacities than commercial graphite after 1000 cycles. All the electrochemical
performances get benefits from the well-designed functional graphene shells. This work demonstrates a new direction towards
the development of high efficient Si anode with high capacity and super cycle stability.
Biography
Jong-Sung Yu earned his BSc in Chemistry from Sogang University in Seoul, Korea and a PhD from the University of Houston in 1990 before Post-doctoral
work at Ohio State University. He was a Professor in Korea University during 2008-2015 before he moved to DGIST. Currently, he is a Supervisor for graduate
students of Light, Salts and Water Research Lab and a Chair Person at Energy Systems Engineering Department of DGIST, where his research focuses on
nanostructured materials, including nanoscale 0-3D materials and their composites, and their energy applications for fuel cells, batteries, super-capacitors, sensors,
and photocatalytic systems.
jsyu@dgist.ac.krJong-Sung Yu et al., J Material Sci Eng 2017, 6:6(Suppl)
DOI: 10.4172/2169-0022-C1-076