3 Dimensional Carbon Nanostructures for Li-ion Battery Anode
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3 Dimensional Carbon Nanostructures for Li-ion Battery Anode Chiwon Kang1, Rangasamy Baskaran2, Won-Gi Kim2, Yang-Kook Sun2, Wonbong Choi1,2,3* 1
Nanomaterials and Device Laboratory, Department of Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, Miami, FL 33174, USA 2 Nanomaterials For Energy Lab, Department of Energy Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Korea 3 Department of Materials Science and Engineering, University of North Texas, North Texas Discovery Park 3940 North Elm St. Suite E-132, Denton, TX 76207, USA Corresponding Author * Email: [email protected] ABSTRACT Carbon nanofibers (CNFs) have been thoroughly investigated as potential anode materials in Li-ion battery owing to their exceptional properties such as the higher surface area to mass ratio, electrical conductivity and mechanical toughness. However, one of the major limitations of nano carbon materials is lower mass loading density. To address this issue, we have developed a novel anode system composed of CNFs directly grown on 3D Cu mesh current collector (hereafter mentioned as 3D CNFs) using a thermal catalytic chemical vapor deposition (CVD) method. Compared to CNF-based anodes on 2D Cu current collector, active The active material loading amount of the 3D CNFs has been found to be 400 % higher while comparing with 2D CNF. Owing to an increase of the active surface area, 3D CNFs demonstrated enhanced electrochemical performance of Li-ion battery in terms of charge capacity (50% improvement), rate capability and cycling life. Interfacial contact between the CNFs and Cu could play a crucial role in promoting the electrochemical properties. The intermediate TiC thin layer, formed at high temperature 750°C, could function as an efficient electric conducting pathway and a strong bonding bridge between the CNFs and Cu. In order to improve the pristine 3D CNF redox reactions, the amorphous Si (a-Si)/3D CNF has been sputter deposited to produce Si wrapped 3D CNF hybrid anode material. It has been found that the electrochemical properties of the a-Si/3D CNF yields superior specific capacity (Cdis 549 mAhg-1, LiC4.1) and cycling stability than that of pristine 3D CNF (461 mAhg-1, LiC4.8). INTRODUCTION The Li-ion battery (LIB) has drawn great attention to the energy storage devices for the application of laptop computers, camcorders, and cameras since it was commercially introduced by Sony [1]. Furthermore, it has been recently considered as a strong candidate for next generation electric vehicles (EV). In particular, the currently used graphite based hard or soft carbons have some specific capacity limitation which is 372 mAhg-1 for their EV application. To address this issue, the research into Li-metal alloy (e.g. Si, Sn, and Ge) has been intensively conducted and in particular, Si element has the higher Li-ion intake capability (LiSi4.4; 4,200 mAhg-1) [2]. However, such alloy anodes have a major problem with the huge volume expansion
and contraction duri
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