| 학회 | 한국재료학회 |
| 학술대회 | 2016년 가을 (11/16 ~ 11/18, 경주 현대호텔) |
| 권호 | 22권 2호 |
| 발표분야 | C. 에너지 재료 분과 |
| 제목 | Si@Hard Carbon@CNTs as Conductive Agent-Free Anodes for High-Energy Density Lithium-Ion Batteries |
| 초록 | The ever-increasing desire to replace fossil fuels with clean energy sources such as solar, hydro, geothermal, and wind have stimulated intense interest in the development of both renewable energy sources and high efficiency energy storage devices. Lithium-Ion batteries (LIBs) have currently dominated the portable device market due to their advantages such as high energy density and power density with high operation voltage. However, rapidly growing electric vehicle (EV) market requires the development of advanced LIBs possessing the high energy and power density which far surpass those of current LIBs.4 In order to develop EVs which can travel for long distances up to 500 km, LIBs have to possess 5 times higher capacity than that of current LIBs. Furthermore, for the practical use of EVs, quick charge less than 3 min is required. In response to the requirements, the conventional graphite anodes have to be replaced for high performance anode materials. Silicon possesses extremely high specific capacity of 4200 mAh g-1 and low lithium reaction potential (＜ 0.4 V). However, huge volume expansion (＞300 %) of Si during the charge process leads to serious degradation of its structure. Moreover, the low electrical conductivity of Si requires the use of large amount of conductive agents which are not directly involved in faradaic reactions of LIBs. Therefore, the use of conductive agents has to be minimized to incorporate more active materials into a fixed volume of electrode for high energy density. To overcome these problems, we herein report a rational design of Si anodes, consisting of directly grown carbon nanotubes (CNTs) on hard carbon encapsulating silicon nanoparticles. The hard carbon derived from natural polysaccharide provides effective conductive and buffer matrix with Si. Furthermore, directly grown CNTs on the surface of hard carbon play an important role as a three-dimensional (3D) electrical circuit between active materials without conductive agents. The electrodes are also composed of very high portion of active materials (90 wt%) and only small portion of binder (10 wt%). This high energy density anode exhibits high initial coulombic efficiency (ICE) of 85.7% and excellent cycle retention after 500 cycles at a rate of 0.5C discharge/charge, which far surpasses the results of hard carbon encapsulating Si anodes containing 10 wt% of conductive agents. |
| 저자 | 김찬훈, 김일두 |
| 소속 | KAIST |
| 키워드 | Hard carbon; Si anode; Natural polysaccharide; Li-ion batteries; Carbon nanotube |
