Synthesis and Characterization of C-coated Si Composite Anode Materials for Lithium-ion Batteries
Date Issued
2006
Date
2006
Author(s)
Yen, Yu-Chan
DOI
en-US
Abstract
The main purpose of this research is to explore new anode materials based on silicon for lithium-ion battery. Silicon possesses a high theoretical capacity (~3500 mAh/g) compared to graphite (372 mAh/g), however, the dramatic volumetric variation during cycling and intrinsic low conductivity, which result in structural instability and poor cyclability, block its commercial application. Si-C composite materials are developed by two different methods to overcome the inherent problems of silicon. One is carbon coating on Si powder, and the other is spray drying method to produce porous-structured Si-C secondary particles.
Carbon-coated Si materials have been synthesized by a fluidized-bed chemical vapor deposition (FBCVD) method or a thermal pyrolysis process. Research reveals that both the FBCVD process and the pyrolysis reaction give the important contribution to the significantly improved morphology stability. As a ductile matrix, the disordered carbon coated from the CVD process could effectively buffer the volume change of Si particles during charge/discharge cycling. On the other hand, the dense-structured carbon coating obtained from the pyrolysis reaction could reduce the volume expansion of Si particles upon cycling.
Porous Si-C particles having a pore size distribution peaks at 300 nm and an intra-particle porosity of nearly 50% have been synthesized by spray drying process. It is expected that the preset intra-particle voids can help accommodate volume expansion arising from alloying of the Si component; nevertheless, the results demonstrate that the porous-structured secondary Si and Si-C particles can not stabilize the electrode architecture during cycling.
Subjects
鋰離子電池
負極
矽
矽碳複合材料
Lithium-ion batteries
Anode
Silicon
Si-C composite
SDGs
Type
thesis
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