Application of Electrospinning and Electrospray to the Fabrication of Anode Materials for Lithium-Ion Batteries
Date Issued
2011
Date
2011
Author(s)
Ho, Wei-Kai
Abstract
In the last decade, silicon has received much attention due to its highest specific capacity (~3500 mAh/g) compared to graphite (372 mAh/g). However, silicon is known for its intrinsic low conductivity while possessing a dramatic volumetric variation upon cycling, which results in structural instability and poor cycle life that hinders its further application.
The main objective of this research is to explore new Si-based anode materials for lithium-ion battery. According to the previous studies, the Si/C composites are believed to overcome the inherent problems of silicon. This study focuses on using electro-hydrodynamic techniques (electrospinning and electrospray) to fabricate Si/C microfibers and porous Si/C composites.
The Si/C microfibers electrode showed the improved cycle performance compared to the pure Si electrode because carbon fiber matrix offers the room to alleviate the huge volume expansion of nano-Si particles upon discharge and charge processes. On the other hand, the porous Si/C composites electrode exhibited the outstanding cycle life (500 cycles without decaying) due to its combination of unique porous structure and carbon matrix. The preset voids in the composites provide more available space to buffer the volume expansion of Si particles, while the net-shaped carbon matrix enclosing Si particles prevents them from aggregating and being detached off the composite upon cycling.
Moreover, the nickel was incorporated into the porous Si/C composites by two different methods because nickel is inactive to lithium and could increase the conductivity of the composites. The results showed that Ni-coated Si/C composites electrode demonstrated the better overall coulombic efficiency and rate capability compared to the porous Si/C composites electrode.
Finally, the pre-lithiation approach was adopted to enhance the coulombic efficiency in the first cycle. The result indicated that this approach is effective and has the potential for practical use.
Subjects
Lithium-ion batteries
silicon
electrospinning
electrospray
porous structure
SDGs
Type
thesis
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