THESIS
2014
xvi, 113 pages : illustrations ; 30 cm
Abstract
Silicon is one of the most promising anode materials with a theoretical capacity of 4212
mAh g
-1 and a relatively low discharge potential at about 370 mV vs. Li/Li
+. There is a great interest in the utilization of silicon-based anode for lithium-ion batteries. Its
application is usually hampered by the dramatic volume change during lithium ion
intercalation and low electric conductivity of silicon.
In this study, the effects of Si particle size, binder, conducting agent and electrolyte additive
on the electrochemical performance of Si-based anode were briefly investigated first. Then
a strategy to fabricate graphene oxide-immobilized NH
2-terminated silicon nanoparticles
anode was proposed and tested. NH
2-terminated silicon nanoparticles were obtained via
surface grafting of (3...[
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Silicon is one of the most promising anode materials with a theoretical capacity of 4212
mAh g
-1 and a relatively low discharge potential at about 370 mV vs. Li/Li
+. There is a great interest in the utilization of silicon-based anode for lithium-ion batteries. Its
application is usually hampered by the dramatic volume change during lithium ion
intercalation and low electric conductivity of silicon.
In this study, the effects of Si particle size, binder, conducting agent and electrolyte additive
on the electrochemical performance of Si-based anode were briefly investigated first. Then
a strategy to fabricate graphene oxide-immobilized NH
2-terminated silicon nanoparticles
anode was proposed and tested. NH
2-terminated silicon nanoparticles were obtained via
surface grafting of (3-Aminopropyl)triethoxysilane (APTES) molecules. Sodium alginate
(Salg) was used as a binder to prepare the anodes.
Experimental results showed that nano-sized Si particles, Salg binder and vinylene carbonate (VC) electrolyte additive had positive effects on the electrochemical performance
of Si-based anode. For the as-prepared NH
2-terminated silicon nanoparticles (Si@APTES
2
NPs)/ graphene oxide (GO) composite anode, Si@APTES
2 NPs were well immobilized by
GO and the composites (Si@APTES
2/GO) were further immobilized by the Salg binder by
strong hydrogen bond and covalent bond, as revealed by the scanning electron microscopy,
transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray
photoelectron spectroscopy. Attributed to the double chemical cross-link/hydrogen bonding
interactions and highly flexible GO, Si@APTES
2/GO anode exhibited excellent cycling
stability and good rate performance, delivering a reversible capacity of 880 mAh g
-1 after
500 cycles at a current density of 420 mA g
-1, which are better than other composite anodes
such as HCl pretreated Si NPs without APTES modification (Si@OH NPs)/ GO composite
anode and Si NPs/Graphite composite anode. These results indicate the importance of
systematic approach for fabricating stable electrodes to improve their electrochemical
performance.
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