Preparation and characterization of silicon/graphene oxide-based anode for lithium ion battery

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 NH₂-terminated silicon nanoparticles anode was proposed and tested. NH₂-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 NH₂-terminated silicon nanoparticles (Si@APTES₂ NPs)/ graphene oxide (GO) composite anode, Si@APTES₂ NPs were well immobilized by GO and the composites (Si@APTES₂/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@APTES₂/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.

Date of Award	2014
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology