A graphene-wrapped silver-porous silicon composite with enhanced electrochemical performance for lithium-ion batteries

摘要

A graphene-wrapped silver-porous silicon composite has been prepared and used as the anode material in lithium-ion batteries (LIBs). Porous silicon (pSi) prepared through a magnesiothermic reduction of mesoporous silica MCM-41 was surface-modified by Ag nanopartides formed via the thermal decomposition of AgNO3 and then graphene nanosheets (GNS) generated through the thermal reduction of graphene oxide. The obtained Ag-pSi/GNS composite exhibits a distinctly high reversible specific capacity, long cycling performance and super rate capability. An initial capacity as high as 3531 mA h g~(-1) is delivered at 0.1 A g~(-1), whereas at a current density of 32 A g~(-1), a specific capacity of 1241 mA h g~(-1), more than three times higher than the theoretical capacity of the graphite anode, is still retained for 50 cycles. The superior electrochemical performance demonstrates that this Ag-pSi/GNS composite is a promising electrode material for high-performance LIBs.