论文部分内容阅读
In recent years,more and more attention has been paid on Si material used as the anodes in lithium ion batteries (LIBs).[1,2] But,in spite of its highest theoretical specific capacity of 4200 mA h/g,the big volume expansion (~400%) in Si anodes during Li-ion intercalation/extraction generally causes mechanical damages in electrodes resulting in capacity fading and poor cycle performance.[1,3] TiO2,as one of the traditional anodes,has a very small volume expansion ratio (>4%) and good cyclic stability,which has been proposed to be used as coating layer on silicon to accommodate its volume change and thus improve its electrochemical properties.[4,5] Recently,Sang-Eun Park et al.have reported the sol-gel-synthesized Si nanoparticles encapsulated with mesoporous TiO2 as the anode material in LIBs,exhibiting improved capacities compared with those in pure Si anode.[4] A TiO2 nanowire/Si composite has also been fabricated through a solvothermal process followed by magnetron sputtering deposition,in which a superior initial discharge coulombic efficiency of 74.8% (vs.32.9% in pure Si) and capacity retention of 54.2% after 200 cycles (vs.17.9% after 3 cycles in pure Si anode) were accomplished.