Nanocomposite of Amorphous Ge and Sn Nanoparticles as an Anode Material for Li Secondary Battery

Nanocomposites of amorphous Ge and Sn nanoparticles are prepared from the vacuum annealing of the butyl-capped Ge gels and SnP(0.94) nanoparticles at 400 degrees C for 7 h, and their electrochemical properties and nanostructure changes are investigated during electrochemical cycling. The nanocomposite displays a first charge capacity of 1078 mAh/g with a capacity retention of 64% after 50 cycles. However, both individual Ge and Sn nanoparticles display rapid capacity fade, showing < 20% capacity retention after 50 cycles. A superior electrochemical property of the nanocomposite to the Sn and Ge nanoparticles is believed to be related to the fact that the amorphous Ge phase acts as an intergrain electrical connecter when Sn particles are pulverized.