A novel silicon nanoparticles-infilled capsule prepared by an oil-in-water emulsion strategy for high-performance Li-ion battery anodes

Conventional approaches for preparing yolk-shell nanostructures require complicated procedures such as multi-step coatings and template removal. Herein, we present a new and general strategy for making yolk-shell nanocomposites based on an oil-in-water emulsion system. As a demonstrating case, silicon nanoparticles were dispersed in an oil phase which was in an oil-in-water emulsion; then the oil/water interface was in-situ polymerized to form microcapsules. After carbonization, the shell of microcapsules was formed. The Li-ion battery anodes based on the microcapsules exhibit a good electrochemical performance including stable capacity and high rate-performance. The capacity remains 1100 mAh g-1 after 500 cycles at a current density of 1.9 A g-1, along with a Coulombic efficiency of ≈ 99.9%. In addition, the method presented here is general, which is applicable for the synthesis of many yolk shell-structured nanocomposites.