Hollow nanospheres of loosely packed Si/SiOx nanoparticles encapsulated in carbon shells with enhanced performance as lithium ion battery anodes

Abstract

Silicon materials are considered as the new generation of high specific energy and energy density anodes for rechargeable lithium ion batteries, but the silicon pulverization during lithium insertion hinders their commercial implementation. Although extensive effort has been put on addressing these problems, the microstructure of the silicon material still needs to be well engineered in order to improve the stability of the anode materials and simplify the synthesis procedure using a scalable and easy available silicon source without any toxicity. In this work, a novel hollow nanosphere with Si/SiO_x nanoparticles incompactly distributed within a spherical carbon shell was successfully fabricated via a facile in situ carbonization/reduction method. With enhanced electrode conductivity and sufficient free space for silicon expansion during the lithiation process, this material shows much better cycle life and rate capability than directly reduced silicon nanoparticles.