Synthesis of Yolk–Shell-Structured Si@C Nanocomposite Anode Material for Lithium-Ion Battery

Abstract

Silicon-based anode materials which are used as electrodes suffer from a short lifespan and unsatisfactory rate capability because of their large volume changes during lithiation/delithiation processes. In this work, we have designed carbon-encapsulated silicon (Si@C) nanocomposites in a yolk–shell-structural anode material for lithium-ion batteries, which were prepared through moderate magnesiothermic reduction and carbonization using mesoporous silica (SBA-15) and dopamine as the raw materials. The obtained yolk–shell-structural Si@C nanocomposites exhibited excellent cycling stability (approaching 616.3 mAh g−1 after 100 cycles at 0.1 A g−1) and high rate capability (448.8 mAh g−1 at 1.0 A g−1 and 351.4 mAh g−1 at 2.0 A g−1). This outstanding performance was attributed to the void space between the core and the shell, which provides sufficient space for silicon expansion. The contained nitrogen of the carbon shell meant that the Li+ has a high diffusion capacity between the electrolyte and the silicon.