Synthesis of Macroporous Si/Al2O3 Composite Anodes for High-Performance Lithium-Ion Batteries

Despite the significant advances of carbon-based materials in lithium ion batteries (LIBs), new anode materials exhibiting higher energy density are needed. Among them, silicon (Si) exhibits highest theoretical capacity (4200 mAh/g with a formation of Li4.4Si). However, the major problem is their significant volume changes (over 300%), which occurs during the alloying and dealloying process, leading to pulverization of the active materials and the consequent loss of electrical contacts between particles, resulting in capacity loss and poor cycling performance. In this study, nanoporous silicon and Alumina composite materials were synthesized to overcome several problems mentioned above by combining various porous silica materials and metallothermic reduction reaction(MRR). The porous Si composit materials having a particle size of 1–10um and pores of 10~500 nm were obtained, and subsequently, Alumina major layers were on the surface of porous Si with Alumina contents of 10–50 wt%, have capacities of 3000~600 mAh/g,respectively.  It means that if we control contents of silicon, have synthesized anode materials of various capacities.  The having 20wt% alumina porous Si showed a highly stable cycling retention over 100 cycles at a high specific capacity of 1000 mAh/g.