Design and Construction of Porous Silicon Materials as Stable Anodes for Lithium-Ion Batteries

Abstract

Silicon is considered to be the most promising anode material for the next generation of lithium-ion batteries (LIBs), but its application is limited by the severe capacity decline due to volume expansion of up to 300%. Considering the inward accumulation of the stress produced during the actual lithiation process and the stabilizing effect of oxygen element, structural design and surface oxygen content regulation work together to improve the cyclic stability of silicon. Herein, we report the design and construction of novel porous silicon materials with regulated pore structure and surface oxygen content. The facile strategy for the synthesis of the materials is using Mg2Si and tetraethyl orthosilicate (TEOS) as Si resource, and the oxygen in the feedstock is ingeniously used at the same time. A series of Si anode materials with different pore structure and surface oxygen content were obtained by adjusting the proportion of Mg2Si and TEOS. Using 0.5 g of Mg2Si and 1 g of TEOS to prepare the material, the electrode reaches the optimum electrochemical performance with a discharge capacity of 935.9 mAh g–1 after 100 cycles and 587.2 mAh g–1 after 300 cycles at 0.5 and 1 A g–1, respectively. This work provides a new strategy for the design and preparation to boost stable lithium ion storage of silicon anode materials.