Metal–Organic Frameworks-Derived Mesoporous Si/SiOx@NC Nanospheres as a Long-Lifespan Anode Material for Lithium-Ion Batteries

Graphical Mesoporous Si/SiO x @NC nanospheres : A core–shell structured Si/SiO x @NC composite with distinct nanostructure was controllably synthesized through metal–organic framework (MOF)-derived magnesio-thermic reduction. Owing to the core–shell structure, the final product with the optimized nanostructure exhibits enhanced electrochemical performance in terms of reversible capacity and long-term cycling stability, which may be attributed to the many beneficial factors. Silicon (Si)-based anode materials with suitable engineered nanostructures generally have improved lithium storage capabilities, which provide great promise for the electrochemical performance in lithium-ion batteries (LIBs). Herein, a metal–organic framework (MOF)-derived unique core–shell Si/SiO x @NC structure has been synthesized by a facile magnesio-thermic reduction, in which the Si and SiO x matrix were encapsulated by nitrogen (N)-doped carbon. Importantly, the well-designed nanostructure has enough space to accommodate the volume change during the lithiation/delithiation process. The conductive porous N-doped carbon was optimized through direct carbonization and reduction of SiO 2 into Si/SiO x simultaneously. Benefiting from the core–shell structure, the synthesized product exhibited enhanced electrochemical performance as an anode material in LIBs. Particularly, the Si/SiO x @NC-650 anode showed the best reversible capacities up to 724 and 702 mAh g −1 even after 100 cycles. The excellent cycling stability of Si/SiO x @NC-650 may be attributed to the core–shell structure as well as the synergistic effect between the Si/SiO x and MOF-derived N-doped carbon.