Sustainable Encapsulation Strategy of Silicon Nanoparticles in Microcarbon Sphere for High-Performance Lithium-Ion Battery Anode

Owing to the high theoretical capacity, low operating potentials, and natural abundance, silicon (Si) is considered as one of the most promising anode materials for lithium-ion batteries. However, a large volume change during alloying-dealloying often results in pulverization, electrical contact loss, and unstable solid-electrolyte interphase (SEI) formation, leading to rapid capacity fading. We present a rational encapsulation strategy of a silicon-carbon (Si-C) composite as a high-performance anode material for lithium-ion batteries (LIBs). The Si-C composite material is prepared via a one-pot hydrothermal method by using silicon nanoparticles modified using an etching route and sucrose as a carbon precursor. The proposed Si-C composite material has a meso-macroporous structure and contains a large weight fraction of silicon nanoparticles (40 wt %) encapsulated in a micrometric carbon sphere (similar to 3 mu m). In the composite material, the carbon framework tightly encapsulates the silicon nanoparticles to the interior of the particle, which not only provides electrical conductivity but also decreases the stress/strain of the material during the alloying-dealloying process. The material demonstrates high initial capacity of 1300 mAh g(-1), excellent capacity retention of 90% after 200 cycles, and fast charging-discharging capability within 12 min. We believe that the proposed encapsulation strategy here will be helpful in developing a highenergy and low-cost Si-C composite anode.