A Novel Structured Si-Based Composite with 2D Structured Graphite for High-Performance Lithium-Ion Batteries

초록

Silicon is a promising alternative to graphite anodes for achieving high-energy-density in lithium-ion batteries (LIBs) because of its high theoretical capacity (3579 mAh g-1). However, silicon anode must be developed to address its disadvantages, such as volume expansion and low electronic conductivity. Therefore, the use of silicon as composed with graphite and carbon anode materials is investigated, which requires properties such as a spherical morphology for high density and encapsulation of silicon particles in the composite. Herein, a graphite@silicon@carbon (Gr@Si@C) micro-sized spherical anode composite is synthesized by mechanofusion process. This composite comprises an outer surface, middle layer, and core pore, which are formed by the capillary force arising from 2D structured graphite and pitch properties. This structure effectively addresses the intrinsic issues associated with Si. Gr@Si@C exhibits a high capacity of 1622 mAh g-1 and capacity retention of 72.2% after 100 cycles, with a high areal capacity 4.2 mAh cm-2. When Gr@Si@C is blended with commercial graphite, the composite exhibits high capacity retention and average Coulombic efficiency after cycling. The Gr@Si@C blended electrode exhibits a high energy density of 820 Wh L-1 with approximate to 16% metallic Si in the electrode (40 wt.% composite), enabling the realization of practical commercial LIBs. Graphite@silicon@carbon (Gr@Si@C) is synthesized by mechanofusion process, consisting of an outer surface, middle layer, and core pore arising from the capillary forces of 2D graphite and pitch properties. It shows good electrochemical performance with high loading level. The blended electrodes employing Gr@Si@C successfully achieve a high energy density, which can be used for the practical implementation of lithium-ion batteries. image

키워드