A scalable silicon/graphite anode with high silicon content for high-energy lithium-ion batteries

Abstract

High-capacity Si-based anodes are urgently needed for high-energy lithium-ion batteries in forthcoming electric vehicles and energy storage systems. However, it is still a challenge to prepare Si anodes with high Si content materials as well as good electrochemical performance because the accumulation and growth of Si lead to large volume expansion, pulverization and cycling degradation. Herein, we demonstrate feasibility of a high-capacity Si-based anode via a scalable and simple route using high Si content (31.6 wt%) Si/graphite composite, consisting of thin Si nanolayer and edge-sites-exposed graphite. This architecture effectively alleviates the volume changes of Si and facilitates lithium-ion transport. As a result, the Si/graphite composite delivers a reversible capacity of 1,080 mAh/g with an initial Coulombic efficiency of 86.3% and achieves outstanding cycling stability (94.3% capacity retention after 100 cycles). When combined with commercial graphite-blended systems for a 1.5 Ah pouch-type full-cell test under a high electrode density (1.6 g/cm3) and areal capacity (3.46 mAh/cm2), the composite demonstrates excellent cycling stability at 25 and 45 °C, respectively, and good high-rate performance. This strategy offers a practical feasibility of next-generation high-capacity anode for high-energy LIBs.