High reversible capacity silicon anode by segregated graphene-carbon nanotube networks for lithium ion half/full batteries

Micron-sized Si-based materials have gained much attention recently in the pursuit of high-performance and low-cost lithium-ion battery (LIBs). However, huge volume variation and poor conductivity induce a rapid performance decline of Si microparticles. Herein, porous silicon microsphere segregated in graphene and carbon nanotube network (pSi/HCNT/rGO) is constructed by one-step hybrid and reduction self-assembly strategy. Carbon nanotubes provide the “safety belt” for the entire structure to block aggregation between rGO layers. The hierarchical porous structure composed by intrinsic pore structure of pSi and flexible carbon network effectively buffers the volume expansion and ensures the structural and interface stability in the lithium storage process, which also delivers multiple conductive pathways to boost Li+/e− migration efficiency. Proper configuration design leads to high charging capacity of 2319 mAh g−1 at 0.1 A g−1, exceptional initial Coulombic efficiency of 87.5 % (vs pSi of 55.8 %) and stable long cycle performance of 583 mAh g−1 after 400 cycles at 5 A g−1 when pSi/HCNT/rGO applying in half battery. The pSi/HCNT/rGO||LiFePO4 (LFP) full battery also shows the capacity maintenance of 96 % after 150 cycles at 1 C.