3D Si/C particulate nanocomposites internally wired with graphene networks for high energy and stable batteries

Abstract

It is challenging to design silicon anodes exhibiting stable cycling behavior, high volumetric and specific capacity, and low volume expansion for Li-based batteries. Herein, we designed Si/C-IWGN composites (Si/C composites internally wired with graphene networks). For this purpose, we used simple aqueous sol-gel systems consisting of varying amounts of silicon nanoparticles, resorcinol-formaldehyde, and graphene oxide. We found that a small amount of graphene (1-10 wt%) in Si/C-IWGNs efficiently stabilized their cycling behavior. The enhanced cycling stability of Si/C-IWGNs could be ascribed to the following facts: (1) ideally dispersed graphene networks were formed in the composites, (2) these graphene networks also created enough void spaces for silicon to expand and contract with the electrode thickness increase comparable to that of graphite. Furthermore, properly designed Si/C-IWGNs exhibited a high volumetric capacity of ∼141% greater than that of commercial graphite. Finally, a hybrid sample, Si-Gr, consisting of a high capacity Si/C-IWGN and graphite was prepared to demonstrate a hybrid strategy for a reliable and cost-effective anode with a capacity level required for high-energy Li-ion cells. The Si-Gr hybrid exhibited not only high capacity (800-900 mA h g-1 at 100 mA g-1) but also a high electrode volumetric capacity of 161% greater than that of graphite.