Hierarchical Porous Carbon Scaffolds As a Materials Scaffold for the Attachment of Silicon in Lithium Ion Battery Anodes

Abstract

Carbon and carbon-based composite materials have long been an important component in electrodes utilized for energy storage applications. Their widespread use can be attributed to their combination of good electrical conductivity, relative chemical inertness and low bulk material density (~2 g/cm3). For lithium ion battery (LIB) anodes, graphite is typically employed, but silicon has been heralded an excellent replacement candidate due to its very high theoretical capacity (~ 4200 mAh/g—a capacity over ten times greater than that of graphite). A principal obstacle for the practical application of a Si anode is the extreme volume changes (> 300%) during the lithiation process which eventually leads to a pulverization of the Si material. This is particularly true for larger Si particles (> 200 nm), which severely compromises the commercialization of Si based LIB anodes. Herein, we present our recent work utilizing various carbon-silicon composite materials systems as LIB anodes. We will show that by using a hierarchical porous carbon scaffold with tailorable textural properties such as pore size, surface area and pore volume, we are able to provide silicon nanoparticles with an excellent scaffold for attachment. Furthermore, we will reveal how this tailorable carbon structure can be further modified via functionalization pathways for both the carbon and silicon materials. We will demonstrate how these strategies improved various performance parameters for these LIB anodes; specifically in terms of cyclic performance—a characteristic weak point for silicon-based LIB anodes.