context: Driven by the urgent demand for electrical energy storage in electric vehicles, rechargeable devices with high energy densities and long cycle life continue to attract great interest. Lithium-ion batteries (LIBs) have attracted increasing attention over the past few decades owing to many merits, including high energy density, no memory effect, and good safety. However, making further improvements in their energy density whilst maintaining high safety remains highly challenging, inhibiting the scale-up of their applications. Developing new electrode materials is one of the most efficient ways to achieve LIBs with high energy and high safety. Silicon (Si) is considered to be a promising replacement for the graphite anodes in conventional LIBs, due to its ultrahigh specific capacity (4200 mA h g−1, ten times that of graphite), low working potential (ca. 0.4 V versus Li+/Li), natural abundance, high safety and environmentally benign nature. Unfortunately, Si has a low intrinsic electronic conductivity and this restricts charge transfer within Si anodes during the charge–discharge process. Moreover, the large volume change (>300%) of the Si anode during the lithiation/delithiation process leads to drastic particle pulverization and uncontrollable growth of a solid electrolyte interphase (SEI), leading to electrical contact loss between the active materials themselves or the active materials and current collectors. All these inherent problems lead to Si anodes having poor rate performance, low coulombic efficiency (CE) and fast capacity decay on cycling.
answer: graphite 