Recent progress and challenges in silicon-based anode materials for lithium-ion batteries

Anode materials for Li-ion batteries (LIBs) utilized in electric vehicles, portable electronics, and other devices are mainly graphite (Gr) and its derivatives. However, the limited energy density of Gr-based anodes promotes the exploration of alternative anode materials such as silicon (Si)-based materials because of their abundance in nature and low cost. Specifically, Si can store 10 times more energy than Gr and also has the potential to enhance the energy density of LIBs. Despite the many advantages of Si-based anodes, such as high theoretical capacity and low price, their widespread use is hindered by two major issues: charge-induced volume expansion and unreliable solid electrolyte interphase (SEI) propagation. In this detailed review, we highlight the key issues, current advances, and prospects in the rational design of Si-based electrodes for practical applications. We first explain the fundamental electrochemistry of Si and the importance of Si-based anodes in LIBs. The excessive volume increase, relatively low charge efficiency, and inadequate areal capacity of Si-based anodes are discussed to identify the barriers in enhancing their performance in LIBs. Subsequently, the use of binders (e.g., linear polymer binders, branched polymer binders, cross-linked polymer binders, and conjugated conductive polymer binders), material-based anode composites (such as carbon and its derivatives, metal oxides, and MXenes), and liquid electrolyte construction techniques are highlighted to overcome the identified barriers. Further, tailoring Si-based materials and reshaping their surfaces and interfaces, including improving binders and electrolytes, are shown to be viable approaches to address their drawbacks, such as volume expansion, low charge efficiency, and poor areal capacity. Finally, we highlight that research and development on Si-based anodes are indispensable for their use in commercial applications.