Opportunities and challenges of nano Si/C composites in lithium ion battery: A mini review

Under the requirements of reducing carbon emissions and developing a green and low-carbon economy, Li ion batteries (LIBs) play an important role in electric vehicles (EV), electric grid energy systems, and other energy storage power plants. R & D of higher energy density, safer and more stable LIBs has become an urgent task in these application fields. Unfortunately, the theoretical capacity of commercial graphite anode is 372 mAhg─1 which cannot meet the future demands for high-performance LIBs. By comparation, silicon (Si) as anode materials has shown good application prospects in the high-performance LIBs, and been intensively investigated worldwide in the past few decades owing to its high theoretical capacity of about 4200 mAhg-1, abundant reserve, low cost, environmentally friendly and so on. However, severe volume expansion, low electronic conductivity, low Coulombic efficiency in the first cycle, and continuous formation of SEI (solid electrolyte interphase) during lithiation/delithiation processes hinder its practical application in the LIBs. To address these shortcomings or alleviate problems, various technologies and strategies have been devoted to the Si anodes. In this review, the research progress of Si and various carbon composite materials including 1D, 2D and 3D structural features are summarized. Porous Si/C 3D architecture materials are considered excellent and promising composite materials due to their abundant pore channels for Li ions transportation, ability to release the significant stress caused by Si volume expansion, and a short distance for mass diffusion. This article also covers two important materials: new polymer binders and electrolyte additives. Their latest research progress and impact on electrochemical performances, as well as future development prospects are outlined.