Surface engineering of nano silicon via in situ copolymer grafting for lithium ion batteries

Abstract

Silicon (Si), characterized by an exceptionally high theoretical capacity, has been explored as a promising anode candidate for lithium-ion batteries. However, during repeated lithiation and delithiation, Si undergoes pronounced volume fluctuations, which induce structural damage and interfacial instability, thereby accelerating electrochemical performance deterioration. In this work, a copolymer-mediated interfacial regulation strategy is proposed to construct Si@void@C core–shell composites. The dopamine-based copolymer with adhesive functional groups shows strong affinity to the Si surface, while the hydrophilic functional group significantly improves the water dispersion stability. The modified Si nanoparticles enabled the feasibility of a uniform polymer coating strategy to prepare Si@carbon composites. The prepared Si@void@C anode features an internal void space and a carbon shell, which effectively accommodate the volume expansion of silicon while enhancing interfacial stability and facilitating charge-transfer processes. As a result, the electrode exhibits a stable solid electrolyte interphase and delivers high reversible capacity along with improved rate performance and long-term cycling stability. This work demonstrates a straightforward and sustainable approach for constructing advanced silicon-based anodes.