How the Si–O–Si Covalent Bond Interface Affects the Electrochemical Performance of the Silicon Anode

Nano-Si can alleviate the structural damage caused by volume expansion while ensuring high reversible lithium storage capacity. However, the abundant specific surface area and unique unbonded electronic properties at the surface of the nanoparticles make them suffer from complex surface side reactions and an agglomeration phenomenon. Here, strategies based on surface modification are developed to enhance the performance of nano-Si anodes. Through the in situ grafting of the SiOC coating, a stable and high-energy Si–O–Si covalent bond is formed between the core–shell, making the core–shell as a whole and avoiding the formation of dead silicon. In addition, it was verified by experiments and density functional theoretical calculations that the introduction of the covalent bond redistributed the electrons on the nano-Si surface, and the interface composed of electron-less silicon and electron-rich oxygen elements ensured high adsorption capacity to the electrolyte and structural stability after the introduction of lithium ions, thus ensuring efficient cycling capacity.