In Situ Construction of High-Performing Compact Si-SiO-CN Composites from Polyaminosiloxane for Li-Ion Batteries

Great efforts have been made to design high-performing Si/C composite anodes for Li-ion batteries to improve their energy density and cycling life. However, challenges remain in achieving fast electrical conductivity while accommodating significant electrode volumetric changes. Here, we report a unique Si/C-based anode architecture, a Si-SiO-CN composite, which is simultaneously constructed via the pyrolysis of a polyaminosiloxane precursor. The obtained structure features high-purity Si nanocrystals embedded in an amorphous silica matrix and then embraced by N-doped carbon layers. Notably, in this structure, all three components derived from the polyaminosiloxane precursor are linked by chemical bonding, forming a compact Si-SiO-CN triple heterostructure. Because of the improvement in the volumetric efficiency for accommodating Si active materials and electrical properties, this anode design enables promising electrochemical performance, including excellent cycle performance (830 mAh g^-1 after 100 cycles at 0.1 A g^-1) and outstanding rate performance (400 mAh g^-1 at 5 A g^-1). Moreover, this composite anode demonstrates great potential for high-energy Li-ion batteries, where a Si-SiO-CN//LiNi_0.9Co_0.1O₂ full-cell shows a high capacity of 180 mAh g^-1 as well as stable cycle performance (150 mAh g^-1 after 200 cycles at 0.19 A g^-1).