Tailoring the Polymer-Derived Carbon Encapsulated Silicon Nanoparticles for High-Performance Lithium-Ion Battery Anodes

The structure, dopants, and surface area of carbon determine the performance of the core-shell structured silicon and carbon composite (Si@C) anode for Li-ion batteries (LIBs). Herein, we report the synthesis of Si@C composite from poly(vinyl alcohol) (PVA)/melamine resin (MR) dual layer polymer derived carbon encapsulated Si nanoparticles using a polymerization-carbonization approach. The dual polymer layer derived carbon coating has adequate void spaces and dopants, possesses a disordered structure, and seals the Si core sufficiently. Hence, the obtained Si@C-MR anode delivers a superior specific capacity of 1279.3 mA h/g at a current density of 2 A/g and with a retention rate of 88.9% after 500 cycles. A full cell with a Li(Ni0.6Co0.2Mn0.2)O-2 cathode and a prelithiated Si@C-MR anode exhibits a high energy density above 518 Wh/kg and capacity retention of 90.1% after 100 cycles. In parallel, the other three polymer-derived Si@C composites were prepared to study the effect of carbon on the performance of the composite anodes. Overall, constructing a dual-polymer layer holds the promise for rationally designing Si@C anodes for high-performance LIBs through the polymerization-carbonization approach.