Polydopamine-mediated synthesis of Si@carbon@graphene aerogels for enhanced lithium storage with long cycle life

The application of Si as the anode materials for lithium-ion batteries(LIBs) is still severely hindered by the rapid capacity decay due to the structural damage caused by large volume change(> 300%) during cycling. Herein, a three-dimensional(3 D) aerogel anode of Si@carbon@graphene(SCG) is rationally constructed via a polydopamine-assisted strategy. Polydopamine is coated on Si nanoparticles to serve as an interface linker to initiate the assembly of Si and graphene oxide, which plays a crucial role in the successful fabrication of SCG aerogels. After annealing the polydopamine is converted into N-doped carbon(N-carbon) coatings to protect Si materials. The dual protection from N-carbon and graphene aerogels synergistically improves the structural stability and electronic conductivity of Si, thereby leading to the significantly improved lithium storage properties. Electrochemical tests show that the SCG with optimized graphene content delivers a high capacity(712 m Ah/g at 100 m A/g) and robust cycling stability(402 m Ah/g at 1 A/g after 1500 cycles). Furthermore, the full cell using SCG aerogels as anode exhibits a reversible capacity of 187.6 m Ah/g after 80 cycles at 0.1 A/g. This work provides a plausible strategy for developing Si anode in LIBs.