3D CNTs networks enable core-shell structured Si@Ni nanoparticle anodes with enhanced reversible capacity and cyclic performance for lithium ion batteries

Silicon, to be a potential anode material of LIBs, possesses a pretty high lithium storage capacity. However, the structural integrity can be destructed by its huge volume expansion through cycles, which results in a large capacity attenuation. Meanwhile, the poor electrochemical performance of silicon-based anodes can be attributed to its poor conductance which reduces the reaction kinetics. According to the above challenges, core-shell structured silicon-nickel nanoparticles have been dispersed on 3D intertwined carbon nanotube networks (Si@Ni-NP/CNTs) via nitric acid pre-treatment and amino functionalization. The nickel-plated shell outside silicon core nanoparticles (Si@Ni-NP) can play a certain supporting role to prevent the volume expansion of silicon, which finally brings down the degree of powdering. Especially, the 3D framework composed of intertwined carbon nanotubes can efficiently provide not only an ample buffer space during intercalation/deintercalation but also a more stable conductive network to increase ion/electron transfer rate. Due to the above improvements in structural stability and reaction kinetics, Si@Ni-NP/CNTs reveal a reversible capacity of 1008 mAh g−1 with a 98% capacity retention over 100 cycles at a current density of 100 mA g−1. Under different current densities in rate test, the specific capacity recovery rate can reach 92%. The novel structure enables Si@Ni-NP/CNTs excellent stability under cycles and various rates, as a promising anode material of LIBs.