Ionic liquids self-assembly preparation of binder-free composites anode with well-dispersed Si nanoparticles on CNTs networks for lithium-ion batteries

Binder-free nano silicon/carbon nanotube composites anodes were synthesized by electrostatic self-assembly of ionic liquids (ILs) and annealing process. The addition of [Emim]Tf2N ILs successfully improved the dispersion of silicon nanoparticles (SiNPs) in the carbon nanotubes (CNTs). And the carbon nanotubes could be self-assembled into a 3D structure network through electrostatic gravitational force. Moreover, the wettability of electrode also be improved due to the heteroatoms of [Emim]Tf2N ILs doped in the CNTs during annealing. By integrating these advantages, the Si30%-CNTs anodes exhibit a high initial reversible discharge capacity of 2580.3 mAh g−1 at a current density of 0.4 A g−1. Even at a much higher current density of 10 A g−1, the Si30%-CNTs anodes can still deliver a high reversible discharge capacity of 871.1 mAh g−1. The outstanding performances compared to traditional coating method are assigned to that the ionic liquids self-assembly method improves the dispersion of SiNPs.