A high-performance binder-free freestanding film anode constructed by Si/NC nanoparticles anchoring in 3D porous N-doped graphene-CNTs networks for Li-ion batteries

The Si-based flexible electrodes attracted increasing research interests owing to the growing demand for high-performance flexible energy storage devices. Herein, a facile and smart self-assembly strategy is adopted to address huge volume expansion and particle aggregation issues of Si-based anodes, and a high-performance freestanding film anode (NC@Si/CNTs/N-rGO) is synthesized. The 3D-crosslinked porous graphene-CNTs networks offer abundant electric conductive pathways, high active sites, large internal space to accommodate the expansion of Si NPs, and facilitate Li+ diffusion and insertion/extraction kinetics. The synergistic effect between the well-dispersed Si/NC nanoparticles and 3D porous networks significantly enhances electrochemical performance of Si NPs. The as-prepared NC@Si/CNTs/N-rGO electrode exhibits a high reversible specific capacity of 1089 mAh·g−1 at a charge–discharge current density of 1 A·g−1 after 500 cycles. Even at 2 A·g−1, the electrode still exhibits an excellent reversible specific capacity of 606 mAh·g−1 after 300 cycles. These indicate that the NC@Si/CNTs/N-rGO is a promising candidate for high-performance flexible anode material in lithium-ion batteries.