Synergistic carbon coating of MOF-derived porous carbon and CNTs on silicon for high performance lithium-ion batteries

摘要

Silicon has been considered as one of the most potential alternatives to traditional graphite anode materials in lithiumion batteries (LIBs) due to its high specific capacity. However, the practical application of silicon is hampered by its inherent low conductivity and huge volumetric expansion during cycling. Herein, a hybrid of Si@carbon nanotubes (CNTs)@carbon nanocomposites in which Si nanoparticles tangled with CNTs are encapsulated into metal-organicframeworks (MOFs) carbon shell was synthesized through chemical vapor deposition and MOF self-template methods. By growing CNTs on the surface of Si nanoparticles, it is possible to facilitate their encapsulation in ZIF-67 crystals. In addition, the synergistic effect between CNTs and carbon shells doped with nitrogen can efficaciously buffer the expansion of structure and enhance the conductivity of materials. Besides, the porosity of carbon shell and the connection of CNTs can provide channels for the penetration and diffusion of Li+. On the basis of the above merits, the reversible capacity of the resulted composite remains 568.8 mAh g?1 after 200 cycles at 1 A g?1. Moreover, it exhibits a preferable rate performance, thus indicating that this composite is a promising anode material for LIBs.