Sulfur Nanocrystals Confined in Carbon Nanotube Network\nAs a Binder-Free Electrode for High-Performance Lithium Sulfur Batteries

Abstract

A binder-free nano sulfur–carbon\nnanotube composite material\nfeatured by clusters of sulfur nanocrystals anchored across the superaligned\ncarbon nanotube (SACNT) matrix is fabricated via a facile solution-based\nmethod. The conductive SACNT matrix not only avoids self-aggregation\nand ensures dispersive distribution of the sulfur nanocrystals but\nalso offers three-dimensional continuous electron pathway, provides\nsufficient porosity in the matrix to benefit electrolyte infiltration,\nconfines the sulfur/polysulfides, and accommodates the volume variations\nof sulfur during cycling. The nanosized sulfur particles shorten lithium\nion diffusion path, and the confinement of sulfur particles in the\nSACNT network guarantees the stability of structure and electrochemical\nperformance of the composite. The nano S-SACNT composite cathode delivers\nan initial discharge capacity of 1071 mAh g^–1, a\npeak capacity of 1088 mAh g^–1, and capacity retention\nof 85% after 100 cycles with high Coulombic efficiency (∼100%)\nat 1 C. Moreover, at high current rates the nano S-SACNT composite\ndisplays impressive capacities of 1006 mAh g^–1 at\n2 C, 960 mAh g^–1 at 5 C, and 879 mAh g^–1 at 10 C.