Sulfur Nanocrystals Confined in Carbon Nanotube Network
As a Binder-Free Electrode for High-Performance Lithium Sulfur Batteries
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Abstract
A binder-free nano sulfur–carbon
nanotube composite material
featured by clusters of sulfur nanocrystals anchored across the superaligned
carbon nanotube (SACNT) matrix is fabricated via a facile solution-based
method. The conductive SACNT matrix not only avoids self-aggregation
and ensures dispersive distribution of the sulfur nanocrystals but
also offers three-dimensional continuous electron pathway, provides
sufficient porosity in the matrix to benefit electrolyte infiltration,
confines the sulfur/polysulfides, and accommodates the volume variations
of sulfur during cycling. The nanosized sulfur particles shorten lithium
ion diffusion path, and the confinement of sulfur particles in the
SACNT network guarantees the stability of structure and electrochemical
performance of the composite. The nano S-SACNT composite cathode delivers
an initial discharge capacity of 1071 mAh g<sup>–1</sup>, a
peak capacity of 1088 mAh g<sup>–1</sup>, and capacity retention
of 85% after 100 cycles with high Coulombic efficiency (∼100%)
at 1 C. Moreover, at high current rates the nano S-SACNT composite
displays impressive capacities of 1006 mAh g<sup>–1</sup> at
2 C, 960 mAh g<sup>–1</sup> at 5 C, and 879 mAh g<sup>–1</sup> at 10 C