3D interconnected porous carbon nanosheets/carbon nanotubes as a polysulfide reservoir for high performance lithium-sulfur batteries

摘要

Carbon materials have attracted considerable attention as the hosts for lithium-sulfur batteries, especially the 3D structural carbon matrix. Herein, novel 3D interconnected porous carbon nanosheets/carbon nanotubes (denoted as PC/CNT) as a poly-sulfide reservoir are synthesized by a simple one-pot pyrolysis method. In the designed hybrid carbon matrix, porous carbon nanosheets exhibit hierarchical porous structures for high sulfur loading and effectively strengthen the physical confinement to trap soluble polysulfides, while carbon nanotubes provide a highly robust conductive pathway which can facilitate electron transport and maintain structural integrity. Moreover, the 3D interconnected structure combining 1D carbon nanotubes and 2D porous carbon nanosheets is beneficial for rapid electrical/ionic transport and favorable electrolyte infiltration. As a result, the S-PC/CNT composite exhibits outstanding electrochemical performance, with a high active-sulfur utilization, high specific capacity (1485.4, 1300.3 and 1138 mA h g(-1) at 0.5, 1 and 2 C, respectively), superior cycling stability (only 0.1 capacity decay per cycle over 400 cycles at 2 C) and excellent rate capability (the reversible capacity of 749 mA h g(-1) even at 4 C).