Free-Standing Sulfur-Carbon Nanotube Electrode with a Deposited Sulfur Layer for High-Energy Lithium-Sulfur Batteries.

To obtain a high S-loading cathode for a Li-S battery, we propose a free-standing carbon nanotube (CNT)-based S cathode, which consists of two layers: a pure S deposition layer with a thickness of 20 m, and a S-containing CNT film (S-CNT). Based on scanning electron microscopic (SEM) studies, it was observed that the S layer completely vanished when the cell with the S/S-CNT cathode was discharged to 2.1 V after cell assembly, indicating that the thick sulfur film dissolved in the form of polysulfide intermediates during discharge. The proposed S/S-CNT cathode delivered double the areal capacity with good capacity retention of 83% after 100 cycles, compared with that of the control cathode (S-CNT). Thus, we believe that our new cathode design will be useful in developing stable, high-energy Li-S batteries.