A sandwiched electrode containing pristine Li2S powder in between two layers of binder-free carbon nanotube electrodes is developed. The carbon matrix provides an ion and electron accessible environment, and a space for trapping the active material. Exceptionally high capacities with superior stability and rate capability are obtained.
A lithium/dissolved polysulfide cell is developed utilizing a self-weaving, free-standing multiwalled carbon nanotube (MWCNT) “paper” as a host for the dissolved polysulfide active material and the reaction products. Exceptionally high capacities of 1600 mAh g−1 initially and 1411 mAh g−1 after 50 cycles (based on the mass of sulfur) are obtained at a rate of C/10.
The limitations in the cathode capacity compared with that of the anode have been an impediment to advance the lithium-ion battery technology. The lithium–sulphur system is appealing in this regard, as sulphur exhibits an order of magnitude higher capacity than the currently used cathodes. However, low active material utilization and poor cycle life hinder the practicality of lithium–sulphur batteries. Here we report a simple adjustment to the traditional lithium–sulphur battery configuration to achieve high capacity with a long cycle life and rapid charge rate. With a bifunctional microporous carbon paper between the cathode and separator, we observe a significant improvement not only in the active material utilization but also in capacity retention, without involving complex synthesis or surface modification. The insertion of a microporous carbon interlayer decreases the internal charge transfer resistance and localizes the soluble polysulphide species, facilitating a commercially feasible means of fabricating the lithium–sulphur batteries.
