Enhanced cycling stability of Li-sulfur battery composites by low pressure penetration of PEDOT:PSS coating.

ABSTRACT

A lithium sulfur composite electrode (SCPV) is prepared by in situ permeation of poly (3,4-dioxyethiophene)poly(styrene sulfonate) (PEDOTPSS) with a thickness of about 10 nm onto the surface of a SC (sulfur and carbon nanotubes) electrode via a low pressure (3.3 kPa) method. The SCPV electrode exhibits a discharge capacity of 1320.0 mA h g-1, which is higher than that of the SC electrode (1265.8 mA h g-1) at 0.1C; furthermore, it exhibits a discharge capacity of 604.9 mA h g-1, which is almost twice that of the SC electrode (306.8 mA h g-1) at 2C, and it is due to the fact that PEDOTPSS gel polymers store large amounts of electrolytes and have excellent electronic and ionic conductivities. However, the discharge capacity of a SCPV cathode remains at 91.87% after 200 cycles at 0.5C, which is more than twice that of the SC cathode (44.70%); this superior cycling stability is mainly due to the in situ fixation of PEDOTPSS inside the SC electrode, which inhibits the shuttle effect and volume change during the cycling process, thus improving the cycling stability.