High performance freestanding composite cathode for lithium-sulfur batteries

Abstract

A freestanding sulfur/dehydrogenated polyacrylonitrile/multiwalled carbon nanotube composite (S/DPAN/MWCNT) was prepared by a simple vacuum filtration of a mixture of S/DPAN composite and MWCNT suspensions, and studied as a cathode for high performance lithium-sulfur batteries. SEM and EDS analysis revealed uniform distribution of sulfur in a conductive pyrolyzed polyacrylonitrile host matrix with MWCNT integrated into the composite. Self-weaving MWCNT create an electronically conductive network and reinforce structural stability of the system, leading to an outstanding electrochemical performance of the composite cathode. Binder/current collector-free composite cathode exhibits high capacities of 1450 mAh g−1 at 0.2 C and 930 mAh g−1 at 2 C charge-discharge rates. A high discharge capacity of 1250 mAh g−1 is achieved after 260 cycles at 0.2 C with a coulombic efficiency around 100%.