Composite cathodes and modified separators based on corn-silk-based porous carbon for high performance lithium–sulfur batteries

Abstract

Corn by-products have been widely studied as a precursor of biomass carbon in energy storage systems. Without further doping or coating processes corn silk can achieve a high electrochemical performance when used as an anode of sodium and potassium ion batteries. Nonetheless, there is no report about corn silk used as a cathode for lithium-sulfur batteries. In this work, corn silk was made into porous carbon and used as sulfur scaffolds and modified materials for commercial separator in lithium-sulfur batteries. Corn silk possesses a natural pipe shape which grants the porous carbon a high specific surface area. With a simple dissolution crystallization method approximately 80% of the sulfur could be easily accommodated onto the porous carbon. The hierarchic pores not only limited the particle size of the sulfur to nanometers, but also buffered the volume expansion of sulfur and absorbed it tightly. Furthermore, with an ultralight porous carbon modified separator, significant improvement was achieved in the utilization of sulfur, cycling stability and alleviation of the polysulfide shuttling efficiently. The batteries delivered a specific capacity of 1290 mAh g-1 in the first discharge and 746 mAh g-1 after 100 cycles. The good electrochemical performance can be ascribed to the rational design of battery configuration.