A novel lithium-sulfur battery cathode from butadiene rubber-caged sulfur-rich polymeric composites

Novel sulfur-rich polymeric materials were readily prepared via facile solution vulcanization of the commercial butadiene rubber (BR) and sulfur element, and were investigated as cathode materials for lithium-sulfur batteries. During the solution vulcanization procedure, the double bonds (CC) in butadiene rubber are chemically cross-linked with sulfur. Moreover, the sulfur canalso self-polymerize into polymeric sulfur with long molecular chain. The polymeric sulfur chains penetrate into the cross-linked BR network to form a unique semi-internal penetration network (semi-IPN) confinement structure, which can effectively alleviate the dissolution and diffusion of intermediate polysulfide into electrolytes. Meanwhile, the obtained sulfur-rich polymeric composites have high sulfur contents even over 90%. As a result, the as-prepared sulfur-rich polymeric composites (BR-SPC) with network confine caged structure exhibit excellent cycling stability and high coulombic efficiency. An initial discharge specific capacity of 811 mA h g^-1 is reached, and retains 671 mA h g^-1 after 50 cycles at 0.1 C. The capacity retention rate and coulombic efficiency are 83%, 100%, respectively. Additionally, Super P (carbon black) was added in situ before vulcanization to increase the conductivity of BR-SPC composites. The BR-SPC composite containing Super P (BR-SPC-SP) reveals higher capacity retention of 85% over 50 cycles at 0.5 C than the BR-SPC composite without Super P.