Confining sulfur in sandwich structure of bamboo charcoal and aluminum fluoride (BC@S@AlF3) as a long cycle performance cathode for Li-S batteries.

The 'shuttle effect' of polysulfide causing rapid capacity fade and low coulombic efficiency of high energy storage lithium-sulfur (Li-S) batteries. Herein, a sandwich structure of bamboo charcoal/sulfur coating by aluminum fluoride (BC@S@AlF 3) composites is designed and fabricated for the first time. The as-designed cathode exhibited excellent electrochemical properties and stable capacity retention. The initial capacity reaches 1119 mA h/g and the capacity after 100 cycles is 869 mA h/g at 0.5 C, which is much stable than that of composite materials without bamboo charcoal or AlF 3 coating. Moreover, the BC@S@AlF 3 cathode presents excellent long-term capacity stability with a capacity decay of 0.073% per cycle during 500 charge/discharge cycles at 1 C, offering a potential for use in high energy Li-S batteries. The physical confinement, chemical anchoring, and catalysis conversion for active sulfur are achieved simultaneously with the AlF 3 coating and bamboo charcoal core with porous structure. [ABSTRACT FROM AUTHOR]