MoN Supported on Graphene as a Bifunctional Interlayer for Advanced Li-S Batteries

Rational design of effective polysulfide barriers is highly important for high-performance lithium-sulfur (Li-S) batteries. A variety of adsorbents have been applied as interlayers to alleviate the shuttle effect. Nevertheless, the unsuccessful oxidation of Li2S on interlayers leads to loss of active materials and blocks Li ion transport. In this work, a MoN-based interlayer sandwiched between the C-S cathode and the separator is developed. Such an interlayer not only strongly binds lithium polysulfides via Mo-S bonding but also efficiently accelerates the decomposition of Li2S. The acceleration mechanism toward Li2S decomposition is determined to be a combination of contributions of catalytic cleavage of Li-S bond in Li2S based on the proposed covalence-activation mechanism and rapid migration of the produced Li ions. As a result, the C-S cathodes with the as-developed interlayer manifest a negligible charging potential barrier and outstanding cycling stability with a very low capacity fading rate of 0.023% per cycle during 1500 cycles at 1 C. High areal capacity of 6.02 mAh cm(-2) is achieved for high sulfur loading of 7.0 mg cm(-2) after cycling at 0.1 C. The material and strategy demonstrated in this work can open the door toward developing shuttle suppression interlayers without impairing cathode performance.