Preparation of Co-nanocluster graphene composite by asymmetric domain-limited electrochemical exfoliation for functionalized lithium-sulfur battery separator applications

Abstract

Transition metal nanocluster graphene composite exhibits better performance in energy storage materials than heteroatom graphene composite. In catalytic function separator materials for lithium-sulfur batteries, the introduction of functionalized graphene into asymmetric separators effectively seals and anchors soluble polysulfides, largely mitigating the notorious “shuttle effect”. Here, we report the development of a novel asymmetric domain-limited electrochemical (ALE) exfoliation of graphite foils (natural-scaled graphite) to prepare Co-nanocluster graphene composite nanosheets (labeled as Co-G). Co-G has a large lateral size, many surface folds, and few intrinsic defects (ID/IG = 0.38). Co-nanocluster graphene composite promotes redox kinetic conversion, and its high electronic conductivity allows it to act as a second collector, accelerating charge transfer, improving the utilization of active material, and increasing cyclic stability. A lithium-sulfur battery incorporating a Co-G modified separator achieved an initial discharge capacity of 1315.5 mAh/g at 0.5 C with excellent multiplicity performance (932.3 mAh/g specific capacity at 2 C multiplicity) and cycling stability (848.4 mAh/g after 400 cycles). The asymmetric domain-limited electrochemical (ALE) method is a viable approach to the preparation of catalytic function separator materials for lithium-sulfur batteries that will have high magnification and high cyclic stability.