Catalytic FeP decorated carbon black as a multifunctional conducting additive for high-performance lithium-sulfur batteries

Sulfur hosts with high sulfur affinities and catalytic activities are widely studied for lithium-sulfur batteries to tackle polysulfide shuttling and the sluggish sulfur redox kinetics. Although conducting additives (typically carbon black) are essential components in slurry-coated cathodes, their modification received much less attentions as an alternative solution to the above-mentioned issues. Herein, we demonstrate that introducing catalytic materials to the conventional conducting additive of carbon black acts as a feasible strategy to improve battery performance. Super P carbon black decorated with FeP nanoparticles (SP/FeP) is synthesized using a scalable method and served as the conducting additive in sulfur cathodes constructed from common carbon hosts, namely carbon nanotubes and nanofibers. At a low addition of SP/FeP of 10 wt% (the conventional 8:1:1 recipe), SP/FeP exhibits strong sulfur immobilizations and effective electrocatalysis for the liquid-liquid and liquid-solid transitions. High specific capacities (1518 mAh g(-1) at 0.2 C), excellent rating performance (728 mAh g(-1) at 5 C) and stable longterm cycling are achieved. Pouch cells with a 7.0 mg cm(-2) sulfur loading are also demonstrated to present high areal capacities and charge/discharge stabilities. Electrochemical measurements and density functional theory calculations were performed to reveal the working mechanism of the SP/FeP conducting additive. (C) 2020 Elsevier Ltd. All rights reserved.