Flexible free-standing cathode enabled via multifunctional Mo2C for high sulfur loading lithium–sulfur batteries

Abstract A free-standing and flexible sulfur host material composed of Mo2C nanoarrays growing on the surface of carbon cloth (Mo2C/CC) is designed for the binder-free cathode of the Lithium-sulfur (Li–S) batteries. The carbon cloth substrate is flexible together with the conductive bottlebrush-like Mo2C, this host material can provide more active sites and a large inner space to accommodate the volume expansion of sulfur to Li2S2/Li2S. The electric conductive Mo2C nanoarrays can not only adsorb the polysulfides through forming Mo–S bonds to inhibit the shuttle of lithium polysulfides (LiPSs), but also can boost the electron transfer and promote the direct conversion of the LiPSs to Li2S2/Li2S on their surface. As a result, the sulfur cathodes based on the Mo2C/CC host material exhibit an impressive specific capacity of 1213 mA h g-1 at 0.1 C, maintain a long-term cyclability with a decay of 0.011% per cycle. More remarkably, excellent capacity of 8.57 mA h cm-2 can be attained with a high sulfur loading (10.8 mg cm−2) benefit from the 3D nanoarrays structure of the Mo2C/CC host material. Meanwhile, a pouch cell based on Mo2C/CC@S cathode can cycle steadily.