Electrodeposited heterostructured manganese oxides on carbonized clothes for enhanced lithium polysulfides conversion as free-standing sulfur cathodes

Abstract

Various metal oxides are investigated to catalyse lithium polysulfides (LiPS) conversion to promote the surface-bound insoluble intermediates and limit the LiPS shuttle. Herein, an effective methodology is reported to enhance LiPS catalytic conversion by applying electrodeposited hybrid phase composite films of manganese oxide (MnOx) on carbonized cotton cloth. Synergistic effects of porous carbon fabric with remnant lumen and high interfacial MnOx composite film of nanoflakes greatly contribute towards freestanding high-loaded sulfur cathodes. Various MnOx phases are realized by controlled annealing of MnOOH electrodeposited nanoflakes on carbon cloth. Oxygen deficient phases especially active interfaces among various phases are proposed to accelerate the LiPS oxidation to polythionate complexes that can interact with LiPS to assist their onsite conversion into sulfides. Pristine and LiPS interacted deposited films are investigated by X-ray photoelectron spectra and X-ray absorption spectra. The cathodes bearing high oxygen-deficient manganese oxide nanoflakes achieve high initial discharge capacity of 1153.7 mA h g−1 at 0.1 C and high reversible capacity of 824 mA h g−1 at 0.5 C over 200 cycles at sulfur areal loading of 5 mg cm−2, while initial discharge capacity of 1085.9 mA h g−1 and reversible capacity of 410 mA h g−1 are obtained for MnO2 rich heterostructure film.