A strategy to achieve high loading and high energy density Li-S batteries

Lithium-sulfur(Li-S) batteries are one of the most promising rechargeable storage devices due to the high theoretical energy density.However,the low areal sulfur loading impedes their commercial development.Herein,a 3 D free-standing sulfur cathode scaffold is rationally designed and fabricated by coaxially coating polar Ti3C2Txflakes on sulfur-impregnated carbon cloth(Ti3C2Tx@S/CC) to achieve high loading and high energy density Li-S batteries,in which,the flexible CC substrate with highly porous structure can accommodate large amounts of sulfur and ensure fast electron transfer,while the outer-coated Ti3C2Txcan serve as a polar and conductive protective layer to further promote the conductivity of the whole electrode,achieve physical blocking and chemical anchoring of lithium-polysulfides as well as catalyze their conversion.Due to these advantages,at a sulfur loading of 4 mg cm-2,Li-S cells with Ti3C2Tx@S/CC cathodes can deliver outstanding cycling stability(746.1 mAh g-1after 200 cycles at1 C),superb rate performance(866.8 mAh g-1up to 2 C) and a high specific energy density(564.2 Wh kg-1after 100 cycles at 0.5 C).More significantly,they also show the commercial potential that can compete with current lithium-ion batteries due to the high areal capacity of 6.7 mAh cm-2at the increased loading of 8 mg cm-2.