Reactivation of dissolved polysulfides in Li-S batteries based on atomic layer deposition of Al2O3 in nanoporous carbon cloth

This work demonstrates the effect of atomic layer deposited (ALD) Al2O3 on the reactivation of dissolved polysulfides in Li-S batteries. A 0.5 nm thick layer of Al2O3 is conformally coated onto highly porous carbon cloth by ALD, and then assembled in a Li-S battery between the sulfur cathode and the anode side (separator and Li anode) to function as a reactivation component. Compared to half cells with no ALD treatment, the ultrathin Al2O3 coating increases the specific discharge capacity by 25% from 907 to 1136 mA h/g at the 1st cycle, and by 114% from 358 to 766 mA h/g at the 40th cycle. Thus the ALD-Al2O3 improves the initial specific capacity and stabilizes the cycle life remarkably. Scanning electron microscopy and energy-dispersive X-ray spectroscopy results indicate that the ALD-Al2O3 coated carbon cloth sorbs (adsorbs/absorbs) more dissolved sulfur species from the electrolyte. Potential mechanisms for the improved sorption properties are proposed. The combination of an ultrathin ALD-oxide coating with highly porous carbons presents a new strategy to improve the performance of Li-S batteries. (C) 2013 Elsevier Ltd. All rights reserved.