LiV 3 O 8 -Based Functional Separator Coating as Effective Polysulfide Mediator for Lithium–Sulfur Batteries

MALETTI, SEBASTIAN; PODETTI, FLORENCIA S.; OSWALD, STEFFEN; GIEBELER, LARS; BARBERO, CÉSAR A.; MIKHAILOVA, DARIA; BALACH, JUAN

ACS Applied Energy Materials

ACS Publications

Año: 2020 vol. 3 p. 2893 - 2899

2574-0962

The commercial development of high-energy lithium?sulfur (Li?S) batteries is still hampered by the irreversible active material loss and fast capacity decay triggered by the dissolution of polysulfide species and the subsequent polysulfide shuttle effect. Carbon-coated separators can limit the diffusion of polar polysulfide intermediates between electrodes. However, the capacity fading still exists owing to the weak interaction of nonpolar carbons. Herein, a novel lithium vanadium(V) oxide-coated hybrid separator (LiV3O8?HS) is designed for enhancing the performance of Li?S batteries. The results show that the LiV3O8 coating acts as a shield-like redox mediator to physically block the diffusion of polysulfide intermediates and chemically promotes the conversion of soluble higher-order polysulfides to insoluble short-chain polysulfides via internal disproportionation reactions, accelerating the redox reaction kinetics and lessening the active material loss during cycling. As a consequence, Li?S cells with the LiV3O8?HS demonstrated superior electrochemical performance despite using a pure sulfur cathode, with a high initial discharge capacity of 1254 mAh g?1 at 0.2 C and superior long-term cyclability with a low average capacity decline of 0.063% per cycle after 500 cycles at 0.5 C. The coating of the commercial separator, which can be straightforwardly adopted in an industrial process, offers a simple and powerful route for boosting the performance of Li?S batteries toward commercial application.