Effective Suppression of Polysulfide Dissolution by Uniformly Transfer-Printed Conducting Polymer on Sulfur Cathode for Li-S Batteries

The lithium-sulfur battery has received much attention in recent years owing to its high gravimetric capacity, far beyond that of current Li-ion batteries. Overcoming the shuttling effect caused by the dissolution of polysulfides during the charge-discharge process is a major challenge for the realization of Li-S cells. Here we report transfer-printing of a conductive polymer to cover and securely passivate the surface of sulfur electrodes to prevent the dissolution of polysulfides and, simultaneously, to provide high electronic conductivity of sulfur cathodes. Highly uniform polyaniline film can be controllably formed on sulfur cathodes via the transfer printing method, and a sulfur cathode with the printed polyaniline layer showed improved cycle performance (capacity retention of 96.4% and an average Coulombic efficiency of 99.6% for 200 cycles) compared to conventional sulfur cathodes. In situ measurement of transmittance during discharge demonstrated that the dissolution of sulfur in electrolytes is considerably suppressed by the printed polyaniline layer, substantiating that transfer-printed polyaniline film can provide robust protection as well as supplement electrical conductivity to the sulfur cathode. This strategy could be extensively applied to sulfur cathodes of diverse morphology and further extended to large-scale production.