Electronic and ionic co-conductive coating on the separator towards high-performance lithium–sulfur batteries

• Separators with co-conductive coating are designed for Li–S batteries.
• The solid ionic conductor can possible catalyze conversion of polysulfides.
• The novel cell delivers a high initial discharge capacity of 1247 mA h g−1.
• The functional separator endows the cell with excellent capacity retention.

A thin coating layer composed of the mixture of the electronic conductive carbon and lithium ionic conductive inorganic solid electrolyte was introduced on one side of the routine Celgard separator. This functional coated separator is designed to localize the polysulfides on the cathode side and act as an upper current collector for further utilization of sulfur while alleviating the ion conductivity decrease induced by the dissolved polysulfides in the discharge and charge process. Moreover, catalytic conversion of polysulfides by the solid state highly ionic conductor is observed. This brings significant improvement in battery specific capacity and cycling stability, with an initial discharge capacity of 1247 mA h g−1 and a reversible capacity of 830 mA h g−1 after 150 extended cycles at 0.5 C rate. Rest-testing proves a low self-discharge and excellent capacity retention of the modified cells.

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