A stable high performance Li–S battery with a polysulfide ion blocking layer

We reported a simple and low cost solution-based process for casting a polysulfide ion blocking layer onto a carbon–sulfur composite for application as a cathode in a lithium ion battery. At a current density of 837 mA g−1, the battery shows a high initial capacity of 980 mA h g−1 and a slow degradation to 738 mA h g−1 after 500 cycles (i.e. only a 0.049% decrease per cycle).