Rechargeable lithium–sulfur batteries have attracted great interest in recent years because of their high theoretical specific energy, which is several times that of current lithium-ion batteries. Compared to sulfur, fully-lithiated Li2S represents a more attractive cathode material because it enables pairing with safer, lithium metal-free anodes. Here, we demonstrate stable and high-performance Li2S cathodes by using ab initio simulations to guide our rational selection of poly(vinylpyrrolidone) binder which exhibits strong affinity with both Li2S and lithium polysulfides. A high discharge capacity of 760 mA h g−1 of Li2S (∼1090 mA h g−1 of S) was achieved at 0.2 C with stable cycling over prolonged 500 charge/discharge cycles.