Lithium sulphur technology for energy storage is considered to be one of the most promising of emerging technologies due to its high theoretical capacity, but the performance of these batteries is limited by problems such as dissolution of polysulphide species in electrolyte, lithium dendrite formation. Previously we demonstrated the capability of Li6PS5Cl, Li6PS6Br and Li10GeP2S12 anode-protecting solid electrolyte membranes to mitigate these problems. To further enhance the stability of these solid electrolyte membranes, here we demonstrate that atomic layer deposition of a thin conformal coating of lithium tantalate leads to lithium poly sulphide semi-flow batteries with superior performance.