Despite the utility of ceramic and PFSA membranes in preventing capacity fade, their high component cost and processing challenges has prevented penetration of Li-S technology into the marketplace. Introduction of Berkeley Lab’s low-cost PIM Membranes for Long-Lived Li-S Batteries is a game changer for Li-S battery commercialization. The performance metrics of PIM membranes match or exceed incumbent membranes in all categories including conductivity, processability and stability. PIM membranes operate by an unconventional nano-sieving mechanism adding novelty to the candidate invention. The economic benefits of deploying Li-S batteries that incorporate Berkeley Lab’s membranes are clear: rechargeable Li-S batteries reduce the cost of electrochemical energy storage three-fold. The environmental benefits are likewise clear: sulfur is a by-product of the oil industry; its use obviates the need for toxic and expensive heavy metals. Li-S batteries are safe and thus attractive for behind-the-meter storage.