Nanoengineering to achieve high efficiency practical lithium-sulfur batteries

Rapidly increasing markets for electric vehicles (EVs), energy storage for backup support systems and high-power portable electronics demand batteries with higher energy density with longer cycle life. Among the various electrochemical energy storage systems, lithium-sulfur (Li-S) batteries have potential to be a next generation rechargeable battery because of their high specific energy at a low cost. However, the development of practical Li-S batteries for commercial products has been challenged by several obstacles, including unstable cycle life and low sulfur utilization. Only few studies have considered the importance of low electrolyte and high sulfur loading parameters to improve the overall energy densities of Li-S cells. Thus, it is necessary to review the recent development of Li-S batteries that passes the benchmark of practical parameters that could exceed practical energy density of lithium-ion batteries (LIBs) including: areal sulfur loading of at least 4 mg cm−2, electrolyte to sulfur ratio of less than 10 μL mg−1, and high cycling stability of over 300 cycles. In this review, we investigate the advancements of each component in Li-S batteries that are developed to enhance the electrochemical properties of sulfur cathodes, lithium anodes, or electrolytes; we also identify several important strategies of nanoengineering and how they address the practical limits of Li-S batteries that prevent them from competing against LIBs. Additionally, we provide further guidance for the development of Li-S batteries based on nanomaterials and nanoengineering so that they could enter the market of high energy density and rechargeable storage system.