Flexible solid-state lithium-sulfur batteries based on structural designs

Flexible solid-state Lithium-sulfur batteries (FSSLSBs) are critical to industrious applications in the area that requires batteries to be low cost, have good mechanical properties, high capacity, and high energy densities. However, the current developments showed that there is no commercialization indication of FSSLSBs due to challenges on creating high sulfur mass loading cathode with high flexibility, optimizing solid-state electrolytes (SSE) designs and their scalability, suppressing Li metal dendrite growth, and optimizing cell geometries to achieve high flexibility at a cell/battery level. These challenges resulted in difficulty on meeting the demands of achieving mechanically robust and electrochemically stable FSSLSBs. Therefore, in this review, we highlight recent significant progress in the following aspects: (1). obtaining high-loading flexible sulfur cathode; (2). the achievement of flexible SSEs with high ionic conductivity; (3). methods on engineering Li metal anode to suppress Li dendrite growth; and (4). cell geometry designs to achieve a flexible cell packaging while sacrificing little energy density. Finally, based on the published results and the best knowledge of the authors, the proposed future research directions on FSSLSBs are discussed.