Contemporary Trends in Lithium‐Sulfur Battery Design: A Comparative Review of Liquid, Quasi‐Solid, and All‐Solid‐State Architectures and Mechanisms

The lithium sulfur battery offers disruptive potential for applications that demand high energy density, and sustainable materials supply chains. Whilst the liquid‐based Li‐S technology has studied for decades, it is only comparatively recently that the chemistry has gained significant commercial traction. Historically significant and persistent challenges have hampered the technology, most pressingly, poor cyclability; however, recent efforts have demonstrated viable routes to overcome these impediments, with commercial traction increasing across the globe. These developments have addressed commercialization barriers, including the use of LiNO3 as an electrolyte additive. For example, recent activity has shown progress toward more ‘solid‐state’ conversion mechanisms, including the so‐called ‘quasi‐solid state’ system. The contemporary research landscape across liquid, quasi‐ and all‐solid‐state Li‐S chemistries is reviewed. For each, a didactic overview of the underpinning operation is provided, and the literature on new mechanistic understanding, state‐of‐the‐art characterization and materials solutions is comprehensively examined. The Li‐S battery is at an inflection point in commercial deployment; this review aims to highlight the need to increase the focus of academic research on overcoming the remaining barriers to commercialization whilst continuing to identify fundamental operating mechanisms and material developments to accelerate the realization of the potential of this chemistry.