Will lithium‐sulfur batteries be the next beyond‐lithium ion batteries and even much better?

Lithium-ion batteries (LIBs) are undoubtedly the current working-horse in almost all portable electronic devices, electric vehicles, and even large-scale stationary energy storage. Given the problems faced by LIBs, a big question arises as to which battery(ies) would be the "Beyond LIBs" batteries. Among the front-runners, lithium-sulfur batteries (LSBs) have been extensively pursued owing to their intrinsically high energy density and extremely low cost. Despite the steady and sometimes exciting progress reported on sulfur chemistry and cell performance at laboratory scales over the past decade, one of the major bottlenecks is the poor cyclability. In this perspective, we examine the key challenges and opportunities faced by LSBs, as well as approaches at the materials, electrode/electrolyte and cell integration levels that can be taken to transform LSBs from a front-runner to a real leading champion in the pursuit of the "Beyond LIBs." While the key new mechanistic insights are very important, we propose a set of the near-future research directions for both the liquid and solid state LSBs, where the currently on-going parallel pursuits of both liquid and solid LSBs will be converging. The "liquid current" will gradually be taken over by "solid future" in the expected LSBs commercialization in the coming decade.