Electrospun Nanofibers Enabled Advanced Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries have been extensively studied because both S and Li have high theoretical capacities, and S is abundant and environmentally friendly. However, their practical applications have been hindered by several challenges, induding poor conductivity of S and its intermediates, shuttle effects of polysulfides, Li dendrite growth, etc. Tremendous efforts have been taken to tackle these issues by developing functional S host materials, separators and interlayers, solid-state electrolytes, etc., during the past decade. Compared to structurally complicated materials and intricate preparation approaches, electrospun nanofibers have obtained tremendous interests since they have played an extremely crucial role in improving the overall performance of Li-S cells due to their unique features such as easy-setup, substantial surface area, outstanding flexibility, high porosity, excellent mechanical properties, etc. In this Account, we highlight the advancements and progress of electrospun nanofibers applied for obtaining advanced Li-S batteries based on our research: from the traditional liquid system to a full solid-state cell. It starts with the fundamental electrochemistry and challenges of Li-S batteries and then focuses on the advantages of utilizing electrospun nanofibers in Li-S batteries and their working mechanisms, which are detailed from five perspectives: (i) cathode design; (ii) interlayers; (iii) separators; (iv) solid-state electrolytes; (v) Li anode protection. For example, we will discuss (1) how the appropriate nanofiber cathode designs improve the electrical conductivity and utilization of the cathode, (2) how nanofiber interlayers minimize the diffusion of polysulfides, (3) how nanofiber separators improve cells' rate capability, (4) how nanofiber-based solid-state electrolytes boost the overall ionic conductivity, accelerating the use of Li-S cells, and (5) how the applications of nanofibers suppress the Li dendrite growth. In the end, the critical research directions needed and the remaining challenges to be addressed are summarized. It is expected that this Account would provide an understanding of the importance for achieving advanced Li-S cells via utilizing electrospun nanofibers, inspiring extensive research on their rational designs and promoting the development of this field.