n‐Hexane Diluted Electrolyte with Ultralow Density enables Li–S Pouch Battery Toward >400 Wh kg⁻¹

Abstract Lithium–sulfur (Li‐S) batteries are attractive candidates for next generation energy storage devices due to their high theoretical energy density of up to 2600 Wh kg⁻¹. However, the uneven deposition of lithium, the undesired shuttle of lithium polysulfides (LiPSs), and the excess weight fraction of electrolyte severely impair the practical energy density of Li‐S batteries. Here, a low concentrated and nonpolar n‐hexane (NH)‐diluted electrolyte (named as LCDE) with ultralow‐density to alleviate the above dilemmas is proposed. The nonpolar NH boosts the diffusion of lithium ion in LCDE, favoring the homogeneous deposition of lithium. This nonpolar effect also reduces the solubilities of LiPSs, promoting a quasi‐solid‐state transformation of sulfur chemistry, thus tremendously eradicating the shuttle of LiPSs. Most importantly, the ultra‐light NH diluent enables the LCDE with an ultralow density of only 0.79 g mL⁻¹, which reduces the weight of LCDE by 32.5% compared with conventional ether‐based electrolyte. Owing to all the merits, the Li‐S pouch cell achieves a high energy density up to 417 Wh kg⁻¹. The nonpolar NH‐diluted electrolyte with multifunction presented in this work provides a new and feasible direction to increase the practical energy density of Li‐S batteries.