Weakening Li + De-solvation Barrier for Cryogenic Li-S Pouch Cells.

Li-S batteries hold promise for pushing cell-level energy densities beyond 300 Wh kg -1 while operating at low temperatures (LTs, below 0 °C). However, the capacity release of existing Li-S batteries at LTs is still barely satisfactory. And there is almost no verification of the practicability of Li-S batteries at LTs in the Ah-level pouch cell. Here, the antecedent molecular dynamics (MDs) combined with density functional theory (DFT) analysis systematically investigated Li + solvation structure in conventional Li-S batteries at LTs, which unprecedentedly revealed the positive correlation between lithium salt concentration and Li + de-solvation barrier, indicating that dilute electrolytes can enhance the Li + de-solvation kinetics and thus improve the capacity performance of cryogenic Li-S batteries. These insights derived from theoretical simulations invested Li-S batteries with a 67.34% capacity retention at -40 °C compared to their room temperature performance. In particular, an Ah-level Li-S pouch cell using dilute electrolytes with a high sulfur loading (5.6 mg cm -2 ) and lean electrolyte condition (E/S = 4 mL g -1 ) was fabricated, which delivered a discharge capacity of about 1000 mAh g -1 and ultra-high energy density of 350 Wh kg -1 at 0 °C, offering a promising route toward practical high-energy cryogenic Li-S battery. This article is protected by copyright. All rights reserved.