Long-Life Lithium-Ion Sulfur Pouch Battery Enabled by Regulating Solvent Molecules and Using Lithiated Graphite Anode

The development of lithium-sulfur (Li-S) batteries is severely limited by the shuttle effect and instability of Li-metal anode. Constructing Li-ion S batteries (LISBs), by using more stable commercial graphite (Gr) anode instead of Li-metal, is an effective way to realize long-cycle-life Li-S batteries. However, Gr electrode is usually incompatible with the ether-based electrolytes commonly used for Li-S batteries due to the Li+-ether complex co-intercalation into Gr interlayers. Herein, a solvent molecule structure regulation strategy is provided to weaken the Li+-solvent binding by increasing steric hindrance and electronegativity, to accelerate Li+ de-solvation process and prevent Li+-ether complex co-intercalation into Gr anode. Meanwhile, the weakly solvating power of solvent can suppress the shuttle effect of lithium polysulfides and makes more anions participate in Li+ solvation structure to generate a stable anion-derived solid electrolyte interface on Gr surface. Therefore, a LISB coin-cell consisting of lithiated graphite anode and S@C cathode displays a stable capacity of & AP;770 mAh g-1 within 200 cycles. Furthermore, an unprecedented practical LISB pouch-cell with a high Gr loading (& AP;10.5 mg cm-2) also delivers a high initial capacity of 802.3 mAh g-1 and releases a stable capacity of 499.1 mAh g-1 with a high Coulombic efficiency (& AP;95.9%) after 120 cycles. TFEE-based electrolyte is fabricated by regulating molecular structure of DME solvent, which can weaken the Li+-solvent binding energy and accelerate Li+ de-solvation process, inherently preventing Li+-ether complex co-intercalation into Gr anode and inhibiting dissolution of lithium polysulfides (LiPSs). Hence, this electrolyte shows a good application potential in long-life lithium-ion sulfur batteries (LISBs) with S@C cathode and lithiated graphite (LG) anode.image

Automated summary

A solvent molecule structure regulation strategy is proposed to weaken the binding between lithium ions and the solvent, accelerate the desolvation process, and prevent the co-intercalation of lithium-ion ether complexes into the graphite anode. This strategy also suppresses the dissolution of lithium polysulfides and promotes the formation of a stable solid electrolyte interface, leading to long-cycle-life lithium-sulfur batteries.