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 ≈770 mAh g −1 within 200 cycles. Furthermore, an unprecedented practical LISB pouch-cell with a high Gr loading (≈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 (≈95.9%) after 120 cycles.
High energy density lithium metal batteries (LMBs) have garnered significant research interests in the past decades. However, the growth of lithium dendrites and the low Coulombic efficiency (CE) of Li metal anode pose significant challenges for the development of LMBs. Herein, we report a triethyl orthoformate (TEOF)-based localized high-concentration electrolyte (LHCE) that facilitates a highly reversible Li metal anode with dendrite-free deposition morphologies and an average Coulombic efficiency of 99.1% for 450 cycles. Mechanistic study reveal that the steric hindrance caused by the terminal ethyl groups in the TEOF solvent molecule results in a weak solvating ability, leading to the formation of anion-dominant solvation structures. The anion-dominant solvation sheaths play an essential role in the formation of a LiF-rich solid-electrolyte interphase (SEI), which effectively suppresses the growth of Li dendrites. Furthermore, the TEOF-based electrolyte demonstrates the stable cycling of high-voltage Li||NMC811 cells. These results provide insights into understanding of steric hindrance effect on electrolyte solvation structure and offer valuable guidance for the design of electrolyte solvents in the development of lithium metal batteries.
Li-Li Tan,Yumo Zhang,Bao Li,Kai Wang,Sean Xiao-An Zhang,Yanchun Tao,Ying-Wei Yang
Highly selective binding of “solvent” molecules by 1,4-dimethoxypillar[5]arene (DMP[5]A) and their host–guest complexation in solution and the solid state have been investigated by multiple methods. Enthalpy changes and the size-fit effect play an important role in the high selectivity.
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