Gomes Luisa, Dai Huidong, Chambers Daniel, Sanctis Victor Ribeiro, Yang Kevin, Dong Ruizhi, Do Anhtu, Ji Tongtai, Mukerjee Sanjeev
Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States.
Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States.
ACS Nano. 2025 Jun 3;19(21):19715-19729. doi: 10.1021/acsnano.5c01797. Epub 2025 May 16.
Li-sulfur (Li-S) batteries are promising as the next-generation energy storage technology but face challenges due to sluggish sulfur redox reaction (SRR) kinetics and a sulfur shuttling effect. While many studies have explored polycaprolactone (PCL)-based gel polymer electrolytes (GPEs) to address these issues, the influence of solvent properties, including dielectric constant (ϵ) and donor and acceptor numbers (DN and AN), remain unexplored despite their critical impact on performance and full-scale implementation. This study systematically compares three distinct electrolytes, dimethoxyethane (DME), dimethyl sulfoxide (DMSO), and tetraethylene glycol dimethyl ether (TEGDME)-paired with PCL, to correlate the varied solvent properties and their effects on the physical properties of the GPE, in terms of Li transport and solvation, and polysulfide's confinement. Among them, the DME-based GPE, with an intermediate DN, exhibited the lowest crystallinity (2.31%), highest ionic conductivity (7.49 mS/cm), and high Li transference number (0.77). As a result, it achieved a specific capacity of 795 mAh/g sulfur and an average Coulombic efficiency of 97.5% after 120 cycles at C/5, outperforming its competitors. Operando Raman and UV-vis spectroscopy confirmed that PCL effectively confines long-chain polysulfides within its network, mitigating the shuttle effect and facilitating reversible polysulfide conversion. These findings demonstrate that GPEs with moderate DN values and balanced ϵ significantly enhance stability, extend cycle life, and improve rate performance for Li-S batteries. This work provides valuable insights into the design of advanced electrolyte systems for practical energy storage applications.
锂硫（Li-S）电池作为下一代储能技术具有广阔前景，但由于硫氧化还原反应（SRR）动力学缓慢和硫穿梭效应而面临挑战。虽然许多研究探索了基于聚己内酯（PCL）的凝胶聚合物电解质（GPE）来解决这些问题，但溶剂性质的影响，包括介电常数（ϵ）以及给体和受体数（DN和AN），尽管对性能和大规模应用有至关重要的影响，却仍未得到探索。本研究系统地比较了三种不同的电解质，即与PCL配对的二甲氧基乙烷（DME）、二甲基亚砜（DMSO）和四甘醇二甲醚（TEGDME），以关联不同的溶剂性质及其对GPE物理性质的影响，包括锂传输和溶剂化以及多硫化物的限制。其中，具有中等DN值的基于DME的GPE表现出最低的结晶度（2.31%）、最高的离子电导率（7.49 mS/cm）和较高的锂迁移数（0.77）。结果，在C/5下循环120次后，它实现了795 mAh/g硫的比容量和97.5%的平均库仑效率，优于其竞争对手。原位拉曼光谱和紫外可见光谱证实，PCL有效地将长链多硫化物限制在其网络内，减轻了穿梭效应并促进了多硫化物的可逆转化。这些发现表明，具有适度DN值和平衡ϵ的GPE显著提高了锂硫电池的稳定性、延长了循环寿命并改善了倍率性能。这项工作为实际储能应用的先进电解质系统设计提供了有价值的见解。
