Ion States Impact Charge Transport and Dielectric Constant for Poly(ethylene oxide)-Based Sulfonylimide Lithium Ionomers
Ion States Impact Charge Transport and Dielectric Constant for Poly(ethylene oxide)-Based Sulfonylimide Lithium Ionomers
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DOI：
10.1021/acs.macromol.3c00294
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发表时间：
2023-06
期刊：
影响因子：
5.5
通讯作者：
Wenwen Mei;Deyang Yu;L. Madsen;R. Hickey;R. Colby
中科院分区：
文献类型：
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作者：
Wenwen Mei;Deyang Yu;L. Madsen;R. Hickey;R. Colby
了解离子聚合物中的介电响应和电荷传输对于设计和实现这些材料在与能源相关的应用中是至关重要的。我们之前的研究发现，阴离子化学组成对聚合物固定磺酰亚胺(MTLi)和磺酸盐阴离子(J.Mater)的聚环氧乙烷锂离聚体的离子导电性有重要影响。化学。C，2022，10,14569)。在本研究中，我们利用密度泛函理论进一步研究了不同离子状态下的介电响应和Li+电导。用四态模型描述了影响介电响应和Li+电导的最相关的离子状态。采用团簇-连续体溶剂化模型的密度泛函计算捕捉到了聚氧乙烷的局域溶剂化效应，揭示了中性和带电状态之间较低的团簇离解能。低的团簇解离能解释了基于X射线散射的低聚集数的弱聚集形态，并暗示了Li+在不同离子状态之间的快速交换。因此，Li+可以沿着聚集体跳跃以获得高离子含量的MTLi，这导致了其显著的介电响应、相当的电导率和较低的Haven比率，尽管聚集性比低离子含量的同类材料更强。与典型的离子含量增加不利于离子输运和介电响应的典型离聚体不同，基于不同离子状态对MTLi的理解为促进单离子导电离聚体的离子传导和介电响应提供了新的见解。
Understanding dielectric response and charge transport in ion-containing polymers is essential for the design and implementation of these materials in energy-related applications. Our previous study identified the significant impacts of anion chemical composition on ion conduction for poly(ethylene oxide)-based lithium ionomers with polymer-fixed sulfonylimide (MTLi) and sulfonate anions (J. Mater. Chem. C,2022,10,14569). In this study, we further explore the dielectric response and Li+conduction in the context of different ion states using DFT. The most relevant ion states impacting the dielectric response and Li+conduction are represented with a four-state model. DFT calculation using the cluster-continuum solvation model captures the local solvation effects of poly(ethylene oxide) and reveals low cluster dissociation energy between neutral and charged states. Low cluster dissociation energy explains the weakly aggregated morphology with low aggregation number based on X-ray scattering and implies that Li+rapidly exchanges between different ion states. Consequently, Li+can hop along aggregates for high ion content MTLi, which results in its significant dielectric response, comparable conductivity, and lower Haven ratio despite stronger aggregation than the low ion content counterparts. Different from typical ionomers where raising ion content is detrimental to the ion transport and dielectric response, the understandings based on different ion states for MTLi offer new insights to promote ion conduction and dielectric response for single-ion conducting ionomers.