Data of research paper: Trade-off in Lithium Diffusivity and Transference in High Lithium Concentration Ternary Polymer Ionic Liquids

Data supporting findings of paper https://doi.org/10.1016/j.ssi.2025.116854<br>HighlightsA local optimum for lithium mobility in ternary IL/PIL/lithium salt is observed.Lithium diffusion in ternary electrolyte system is analogous to ILE at low to moderate lithium salt concentrations.A change from neutral pair to free lithium ion conductivity is observed at high lithium salt concentrations.<br>AbstractFor battery architectures that need a solid ion conductor with good contacting performance and high stability against electrochemical oxidation, polymerized ionic liquids (PIL) pose a valuable class of materials. The low conductivity of the binary PIL/ lithium salt system can be increased using a ternary ionic liquid acting as plasticiser. The conductive mechanism of the ternary system is however not fully understood. This work shows the shift in conduction mechanism for the ternary Li−/[1,3]PYR-/PDADMA-FSI system by increasing the lithium salt concentration and comparing the transfer mechanism to binary ionic liquid (IL) electrolyte analogues using pulsed field gradient (PFG) nuclear magnetic resonance (NMR), NMR relaxometry, Raman spectroscopy and electrochemical techniques. Two conducting regimes were found which show a strong trade-off between conductivity and transference number. In the low lithium salt regime (≤35 wt% LiFSI), cluster diffusion of aggregated lithium is the dominating mechanism leading to low transference numbers (0.04–0.15 at room temperature (RT)). The high salt regime (≥50 wt% LiFSI) shows diffusion through free lithium ion hopping transfer, which has a stronger dependence on temperature and yields higher transference numbers (0.31 at RT). Increasing lithium salt concentration shows an inverse linear correlation with conductivity. The electrochemical characteristics of ternary IL/PIL/lithium salt are shown to be highly tuneable by varying the lithium salt fraction, while it maintains excellent characteristics like processability, stability and mechanical function.

本数据集支撑论文https://doi.org/10.1016/j.ssi.2025.116854的研究发现

研究亮点：
1. 本研究观测到三元离子液体（ionic liquid, IL）/聚合离子液体（polymerized ionic liquids, PIL）/锂盐体系中锂的迁移率存在局部最优值。
2. 在低至中等锂盐浓度条件下，三元电解质体系的锂扩散行为与纯离子液体电解质（ionic liquid electrolyte, ILE）相似。
3. 当锂盐浓度较高时，体系的导电机制会从离子中性对传导转变为游离锂离子传导。

摘要：
针对需要兼具良好接触性能与优异电化学氧化稳定性的固态离子导体的电池架构，聚合离子液体（PIL）是一类极具应用价值的材料。二元PIL/锂盐体系的电导率偏低，通过引入三元离子液体作为增塑剂可有效提升其电导率，但目前学界尚未完全厘清该三元体系的导电机制。本研究通过调控锂盐浓度，并借助脉冲场梯度（pulsed field gradient, PFG）核磁共振（nuclear magnetic resonance, NMR）、NMR弛豫谱、拉曼光谱及电化学表征手段，将三元Li−/[1,3]PYR-/PDADMA-FSI体系的传输机制与二元离子液体（IL）电解质对照体系进行对比，阐明了其导电机制的转变规律。该体系存在两类导电区间，且电导率与锂离子迁移数之间呈现显著的权衡关系：在低锂盐浓度区间（LiFSI占比≤35 wt%），聚集态锂的团簇扩散为主要导电机制，对应室温下0.04~0.15的低锂离子迁移数；在高锂盐浓度区间（LiFSI占比≥50 wt%），导电机制转变为游离锂离子跳跃扩散，该机制对温度的依赖性更强，室温下可获得0.31的更高锂离子迁移数。锂盐浓度的提升与体系电导率呈负线性相关关系。研究表明，通过调控锂盐占比可灵活调节三元IL/PIL/锂盐体系的电化学性能，同时该体系仍可保持优异的可加工性、化学稳定性与机械性能。