Hosseinioun Ava, Nürnberg Pinchas, Schönhoff Monika, Diddens Diddo, Paillard Elie
Helmholtz Institute Münster, Forschungszentrum Jülich (IEK-12) Corrensstr. 46 48149 Münster Germany
Institute of Physical Chemistry, University of Münster Corrensstr. 28/30 48149 Münster Germany
RSC Adv. 2019 Sep 2;9(47):27574-27582. doi: 10.1039/c9ra05917b. eCollection 2019 Aug 29.
Since PMMA-based gel polymer electrolytes could substitute PVDF-HFP based gels currently used in Li-ion batteries at lower financial and environmental costs, we investigate here the solvation and transport properties of the lithium ions in a crosslinked PMMA-based gel polymer electrolyte by a combination of thermal and electrochemical methods, Raman spectroscopy, pulse field gradient (PFG) and electrophoretic NMR (eNMR) techniques, as well as calculations. The conductivity of the gel containing 10 wt% polymer is only reduced by 14% relative to the liquid electrolyte. In addition, the co-solvation by polymer functional groups, expected to slow lithium transport relatively to the anion, has instead a positive effect on lithium transport. Indeed, the ester groups not only participate in lithium solvation and increase ionic dissociation, but since this interaction is rather weak, rather than lowering the lithium diffusion relatively to other species, it mainly decorrelates lithium transport from anionic mobility. Compared to its liquid fraction, the gels show, at the same time, better dissociation and a higher lithium transference number, which results in a higher cationic conductivity, despite the overall conductivity loss.
由于基于聚甲基丙烯酸甲酯（PMMA）的凝胶聚合物电解质能够以更低的经济和环境成本替代目前锂离子电池中使用的基于聚偏氟乙烯-六氟丙烯（PVDF-HFP）的凝胶，我们在此通过热分析和电化学方法、拉曼光谱、脉冲场梯度（PFG）和电泳核磁共振（eNMR）技术以及计算相结合的方式，研究了交联的基于PMMA的凝胶聚合物电解质中锂离子的溶剂化和传输特性。含10 wt%聚合物的凝胶的电导率相对于液体电解质仅降低了14%。此外，聚合物官能团的共溶剂化作用本应相对于阴离子减缓锂的传输，但实际上却对锂的传输产生了积极影响。事实上，酯基不仅参与锂的溶剂化并增加离子解离，而且由于这种相互作用相当弱，它并非相对于其他物种降低锂的扩散，而是主要使锂的传输与阴离子迁移解耦。与液体部分相比，凝胶同时表现出更好的解离和更高的锂迁移数，尽管总体电导率有所损失，但这导致了更高的阳离子电导率。
