Papamichail Chrysostomos, Techlemtzi Olympia, Nikolakakou Georgia, Glynos Emmanouil
Department of Materials Science and Engineering, University of Crete, P.O. Box 2208, 710 03, Heraklion, Crete, Greece.
Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P.O. Box 1385, 711 10 Heraklion, Crete, Greece.
ACS Macro Lett. 2025 Feb 18;14(2):225-230. doi: 10.1021/acsmacrolett.4c00802. Epub 2025 Feb 10.
This study investigates the fundamental influence of cation chemistry on the ionic conductivity of PEO-based electrolytes, with implications for advancing polymer electrolyte design. Two PEO systems─high molecular weight ( = 100 kg/mol) and low molecular weight ( = 0.35 kg/mol)─were blended with LiTFSI and NaTFSI salts to explore ion transport mechanisms. In the high- PEO, where ion hopping dominates, smaller Li ions exhibit higher conductivity (σ > σ). In contrast, the low- PEO, where ion diffusion is the primary mechanism, shows higher conductivity for larger Na ions (σ > σ). In the former, rheology measurements indicate that larger Na cations form more transient EO:Na contact, hindering cation hopping and reducing conductivity. In the latter, the stronger EO:Li interactions lead to a larger hydrodynamic radius and slower diffusion. Notably, PEO-0.35K:NaTFSI exhibits a room-temperature conductivity of σ ≈ 4 × 10 S/cm, meeting the requirements for practical applications. These findings highlight the potential of low- PEO and Na-based electrolytes for the development of efficient Na-ion batteries.
本研究探讨了阳离子化学对聚环氧乙烷（PEO）基电解质离子电导率的基本影响，这对推进聚合物电解质设计具有重要意义。将两种PEO体系——高分子量（ = 100 kg/mol）和低分子量（ = 0.35 kg/mol）——与双三氟甲烷磺酰亚胺锂（LiTFSI）和双三氟甲烷磺酰亚胺钠（NaTFSI）盐混合，以探索离子传输机制。在高分子量PEO中，离子跳跃起主导作用，较小的锂离子表现出更高的电导率（σ > σ）。相比之下，在低分子量PEO中，离子扩散是主要机制，较大的钠离子表现出更高的电导率（σ > σ）。在前者中，流变学测量表明，较大的钠离子形成更多短暂的EO:Na接触，阻碍阳离子跳跃并降低电导率。在后者中，更强的EO:Li相互作用导致更大的流体动力学半径和更慢的扩散。值得注意的是，PEO - 0.35K:NaTFSI在室温下的电导率为σ ≈ 4 × 10 S/cm，满足实际应用的要求。这些发现突出了低分子量PEO和钠基电解质在开发高效钠离子电池方面的潜力。
