Sharma S K, Mor J
Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India.
ACS Macro Lett. 2024 Sep 17;13(9):1211-1217. doi: 10.1021/acsmacrolett.4c00467. Epub 2024 Sep 3.
Coupling between segmental relaxation and ionic conduction has limited the ionic conductivity of flexible polymers like poly(ethylene oxide), PEO, based electrolytes especially at low temperatures where segmental relaxation becomes extremely slow. In the present study, we show that ionic conduction becomes decoupled from segmental relaxation in PEO-based electrolytes simply by loading succinonitrile (SN). As a result of SN interactions induced rigid chain packing of PEO, the semicrystalline morphology of PEO is completely altered along with the enhancement in number density of free volumes having smaller size and narrower size distribution. These free volumes provide additional pathways for ionic diffusion independent of segmental relaxations of PEO leading to decoupling of ionic diffusion from the segmental relaxation process. The decoupling finally leads to nearly two orders higher ionic conductivity (∼10 Scm)at glass transition temperature ( ∼ 210 K), than what is expected in the case of complete coupling.
链段松弛与离子传导之间的耦合限制了聚环氧乙烷（PEO）等柔性聚合物基电解质的离子电导率，尤其是在低温下，此时链段松弛变得极其缓慢。在本研究中，我们表明，通过加入丁二腈（SN），基于PEO的电解质中的离子传导与链段松弛解耦。由于SN相互作用导致PEO的刚性链堆积，PEO的半结晶形态完全改变，同时尺寸更小、尺寸分布更窄的自由体积数密度增加。这些自由体积为离子扩散提供了独立于PEO链段松弛的额外途径，导致离子扩散与链段松弛过程解耦。这种解耦最终导致在玻璃化转变温度（约210K）下离子电导率比完全耦合情况下预期的高出近两个数量级（约10 S/cm）。
