Schauser Nicole S, Nikolaev Andrei, Richardson Peter M, Xie Shuyi, Johnson Keith, Susca Ethan M, Wang Hengbin, Seshadri Ram, Clément Raphaële J, Read de Alaniz Javier, Segalman Rachel A
Materials Department, University of California, Santa Barbara, California 93106, United States.
Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States.
ACS Macro Lett. 2021 Jan 19;10(1):104-109. doi: 10.1021/acsmacrolett.0c00788. Epub 2020 Dec 22.
Polymer electrolytes with high Li-ion conductivity provide a route toward improved safety and performance of Li-ion batteries. However, most polymer electrolytes suffer from low ionic conduction and an even lower Li-ion contribution to the conductivity (the transport number, ), with the anion typically transporting over 80% of the charge. Here, we show that subtle and potentially undetected associations within a polymer electrolyte can entrain both the anion and the cation. When removed, the conductivity performance of the electrolyte can be improved by almost 2 orders of magnitude. Importantly, while some of this improvement can be attributed to a decreased glass transition temperature, , the removal of the amide functional group reduces interactions between the polymer and the Li cations, doubling the Li to 0.43, as measured using pulsed-field-gradient NMR. This work highlights the importance of strategic synthetic design and emphasizes the dual role of and ion binding for the development of polymer electrolytes with increased total ionic conductivity and the Li ion contribution to it.
具有高锂离子传导率的聚合物电解质为提高锂离子电池的安全性和性能提供了一条途径。然而，大多数聚合物电解质存在离子传导率低以及锂离子对传导率的贡献更低（迁移数）的问题，阴离子通常传输超过80%的电荷。在此，我们表明聚合物电解质中细微且可能未被检测到的缔合作用能够夹带阴离子和阳离子。当这种缔合作用消除后，电解质的传导性能可提高近两个数量级。重要的是，虽然这种改善部分可归因于玻璃化转变温度的降低，但酰胺官能团的去除减少了聚合物与锂阳离子之间的相互作用，使用脉冲场梯度核磁共振测量发现锂离子迁移数翻倍至0.43。这项工作突出了策略性合成设计的重要性，并强调了玻璃化转变温度和离子结合对于开发具有更高总离子传导率以及锂离子对其贡献的聚合物电解质的双重作用。
