Hua Haiming, Huang Boyang, Yang Xueying, Cheng Jun, Zhang Peng, Zhao Jinbao
College of Chemistry and Chemical Engineering, State-Province Joint Engineering Laboratory of Power Source Technology for New Energy Vehicle, State Key Laboratory of Physical Chemistry of Solid Surfaces, Engineering Research Center of Electrochemical Technology, Ministry of Education, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University, Xiamen 361005, Fujian, China.
College of Energy, Xiamen University, Xiamen 361102, Fujian, China.
Phys Chem Chem Phys. 2023 Nov 8;25(43):29894-29904. doi: 10.1039/d3cp02225k.
With the improved lithium-ion transference number near unity, the low conductivity of single lithium-ion conducting solid polymer electrolytes (SLIC-SPEs) still hinders their application in high-rate batteries. Though some empirical conclusions on the conducting mechanism of SLIC-SPEs have been obtained, a more comprehensive study on the quantitative relationship between the molecular structure factors and ionic conduction performance is expected. In this study, a model structure that contains adjustable main chain and anion groups in the polyethylene oxide (PEO) matrix was used to clarify the influence of molecular structural factors on ionic conductivity and electrochemical stability of SLIC-SPEs. The anionic group was further disassembled into the intermediate group and end group while the main chain structure was distinguished into different degrees of polymerization and various lengths of the spacers between anions. Therefore, a well-defined molecular structure was employed to describe its relationship with ionic conductivity. In addition, the dissociation degree of salts and mobility of ions changing with the molecular structure were also discussed to explore the fundamental causes of conductivity. It can be concluded that the anion group affects the conductivity mainly the dissociation degree, while the main chain structure impacts the conductivity by both dissociation degree and mobility.
随着锂离子迁移数接近1有所改善，但单锂离子传导固体聚合物电解质（SLIC-SPEs）的低电导率仍然阻碍了它们在高倍率电池中的应用。尽管已经获得了一些关于SLIC-SPEs传导机制的经验性结论，但人们期望对分子结构因素与离子传导性能之间的定量关系进行更全面的研究。在本研究中，使用了一种在聚环氧乙烷（PEO）基体中包含可调节主链和阴离子基团的模型结构，以阐明分子结构因素对SLIC-SPEs离子电导率和电化学稳定性的影响。阴离子基团进一步分解为中间基团和端基，而主链结构则分为不同的聚合度和阴离子之间不同长度的间隔基团。因此，采用明确的分子结构来描述其与离子电导率的关系。此外，还讨论了盐的解离度和离子迁移率随分子结构的变化，以探究电导率的根本原因。可以得出结论，阴离子基团主要通过解离度影响电导率，而主链结构则通过解离度和迁移率两者来影响电导率。
