Fang Zhao, Deng Qinghua, Zhou Yang, Fu Xiaolong, Yi Jiacheng, Wu Lizhi, Dai Qingyang, Yang Yong
School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing210094, P. R. China.
The Green Aerotechnics Research Institute of Chongqing Jiaotong University, Chongqing401120, P. R. China.
ACS Appl Mater Interfaces. 2023 Feb 1;15(4):5283-5292. doi: 10.1021/acsami.2c20127. Epub 2023 Jan 24.
The development of solid-state polymer electrolytes (SPEs) has been plagued by poor ionic conductivity, low ionic transference number, and limited electrochemical potential window. The exploitation of ionized SPEs is a feasible avenue to solve this problem. Herein, conjugated organic polymers (COPs) with excellent designability and rich pore structures have been selected as platforms for exploration. Three cationic COPs with different chain lengths of quaternary ammonium salts (CbzT@C, = 4, 6, 9) are designed and applied to SPEs for the first time. Meanwhile, the effects of chain lengths on their electrochemical performances are compared. Especially, CbzT@C shows the most attractive electrochemical performance due to its high specific surface area of 212.3 m g. The larger specific surface area allows more exposure of the long-chain quaternary ammonium cation groups, which is more favorable for the dissociation of lithium salts. Moreover, the flexible long-chain structure increases the compatibility with poly(ethylene oxide) (PEO) and reduces the crystallinity of PEO to some extent. The richer pore structure can accommodate more PEO, further disrupting the crystallinity of PEO and creating more channels for the ether-oxygen chain to transport lithium ions. At 60 °C, the SPE (CbzTM@C) presents an excellent ionic conductivity (σ) of 8.00 × 10 S cm. CbzTM@C has a lithium-ion transference number () of 0.48. Thus, the assembled Li/CbzTM@C/LiFePO battery provides a good discharge capacity of 158.8 mAh g at 0.1C. After 70 cycles, the capacity retention rate is 93.8% with a Coulombic efficiency of 98%. The excellent flexibility brings stable power supply capability under various bending angles to the assembled Li/CbzTM@C/LiFePO soft-packed battery. The project uses conjugated organic polymers in SPEs and creates an avenue to develop flexible energy storage equipment.
固态聚合物电解质（SPEs）的发展一直受到离子电导率低、离子迁移数低和电化学势窗有限的困扰。开发离子化的SPEs是解决这一问题的可行途径。在此，具有出色可设计性和丰富孔结构的共轭有机聚合物（COPs）被选为探索平台。首次设计了三种季铵盐链长不同的阳离子COPs（CbzT@C，n = 4、6、9）并将其应用于SPEs。同时，比较了链长对其电化学性能的影响。特别是，CbzT@C因其212.3 m²/g的高比表面积而表现出最具吸引力的电化学性能。更大的比表面积使长链季铵阳离子基团更多地暴露出来，这更有利于锂盐的解离。此外，柔性长链结构增加了与聚环氧乙烷（PEO）的相容性，并在一定程度上降低了PEO的结晶度。更丰富的孔结构可以容纳更多的PEO，进一步破坏PEO的结晶度，并为醚氧链传输锂离子创造更多通道。在60°C时，SPE（CbzTM@C）呈现出8.00×1e-5 S/cm的优异离子电导率（σ）。CbzTM@C的锂离子迁移数（tLi+）为0.48。因此，组装的Li/CbzTM@C/LiFePO4电池在0.1C时提供了158.8 mAh/g的良好放电容量。70次循环后，容量保持率为93.8%，库仑效率为98%。出色的柔韧性为组装的Li/CbzTM@C/LiFePO4软包电池在各种弯曲角度下带来了稳定的供电能力。该项目在SPEs中使用共轭有机聚合物，为开发柔性储能设备开辟了一条途径。
