College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China.
Angew Chem Int Ed Engl. 2023 Jun 26;62(26):e202300243. doi: 10.1002/anie.202300243. Epub 2023 May 3.
Ionic liquids (ILs)-incorporated solid-state polymer electrolytes (iono-SPEs) have high ionic conductivities but show non-uniform Li transport in different phases. This work greatly promotes Li transport in polymer phases by employing a poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE), PTC] as the framework of ILs to prepare iono-SPEs. Unlike PVDF, PTC with suitable polarity shows weaker adsorption energy on IL cations, reducing their possibility of occupying Li -hopping sites. The significantly higher dielectric constant of PTC than PVDF facilitates the dissociation of Li-anions clusters. These two factors motivate Li transport along PTC chains, narrowing the difference in Li transport among varied phases. The LiFePO /PTC iono-SPE/Li cells cycle steadily with capacity retention of 91.5 % after 1000 cycles at 1 C and 25 °C. This work paves a new way to induce uniform Li flux in iono-SPEs through polarity and dielectric design of polymer matrix.
离子液体（ILs）-固溶体聚合物电解质（iono-SPE）具有高离子电导率，但在不同相中表现出不均匀的 Li 传输。本工作通过采用聚（偏二氟乙烯-三氟乙烯-氯三氟乙烯）[P（VDF-TrFE-CTFE），PTC]作为 ILs 的骨架来制备 iono-SPE，从而极大地促进了聚合物相中 Li 的传输。与 PVDF 不同，具有适当极性的 PTC 对 IL 阳离子的吸附能较弱，降低了它们占据 Li 跳跃位的可能性。PTC 比 PVDF 显著更高的介电常数促进了 Li 阴离子簇的解离。这两个因素促使 Li 沿着 PTC 链传输，缩小了不同相中 Li 传输的差异。LiFePO /PTC iono-SPE/Li 电池在 1C 和 25°C 下循环 1000 次后，容量保持率为 91.5%，稳定循环。这项工作通过聚合物基质的极性和介电设计为诱导 iono-SPE 中均匀的 Li 通量开辟了一条新途径。
