Hu Ajuan, Sun Cui, Li Chen, Sun Zongqiang, Fan Jingmin, Zheng Mingsen, Dong Quanfeng
State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (i-ChEM), Engineering Research Centre of Electrochemical Technologies of Ministry of Education, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China.
ACS Appl Mater Interfaces. 2023 Jul 26;15(29):35034-35042. doi: 10.1021/acsami.3c06456. Epub 2023 Jul 12.
Solid-state lithium metal batteries are hindered from practical applications by insufficient room-temperature ionic conductivity and poor electrode/electrolyte interfaces. Herein, we designed and synthesized a high ionic conductivity metal-organic-framework-based composite solid electrolyte (MCSE) with the synergy of high DN value ligands from Uio66-NH and succinonitrile (SN). XPS and FTIR reveal that the amino group (-NH) of Uio66-NH and the cyano group (-C≡N) of SN have a stronger solvated coordination with Li, which can promote the dissociation of crystalline LiTFSI, achieving an ionic conductivity of 9.23 × 10 S cm at RT. Afterward, a flexible polymer electrolyte membrane (FPEM) with admirable ionic conductivity (1.56 × 10 S cm at RT) and excellent electrode/electrolyte interfaces (86.2 Ω for the Li|20% FPEM|Li cell and 303.1 Ω for the LiFePO|20% FPEM|Li cell) was successfully obtained after compounding the MCSE with polyethylene oxide (PEO). Moreover, a stable solid electrolyte layer (SEI) was formed in situ on the surface of the lithium metal, which enables the Li|20% FPEM|Li cell to exhibit remarkable cycling stability (1000 h at a current density of 0.05 mA cm). At the same time, the assembled LiFePO|20% FPEM|Li cell offers a discharge-specific capacity of 155 mAh g at 0.1 C and a columbic efficiency of 99.5% after 200 cycles. This flexible polymer electrolyte provides a possibility for operating long lifespan solid-state electrochemical energy storage systems at RT.
固态锂金属电池因室温离子电导率不足和电极/电解质界面较差而阻碍了其实际应用。在此，我们设计并合成了一种基于金属有机框架的高离子电导率复合固体电解质（MCSE），它具有来自Uio66-NH的高DN值配体和丁二腈（SN）的协同作用。X射线光电子能谱（XPS）和傅里叶变换红外光谱（FTIR）表明，Uio66-NH的氨基（-NH）和SN的氰基（-C≡N）与Li具有更强的溶剂化配位作用，这可以促进结晶LiTFSI的解离，在室温下实现9.23×10⁻⁴ S cm⁻¹的离子电导率。随后，将MCSE与聚环氧乙烷（PEO）复合后，成功获得了具有优异离子电导率（室温下为1.56×10⁻⁴ S cm⁻¹）和出色电极/电解质界面（Li|20% FPEM|Li电池为86.2 Ω，LiFePO₄|20% FPEM|Li电池为303.1 Ω）的柔性聚合物电解质膜（FPEM）。此外，在锂金属表面原位形成了稳定的固体电解质界面（SEI），这使得Li|20% FPEM|Li电池表现出显著的循环稳定性（在0.05 mA cm⁻²的电流密度下循环1000 h）。同时，组装的LiFePO₄|20% FPEM|Li电池在0.1 C下的放电比容量为155 mAh g⁻¹，200次循环后的库仑效率为99.5%。这种柔性聚合物电解质为在室温下运行长寿命固态电化学储能系统提供了可能性。
