Improvement of ionic conductivity of solid polymer electrolyte based on Cu-Al bimetallic metal-organic framework fabricated through molecular grafting
(1. College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, China;
2. Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation, Changsha University of Science and Technology, Changsha 410114, China;
3. College of New Energy, Ningbo University of Technology, Ningbo 315336, China)
2. Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation, Changsha University of Science and Technology, Changsha 410114, China;
3. College of New Energy, Ningbo University of Technology, Ningbo 315336, China)
Abstract: A composite solid electrolyte comprising a Cu-Al bimetallic metal-organic framework (CAB), lithium salt (LiTFSI) and polyethylene oxide (PEO) was fabricated through molecular grafting to enhance the ionic conductivity of the PEO-based electrolytes. Experimental and molecular dynamics simulation results indicated that the electrolyte with 10 wt.% CAB (PL-CAB-10%) exhibits high ionic conductivity (8.42×10-4 S/cm at 60 °C), high Li+ transference number (0.46), wide electrochemical window (4.91 V), good thermal stability, and outstanding mechanical properties. Furthermore, PL-CAB-10% exhibits excellent cycle stability in both Li-Li symmetric battery and Li/PL-CAB- 10%/LiFePO4 asymmetric battery setups. These enhanced performances are primarily attributable to the introduction of the versatile CAB. The abundant metal sites in CAB can react with TFSI- and PEO through Lewis acid–base interactions, promoting LiTFSI dissociation and improving ionic conductivity. Additionally, regular pores in CAB provide uniformly distributed sites for cation plating during cycling.
Key words: polyethylene oxide; Cu-Al bimetallic metal-organic framework; solid lithium metal battery; molecular grafting; ionic conductivity