Chromium-based metal-organic framework coated separator for improving electrochemical performance and safety of lithium-ion battery

To improve the electrochemical performance and safety of the traditional polymer separator, two kinds of chromium-based MOFs (Cr-MOFs) (namely MIL-88B(Cr) and MIL-101(Cr)) were studied as separator coatings. Compared with inorganic coating (Al2O3), Cr-MOFs coated separators exhibited improved thermal stability, better flame retardance, superior electrolyte wettability, high electrolyte uptake, good ionic conductivity and enhanced electrochemical performance. Moreover, although MIL-88B(Cr) and MIL-101(Cr) have the same metal center (Cr3+) and organic ligand (1,4-benzene dicarboxylate), their improvements on the performance of coated separators are obvious different. The detailed analyses reveal that the specific surface area, pore size and structure stability of Cr-MOFs are the main factors that affect their performances. The result of this work provides an essential basis for developing high performance separators with MOFs.