Tris(2,4,6‐trimethylphenyl) phosphine with Aluminum Oxide Incorporated Polyethylene Separator for Lithium‐Ion Batteries

Radical‐scavenging Al 2 O 3 ‐tris(2,4,6‐trimethylphenyl) phosphine (TMPP)‐functionalized polyethylene (PE) separator is modified by preparation of the Al 2 O 3 ‐TMPP composites and embedding them onto the PE separator by dip‐coating process. Scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, and Fourier‐transform infrared spectroscopy analyses indicate that Al 2 O 3 ‐TMPP is well coated onto the PE separator. The Al 2 O 3 ‐TMPP‐embedded PE separator exhibits a lower contact angle and higher electrolyte uptake than the bare PE separator, indicating a more hydrophilic surface is developed in the Al 2 O 3 ‐TMPP‐embedded PE separator. The cell cycled with the Al 2 O 3 ‐TMPP‐embedded PE separator exhibits stable cycling behavior after 150 cycles at high temperature (59.8%) while the cell cycled with a bare PE separator shows a continuous decrease in cycling retention (47.1%). The use of the Al 2 O 3 ‐TMPP‐embedded PE separator is therefore an effective way to improve the cell cycling retention because it can effectively lower the radical concentration via a chemical scavenging process.