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

Abstract

Radical‐scavenging Al2O3‐tris(2,4,6‐trimethylphenyl) phosphine (TMPP)‐functionalized polyethylene (PE) separator is modified by preparation of the Al2O3‐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 Al2O3‐TMPP is well coated onto the PE separator. The Al2O3‐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 Al2O3‐TMPP‐embedded PE separator. The cell cycled with the Al2O3‐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 Al2O3‐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.