Radiation graft of acrylamide onto polyethylene separators for lithium ion batteries

To improve the affinity between separators and electrolyte in lithium-ion battery, microporous polyethylene (PE) separator was grafted of polyacrylamide (PAAm) by radiation. Chemical structure of the PAAmgrafted PE separators (denoted as PE-g-PAAm) was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Properties of the pristine PE and PE-g-PAAm were tested by scanning electron microscope, liquid electrolyte uptake and lithium-ion conductivity. Electrochemical performances of the grafted PE separators (up to 0.76 × 10^-3 S/cm of ionic conductivity at room temperature) were much better than pristine PE, and performance of the battery with the grafted separator behaved better than with the virgin PE separator, under the same condition (assembled in Ar-filled glove box). (authors)