Preparation and characterization of a special structural poly(acrylonitrile)-based microporous membrane for lithium-ion batteries

In this work, a special structural poly(acrylonitrile) (PAN)-based microporous membrane for lithium-ion batteries is prepared from PAN emulsion by simple casting and extracting techniques. It is found that the microporous membrane is fabricated by PAN particles with uniform size (about 580 nm), and a lot of micropores exist among the particles. The Gurley number of the microporous membrane obviously depends on the amount of additive but the porosity does not. The PAN-based microporous membrane is activated by non-aqueous liquid electrolyte to form microporous gel electrolyte (MGE), and its ionic conductivity increases with the decrease of the Gurley number. The resulting MGE shows typical thermal shut-down action because of the swelling-incorporating behaviors of PAN-based particles by the help of the solvent of liquid electrolyte at high temperature. In addition, the electrochemical stability window of the MGE can extend to 5.5 V vs. Li+/Li. The test cell using MGE as separator shows high initial discharge capacity (143 mAh g(-1) based on LiCoO2) and high capacity retention ratio (around 94.8% at the 50th cycle). Generally, the special structural microporous membrane is promisingly used to prepare high-safety lithium-ion batteries.