Heat-resistant Al_(2)O_(3) nanowire-polyetherimide separator for safer and faster lithium-ion batteries

Poor heat/flame-resistance of polyolefin(e.g.,polyethylene and polypropylene)separators and high flammability of organic electrolytes used in today’s lithium-ion batteries(LIBs)may trigger rare yet potentially catastrophic safety issues.Here,we mitigate this challenge by developing a heat-resistant and flame-retardant porous composite membrane composed of polyetherimide(PEI)and Al_(2)O_(3) nanowires(NWs).The membranes are fabricated based on an industrially scalable non-solvent-induced phase separation process,which results in an intimately interconnected porous network of Al_(2)O_(3) NWs and PEI.The produced composite membranes exhibit excellent flexibility,thermal stability,and flame-retardancy.Importantly,the composite membranes exhibit minimal thermal shrinkage and superior tensile strength(16 MPa)at temperatures as high as 200℃,significantly exceeding the performance of conventional polyolefin separators.Compared with commercial separators,their superior wettability and higher ionic conductivity(by up to 2.4 times)when filled with the same electrolyte,larger electrolyte uptake(-190 wt.%),as well as improved cycle and rate performance demonstrated in LiNiMnCoO_(2)(NCM)-based LIBs make them attractive choices for a variety of electrochemical energy storage devices.