To enhance thermal stability and high-rate capability of lithium-ion batteries, both sides of porous polyethylene (PE) and poly(vinylidene fluoride) (PVdF) separators are coated with nanosized Al2O3 powder and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) binder dispersed in acetone-water solvent. For comparison, PVdF is also used as a polymer binder for coating. The Al2O3/PAMPS-coated separators show an improved thermal shrinkage resistance at 120 oC and enhanced electrochemical performance of LiCoO2||graphite full-cell. These improvements are due to the binding ability of PAMPS, the large surface area of the Al2O3 nanoparticles, and their surface hydrophilicity maintained by the PAMPS binder to exhibit outstanding wettability towards the electrolyte, resulting in the increase in discharge capacity and high-rate capability.