A macro-porous graphene oxide-based membrane as a separator with enhanced thermal stability for high-safety lithium-ion batteries

To develop a separator with remarkable thermal-resistance for high-safety lithium-ion (Li-ion) batteries, a graphene oxide (GO)-grafted hyper-branched polyether (GO-g-HBPE) macro-porous membrane without any polymer binder was designed and prepared using polystyrene (PS) nanoparticles as hard templates. GO (inorganic part) provides the membrane-formation ability for GO-g-HBPE separator and HBPE (polymer part) imparts excellent affinity with the liquid electrolyte (158% for liquid electrolyte uptake). The GO-g-HBPE membrane, serving as a separator for the batteries, exhibited robust thermal dimensional stability with no dimensional changes at 200 °C for 0.5 h. Moreover, it shows a better electrochemical performance (cycle performance and rate capability) than a commercialized PP separator, implying a promising potential for application in high-safety and high-power Li-ion batteries.