Cellulose-based battery diaphragm with flame retardant property and preparation method thereof

The invention discloses a cellulose-based battery diaphragm with flame retardant property and a preparation method thereof. The preparation method comprises the following steps: adding cellulose and a polyvinyl alcohol solution into a sodium hydroxide/urea/aqueous solution, stirring and dissolving, then carrying out ultrasonic dispersion and centrifugation, casting the obtained membrane casting solution on a substrate, obtaining a gelatinous sheet through a tape casting method, then sequentially immersing the gelatinous sheet into a coagulating bath for curing and regeneration and washing in deionized water, and drying to obtain the cellulose/urea composite membrane. And then loading nano aluminum oxide on the surface of the wet membrane by adopting a suction filtration mode, washing, and carrying out vacuum freeze drying to obtain the flame-retardant cellulose-based composite membrane. The battery diaphragm prepared by the invention has excellent flame retardant property, good mechanical property, thermal st