context: To assemble the ssZIBs, the polymer electrolyte was synthesized via polymerization of PAM combined with CNFs. Specifically, 1.33 g of CNFs (1.5 wt% water suspension, University of Maine, Orono, ME, USA) were first dispersed in 20 mL of 1 M Zn(CF3SO3)2 solution with extensive high-speed stirring. After that, 50 mg of ammonium persulfate, 3 g of acrylamide (AM) monomers and 50 mg of N,N′-methylenebisacrylamide (BIS) were added to the suspension. After being stirred at 25 °C for 2 h, the mixture was cast onto a glass Petri dish. Then, the formed membrane was put in an oven and heated at 60 °C for half an hour. During this heating treatment, acrylamide was grafted onto the CNF surface through free radical polymerization. Finally, after being cooled to room temperature, a crosslinked CNF–PAM film was obtained. The prepared polymeric film shows high flexibility, and can be applied as a solid-state separator directly.