Abandoned wood wastes from industries pose significant environmental challenges recently. Utilization of these industrial wood wastes (IWWs) in the production of nanocellulose, particularly cellulose nanofibrils (CNFs) can offer a promising solution to overcome this issue. CNFs can be derived from various plant materials, including IWWs, which are eco-friendly, making them an ideal candidate for sustainable material development, especially for energy storage applications. This study investigates the production of CNF membranes from IWW, focusing on their unique physical and tensile properties. CNF membranes with varying thicknesses (25, 30, 35, and 40 µm) were prepared using a solution casting method. Morphology, tensile properties, porosity, and electrolyte uptake ability of the membranes were determined. Notably, the CNF membrane with a thickness of 25 µm (CNF25) demonstrated promising tensile properties, including a tensile strength of 11.86 MPa, 4.59% of elongation at break and a tensile modulus of 410.13 MPa. The prepared CNF25 membrane exhibited high porosity and electrolyte uptake of 52.14% and 219.52%, respectively. These findings are comparable to the commercially available cellulose membrane separator, CS30 (NKK-TF4030 with a thickness of 30 µm), highlighting the potential of CNF membranes derived from IWW as versatile and sustainable separators for energy storage devices.