Cellulose composite membranes induced by multiple hydrogen bonds as lightweight current collectors for high-performance batteries

While reducing current collector thickness improves battery energy density, further thinning commercial collectors compromises mechanical integrity and increases manufacturing costs. Here, we overcome these limitations by developing a lightweight (1.23 mg·cm-2), cost-effective cellulose composite membrane (CCM) via solution casting from an alkali/urea solvent. This CCM, composed of modified carbon nanotubes and natural cellulose, exhibits high electrochemical stability and flexibility, serving as both cathode and anode current collectors. CCM-containing batteries show 99.40% capacity retention after 500 cycles at 3 C. Replacing commercial collectors with CCM reduced their battery proportion to 6.23% and increased gravimetric energy density by 41.32%, while also reducing current collector costs by 50.36%. The CCM, produced through regenerated cellulose technology, is suitable for industrial-scale production, offering a strategy to enhance battery energy density with lightweight, low-cost current collectors. Thinning commercial current collectors for better battery energy density compromises mechanical integrity and increases costs. Here, a lightweight, cost-effective cellulose composite membrane was developed with high stability and flexibility, improving energy density by 41.32% and reducing costs by 50.36%.