A De Novo Sacrificial-MOF Strategy for Fabricating Cellulose Nanofibers/ZIF-8/PANI Gel Composite Membranes for High-Performance Flexible Supercapacitors

Cellulose nanofibers/metal-organic framework (CNFs/MOF) composites hold promise for energy storage thanks to high porosity, large specific surface area, and inherent flexibility, but their poor conductivity limits applications to environmental remediation and gas adsorption. Herein, flexible CNFs served as substrates for in situ growth of continuous ZIF-8 nanolayers via interfacial synthesis, with a CNFs/ZIF-8 gel network built to enhance structural integrity and flexibility. A novel strategy first regulated the layered pore structure: ZIF-8 in CNFs/ZIF-8 nanofibers was etched in the acidic environment of aniline in situ polymerization, constructing a hierarchical porous architecture with interconnected micropores and mesopores. CNFs/ZIF-8/PANI gel composite membranes were then fabricated. As self-supporting electrodes for symmetric supercapacitors, the composites showed excellent electrochemical performance: 1350 F/g at 1 A/g for the electrode, and the flexible solid-state device delivered a specific capacitance of 220.9 F/g at 0.5 A/g, along with a capacitance retention rate of 74% after 5000 charge-discharge cycles at 10 A/g. The superior performance stems from synergistic hierarchical pore structure regulation via partial MOF sacrificial templating and gel matrix-mediated rapid ion diffusion, offering a feasible approach for high-performance flexible energy storage devices.