N-Doped MXene Supported on a Nanocomposite Membrane of Bacterial Cellulose and Polyaniline Prepared by Freeze Polymerization as Supercapacitor

In this work, we successfully fabricated high-performance bacterial cellulose-polyaniline/nitrogen-doped MXene (BC-PANI/N-MXene) composite membrane electrodes. Utilizing a controlled freeze polymerization technique, polyaniline (PANI) was controllably and orderly grown within and on the surface of the bacterial cellulose (BC) nanofiber network, forming a unique three-dimensional (3D) interconnected, flower-like nanostructured conductive scaffold. Vacuum-assisted self-assembly then enabled uniform deposition and firm anchoring of highly nitrogen-doped MXene nanosheets onto the BC-PANI scaffold, yielding an integrated BC-PANI/N-MXene composite membrane. This approach effectively circumvented uncontrolled agglomeration or structural damage typically encountered during direct mixing of MXene and PANI, achieving stable and ordered integration of the two high-activity materials. The morphological structure and electrochemical performance of the as-prepared BC-PANI/N-MXene composite membranes were comprehensively characterized and evaluated. As the mass fraction of N-MXene in the BC-PANI/N-MXene composite electrode increases, the specific capacitance first increases and then decreases. The optimized composite membrane, BC-PANI/N-MXene (3%), exhibited an excellent specific capacitance of 5525 mF/cm2 (635 F/g) at a current density of 5 mA/cm2. Even at a higher current density of 20 mA/cm2, it retained 61% of its initial capacitance, indicating its promising potential application in energy storage. This study provides a strategy for enhancing the electrochemical efficiency of PANI-based energy storage materials.