Laser-etched flexible microsupercapacitors based on nanocellulose and conductive metal–organic frameworks

Freestanding, conductive, and flexible nanopapers composed of cellulose nanofibers (CNF) and conductive metal–organic frameworks (c-MOF) was prepared. A simple laser etching technique was employed to process the CNF@c-MOF nanopapers into interdigitated electrodes, enabling the assembly of ultrathin microsupercapacitors (MSCs). The MSCs exhibit a high volumetric capacitance of 36.7 F cm −3 , rapid charge–discharge rates, excellent flexibility, and outstanding cycle stability. • Freestanding, flexible cellulose@conductive MOF nanopaper electrodes were prepared. • Laser etching enabled the design of nanopaper-based microsupercapacitors (MSCs). • MSCs are ultrathin (45 µm) and exhibit excellent flexibility. • Ultrathin MSCs achieved a high volumetric capacitance of up to 36.7 F cm −3 . Flexible supercapacitors hold promise for applications in wearable electronic devices. However, the challenges of achieving flexibility, miniaturization, and high volumetric capacitance persist. In this work, precise laser etching of cellulose composites, prepared via in-situ growth of conductive metal–organic frameworks (c-MOFs) on cellulose nanofibers (CNF), was employed to fabricate flexible, binder-free, and integrated microsupercapacitors (MSCs). The interfacial synthesis of Ni 3 (HITP) 2 (a type of c-MOF) on the surface of CNF yields a continuous and uniform conductive shell, enabling efficient electron transfer along the CNF@c-MOF nanofibers. The interwoven structure of the nanofibers creates a hierarchical porous network with enhanced surface area featuring interconnected porous channels, enabling rapid ion transport. The laser etching technique facilitates one-step production of integrated MSCs with a precisely interdigitated configurations and micron-scale accuracy. The fabricated MSCs demonstrate excellent mechanical stability, with a tensile strength of up to 81.9 MPa, and remarkable flexibility, maintaining consistent electrochemical performance under bending stress. The flexible device, with a thickness of only 45 µm, achieves a high volumetric specific capacitance of 36.7 F cm −3 at a current density of 0.17 mA cm −2 and a specific energy density of 2,497.5 µWh cm −3 at a power density of 53.3 mW cm −3 . This study provides a new strategy for designing flexible, binder-free, integrated MSCs with high capacitances and long cyclic stability, demonstrating significant potential for applications in wearable electronics.