Algae-Derived\nNacre-like Dielectric Bionanocomposite\nwith High Loading Hexagonal Boron Nitride for Green Electronics

The surging demand for electronics\nis causing detrimental environmental\nconsequences through massive electronic waste production. Urgently\nshifting toward renewable and eco-friendly materials is crucial for\nfostering a green circular economy. Herein, we develop a multifunctional\nbionanocomposite using an algae-derived carbohydrate biopolymer (alginate)\nand boron nitride nanosheet (BNNS) that can be readily employed as\na multifunctional dielectric material. The adopted rational design\nprinciple includes spatial locking of superhigh loading of BNNS via\nhydrogel casting followed by layer-by-layer assembly via solvent evaporation,\nsuccessive cross-link engineering, and hot pressing. We harness the\nhierarchical assembly of BNNS and the molecular interaction of alginates\nwith BNNS to achieve synergistic material properties with excellent\nmechanical robustness (tensile strength ∼135 MPa, Young’s\nmodulus ∼18 GPa), flexibility, thermal conductivity (∼4.5\nW m<sup>–1</sup> K<sup>–1</sup>), flame retardance,\nand dielectric properties (dielectric constant ∼7, dielectric\nstrength ∼400 V/μm, and maximum energy density ∼4.33\nJ/cm<sup>3</sup>) that outperform traditional synthetic polymer dielectrics.\nFinally, we leverage the synergistic material properties of our engineered\nbionanocomposite to showcase its potential in green electronic applications,\nfor example, supercapacitors and flexible interconnects. The supercapacitor\ndevice consisting of aerosol jet-printed single-walled carbon nanotube\nelectrodes on our engineered bionanocomposite demonstrated a volumetric\ncapacitance of ∼7 F/cm<sup>3</sup> and robust rate capability,\nwhile the printed silver interconnects maintained conductivity in\nvarious deformed states (i.e., bending or flexing).