In-situ synthesized magnesium phosphate/bacterial nanocellulose composite as a sustainable material for high-performance symmetric supercapacitors

Electrochemical supercapacitors (ECSCs) are crucial for the energy storage sector, particularly in managing intermittent renewable energy sources. This work innovatively develops an environmentally friendly composite material of Mg₃(PO₄)₂ (magnesium phosphate, MP) within bacterial cellulose (BC) using the Gluconacetobacter xylinum ATCC 10245 bacterial strain. Various characterization techniques, including XRD, FT-IR, TGA, and TEM, were used to evaluate the structural properties of the synthesized MP, BC, and magnesium phosphate/bacterial nanocellulose (BC-MP) composite. The electrochemical properties of the material were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in 0.5 M H₂SO₄. The BC-MP electrode was found to have a high specific capacitance of ≈2000 F/g at 2 A/g. Additionally, a symmetric supercapacitor device based on BC/MP electrodes showed outstanding energy (≈52 Wh/kg) and power densities (≈890 W/kg) at 1 A/g, as well as an excellent cycle life stability (100 % after 5000 cycles and ≈97 % after 7000 cycles) at 10 A/g. The remarkable performance of the BC/MP composite can be attributed to the high surface area of the BC and MP and their synergistic effect in increasing hydrophilicity and conductivity. This study highlights the potential of BC/MP composite as a promising electrode material for high-capacity electrochemical supercapacitors.