Flexible Ti-Doped FeOOH Quantum Dots/Graphene/Bacterial Cellulose Anode for High-Energy Asymmetric Supercapacitors

Ti-doped FeOOH quantum dots (QD) decorated on graphene (GN) sheets are designed and fabricated by a facile and scalable synthesis route. Importantly, the Ti-doped FeOOH QD/GN are successfully dispersed within bacterial cellulose (BC) substrate as bending anode with large loading mass for flexible supercapacitor. By virtue of its favorable architecture, this composite electrode exhibits a remarkable areal capacitance of 3322 mF cm⁻² at 2 mA cm⁻², outstanding cycle performance (94.7% capacitance retention after 6000 cycles), and excellent mechanical strength (68.7 MPa). To push the energy density of flexible supercapacitors, the optimized asymmetric supercapacitor using Mn₃O₄/GN/BC as positive electrode and Ti-doped FeOOH QD/GN/BC as negative electrode can be cycled reversibly in the operating voltage range of 0–1.8 V and displays ultrahigh areal energy density of 0.541 mWh cm⁻², ultrahigh volumetric energy density of 9.02 mWh cm⁻³, reasonable cycling performance (9.4% decay in specific capacitance after 5000 cycles), and good capacitive retention at bending state.