Bacterial cellulose–reduced graphene oxide composite scaffold for loading NiCo₂O₄ as cathode material for flexible semi-solid asymmetric supercapacitors

This study synthesized a NiCo₂O₄–bacterial cellulose (BC)–reduced graphene oxide (GO) composite material suitable for flexible supercapacitors using a two-step hydrothermal method. The BC@GO framework consisted of two carbon-based materials: BC retained a 3D interconnected nanofiber network after carbonization, while GO provided a layered structure. This multi-scale porous structure enabled high specific capacitance, mechanical flexibility, and electrochemical stability in the composite. In a three-electrode system, the composite material exhibited a specific capacitance of 1386.4 F g −1 at a current density of 1 A g −1 , with a capacitance retention rate of 73.4 % from 1 to 10 A g −1 . Finally, this study fabricated a high-performance semi-solid flexible asymmetric supercapacitor (FASC) using NiCo₂O₄/BC@GO as the cathode, activated carbon (AC) as the anode, and polyacrylic acid gel as the electrolyte. The fabricated NiCo₂O₄/BC@GO//AC FASC achieved a high energy density of 29.6 Wh kg −1 (19.7 Wh m −2 ) at 7948 W kg −1 (53 kW m −2 ) and 54.8 Wh kg −1 (365 Wh m −2 ) at 836 W kg −1 (5.6 kW m −2 ), with a capacitance retention of 92.2 % after 10,000 cycles. Two fully charged FASCs devices connected in series simultaneously powered 18 LED lights for approximately 50 s. The FASC exhibited exceptional specific capacitance and cycling stability, surpassing other controls in flexible mechanical performance, indicating its potential for flexible semi-solid supercapacitor applications.