Structural energy storage composites based on modified carbon fiber electrode with metal-organic frame enhancing layered double hydroxide

Structural energy storage composites present advantages in simultaneously achieving structural strength and electrochemical properties. Adoption of carbon fiber electrodes and resin structural electrolytes in energy storage composite poses challenges in maintaining good mechanical and electrochemical properties at reasonable cost and effort. Here, we report a simple method to fabricate structural supercapacitor using carbon fiber electrodes (modified by Ni-layered double hydroxide (Ni-LDH) and in-situ growth of Co-metal-organic framework (Co-MOF) in a two-step process denoted as Co-MOF/Ni-LDH@CF) and bicontinuous-phase epoxy resin-based structural electrolyte. Co-MOF/Ni-LDH@CF as electrode material exhibits improved specific capacity (42.45 F·g⁻¹) and cycle performance (93.3% capacity retention after 1000 cycles) in a three-electrode system. The bicontinuous-phase epoxy resin-based structural electrolyte exhibits an ionic conductivity of 3.27 × 10⁻⁴ S·cm⁻¹. The fabricated Co-MOF/Ni-LDH@CF/SPE-50 structural supercapacitor has an energy density of 3.21 Wh·kg⁻¹ at a power density of 42.25 W·kg⁻¹, whilst maintaining tensile strength and modulus of 334.6 MPa and 25.2 GPa. These results show practical potential of employing modified commercial carbon fiber electrodes and epoxy resin-based structural electrolytes in structural energy storage applications.