A composite structural supercapacitor based on Ni–Co-layered double hydroxide–coated carbon cloth electrodes

Composite structural supercapacitors (CSSs) are valuable for their use in structural optimization because they can provide energy storage capacity while bearing mechanical loads, thereby enabling weight and volume reduction. Herein, flexible energy storage devices are embedded into carbon fiber reinforced polymer (CFRP) to form a CSS. In the flexible device, a positive electrode (carbon cloth coated with Ni–Co-layered hydroxide, NiCo-LDH@CC), a negative electrode (activated carbon–coated carbon cloth, AC@CC), and a separator (glass fabric) are bonded together by PVA-KOH gel electrolyte. The CSS (5:5 NiCo-LDH-CSS) provides competitive electrochemical properties (specific capacitance of 610 mF g⁻¹, energy density of 191 mWh kg⁻¹, and power density of 1,508 mW kg⁻¹) and good mechanical properties (flexural strength of 495 MPa and flexural modulus of 125 GPa). The study conducts a systematic analysis of capacity decay during the electrochemical cycling process of 5:5 NiCo-LDH-CSS. In-situ mechano-electrochemical tests are also performed to verify the stable electrochemical behavior under external dynamic and static loads, which is a rarely studied aspect in other reports. This investigation provides assurance for the safety and reliability of future CSS applications. The study findings suggest that the 5:5 NiCo-LDH-CSS possesses good multifunctionality, and can provide a new idea for further development in CSSs.