Design and fabrication of 3D-printed structural supercapacitors with vertically aligned carbon nanotube-enhanced carbon fibers

This study presents a novel hierarchical strategy for the design and manufacture of sustainable complex-shaped Structural Supercapacitors (SSCs) via an additive manufacturing approach using vertically aligned carbon nanotube (VACNT)-functionalized carbon fiber electrodes. The SSC core, based on a poly(vinyl alcohol)-NaCl gel polymer electrolyte, is integrated within a load-bearing polyethylene terephthalate glycol-modified carbon fiber (PETG-CF) reinforcement hull. While the VACNT functionalization effectively boosted the component-level integral specific capacitance to 5.75F/g, the process induced a 70% reduction in fiber’s tensile strength. This limitation was mitigated through topology optimization, which minimized the composite reinforcement hull mass while ensuring the required structural integrity for complex geometries. Additive-manufacturing successfully overcomes the geometric constraints of traditional lamination methods. However, the study identifies a manufacturing bottleneck: device performance (415 µF/g) was limited by process losses, specifically high current collector contact resistance and gel polymer swelling-induced short-circuiting. A demonstrated closed-loop system, including the mechanical recycling of the PETG-CF hull and chemical recovery of the water-soluble PVA, establishes a strong sustainability profile for this novel multifunctional composite system. This work provides a scalable pathway for designing weight-efficient, energy-storing structures in aerospace and automotive applications.