Electrostatic–Mechanical Interaction Modeling in Structural Supercapacitors

Structural supercapacitors (SSCs) are multifunctional carbon fiber-reinforced composites that combine mechanical load-bearing capacity with energy storage functionality. However, the interplay between mechanical deformation and electrostatic charge storage remains insufficiently understood. This study presents a finite element modeling framework to investigate electro-mechanical interactions at the microscale in SSCs. The model captures how mechanical stress influences the spatial distribution of the electrostatic field within a representative fiber–electrolyte architecture. Results reveal a deformation-induced evolution of electric field morphology, particularly near fiber–separator interfaces, which in turn affects the local charge storage behavior. Although the overall capacitance is largely retained under compressive deformation, minor variations arise due to small changes in fiber proximity and field screening. Parametric studies demonstrate that fiber volume fraction and spatial arrangement play a significant role in specific capacitance, with optimized geometries enabling up to 20% improvement in charge storage. Furthermore, extending electrode length in the fiber-aligned direction enhances capacitance more effectively than increasing thickness due to electrostatic screening effects. This framework provides insights into the interplay between structural geometry and electrostatic performance, serving as a basis for the design of high-performance multifunctional composites.