Mechanical- Electrostatic Sequential Interaction Modeling in Structural Supercapacitors

Abstract 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 quasi-static finite element sequential interaction modeling framework to investigate electro-mechanical phenomena at the microscale in SSCs. By explicitly excluding the Electric Double Layer (EDL) physics, the model focuses on how compressive stress influences the bulk electrostatic field distribution within a representative fiber-electrolyte architecture. This approach serves as a geometric benchmark to isolate first-order effects. Results reveal a deformation-induced evolution of electric field distribution, particularly near fiber-separator line 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 the mechanism termed Geometric Electrostatic Screening. Parametric studies demonstrate that fiber volume fraction and spatial arrangement play a significant role in the 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.