Simulation‐Based Design and Performance Analysis of Energy‐Storage Carbon Fiber Composites

ABSTRACT Energy‐Storage Carbon Fiber Composites (ESCFCs) represent a promising route toward multifunctional structural systems capable of simultaneously bearing mechanical loads and storing electrical energy. In this work, a coupled electro‐chemo‐mechanical framework is formulated to capture the interaction between lithium diffusion, interfacial charge transfer, and diffusion‐induced stress evolution within carbon fibers. The governing relationships are established by combining solid‐state diffusion theory, charge conservation principles, Butler–Volmer reaction kinetics, and continuum mechanics. The proposed framework is implemented in COMSOL multiphysics to construct a three‐dimensional finite element model, enabling a parametric investigation of key structural variables. Particular emphasis is placed on fiber diameter, fiber spacing, separator thickness, electrolyte properties, and charging rate. Rather than examining isolated effects, the study seeks to identify parameter windows in which mechanical reliability and electrochemical efficiency can be concurrently optimized. The simulations reveal that, for solid electrolytes with relatively high ionic conductivity and modulus, reducing fiber diameter and moderately increasing fiber spacing effectively alleviate stress concentration within the fibers. In contrast, when the electrolyte exhibits limited conductivity and lower stiffness, excessive separator thickness aggravates polarization phenomena, whereas thinner structural configurations help relieve internal stress. Additionally, elevated charging rates intensify concentration gradients and polarization effects, leading to a noticeable decline in charging efficiency.