Multilayer Composite Electrodes for Simultaneously Improved Mechanical and Electrochemical Performance

Structural batteries offer a transformative approach to integrate energy storage directly into the frameworks of electric vehicles and aircrafts, enabling multifunctional construction. This study presents a nacre-inspired multilayer composite electrode fabricated via the cold sintering process (CSP), achieving a balance of enhanced electrochemical performance and mechanical robustness. The composite electrode combines active electrode materials with a ductile conducting polymer-carbon-mixture phase in a layered architecture. The resulting electrodes exhibit a material toughness of 0.635 MJ m^-3, approximately 9 times greater than conventional single-layer electrodes, alongside maintained ultimate strength. Full-field strain mapping using digital image correlation (DIC) reveals the underlying strengthening mechanisms. The influence of soft-layer thickness variations on both mechanical and electrochemical properties was also systematically analyzed to achieve optimal performance. Notably, the multilayer composite electrode delivered a reversible specific capacity of 177 mAh g^-1 and an areal capacity of 22 mAh cm^-2 at a high mass loading of 136 mg cm^-2, significantly outperforming commercial cathodes (e.g., 3 to 4.5 mAh/cm²).