A structural battery with carbon fibre electrodes balancing multifunctional performance

Structural multifunctional materials have the potential to transform current technologies by implementing several functions to one material. In a multifunctional structural battery, mass saving and energy efficiency are created by the synergy between the mechanical and electrochemical properties of the material's constituents. Consequently, structural batteries could e.g. mitigate electric vehicle overweight or enable thinner portable electronics. This requires combining the best composite and battery manufacturing practices. In the present work this is achieved through the infusion of a stack of carbon fibre-based electrodes with a hybrid polymer-liquid electrolyte. The realised full cell structural battery is based on carbon fibre electrodes with a lithium iron phosphate (LiFePO4) coating on the positive side. This battery laminate shows a very good balance between energy density, stiffness and strength of 33.4 Wh/kg, 38 GPa and 234 MPa, respectively. To push these performances further, different improvement strategies are discussed, and the results are compared with previously published target performances. Ultimately, we demonstrate the feasibility of designing and manufacturing all-fibre solid-state structural batteries as a material solution for future lightweight electric commodities.