Structural Positive Electrodes Engineered for Multifunctionality

Abstract

Abstract Multifunctional structural batteries are of high and emerging interest in a wide variety of high‐strength and lightweight applications. Structural batteries typically use pristine carbon fiber as the negative electrode, functionalized carbon fiber as the positive electrode, and a mechanically robust lithium‐ion transporting electrolyte. However, electrochemical cycling of carbon fibre‐based positive electrodes is still limited to tests in liquid electrolytes, which does not allow for to introduction of multifunctionality in real terms. To overcome these limitations, structural batteries with a structural battery electrolyte (SBE) are developed. This approach offers massless energy storage. The electrodes are manufactured using economically friendly, abundant, cheap, and non‐toxic iron‐based materials like olivine LiFePO4. Reduced graphene oxide, renowned for its high surface area and electrical conductivity, is incorporated to enhance the ion transport mechanism. Furthermore, a vacuum‐infused solid‐liquid electrolyte is cured to bolster the mechanical strength of the carbon fibers and provide a medium for lithium‐ion migration. Electrophoretic deposition is selected as a green process to manufacture the structural positive electrodes with homogeneous mass loading. A specific capacity of 112 mAh g−1 can be reached at C/20, allowing the smooth transport of Li‐ion in the presence of SBE. The modulus of positive electrodes exceeded 80 GPa. Structural battery‐positive half‐cells are demonstrated across various mass‐loadings, enabling them to be tailored for a diverse array of applications in consumer technology, electric vehicles, and aerospace sectors.

Keywords

• carbon fibre
• electrophoretic deposition
• lithium‐ion batteries
• lithium‐iron phosphate
• reduced graphene oxide
• structural batteries