Polymer-based electrolytes with high mechanical strength for multifunctional structural batteries

Structural batteries are an emerging class of multifunctional electrochemical energy storage devices that combine mechanical load-bearing capabilities with energy storage. These batteries aim to address the weight and volume efficiency challenges faced by conventional batteries, particularly in electric vehicles, thereby extending driving range. As a crucial component of structural batteries, the electrolyte must not only facilitate ion transport but also provide mechanical integrity under flexural loads or impacts. However, developing a structurally strong electrolyte is a significant challenge, as high mechanical strength often leads to reduced ionic conductivity. Therefore, the full potential of structural batteries can only be realized once suitable multifunctional structural electrolytes are developed. This review examines the state-of-the-art in structural electrolytes, focusing on thermoplastic and thermoset polymer-based electrolytes for structural batteries. It explores the underlying ion transport mechanisms and mechanical enhancement strategies. The review also discusses how electrolyte composition—such as the choice of polymer matrix, inorganic fillers, solvents, and ionic liquid additives—affects both mechanical and electrochemical properties, as well as the role of interfacial stability. Furthermore, block copolymer electrolytes and molecular ion composite solid electrolytes based on rigid-rod polymers are proposed as promising candidates for structural electrolytes. The article also addresses the challenges and future prospects for these materials, aiming to provide insights into overcoming the limitations of polymer-based electrolytes with high mechanical strength, thus promoting their practical application in structural batteries.