Functional binders in lithium batteries: From molecular structure design to practical applications

Lithium batteries (LBs) are pivotal for meeting the escalating global need for high-performance energy storage devices. Despite their critical role in electrode and solid electrolyte fabrication, binders remain under-investigated compared to active materials, creating a significant knowledge-to-application gap. This review summarizes recent developments in binder design, focusing on their structure-property relationships. It starts with elucidating the operation and failure mechanisms of binders, underscoring their crucial roles and ideal properties in practical applications. Building on this foundation, it further elucidates molecular design strategies to impart multifunctionality to binders, including adhesion, mechanical properties, ionic/electronic conductivity, self-healing capabilities, interfacial stabilization and other functional attributes. Also, industrial application challenges and scale-up considerations for advanced binders are critically evaluated across three key aspects: ultra-thick electrodes, ultra-thin electrolytes and sustainability requirements, filling the gap between molecular design and practical applications of binders. This review outlines pathways for future development of functional binders, with the aim of providing new insights into the design of binders for next-generation high-energy-density LBs.