58 January/February 2026 | E-Mobility Engineering Binders in EV batteries do far more than simply act as a glue holding the electrodes together, as revealed by Peter Donaldson Bonding power Efforts to improve crucial metrics such as energy density and cycle life in lithium-ion batteries often focus on anode and cathode chemistry at cell level or on pack architecture at the system level – for very good reason because r&d along these avenues continues to yield good results. As in any complex system, however, there are areas that don’t receive as much attention as they deserve, and the ‘glues’ that hold the active particles together in both electrodes, also known as binders, fall into that category. Far more than a glue, a binder is a polymer system that impacts the manufacturing process, the performance and longevity of the cell and, by extension, the battery system and even the vehicle as a whole. The glue function, however, is central because without it, the electrodes would literally crumble. Providing mechanical cohesion and adhesion – holding electrode active materials together – through many thousands of charge–discharge cycles in which significant and sometimes enormous volume changes take place is a demanding task. Throughout the cell’s life, the binder additionally has the job of maintaining stable electrical and ionic connections within the electrode, ensuring that all particles of the active material remain in contact with each other and with the current collector. This prevents the formation of isolated ‘islands’ of material that cannot take part in the chemical reaction and reduce the cell’s capacity as a consequence. Preventing cracking and other forms of electrode degradation is a closely related function crucial to achieving the battery’s desired cycle life. The binder can also affect the electrode’s thermal stability and its resistance to short-circuiting. Furthermore, the binder can influence the formation and long-term robustness of the solid–electrolyte interphase (SEI) layer, which is a key factor in cycle life and coulombic efficiency, making engineering of the binder with the SEI in mind a key consideration. Binder performance in all aspects can also be highly dependent on the particle morphology and surface chemistry of the active materials. PVDF dominance challenged Today, the dominant binder materials that are familiar to the industry, and which have supported the improvement of battery chemistries for years, are based on polyvinylidene fluoride (PVDF). A close look at this semicrystalline thermoplastic fluoropolymer reveals its pros and cons and sheds light on the key attributes desirable in the current generation of binders, as well as the gaps to be filled by the next. Lithium batteries represent a demanding application for polymeric All lithium-ion batteries depend on binders to hold their electrodes together, keeping their active material particles in contact with each other and their respective current collectors (Image: Andra Febrian)
RkJQdWJsaXNoZXIy MjI2Mzk4