Self-healing polymer binders: next-generation battery applications

Abstract

Polymer binders are crucial in electrodes, as they both hold together active material particles and conductive additives and firmly bond the composite to the current collector. Thus, they maintain the mechanical integrity of battery systems and stabilize electron pathways during repeated cycling. However, mechanical stresses such as bending, stretching, and volumetric changes can generate internal fractures that disrupt conductive pathways, detach active particles, and compromise electrode–collector interfaces, ultimately degrading electrochemical performance. Although conventional binders provide adequate adhesion and processability, they are inherently passive and cannot respond to such structural damage. Once cracks form or particle contact is lost, they cannot re-establish connectivity, causing irreversible capacity loss. In contrast, self-healing polymer binders (SHPBs), a new class of smart materials, can autonomously repair the mechanical and structural damage incurred during battery operation. Their unique ability to re-establish chemical or physical bonds within the polymer matrix enables them to effectively mend microcracks, preserving electrode cohesion and conductive networks. These adaptive properties offer several compelling advantages, e.g., improved mechanical resilience and extended cycle life. They also mitigate internal short circuits and potential thermal runaway, enhancing safety. Furthermore, SHPBs support consistent electrochemical performance by maintaining interfacial integrity among active materials, conductive additives, and current collectors. This reduces the need to maintain or replace batteries and/or their components, improving the cost-effectiveness and environmental sustainability of energy storage systems. In contrast to earlier reviews that focused on binders for Si-based lithium-ion batteries, this review explores recent advancements in the molecular design strategies and healing mechanisms of SHPBs, and their impact on cell-level performance across battery platforms such as lithium-ion, lithium–sulfur, and emerging sodium-based batteries. We discuss critical challenges, key future research directions, and opportunities for advancing resilient, safe, high-energy-density batteries with prolonged cycle lives.