Why Will Polymers Win the Race for Solid-State Batteries?

Solid-state batteries (SSBs) promise to revolutionize energy storage by offering enhanced safety, higher energy density, and improved cycle lifespan over conventional lithium-ion batteries. Among the various solid electrolytes, polymers stand out for their unique combination of processability, mechanical compliance, and chemical versatility. This review explores why polymers are poised to lead the race toward commercial SSBs. Their intrinsic advantages-such as superior interfacial contact with electrodes, tunable ionic conductivity, and compatibility with scalable manufacturing methods-as well as the key technical challenges they face, including limited thermal stability, narrow electrochemical windows, and interfacial degradation, are examined. This study highlights emerging solutions from recent research, including polymer molecular design, polymer-ceramic composites, and in situ polymerization strategies. In contrast to oxide and sulfide systems, which face significant barriers in cost, manufacturability, and integration, polymer-based electrolytes offer a realistic and economically viable path to large-scale deployment. With continuing advances in materials design and industrial processing, polymers are not only competitive-they are leading the transition to next-generation solid-state batteries.