Various types of A.C conduction mechanism models for solid polymer electrolytes (SPE): A review

This review explores the various AC conduction mechanism models for solid polymer electrolytes (SPEs), which are critical for advancing electrochemical devices like batteries and fuel cells. SPEs are considered promising alternatives to conventional liquid electrolytes due to their enhanced safety and flexibility. However, their relatively low ionic conductivity, especially at room temperature, remains a challenge. To address this, the paper discusses four key AC conduction models: Correlated Barrier Hopping (CBH), Quantum Mechanical Tunnelling (QMT), Small Polaron Hopping (SPH), and Overlapping Large Polaron Tunnelling (OLPT). Each model provides insights into different charge transport processes, such as thermally activated ion hopping and quantum tunnelling. The study highlights how factors like temperature and frequency influence conduction mechanisms, with each model describing distinct behaviours for charge carriers. For example, CBH and SPH rely on hopping mechanisms, while QMT and OLPT focus on tunnelling. By understanding these mechanisms, researchers can optimize the SPE system to enhance ionic conductivity. The paper concludes that selecting the appropriate model depends on the specific SPE material and environmental conditions, emphasizing the need for continued research to further refine these models and explore new SPE formulations for improved performance in practical applications.