Unveiling performance limitations in all-solid-state Na-O2 batteries through EIS-DRT analysis

Summary

All-solid-state Na-O₂ batteries offer high energy density and safety but suffer from poor rate capability and short cyclability. In this study, we utilize electrochemical impedance spectroscopy (EIS) coupled with distribution of relaxation times (DRT) analysis to identify the key performance-limiting factors. Our results reveal that insufficient contact at the Na metal anode/solid-state electrolyte (SE) interface is the primary bottleneck. By implementing a rub-coating technique to improve Na/SE interfacial contact, we achieve significant performance enhancements. Additionally, the use of Ag/carbon nanotube composites as the cathode material further optimizes the system, enabling extended cycle life. The optimized battery delivers a high capacity of 4.2 mAh cm⁻², a current density of 0.84 mA cm⁻², and stable cycling over 100 cycles at 2.8 mAh cm⁻² with 90% energy efficiency. These findings not only advance the understanding of all-solid-state Na-O₂ batteries but also provide a strategic framework for optimizing solid-state electrochemical systems.