Sustainable Solid-State Sodium-Ion Batteries Featuring Ferroelectric Electrolytes

Solid-state batteries offer significant advantages but present several challenges. Given the complexity of these systems, it is good practice to begin the study with simpler models and progressively advance to more complex configurations, all while maintaining an understanding of the physical principles governing solid-state battery operation. The results presented in this work pertain to cells without traditional electrodes, thus providing a foundation for guiding the development of fully functional solid-state cells. The open circuit voltage (OCV) of the Cu/Na_2.99Ba_0.005ClO composite in a cellulose/Zn pouch cell achieves 1.10 V, reflecting the difference in the chemical potentials of the current collectors (CCs), Zn and Cu, serving as electrodes. After 120 days, while set to discharge, conversely to what was expected, a higher potential difference of 1.13 V was attained (capacity of 5.9 mAh·g^-1_electrolyte). By incorporating a layer of carbon felt, the OCV became 0.85 V; however, after 95 days, the potential difference increased to 1.20 V. Ab initio simulations were additionally performed on a Cu/Na₃ClO/Zn heterojunction showing the formation of dipoles and the Na deposition on Zn which is demonstrated experimentally. The sodium plating on the negative CC (Zn) takes place as the cell is set to discharge at room temperature but is not observed at 40 °C.