Assessing the Efficacy of Seawater Batteries Using NASICON Solid Electrolyte

The need to reduce greenhouse gas emissions and guarantee a stable and reliable energy supply has resulted in an increase in the demand for sustainable energy storage solutions over the last decade. Rechargeable batteries with solid-state electrolytes (SSE) have become a focus area due to their potential for increased energy density, longer cycle life, and safety over conventional liquid electrolytic batteries. The superionic sodium conductor (NASICON) Na3Zr2Si2PO12 has gained a lot of attention among ESS because of its exceptional electrochemical properties, which make it a promising candidate for solid-state sodium-ion batteries. NASICON’s open frame structure makes it possible to transport sodium ions efficiently even at room temperature, while its wide electrochemical window enables high-voltage operation and reduces side reactions, resulting in safer battery performance. Furthermore, NASICON is more compatible with sodium ion systems, can help with electrode interface issues, and is simple to process. The characteristics of NASICON make it a highly desirable and vital material for solid-state sodium-ion batteries. The aim of this study is to prepare and characterize ceramic membranes that contain Na3.06Zr2Si2PO12 and Na3.18Zr2Si2PO12, and measure their stability in seawater batteries that serve as solid electrolytes. The surface analysis revealed that the Na3.06Zr2Si2PO12 powder has a specific surface area of 7.17 m2 g−1, which is more than the Na3.18Zr2Si2PO12 powder’s 6.61 m2 g−1. During measurement, the NASICON samples showed ionic conductivities of 8.5 × 10−5 and 6.19 × 10−4 S cm−1. Using platinum/carbon (Pt/C) as a catalyst and seawater as a source of cathodes with sodium ions (Na+), batteries were charged and discharged using different current values (50 and 100 µA) for testing. In an electrochemical cell, a battery with a NASICON membrane and Pt/C catalysts with 0.00033 g platinum content was used to assess reproducibility at a constant current of 2 h. After 100 h of operation, charging and discharging voltage efficiency was 71% (50/100 µA) and 83.5% (100 µA). The electric power level is observed to increase with the number of operating cycles.