Electrochemical\nRedox Potential of Li<sub>2</sub>SO<sub>4</sub> Investigated Using\nthe Appropriate All-Solid-State Cell Configuration

Understanding the electrochemical\nwindow of battery materials\nis\nessential for designing all-solid-state batteries with stable cycling\ncharacteristics. Solid electrolytes (SEs) with high ionic conductivity\nhave been extensively studied by using both electrochemical experiments\nand computational methods. However, lithium-containing materials with\nlow ionic conductivity have not received the same level of attention,\ndespite their widespread use in all-solid-state batteries. In this\nstudy, we focused on Li<sub>2</sub>SO<sub>4</sub>, a material with\nlow ionic conductivity used in all-solid-state batteries, and measured\nits redox potential using all-solid-state cells. Accurate determination\nof the potential window requires the use of a SE with an appropriate\noxidation and reduction tolerance. For our experiments, we used an\noxide SE to target Li<sub>2</sub>SO<sub>4</sub>, and the redox potential\nof Li<sub>2</sub>SO<sub>4</sub> was found to be consistent with the\nreported standard electrode potential. Notably, Li<sub>2</sub>SO<sub>4</sub> exhibit high oxidation resistance. These findings highlight\nthe importance of studying the electrochemical window in the design\nof all-solid-state batteries.