Electrochemical Redox Potential of Li₂SO₄ Investigated Using the Appropriate All-Solid-State Cell Configuration

Understanding the electrochemical window of battery materials is essential for designing all-solid-state batteries with stable cycling characteristics. Solid electrolytes (SEs) with high ionic conductivity have been extensively studied by using both electrochemical experiments and computational methods. However, lithium-containing materials with low ionic conductivity have not received the same level of attention, despite their widespread use in all-solid-state batteries. In this study, we focused on Li2SO4, a material with low ionic conductivity used in all-solid-state batteries, and measured its redox potential using all-solid-state cells. Accurate determination of the potential window requires the use of a SE with an appropriate oxidation and reduction tolerance. For our experiments, we used an oxide SE to target Li2SO4, and the redox potential of Li2SO4 was found to be consistent with the reported standard electrode potential. Notably, Li2SO4 exhibit high oxidation resistance. These findings highlight the importance of studying the electrochemical window in the design of all-solid-state batteries.