In recent years, there has been growing interest in rechargeable batteries utilizing protons or hydronium ions as charge carriers, driven by the rapid ionic conduction enabled by the proton-specific Grötthuss mechanism. However, the use of acidic aqueous electrolytes introduces side reactions, such as irreversible hydrogen evolution and the dissolution of active materials into the electrolyte, which are influenced by the reaction potential of the active materials. These challenges complicate the identification and development of active materials. While some combinations of Brønsted acids and bases may potentially compromise the advantages of the Grötthuss mechanism, this study successfully demonstrated the electrochemical protonation of TiNb