Revealing the Roles of Electrolyte Concentration on Transition Metal Dissolution and Reaction Pathway of Anion Adsorption Pseudocapacitance

Conventional lithium‐ion battery cathodes predominantly rely on reversible lithium intercalation in bulk, which inevitably induces phase transitions, transition metal migration, and voltage decay. Electrolytic anion adsorption pseudocapacitance provides a chance for bypassing these issues via a surface‐dominated reaction, especially in nanosized lithium‐free transition metal oxides. Nevertheless, an additional issue arises pertaining to the transition metal dissolution that highly limits the cycle life of such anion adsorption pseudocapacitance. Here, we investigated how the electrolyte concentration affects the long‐term cycling stability as well as the reaction mechanism in a pseudocapacitance‐active oxide, Mn 3 O 4 . We show that the concentration of LiPF 6 electrolyte in EC:DMC (1:1 vol%) system directly governs the extent of anion participation in interfacial reactions, thereby dictating the reaction pathway and cycling stability of Mn 3 O 4 . Within an optimal concentration window, electrolyte anions establish stable and reversible surface interactions with Mn 3 O 4 , inducing pronounced pseudocapacitive behavior while effectively suppressing lithium insertion‐induced phase transitions and manganese dissolution. In contrast, low electrolyte concentration fails to stabilize interfacial reactions, whereas excessive concentration disrupts the balance of surface‐controlled processes, leading to deviation of the reaction pathway and rapid performance degradation. These findings demonstrate that electrolyte concentration is not merely a kinetic parameter but a decisive factor in defining electrolytic anion pseudocapacitance reaction mechanisms, offering a new strategy for overcoming the intrinsic limitations of conventional intercalation chemistry through electrolyte‐interface co‐design.