Key Parameters Controlling Energy Performance in Manganese Cathodes

Ideal battery performance can be characterized by high energy density that remains stable over many charge-discharge cycles. While energy degradation is typically unavoidable as batteries age, we observed a unique phenomenon in cells using low-cost, high-manganese (Mn) disordered rocksalt-type cathodes: energy gains, accompanied by voltage stabilization during cycling—an effect linked to phase transformations. To understand and enhance this unconventional performance, we introduce a new methodology that identifies key Mn cathode parameters using newly proposed critical energy metrics, such as maximum energy density, total energy throughput, and energy degradation. Through a range of analytical techniques, we reveal how enhanced kinetics and facilitated phase transformations influence performance. Our analysis investigates cathode active material properties, including conductivity, particle morphology, length-dependent structure, chemical state distributions, and cathode reactivity under varying temperature, current, and voltage window. By mapping the interplay of these factors, our study provides a mechanistic understanding of the newly discovered phenomena that drive maximized energy density, along with strategies for materials engineering and electrochemical protocols to enhance battery efficiency and durability.