M 3 + ‐Modified LiMn2 O 4 Spinel Intercalation Cathodes: I. Admetal Effects on Morphology and Electrochemical Performance

Low levels of trivalent cations were utilized to stabilize spinel cathode materials against capacity decline during electrochemical cycling. Of the several single‐phase products obtained, only those with and prevented capacity fade, and only , exhibited acceptable initial reversible capacity. The external particle morphology was unchanged by the preparation or the admetal, and the internal structures were all converted to cong tou (onion) configurations during product synthesis. Grain size played a surprising role in cathode performance: <25 μm material had at least 10% lower capacity than larger or as‐prepared Cr‐doped .