Dual lanthanides synergistically boost stability and kinetics for spinel LiMn2O4 cathodes.

Mn-site doping in spinel LiMn2O4 (LMO) mitigates Mn3+-induced Jahn-Teller distortion. However, this strategy faces inherent trade-offs. Specifically, low-valent doping weakens oxygen bonding, while high-valent doping increases Mn3+ content. To overcome these limitations, this work proposes dual-lanthanide (La3+/Ce3+) co-doping. Through sol-gel synthesis, LiLa0.1Ce0.1Mn1.8O4 (LLCMO) achieves synergistic performance enhancements. Particularly, La reduces Mn3+ content to 43.13%, suppressing lattice distortion and widening Li+ diffusion pathways via its large ionic radius. Concurrently, Ce (in a mixed Ce3+/Ce4+ state) enhances charge delocalization, lowering electron transfer barriers and boosting conductivity. Critically, La-Ce cooperation mitigates Mn dissolution while stabilizing the spinel framework. Consequently, LLCMO exhibits a 3.2-fold higher Li+ diffusion coefficient than pristine LMO. Furthermore, it delivers 111.2 mAh g-1 at 0.5 C with 90.9% retention after 100 cycles, and remarkably retains 76.0 mAh g-1 after 1000 cycles even at 10 C. Thus, this dual-doping strategy establishes a generalizable design principle for enhancing stability/kinetics in diverse cathodes via a synergistic division-of-labor mechanism.