Enhancing Electrochemical Performance of LiNi 0.5 Mn 1.5 O 4 Cathodes via Synergistic Ti/Zr Co-doping

To address manganese dissolution and structural instability in high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathodes, a synergistic Ti/Zr co-doping strategy was proposed. LiNi 0.5-x Zr x Mn 1.5-y Ti y O 4 (LNZMTO) materials were synthesized via a solid-state reaction method. Structural analysis reveals that Zr 4+ substitution at Ni 2+ sites induce lattice expansion, while Ti incorporation at Mn sites effectively suppresses Mn 3+ formation and Jahn–Teller distortion, thereby enhancing structural stability. The optimized LNZMTO cathode (x = 0.05, y = 0.1) delivers a high initial discharge capacity of 127.8 mAh g −1 at 1 C, excellent cycling stability with 94.7% capacity retention after 100 cycles, and a reduced charge-transfer resistance of 134.4 Ω. Density functional theory calculations show that Ti/Zr co-doping narrows the bandgap to 0.441 eV, indicating improved electronic conductivity. Projected density of states analysis further reveals enhanced transition-metal–oxygen orbital hybridization near the Fermi level, facilitating electron transport and contributing to the improved electrochemical performance, thus providing an efficient design strategy for next-generation high-voltage LNMO cathodes.