Synergistic Anionic and Cationic Codoping Enables High-Performance LiNi_0.5Mn_1.5O₄ Cathodes

LiNi_0.5Mn_1.5O₄ has attracted significant attention as a generation cobalt-free cathode material with high potential (4.7 V vs Li⁺/Li) and high-energy density (650 Wh kg^-1) in recent years. However, phenomena such as manganese dissolution have greatly hindered the large-scale commercial application of the material. LiNi_0.47Cu_0.01Al_0.01Mn_1.47Ti_0.01V_0.01O_4-xF_x (CATVF) was successfully synthesized via an anionic and cationic codoping strategy. The XPS spectrum indicates that appropriate doping of F^- facilitates the formation of stronger M-F bonds (M: Mn, Ni, Cu, Al, Ti, V) and promotes the reduction of Mn⁴⁺ to Mn³⁺, thereby increasing the degree of ionic disorder. Furthermore, the results obtained from SEM indicate that F^- not only facilitates the growth of the (110) planes but also effectively reduces the proportion of the (111) planes. Overall, this study has significantly increased the lithium-ion diffusion coefficient of the material by 4 orders of magnitude, and has achieved remarkable results in inhibiting manganese dissolution. Specifically, CATV-0.01F delivered a discharge specific capacity of 101.9 mAh g^-1 at 30 C, and the capacity retention rate is close to 90% after 300 cycles at 1 C. This anionic and cationic codoping strategy provides an idea for high-performance spinel cathode materials.