Cr3+ and Co2+ doping modification on electrochemical performance of LiNi0.5Mn1.5O4 for Li-ion battery.

It is exactly the high potential and high energy density that makes the LiNi_0.5Mn_1.5O₄ (LNMO) an attractive material for lithium-ion battery cathode. However, the poor cycle performance of LNMO caused by John-Teller effect during the Li⁺ ion insertion/desertion process has been a hindrance for its practical application. Herein, the influence of M-doped (M= Cr and Co) on structure, morphology, and electrochemical performances of LiM_yNi_0.5-yNi_1.5O₄ spinel materials are deeply investigated to improve the structural stability and cycling ability. The results reveal that the cell volume and of LiNi_0.5Mn_1.5O₄ are decreased with Cr³⁺ and Co²⁺ doping; the stability of structure and electrical conductivity is correspondingly improved. The state density diagrams demonstrate that Cr³⁺ and Co²⁺ cationic doping have clearly enhanced the interaction between oxygen and transition metals (Ni and Mn) and improved the transition capacity of Li⁺. The initial discharge specific capacities of LiCo_0.12Ni_0.38Mn_1.5O₄ and LiCr_0.12Ni_0.38Mn_1.5O₄ samples are 113.3 mAh·g⁻¹ and 107.7 mAh·g⁻¹ respectively at a high rate of 0.5 C, which are higher than that of pure LiNi_0.5Mn_1.5O₄. Additionally, the capacity retention rates of 87.2% and 63.97% come through respectively after 50 cycles while only 59.8% for pure LNMO. The rate of LiCo_0.12Ni_0.38Mn_1.5O₄ exhibits a better stability than LiCr_0.12Ni_0.38Mn_1.5O₄. [ABSTRACT FROM AUTHOR]