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 LiNi0.5Mn1.5O4 (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 LiMyNi0.5-yNi1.5O4 spinel materials are deeply investigated to improve the structural stability and cycling ability. The results reveal that the cell volume and of LiNi0.5Mn1.5O4 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 LiCo0.12Ni0.38Mn1.5O4 and LiCr0.12Ni0.38Mn1.5O4 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 LiNi0.5Mn1.5O4. 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 LiCo0.12Ni0.38Mn1.5O4 exhibits a better stability than LiCr0.12Ni0.38Mn1.5O4.