Sc-doping induced cation-disorder in LiNi0.5Mn1.5O4 spinel leading to improved electrochemical performance as cathode in lithium ion batteries

Ni/Mn disordered LiNi0.5Mn1.5O4 spinel is the most promising cathode material for lithium ion batteries due to its high energy and power densities. However, the Ni/Mn disorder coupled with high Mn3+ content and concomitant formations of NiO/LiyNi1-yO impurities deteriorate its electrochemical performances. To overcome this issue, Sc-doped disordered spinel LiNi0.5Mn1.44Sc0.06O4 without NiO/LiyNi1-yO impurities has been synthesized. Infrared spectroscopy, magnetic measurements and cyclic voltammetry results reveal the increase in Ni/Mn disordering of LiNi0.5Mn1.44Sc0.06O4 than pristine spinel which decreases the charge transfer resistance and enhances the electrochemical performances. The XPS spectrum of LiNi0.5Mn1.44Sc0.06O4 exhibits Sc2p3/2 (402.3 eV) and Sc2p1/2 (406.5 eV) bands confirming the presence of Sc3+ in the spinel lattice. Sc-doped spinel delivers an initial discharge capacity 131 mAhg−1 with 88% columbic efficiency at 0.1C rate. Under similar condition, the undoped spinel yields only 123 mAhg−1 with 81% columbic efficiency. In addition, cycling stability of the doped spinel has increased dramatically with increase in the C-rate. At 5C, it exhibits a specific capacity of 102 mAhg−1 with 98% capacity retention even after 1000 cycles. Furthermore, it demonstrates excellent rate capability due to enhanced lithium-ion diffusion kinetics. The improved performance of the spinel can be attributed to the stabilization of the cation disordered structure. Thus, the Sc-doped spinel could be a potential cathode material for lithium ion batteries for electric vehicle applications. LiNi0.5Mn1.44Sc0.06O4 spinel prepared by solution combustion shows enhanced cycling stability and rate capability than pristine LiNi0.5Mn1.5O4 as cathode in lithium ion batteries. [Display omitted] •Synthesis of phase pure Sc-doped cation-disordered LiNi0.5Mn1.5O4 by solution combustion method.•Spherical morphology with uniform particle size.•Exhibited a capacity of 102 mA h/g at 5C with capacity retention of 98% after 1000 cycles.•Showed excellent rate capability (12C).•The morphology of the doped spinel remains intact after prolonged cycling.