Spherically shaped Ni-substituted LiNixMn2-xO4 (x=0, 0.1, 0.2) spinel cathode materials for lithium ion battery with high first cycle discharge capacity and remarkable cycling performance were synthesized using the solution-combustion technique. XRD confirmed the successful synthesis of the various spinel structures, with the Bragg diffraction peaks shifting to higher 2θ angles accompanied with lattice shrinking as the Ni concentration increased. The SEM images of the spinels revealed essentially spherical morphology. Galvanostatic charge-discharge experiments showed that by substituting the pristine spinel with a low amount of nickel enhanced the cell potential (hence the energy storage capability) and greatly improved the capacity retention (ca. 99%) even after 100 cycles. Electrochemical impedance spectroscopy experiments corroborated the enhanced capacity retention as lithium ion intercalation/de-intercalation resistance for the Ni substituted spinels was significantly improved (more than a magnitude higher) compared to the pristine spinel.