Cobalt-free LiNi_0.5Mn_1.5O₄ (Lithium Nickel Manganese Oxide; LNMO) has attracted much attention as a cathode material due to its high operating voltage, high energy density, lower cost, and environmental friendliness. However, LNMO cathodes are currently suffering from poor cyclability, and capacity degradation at elevated temperatures and high voltages, greatly limiting their large-scale adaptation. To this end, we used a microwave-assisted chemical co-precipitation approach to manufacture pure LiNi_0.5Mn_1.5O₄ (LNMO-P) and CeO₂-coated LMNO (LNMO-Ce) microspheres. Cells with these cathodes were cycled between 4.9 V and 3.5 V to study their stability and performance. During cell cycling, the LNMO cell exhibited an initial capacity of 139 mAhg^-1 at the C/10 rate with a capacity retention of 82% after 100 cycles. Remarkably, LNMO-Ce exhibits an initial capacity of 169 mAhg^-1 with a 92% capacity retention at the same conditions. The microwave-assisted co-precipitation technique enables the development of microspheres with high interfacial stability and tap density, also the addition of protective ceria coating over the cathode enhances the cycling stability of the cathode at high voltage operation. Due to the novel material architecture and synthesis techniques, parasitic reactions at the electrolyte and active electrode material interface are avoided, Mn³⁺ dissolution is reduced due to the Jahn Teller effect, and conductive pathways are improved, significantly improving the electrochemical performance. When applied to other types of electrode materials, the suggested technique for material production is capable of significantly improving the materials' cyclic performance.