The necessity for a 300-mile driving range with 60–70 kWh of energy at the battery pack level has steered LIB research toward high-energy-density-based cathode materials. Because of its larger theoretical capacity (274 mAh g^-1) compared to lithium iron phosphate and lithium manganese oxide-based cathodes, layered oxide cathodes have the potential to attain higher energy density LIBs. Despite its greater cost, LCO still has a higher demand (>21%) than any other cathode material. The current research on LiCoO₂ (LCO) as a cathode is centered on its surface protection which allows for the extraction of more than half of the Li. Several techniques have been investigated to protect the LCO surface from direct contact with the liquid electrolyte while retaining structural integrity at higher cut-off voltages (≥4.5 V). The LiCo_0.5Mn_1.5O₄ (LCMO) coating material is utilized here, which has a spinel structure and allows for three-dimensional (3D) lithium diffusion. Microwave-assisted heating was used for the synthesis of surface-modified LCO material. During synthesis, some Mn³⁺ diffused into the bulk of LCO, increasing its lattice parameter and allowing Li-ion kinetics in LCO to function at a faster cycling rate for longer cycle life. The modified LCO is subjected to a higher rate (3C) for longer cycle life with ~57.3 % capacity retention after 500 cycles. Here, a novel understanding of higher rate capability (at 3C, 5C, and 10C current rates) and stability at the higher cut-off voltage for modified LCO has been proposed. Entropy measurements were used to evaluate the arrangement of Li-ion and vacancy in the LCO lattice at different states of charge to investigate the stability of coated LCO at the higher voltage. The full cell and 15 mAh pouch-type cell were also fabricated with Si as an anode for its commercial scalability.