A transition to fossil-free energy sources requires a sustainable energy storage system. Lithium-ion batteries have been one of the preferred solutions for energy storage. Lithium-ion batteries especially had a vast impact on electrification in the automotive industry. However, the next-generation of lithium-ion batteries are faced with high demands regarding safety, cost, and energy density. To enhance the energy density, one strategy is to use high-voltage positive electrode materials. LiNi_0.5Mn_1.5O₄ (LNMO) to develop high voltage batteries.  Is one such material that operates at the high voltage of 4.7 V vs Li+/Li. Contrary to common layered oxide materials, LNMO is cobalt-free and operates at higher voltage, 4.7 V vs Li+/Li. Therefore, a promising alternative.

 However, LNMO suffers from transition metal dissolution, electrolyte decomposition, and self-discharge processes due to the high voltage. A common approach to address the issues is by either doping of LNMO to stabilize the crystal structure or coating of the active material particles. In this work, we present various synthesis methods and coating solutions for LNMO cathode active material, especially present graphene and FePO₄ -coated LNMO and cell performance.