KOH-Assisted Molten Salt Route to High-Performance LiNi_0.5Mn_1.5O₄ Cathode Materials

A simple and cost-effective route based on a KOH-assisted molten salt method is designed here to synthesize LiNi_0.5Mn_1.5O₄ spinel. Pure-phase LiNi_0.5Mn_1.5O₄ can be successfully prepared using chlorides as raw materials and adding KOH at 700 °C. The structure, morphology, and performance are discussed in detail. The measurements reveal that using KOH-assisted synthesis can optimize the crystal structure of the obtained LiNi_0.5Mn_1.5O₄ samples, resulting in grain refinement while maintaining the predominantly octahedral structure that grows along the (111) crystal plane. This new synthesis pathway provides excellent performance in terms of cycle life. Electrochemical tests show that the KOH-assisted sample exhibits higher initial specific capacities (124.1 mAh·g^-1 at 0.2 C and 111.4 mAh·g^-1 at 3 C) and superior cycling performances (capacity retention of 85.0% after 200 cycles at 0.2 C and 95.70% after 100 cycles at 3 C). This provides a potential solution for the practical application of high-voltage LiNi_0.5Mn_1.5O₄ lithium-ion batteries.