Tailoring the structural and morphological properties of LiNi0.5Co0.2Mn0.3O2 cathode materials via a novel mixed-solvothermal method

Abstract

LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) is a promising cathode material for lithium-ion batteries with high capacity, stability, and environmental benefits, but conventional synthesis methods often cause structural degradation and cation mixing that hinder performance. In this study, a novel, optimized, and facile mixed-solvothermal approach mediated by ethylene glycol, water, and ethanolamine was employed to synthesize NCM523 cathode materials with enhanced crystallinity and optimized morphology. The effects of different calcination temperatures (700 °C, 800 °C, and 900 °C) on the structural, morphological, and chemical properties were systematically investigated. X-ray diffraction (XRD) analysis confirmed the formation of a well-ordered layered structure, with the sample mediated in ethylene glycol, water and ethanolamine and calcined at 800 °C (NCM-800) exhibiting superior phase purity and minimal cation disorder. The sample calcined at 800 °C exhibited the highest crystallite size of 37 nm and an intensity ratio of 1.42 in the case of the (003) to (104) planes, which indicates the lowest cation mixing of Li⁺/Ni²⁺ ions. X-ray photoelectron spectroscopy (XPS) further revealed optimal Ni²⁺/Ni³⁺ ratios (0.23) and lattice oxygen retention in NCM-800, indicating robust redox activity and minimal oxygen vacancies. Field emission scanning electron microscopy (FE-SEM) demonstrated that NCM-800 possessed uniform, densely packed spherical particles with minimal surface defects, contributing to improved mechanical integrity and electrochemical stability. Compared to samples calcined at lower or higher temperatures, NCM-800 achieved an optimal balance between crystallinity, particle morphology, and structural robustness. These findings highlight the potential of the mixed-solvothermal method as a promising, scalable, and cost-effective strategy for the synthesis of high-performance NCM523 cathode materials, paving the way for their application in next-generation lithium-ion batteries and advanced energy storage systems.