Tailoring the structural and morphological properties of LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode material via a novel mixedsolvothermal method

Abstract

LiNi₀.₅Co₀.₂Mn₀.₃O₂ (NCM523) is a promising cathode material for lithium-ion battery 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 & 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 (003) plane to (104), 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.