Structural evolutions of LiNi0.5Mn1.5O4 nanorods synthesized by different lithium sources and effects on electrochemical performances

Abstract

It is crucial to prepare the material LiNi0.5Mn1.5O4 (LNMO) with good cycling and rate performances for lithium-ion batteries. The growing process of LNMO nanorods with different lithium sources was investigated with β-MnO2 nanofibers as the templates, and Li(CH3COO)·2H2O and LiOH·H2O as lithium sources respectively. The structures and morphologies of the LNMO samples were characterized by XRD, FTIR, Raman, SEM, and TEM. Results show that by taking Li(CH3COO)·2H2O as the lithium source, the LNMO nanorods grow slowly. The nanorod structure can be maintained in a larger range of annealing temperature (700–750 °C). XRD analysis results show that the nanocrystalline of LNMO synthesized by Li(CH3COO)·2H2O as lithium source is smaller and with lower disorder degree than that synthesized by LiOH·H2O as the lithium source under the same annealing temperatures. The LNMO synthesized by Li(CH3COO)·2H2O as lithium source performed better rate and cycling performances attributed to smaller polarization effect, which was confirmed by the CV results. EIS test data implied that the LNMO samples synthesized by Li(CH3COO)·2H2O as the lithium sources presented smaller charge transfer resistances. Consequently, Li(CH3COO)·2H2O is an ideal lithium source to control the disorder degree and growing process of LNMO nanorods.