Electrochemical characterization of one-dimensional Li2MnO3 nanorod as Cathodes for Lithium Ion Battery

Abstract

In recent times, layered lithium-rich transition metal oxide containing manganese (Li2MnO3), discharge capacity >200 mAh/g, is receiving much attention as possible alternatives for the LiCoO2 electrode of conventional lithium-ion batteries. Mn-based oxide has the advantages of low-cost, environmental friendliness, and high abundance. Li2MnO3 has a layered rocksalt-type structure in which the excess monovalent lithium ions (1/3-2/3) are accommodated within the transition-metal layers and surrounded predominantly by tetravalent, nearestneighbor manganese ions that can be represented Li[Li1/3Mn2/3]O2. In theory, Li2MnO3 has a capacity of ~458 mAh/g if all Li can be extracted. However, this material showed a limited capacity observed in practical. The Li2MnO3 transform to the spinel-like phases by Jahn-Teller distortion during electrochemical cycling. To prevail over this problem, a number of research groups have investigated for increasing the structural stability of layered lithium manganese oxides. D. Y. W. Yu, suggested the relationship between discharge capacity and particle size, showing larger capacity from Li2MnO3 nanoparticles. In addition, they attribute this to a smaller diffusion path for smaller particles, which allows the material to be charged to a higher capacity. Recently, Kim et al., reported one-dimensional (1-D) nanostructured spinel LiMn2O4 cathodes materials that showed enhanced electrochemical performance because of the large surface-to-volume ratio and space-confined transport phenomena. In this study, the 1-D Li2MnO3 nanorods with different diameters were synthesized via a simple hydrothermal method followed by solid-state reaction. The synthesized Li2MnO3 was characterized by an X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical investigation.