Synthesis and Electrochemical Performance of Spinel LiNi0.5Mn1.5O4 Nanorods as High Voltage Cathode materials for Li-Ion Batteries

Abstract

The high energy and power density capability of lithium ion battery technology attracted widespread interest over the past few years due to potential applications in both hybrid electric vehicles and full electric vehicles. Spinel LiNi0.5Mn1.5O4 is a promising material due to its high average voltage around 4.7 V vs. Li counter electrode. In LiNi0.5Mn1.5O4, Mn4+ is electrochemically inactive throughout the insertion and extraction of Li-ion, and the Ni2+/4+ redox couple contributes to the specific capacity during the charge/discharge process. In our previous works,[1-2] we verified that the one-dimensional (1-D) nanosized electrode materials have superior rate capability due to the large contact area with electrolyte, which results to shorter distances for Li-ion transport, and enhancement of an electronic pathway. In this presentation, we fabricate ordered LiNi0.5Mn1.5O4 nanorods via a hydrothermal reaction to synthesize betamanganese oxide (-MnO2) nanorod precursor followed by a solid state reaction with Ni acetate and Li hydroxide. The nanorod structure and morphology are verified to confirm ordered spinel structure and nanorod shape. Two types of electrolyte are applied in battery characterization because commercial 1 M LiPF6 solution in a 1:1 ethylene carbonate and dimethyl carbonate generates oxygen over 4.5 V during electrochemical charge/discharge. The fabricated LiNi0.5Mn1.5O4 nanorods are characterized to evaluate an excellent performance as a high voltage cathode material.