The study of LiNi 0.5Mn 1.5O 4 5-V cathodes for Li-ion batteries

Abstract

In this work, we studied cycling and storage behavior at elevated temperatures of substituted spinel–nickel electrodes LiNi x Mn 2− x O 4 ( x = 0.5) that can operate as cathodes in 5-V advanced lithium-ion batteries. A stable electrochemical performance and low capacity fading were found upon cycling and storage (charged state) of LiNi 0.5Mn 1.5O 4 electrodes in DMC-EC/LiPF 6 solutions at elevated temperatures (60 °C). It was established that cycling/storage of these electrodes led to dissolution of manganese and nickel and reduction of Mn 2+ and Ni 2+ on the lithium counter electrode. These phenomena were studied by solution analysis (ICP) and surface chemistry and morphological measurements (ex situ X-ray photoelectron and Raman spectroscopies, and SEM) of the lithium and LiNi 0.5Mn 1.5O 4 electrodes. Since these electrodes perform well during prolonged cycling, it is clear that the above changes relate to surface phenomena and not changes in the bulk of the active mass.