Continuous activation of Li2MnO3 component upon cycling in Li1.167Ni0.233Co0.100Mn0.467Mo0.033O2 cathode material for lithium ion batteries

Abstract

Li-rich layered cathode materials are very promising candidates for next generation high energy lithium ion batteries. One of the Li-rich layered cathode materials, Li_1.167Ni_0.233Co_0.100Mn_0.467Mo_0.033O₂ is prepared by a co-precipitation method. In this report, we focus on anomalous changes upon cycling in Li_1.167Ni_0.233Co_0.100Mn_0.467Mo_0.033O₂ cathode material in a voltage range of 2.0–4.55 V at room temperature. The structural transitions upon cycling are analyzed by ex situ X-ray diffraction. In addition, the changes in local structure during cycling are studied by X-ray absorption near edge structure. With differential capacity plots by controlling the cut-off voltage, the voltage decay during cycling is intensively studied. The continuous activation process of the residual Li₂MnO₃ component during cycling is correlated with voltage decay during cycling, and increasing capacity during the initial several cycles. Also, the electrochemical performance in Li_1.167Ni_0.233Co_0.100Mn_0.467Mo_0.033O₂ cathode material below 4.4 V is discussed. Furthermore, cycle performance is improved by reassembling Li_1.167Ni_0.233Co_0.100Mn_0.467Mo_0.033O₂ into another cell after washing.