High-energy ‘composite’ layered manganese-rich cathode materials via controlling Li2MnO3 phase activation for lithium-ion batteries

Abstract

The ‘composite’ layered materials for lithium-ion batteries have recently attracted great attention owing to their large discharge capacities. Here, the 0.5Li₂MnO₃·0.5LiMn_0.42Ni_0.42Co_0.16O₂ ‘composite’ layered manganese-rich material is prepared and characterized by the synchrotron X-ray powder diffraction (SXPD). The relationship between its electrochemical performance and its ‘composite’ components, the Li₂MnO₃ phase activation process during cycling and the cycle stability of this material at room temperature are elucidated based on its kinetic controlled electrochemical properties, dQ/dV curves and Raman scattering spectroscopies associated with different initial charge–discharge current densities (5 mA g⁻¹, 20 mA g⁻¹ and 50 mA g⁻¹), cut-off voltages (4.6 V and 4.8 V) and cycle numbers (50 cycles and 150 cycles). Furthermore, its reaction pathways are tracked via a firstly introduced integrated compositional phase diagram of four components, Li₂MnO₃, LiMn_0.42Ni_0.42Co_0.16O₂, MO₂ (M = Mn_1−α−βNi_αCo_β; 0 ≤ α ≤ 5/12, 0 ≤ β ≤ 1/6) and LiMnO₂, which turns out to be a very important guiding tool for understanding and utilizing this ‘composite’ material.