Suppressing the Phase Transition of the Layered Ni-Rich Oxide Cathode during High-Voltage Cycling by Introducing Low-Content Li2MnO3.

The layered Ni-rich oxide cathode (LiNi0.8Co0.1Mn0.1O2) suffers from a tremendous structural degradation during high-voltage cycling (4.8 V), causing the drastic rise of electrode impedance and deterioration of the capacity retention. Here, we develop an effective strategy to overcome these problems of the Ni-rich cathode material through doping low-content Li2MnO3 as an excellent structure stabilizer. Cyclic voltammogram and ex-situ X-ray diffraction measurements have reveled that Li2MnO3 could display a remarkable suppression effect on the phase transition of LiNi0.8Co0.1Mn0.1O2. The electrochemical tests showed that Li2MnO3-stabilized LiNi0.8Co0.1Mn0.1O2 could realize the large reversible capacity, stable discharge voltage and excellent cycling life during high-voltage cycling, which could be benefited from the enhanced structural stability of the modified Ni-rich cathode. The Li2MnO3 could sufficiently suppress the phase transition between two hexagonal phase (H2 and H3) with distinctly different lattice parameters, significantly reducing variation of unit-cell volume, which facilitates stabilization of the original layered structure of LiNi0.8Co0.1Mn0.1O2 cathode during high-voltage cycling.