High-Performance Li-Rich Layered Transition Metal Oxide Cathode Materials for Li-Ion Batteries

Abstract

New stoichiometric Li-rich layered oxides (xLi₂MnO₃·(1-x)LiMn_0.5Ni_0.25Co_0.25O₂ or Li[Li_yMn_1-y-2zNi_zCo_z]O₂) were proposed as high-energy density cathode materials for Li-ion batteries. The correlation between chemical composition of the materials and their structural as well as electrochemical performances is discussed. It was found that all synthesized materials crystalize within C2/m space group with existence of superstructure and possess nanometric spherical-shaped morphology. The analysis of the charge/discharge tests shows that Li[Li_0.2Mn_0.6Ni_0.1Co_0.1]O₂ electrode delivers nearly 350 mAh·g⁻¹ for the first discharge process and 250 mAh·g⁻¹ for following cycles. The investigation of the kinetics of the electrode reactions by means of CV and EIS methods confirmed that Li[Li_0.2Mn_0.6Ni_0.1Co_0.1]O₂ exhibits highest lithium diffusion coefficients, what with obtained electrochemical cycling tests suggest optimal chemical composition of this material ensuring high energy density along with long-term endurance.