Temperature-Driven Chemical Segregation in Co-Free Li-Rich-Layered Oxides and Its Influence on Electrochemical Performance

Co-free Li-rich layered oxides are gaining interest as feasible positiveelectrode materials in lithium-ion batteries (LIBs) in terms of energy density, costreduction, and alleviating safety concerns. Unfortunately, their commercialization ishindered by severe structural degradation that occurs during electrochemical operation.The study at hand demonstrates advanced structural engineering of a Li-rich Co-freeoxide with composition Li1.1Ni0.35Mn0.55O2by spray pyrolysis and subsequentcalcination of an aqueous precursor, creating a segregated structure of two distinctlayered phases with space groupsR3??m(rhombohedral) andC2/m(monoclinic). Thisparticular structure was investigated with powder neutron diffraction, high-resolutionanalytical transmission electron microscopy imaging, and electron energy loss spectroscopic characterization. This complex structurecontributes to the high electrochemical stability and good rate capability observed for this compound (160 mAh/g at C/3 and 100mAh/g at 1C).These results provide new insights into the feasibility of developing and commercializing cobalt-free positiveelectrode materials for LIBs