LiNi0.8Co0.15Al0.05O2 (NCA) material is successfully synthesized with a modified co-precipitation method, in which NH3·H2O and EDTA are used as two chelating agents. The obtained LiNi0.8Co0.15Al0.05O2 material has well-defined layered structure and uniform element distribution, which reveals an enhanced electrochemical performance with a capacity retention of 97.9% after 100 cycles at 0.2 C, and reduced thermal runaway from the isothermal calorimetry test. In situ X-ray diffraction (XRD) was employed to capture the structural changes during the charge–discharge process. The reversible evolutions of lattice parameters (a, b, c, and V) further verify the structural stability.