ABSTRACT In order to investigate the influences of Mg–Al–B co-substitution on LiNi0.5Co0.2Mn0.3O2 material, the uniform and spherical doped Li[Ni0.5Co0.2Mn0.3]0.992Mg0.003Al0.003B0.002O2 material is successfully prepared through a simple solid state synthesis. X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and electrochemical tests have been applied for material characterizations and electrochemical measurements. Through the result of XRD and the Rietveld refinements, Mg, Al and B atoms may be incorporated into the crystal lattice. Similarly, the results of EDX and XPS confirm the existence of Mg2+, Al3+ and B3+ in accordance with the chemical formula. The Mg–Al–B co-substitution LiNi0.5Co0.2Mn0.3O2 material shows excellent electrochemical performance, especially the superior cycling stability under high cutoff voltages. The Mg–Al–B co-substitution LiNi0.5Co0.2Mn0.3O2 material exhibits the higher capacity retentions of 83.8%, 84.9%, 83.2% and 80.4% than that of the bare one (71%, 62.5%, 40.9% and 25%) after 200 cycles at a cutoff voltage of 4.2, 4.3, 4.4 and 4.5V, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) confirm that the modification of Mg–Al–B co-substitution plays an important role in improving the electrochemical performance of the bare LiNi0.5Co0.2Mn0.3O2.