Precursor Morphology Control and Electrochemical Properties of LiNi_0.35Mn_0.30Co_0.35O₂ as a Li-Ion Battery Positive Electrode Material

To control the electrochemical properties of LiNi0.35Mn0.30Co0.35O2 (NMC) acting as a positive electrode material, Ni0.35Mn0.30Co0.35(OH)2 precursors with different morphologies were synthesized by controlling the dissolved oxygen concentration during coprecipitation. As the dissolved oxygen concentration increases, precursor particles become more porous and have higher specific surface area. X-ray absorption spectroscopy clearly shows that only the Mn valence in the precursors increased with increasing dissolved oxygen concentration. X-ray diffraction patterns of the precursor synthesized under a high dissolved oxygen concentration suggested the formation of oxyhidroxide. The morphology of NMC synthesized using the developed precursors resembled that of the precursors. NMC with dense morphology exhibited high volumetric energy density, while that with porous morphology exhibited a high discharge capacity and rate performance without any cycle performance drawbacks. We expect that this simple method of morphology control by control of precursor dissolved oxygen concentration can be applied to improve the electrochemical properties of positive electrode materials with a wide range of Mn-containing compositions.