Morphology and Particle Size of a Synthesized NMC 811 Cathode Precursor with Mixed Hydroxide Precipitate and Nickel Sulfate as Nickel Sources and Comparison of Their Electrochemical Performances in an NMC 811 Lithium-Ion Battery

Abstract

Cathode precursors of lithium-NMC 811 were synthesized by the coprecipitation method using two different nickel sources, namely mixed nickel–cobalt hydroxide precipitate (MHP) and nickel sulfate. The characteristics of the synthesized precursors were compared with the characteristics of the commercial NMC 811 cathode precursor obtained from the international market. The XRD analyses identified that the diffraction peaks of the three precursor materials were in close agreement to that of Li0.05Ni0.75Co0.1Mn0.1O2, with the figure(s) of merit (FoM) of 0.81, 0.88, and 0.9, respectively, for the synthesized precursor that used MHP as the source of nickel (SM-LNMCO-811), nickel sulfate as the source of nickel (SX-LNMCO-811), and the commercial precursor (K-NMC-811). The elemental analysis of the synthesized precursors revealed the Ni:Mn:Co mol ratios of 0.8:0.08:0.12 and 0.76:0.11:0.13 for SM-LNMCO-811 and SX-LNMCO-811, respectively. The SEM analysis revealed that SX-LNMCO-811 and K-NMC-811 showed a similar particle morphology with a spherical shape; the SM-LNMCO-811 exhibited an irregular particle morphology. The particle size analysis showed that SM-LNMCO-811 had the largest average particle size (285.2 μm) while K-NMC-811 and SX-LNMCO-811 samples had almost the same average values (i.e., 18.28 and 17.16 µm, respectively). The results of the charge–discharge measurement of the fabricated battery cylindrical cells with SM-LNMCO-811, SX-LNMCO-811, and K-NMC-811 as cathode materials showed the best discharge value of the SX-LNMCO-811 sample at 178.93 mAh/g with an initial efficiency of 94.32%, which is in line with the electrochemical impedance measurement results that showed the largest ion conductivity and lithium ion diffusion coefficient value of the SX-LNMCO-811 sample that utilized the synthesized nickel sulfate as the source of the nickel.

Keywords

• nickel
• co-precipitation
• synthesis
• cathode precursor
• charge–discharge