Preparation and characterization of high-density spherical LiCoO2 cathode material for lithium ion batteries

Abstract The high-density spherical LiCoO 2 is expected as an important direction for LiCoO 2 cathode material. Spherical Co(OH) 2 powders were prepared via a “controlled crystallization” method using Co(NO 3 ) 2 , NaOH and NH 3 . To mix Co(OH) 2 and lithium sources in a molar ratio of Li:Co=1.05:1.00, the Li 2 CO 3 was uniformly coated on the surface of the spherical Co(OH) 2 precursor using LiOH·H 2 O and NH 4 HCO 3 . The mixed powders were sintered at 700–800 °C for 12–16 h to obtain spherical LiCoO 2 powders. The structures of Co(OH) 2 , Li 2 CO 3 coated Co(OH) 2 and LiCoO 2 were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electrochemical test of charge–discharge proved the spherical LiCoO 2 cathode material had excellent electrochemical performance. At the current of 0.2 and 1.0 C, the cathode material showed initial discharge capacity of 148.4 and 141.7 mAh g −1 , and retention of 97.6 and 91.7% after 40 cycles, respectively. The lax pile-density and tap-density of the powders are as high as 1.9 and 2.8 g cm −3 , respectively, which are remarkably higher than the non-spherical LiCoO 2 powders available as commercial cathode materials. The high-density spherical LiCoO 2 cathode material can be used in the lithium ion batteries to greatly increase the batteries’ energy density.