Synthesis of Spherical and Dense Particles of the Pure Hydroxide Phase Ni[sub 1∕3]Mn[sub 1∕3]Co[sub 1∕3](OH)[sub 2]

Abstract

Thestructure of the coprecipitated precursor to the positive electrode material,Li[Ni1/3Mn1/3Co1/3]O2 (NMC), is typically synthesized via a coprecipitation reaction andassumed to be Ni1/3Mn1/3Co1/3(OH)2 or Ni1/3Mn1/3Co1/3OOH. The coprecipitation reaction andits products are not thoroughly understood. Here, pure phase Ni1/3Mn1/3Co1/3(OH)2is synthesized in the presence of aqueous ammonia, yielding denseand spherical particles. Ni1/3Mn1/3Co1/3(OH)2 was found to readily oxidize inair, especially during heating. The obtained product was analyzed withpowder X-ray diffraction and thermogravimetric analysis. The results indicate thatNi1/3Mn1/3Co1/3(OH)2 undergoes oxidation to the oxyhydroxide phase, Ni1/3Mn1/3Co1/3OOH. Heating alsoresulted in an increase in tap density of the oxyhydroxide;the final tap density of the material was found tobe 2.0  g  cm−3.\r\r \r ©2009 The Electrochemical Society