Water Adsorption and Storage Characteristics of Optimized LiCoO[sub 2] and LiNi[sub 1∕3]Co[sub 1∕3]Mn[sub 1∕3]O[sub 2] Composite Cathode Material for Li-Ion Cells

This study investigated water adsorption and storage characterization of optimized and composite with a weight ratio of 4:1 in terms of the electrochemical properties and metal dissolution upon storage in air or in an electrolyte at . and exhibited moisture (LiOH) and carbon contents of 198 and , respectively, after storage in air with a relative humidity of 60%. However, the composite sample annealed at showed moisture content of under the same condition. The simple mixing of and exhibited a twofold higher moisture and carbon content than the same material annealed at . This enhancement was attributed to the possible formation of a structurally robust phase after annealing. The annealed sample showed no reduction in its initial capacity and capacity retention even after exposure to air, compared with the samples before being exposure to air. The results indicate that LiOH and at amounts had little influence on the electrochemical properties. Upon storage at , the concentration of Ni and Co in the electrolyte dissolved from the individual and cathodes was but that from the annealed composite was only . Such metals dissolution resulted in local destruction of the and structure, but the composite annealed at for was structurally stable.