Particulate Sol-Gel Synthesis and Characterization of LiMO2 (M=Ni, Ni(0.75)Co(0.25) Using the Thermal and Mass Spectrometry Analyses Work-Station
Abstract
Lithiated transition metal oxides, LiMO2 (M= Ni, Co, Mn) are useful cathode materials for high voltage 4V Li-ion batteries. Among these, LiCoO2 and LiNiO2 have received considerable attention. Solid state processes are conventionally used for synthesizing these oxides. These methods do not in general provide good control of the stoichiometry, particle size, point defects and morphology. In the present study, the particulate sol-gel (PSG) process has been developed for synthesizing electrochemically active LiNiO2 and LiNi(x)Co(1-x)O2 (x=0.75) powders. Four different processes: (a)rotary evaporation (b)gelation (c)spray drying and (d)spray decomposition have been developed and studied using inorganic and organometallic precursors other than metal alkoxides. Three aspects were studied on each newly developed process, namely the structure of the synthesized xerogels, the phase evolution pathways, and the electrochemical response of the desired LiMO2 (M=Ni, Ni(0.75)Co(0.25) oxide. The final oxide in each of the processes is formed by a reaction between the in-situ synthesized intimate mixture of Li2CO3 and the transition metal oxide. The reaction kinetics and mechanisms involved in the formation of the lithiated oxide have also been elucidated in this study using the LiNiO2 xerogel derived from the rotary evaporation process as the model system. The results of these studies show that the structure of the xerogel is influenced by the processing method, which in turn influence the kinetics of formation of the desired oxide. For example, the xerogels obtained by rotary evaporation of an aqueous solution of LiOH and nickel acetate Ni(OAc)2 show the formation of Ni(OH)(OAc) species in the svnthesized xerogel. In contrast the xerogel generated bv the spray drying of LiOH and Ni(OAc)2 in a polar non-aqueous solvent leads to hydrolysis and condensation reaction resulting in a xerogel containing a polymeric network of metal-oxygen-metal chains.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 05, 2000
- Accession Number
- ADA379054
Entities
People
- Chun-chieh Chang
- P. N. Kumta
Organizations
- Carnegie Mellon University