クエン酸ゲルプロセスによって合成したLiMn_2O_4粉末の相安定性と形態に及ぼす熱処理温度と雰囲気の影響

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Defect spinel lithium manganese oxide and spinel LiMn_2O_4 compounds (which are of potential interest for lithium-ion battery cathode materials) with different crystallization degrees have been synthesized by a citric acid gel process using lithium acetate and manganese acetate as sources for lithium and manganese at various temperatures and in different atmospheres. Non-stoichiometric lithium-manganese-oxide spinel, Li_<1-δ>Mn_<2-2δ>O_4, had been synthesized at temperatures as low as 200℃. The structure of the crystalline compounds was found to be cubic spinel in which the lattice parameter and full width at half maximum (FWHM) were sensitive to calcination temperature. As the calcined temperature increased, the oxygen was lost and cation defects were removed from the structure with better crystallization. At temperatures >700℃, LiMn_2O_4 underwent phase transition from a cubic to a tetragonal phase by removing oxygen ion from the surface of powder in air. However, the samples calcined in O_2 atmosphere did not show any phase transformation. These results highlight the importance of temperature and atmosphere control when synthesizing LiMn_2O_4 powder using a citric acid gel process. The specific surface area of the LiMn_2O_<4-x> powder prepared at 800℃ for 24 h was 11.6m^2/g that is distinctly larger than that prepared by solid-state reaction. From the result of scanning electron microscope (SEM), the synthesized powders showed a spherical shape and a narrow particle size distribution.
社団法人日本セラミックス協会の論文
2000-05-01

クエン酸ゲルプロセスによって合成したLiMn_2O_4粉末の相安定性と形態に及ぼす熱処理温度と雰囲気の影響

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