[ ] powders for lithium ion batteries were synthesized from two separate raw material pairs of LiOH/MnO and . The powders prepared at 780 and and their difference of electrochemical properties were investigated. Both powders calcined at 780 and were composed of a single-phase spinel structure but those treated at showed a lower intensity ratio of to , a slightly larger lattice parameter, and an increased discharge capacity by 10% under voltage range. The XPS study on the oxidation states of manganese repealed that powders made from LiOH/MnO had less ion and gave better battery performances than those from .

LiMn2O4 catalyst for CO2 decomposition was synthesized by oxidation method for 30 min at 600℃ in an electric furnace under air condition using manganese(II) nitrate (Mn(NO3)2·6H2O), Lithium nitrate (LiNO3) and Urea (CO(NH2)2). The synthesized catalyst was reduced by H2 at various temperatures for 3 hr. The reduction degree of the reduced catalysts were measured using the TGA. And then CO2 decomposition rate was measured using the reduced catalysts. Phase-transitions of the catalysts were observed after CO2 decomposition reaction at an optimal decomposition temperature. As the result of X-ray powder diffraction analysis, the synthesized catalyst was confirmed that the catalyst has the spinel structure, and also confirmed that when it was reduced by H2, the phase of LiMn2O4 catalyst was transformed into Li2MnO3 and Li1-2δMn2-δO4-3δ-δ' of tetragonal spinel phase. After CO2 decomposition reaction, it was confirmed that the peak of LiMn2O4 of spinel phase. The optimal reduction temperature of the catalyst with H2 was confirmed to be 450℃(maximum weight-increasing ratio 9.47%) in the case of LiMn2O4 through the TGA analysis. Decomposition rate(%) using the LiMn2O4 catalyst showed the 67%. The crystal structure of the synthesized LiMn2O4 observed with a scanning electron microscope(SEM) shows cubic form. After reduction, LiMn2O4 catalyst became condensed each other to form interface. It was confirmed that after CO2 decomposition, crystal structure of LiMn2O4 catalyst showed that its particle grew up more than that of reduction. Phase-transition by reduction and CO2 decomposition ; Li2MnO3 and Li1-2δMn2-δO4-3δ-δ' of tetragonal spinel phase at the first time of CO2 decomposition appear like the same as the above contents. Phase-transition at 2~5 time ; Li2MnO3 and Li1-2δMn2-δO4-3δ-δ' of tetragonal spinel phase by reduction and LiMn2O4 of spinel phase after CO2 decomposition appear like the same as the first time case. The result of the TGA analysis by catalyst reduction ; The first time, weight of reduced catalyst increased by 9.47%, for 2~5 times, weight of reduced catalyst increased by average 2.3% But, in any time, there is little difference in the decomposition ratio of CO2. That is to say, at the first time, it showed 67% in CO2 decomposition rate and after 5 times reaction of CO2 decomposition, it showed 67% nearly the same as the first time.

The spinel Fe3O4 powders were synthesized using 0.2 M-FeSO4·7H2O and 0.5 M-NaOH by oxidation in air and the spinel LiMn2O4 powders were synthesized at 480 ℃ for 12 h in air by a sol-gel method using manganese acetate and lithium hydroxide as starting materials. The synthesized LiMn2O4 powders were mixed at portion of 5, 10, 15 and 20 wt% of Fe3O4 powders using a ball-mill. The mixed catalysts were dried at room temperature for 24 hrs. The mixed catalysts were reduced by hydrogen gas at 350 ℃ for 2 h. The carbon dioxide decomposition rates of the mixed catalysts were 90% in all the mixed catalysts but the decomposition rate of carbon dioxide was increased with adding LiMn2O4 powders to Fe3O4 powders.

The spinel LiMn2O4 powders were synthesized at 480℃ for 12 h in air by a sol-gel method using manganese acetate and lithium hydroxide as starting material and the Fe3O4 powders were synthesized by the precipitation method using 0.2M-FeSO4·H2O and 0.5M-NaOH. The synthesized Fe3O4 powders were mixed at portion of 5, 10, 15 and 20 wt% about LiMn2O4 powders through ball-milling followed by drying at room temperature for 48 h in air. The mixed catalysts were reduced at 350℃ for 3 h by hydrogen and the decomposition rate of carbon dioxide was measured at 350℃ using the reduced catalysts. As the results of CO2 decomposition experiments, the decomposition rates of carbon dioxide were 85% in all catalysts but the initial decomposition rates of CO2 were slightly high in the case of the 5%-Fe3O4 added catalyst.

Li ion전지용 LiMn2O4분말을 졸-겔법과 고상반응법으로 제조하여 분말의 특성과 전지의 특성을 비교하였다. 졸-겔법에 의해 제조된 LiMn2O4분말은 고상반응법에 의해 제조된 분말보다 낮은 온도에서 합성이 가능하고, 균질하고 작은 입자들로 구성되었으며, Li stoichiometry가 우수하여 전지의 방전용량이 크나 양이온 혼합도가 높아 전지의 내부저항이 크게 나타났다. 졸-겔법은 높은 Li stoichiometry와 균질한 입자 크기를 갖는 LiMn2O4분말 제조에 적당한 것으로 생각되며, 전지의 내부저항 문제는 분말의 하소온도와 냉각속도의 조절에 의해 가능할 것으로 판단된다.