| 研究概要 |
Lithium batteries have been used in electronic devices, such as mobile phones, lap-top and others due to the high value of the energy content. However, the highest energy storage possible for commercial Li-ion batteries is insufficient for the long-term needs of society, for example, extended-range electric vehicles. The use of solid electrolyte has an especial feature because their stability with Li metal than could prevent a short-circuit occurring between electrodes during recharging. The activities developed in this first stage of the research were focus on the synthesis of the solid Li_7La_3Zr_2O_<12> (LLZO) ceramic lectrolyte with a garnet crystal structure by a sol-gel process. Positive properties of the electrolyte include high ionic conductivity (4x10^<-4> Scm^<-1> at 25℃), electrochemical stability with Li metal, and thermal and chemical stability. The main disadvantage is related with the loss of lithium during the sintering process up to 1200℃ to obtain the cubic structure, responsible for the production of the high conductivity. The partial substitution of the Niobium in the typical LLZO (Li_7La_3 (Zr_<2-x>, Nb_x) O_12, X=0-1, LLZNbO) was developed in order to produce a cubic phase at lower thermal treatment and minimizes the loss of lithium. Thus, low-temperature process for the LLZNbO has been developed. The synthesis of these materials has allowed obtaining homogenous composites with particles size between 5-10 μm, relative density of the materials ～70% and stable cubic phase, using 900℃ as a maximum sintering temperature. The research at this point is approached in the optimization of the parameters involved in the synthesis in order to improve the density.
|
| 今後の研究の推進方策 |
After optimization of the electrolytes to select the best properties and operation conditions, the objective is testing together with some commercial or homemade electrodes. The objective will be the optimization of chemical composition of each part and preparation procedures to improve the interfaces. Characterization will include electrochemical measurements as voltammetry, electrochemical impedance spectroscopy and charge-discharge cycling, and structural characterization.
|
