Studies on New Materials for Battery Application by Micro-electrode Techniques

1)开发了一项新技术，即针对水和非水系统中氧化还原材料的单个颗粒的微伏安法——我们已经建立了一个实验装置，使我们能够测量单个固体颗粒的伏安图。通过显微操作技术，在显微镜下，灯丝的尖端作为电流铅废物与固体颗粒目标接触，扩散在浸有电解质的分离片上。对碱溶液中的金属氢化物和有机溶液中含锂层状氧化物进行了小颗粒实验，成功地制成了10微米大小的单颗粒工作电极。2)利用上述技术对LaNi_5、Cl5型Laves相合金和AB_5合金进行了微伏安研究，测定了氢的化学扩散系数。这一研究已扩展到LiSB材料，在碳酸丙烯溶液中的层状氧化物如LiCoO_2和LiMn_2O_4，以及锂离子的插/脱插动力学研究。3)利用微盘电极对有机溶液中不同基质上的锂沉积/溶解和合金形成过程进行了动力学研究，确定了交换电流密度和扩散系数等动力学参数随温度和溶剂组成的函数关系。4)应用微阵列电极测量了锂离子插入/脱嵌锂离子阴极的电导率变化。结果表明，这种双恒电位器的原位电导率测量在同时测量电流电位和电导率电位关系时特别有用。

1) Development of a new technique, micro-voltammetry targeting a single particle of redox materials in aqueous and non-aqueous systems-An experimental set-up to enable us to measure voltammograms for a single solid particle has been constructed. By using micro-manipulation techniques, the tip of a filament acting as a current lead wase contacted with a target of solid particle spread on a separator sheet soaked with an electrolyte under a microscope. Small particle experiments were carried out for metal hydrides in alkali solutions and for Li-containing layred oxides in organic solutions, and demonstrated that single particles having 10 micrometer sized were successfully made into the working electrode.2) Using the above technique, we carried out microvoltammetric studies on LaNi_5, Cl5 type Laves phase alloys and AB_5 alloys, and determined the chemical diffusion coefficients of hydrogen. This studies have been extended to LiSB materials, the layred oxides such as LiCoO_2 and LiMn_2O_4, in propylene carbonate solutions, and kinetic studies of Li-ion intercalation/deintercalation are now under investigation.3) Kinetic studies on lithium deposition/dissolution and alloy formation processes on various substrates in organic solutions were carried out by micro-disk electrodes, and kinetic parameters such as the exchange current density and diffusion coefficient have been determined as functions of temperature and solvent compositions.4) Micro-array electrodes have been applied to measure the conductivity change during Li-ion intercalation/deintercalation of LiSB cathodes. It was demonstrated that this in situ conductivity measurement with a bi-potentiostat is particularly useful in measuring both current-potential and conductivity-potential relationships simultaneously.