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

1)发展了一种新的技术，微伏安法针对单一颗粒的氧化还原材料在水和非水系统中，一个实验装置，使我们能够测量伏安图的一个单一的固体颗粒已经建成。通过使用显微操作技术，在显微镜下，用作电流引线的细丝的尖端与散布在用电解质浸泡的隔板上的固体颗粒的目标接触。对碱溶液中的金属氧化物和有机溶液中的含锂层状氧化物进行了小颗粒实验，成功地将10 μ m的单颗粒制成了工作电极。2）利用上述技术对LaNi_5、Cl_5型Laves相合金和AB_5型合金进行了微伏安研究。并测定了氢的化学扩散系数。本研究已扩展到碳酸丙烯酯溶液中的层状氧化物LiCoO_2和LiMn_2O_4等LiSB材料，锂离子的嵌入/脱嵌动力学研究正在进行中。3）采用微盘电极研究了有机溶液中锂在各种衬底上的沉积/溶解和合金形成过程，采用微阵列电极技术研究了锂离子在LiSB阴极中的嵌入/脱嵌过程，并测定了交换电流密度、扩散系数等动力学参数随温度和溶剂组成的变化规律。结果表明，这种原位电导率测量与双恒电位仪是特别有用的，同时测量电流-电位和电导率-电位的关系。

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.