DEVELOPMENTAL RESEARCH FOR INTERCALATION ELECTRODE MATERIALS FOR HIGH ENERGY DENSITY BATTERIES

本课题的研究成果总结如下：1。具有M=Co和/或Ni的层状岩盐氧化物LiMo_2氧化物LiMo_2是很有前途的正极材料。然而，提取和重新插入Li的能力严重依赖于Li和M原子进入结构交替平面的化学计量比和有序性。Li的退出产生了Li_1-X&Gt；MO_2组分相对于原子位移的亚稳，而在Li引出过程中M原子向Li层的位移大大降低了Li+-离子在Li层中的迁移率。我们首先研究了Li_1-y&Gt；NiO_2体系的合成和脱嵌过程对阳离子化学计量比、有序度和稳定性的影响。为了优化Li_&Lt；1-X&GT；NiO_2阴极系统，(B)在起始锂化合物中产生化学计量和阳离子顺序的精确控制的合成条件，(C)在较高温度下操作的分解或无序过程与Li浓度的关系，(D)化学计量、有序和物理性质之间的关系，(E)脱嵌引起的晶格变化，和(F)阳离子无序对脱嵌过程的影响。新的氧化物宿主。我们尝试通过离子交换、高压、高氧压等非常规途径合成新的氧化物主体。LiFeO_2不在层状岩盐结构中结晶，而NaFeO_2在层状岩盐结构中结晶，通过Li+与Na+在LiCl/KCl熔体中的离子交换，可以制备出具有层状岩盐结构的亚稳LiFeO_2。此外，我们还合成了具有锯齿状层状结构的新型正极LiFeO_2。阐明了具有层状结构和锯齿状层状结构的LiFeO_2正极的结构和电化学性能。

The results of our research projects are summarized as follows1. Layred-rocksalt oxides LiMO_2 Oxides LiMO_2 with M=Co and/or Ni are promising cathode materials. However, the ability to extract and reinsert Li depends critically on the stoichiometry and ordering of the Li and M atoms into alternate planes of the structure. The withdrawal of Li creates Li_<1-X>MO_2 compositions metastable relative to atomic displacements, and displacement of M atoms to the Li layrs on Li extraction lowers sharply the Li+-ion mobility in the Li layrs. We focused on the influence of synthesis and the deintercalation process on the degree of cation stoichiometry, order, and stability of the ordered phase first for the system Li_<1-y>NiO_2. We clarified (a) the phase relationships in the Li-Ni-O ternary system in order to optimize the performance of the Li_<1-X>NiO_2 cathode system, (b) the synthetic conditions that yield precise control of stoichiometry and cation order in the starting lithiated compounds, (c) the decomposition or disordering processes operative at higher temperatures versus the Li concentration, (d) the relationship between stoichiometry, order, and physical properties, (e) the lattice changes induced by deintercalation, and (f) the influence of cation disorder on the deintercalation process.2. New oxide hosts. We attempted to synthesize new oxide hosts by unconventional routes such as ion exchange, high pressure, and high oxygen pressure. LiFeO_2 does not crystallize in the layred-rocksalt structure, but NaFeO_2 does ; it was possible to prepare metastable LiFeO_2 with the layred-rocksalt structure by ion exchange of Li+ for Na+ in molten LiCl/KCl. Furthermore, we synthesized new cathode, LiFeO_2 with the zig-zag layred structure. We clarifed the structure and electrochemical properties of these LiFeO_2 cathodes with the layred structure and zig-zag layred structures.