Functions of low crystallinity in lithium-rich positive electrode

Abstract

Intensive research is being conducted to further improve the performance of lithium-ion secondary batteries. Conventional cathode materials exhibit excellent charge-discharge cycle characteristics because only Li ions are extracted and inserted while maintaining the crystalline structure of the material. On the other hand, lithium-rich layered oxide (LLO) materials with high energy density have achieved extraction/insertion of a large amount of Li ions with a low crystalline structure. This paper introduces an example of research that clarified the existence of a low-crystal structure in LLO formed by the crystal structure change accompanying the migration of pillar metal ions that support the Li deficient layer during extraction of Li-ions revealed by a pair distribution function analysis.