(380j) Correlation of Structure-Property Relationship of Dry-Coated Particle for All-Solid-State Battery

Recently all-solid state lithium ion secondary batteries have attracted much attention because of high-energy density and safety. All-solid-state batteries are composed of cathode, anode and inorganic solid electrolytes instead of organic liquid electrolytes. For commercial application, it is necessary to construct a solid-solid contact interface between solid electrolytes and active materials in order to produce a pass of lithium ion transport during charge and discharge. To construct a solid-solid contact interface, we have proposed to use a dry coating process. By using this process, a coated particle in which electrode are coated with solid electrolytes is able to be produced. In this study, the effect of thickness of the solid electrolyte layer on the performance of all-solid-state battery cells was investigated. In this study, LiNi_1/3Co_1/3Mn_1/3O₂(NCM) and Li₃PS₄(LPS) were used as an active material and solid electrolyte, respectively. SEM images of the coated particle showed that NCM particles were uniformly coated with LPS and its surface was smooth. Additionally, width of the particle size distribution of the coated particles was unchanged form the original NCM. These results suggest that all LPS particles uniformly covered the NCM particles. Result of particle size distribution showed that coated particles with difference thickness of coating layer were successfully prepared. The thickness of LPS layer was 0.03 μm to 0.61 μm. From the result of charge/discharge test, the cells exhibited significant different performance depending on thickness of LPS layer. Cross-sectional structure of the electrode was analyzed to investigate an essential reason of the influence of the thickness of LPS layer. As a result, we revealed that the balance of both of lithium ion and electron conducting paths is a key for enhancing the high–rate cell performances of the all-solid-state lithium ion secondary batteries.