Via Cold Sintering Process densification and recrystallization of Strontium doped LISICON material

Ion conducting materials haveattracted much attention and being studied as electrolytes of intermediatetemperature fuel cells, lithium ion batteries and so on. LISICON materials havebeen studied as lithium ion conducting and... [ view full abstract ]

Ion conducting materials haveattracted much attention and being studied as electrolytes of intermediatetemperature fuel cells, lithium ion batteries and so on. LISICON materials havebeen studied as lithium ion conducting and also proton conducting material.However, these materials require high temperature (e.g. >1150°C) insintering process to obtain high density and good electrical properties. Recentyears, we have reported Cold Sintering Process, which densifies the materialsthrough the transient liquid phase sintering process enabling dissolution and reprecipitationto densify. In addition, this process permits densification of the materials atextremely low temperature (<300°C) and requires short processing times. Inthis study, we investigated the densification and recrystallization mechanismsin Cold Sintering Process of a multicomponent material (Li_13.9Zn(GeO₄)₄). X-raydiffraction measurement, ICP-AES and thermal analysis were carried out toclarify the kinetics, and results suggest Li_13.9SrZn(GeO₄)₄ dissolved in water incongruently and precipitated as amorphousand secondary phase. And these phases were recrystallized to same LISICON phaseafter the post annealing process which requires lower temperature (<800°C) than conventional calcination or sintering process. TEM observation andelectrical measurement were carried out to compare a Cold Sintered and post annealedsample with conventional sintered one. Grain boundaries of Cold Sintered andpost annealed sample did not have critical defects (i.e. elementalsegregation). And also electrical properties suggest Cold Sintering and postannealing sample has same lithium ion conductivity as conventional sinteredone. To conclude, we successfully obtained dense sample by Cold SinteringProcess and post annealing process which is lower process than conventionalsintering process.