Nasicon-Type Li-on Conductor for All-Solid-State Li-Ion Batteries

Abstract

All-solid-state lithium batteries are regarded as the next-generation power sources because of its superior safety and long cycle lives. But its development is prevented by the lack of solid electrolyte materials with high conductivity and high electrochemical stability. [1]In past decades, a new family of lithium-ion conductors with Nasicon-type structure has attracted lots of interests due to its high bulk conductivity. However, several drawbacks prevent them from practical application such as low grain boundary conductivity and low electrochemical stability. [2]To solve these problems, the present study is focused on optmizing the preparation process of an electrolyte material based on NASICON-type structure. A melting quench method has been adopted to eliminate the grain boundary resistance of Nasicon-type electrolyte Li1.5Al0.5Ge1.5P3O12 (LAGP) and the amorphous sheets are heat treated at different temperatures to investigate the relationship between microstructure and ionic conductivity. The highest total conductivity of 2.907x10-3S/cm at 27℃ has been achieved by crystallizing the glass at 800℃ for 8h and its activation energy is measured to be 0.27eV. Systematic characterizations on crystal structure and grain size are conducted to lead to further understandings on mechanism of lithium-ion transportation and grain growth kinetic.