Regulating the grain size of garnet type Ga0.3Li6.1La3Zr2O12 for ultrafast Li+ diffusion and enhanced cycling performance

초록

Solid state electrolyte is a promising candidate to replace the liquid electrolytes in lithium ion batteries, although it has a fatal drawback of inferior ionic conductivity. Garnet-type LiLaZrO can be regarded as a favorable material for all-solid-state lithium batteries since it has better lithium ion kinetics, non-flammability and outstanding electrochemical/thermal stability. The grain size is closely related to the microstructure, affecting electrochemical and mechanical properties. Here, we control the grain size by adjusting the sintering time and demonstrate that Li6.1Ga0.3La3Zr2O12 (LGLZO) sintered at 1250 degrees C for 10 h delivers relative density of 97.5 & PLUSMN;0.5 %, hardness of 9.7 & PLUSMN;0.46 GPa, ionic conductivities of 8.9 x 10-4 S/cm (Au/LGLZO/Au symmetric cell) and 4.5 x 10-5 S/cm (Li/LGLZO/Li symmetric cell), activation energy (bulk: 0.31 eV and grain boundary: 0.64 eV), critical current density of 0.58 mA/cm2, which are superior than those of LGLZO sintered for 20 h. It can be elucidated by higher crystallinity and microstructure of LGLZO sintered for 10 h. These not only accelerate the kinetics of lithium ions at the bulk, grain boundary and interface, but also enable uniform current distribution at the interfaces. Therefore, we can conclude that regulating sintering time is a simple and easy approach for high performance LGLZO electrolyte.

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