AUTHOR=Nguyen Quoc Hung , Luu Van Tung , Nguyen Hoang Long , Lee Young-Woo , Cho Younghyun , Kim Se Young , Jun Yun-Seok , Ahn Wook 

TITLE=Li7La3Zr2O12 Garnet Solid Polymer Electrolyte for Highly Stable All-Solid-State Batteries

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 8 - 2020

YEAR=2021

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.619832

DOI=10.3389/fchem.2020.619832

ISSN=2296-2646

ABSTRACT=All-solid-state batteries that utilize solid polymer electrolytes have been considered as promising candidates to replace liquid electrolytes in lithium-ion batteries for high safety, energy storage performance, and stability under elevated temperature conditions. However, the low ionic conductivity and unsuitability of lithium metal in solid polymer electrolytes is a critical problem. To resolve this, we used a cubic garnet oxide electrolyte (Li7La3Zr2O12 - LLZO) and ionic liquid in combination with a polymer electrolyte to produce a composite electrolyte membrane. By applying a solid polymer electrolyte on symmetric stainless steel, the composite electrolyte membrane shows high ionic conductivity at elevated temperatures. The effect of LLZO in suppressing lithium dendrite growth within the composite electrolyte was confirmed through symmetric cell test of lithium stripping/plating under various current densities showing small polarization voltages. The full cell with lithium iron phosphate as the cathode active material achieved a highest specific capacity of 137.4 mAh g-1 and a high capacity retention of 98.47% after 100 cycles at a current density of 50 mA g-1 and a temperature of 60 °C. Moreover, the specific discharge capacities were 137 mAh g-1 and 100.8 mAh g-1 at current densities of 100 mA g-1 and 200 mA g-1, respectively. This research highlights the ability of solid polymer electrolytes to suppress the growth of lithium dendrites and improve the performance of all-solid-state batteries.