On December 7, 2022, Professor Moon Jang-hyeok’s team from Chung-Ang University and Professor Lee Jong-won’s team from the Department of Energy Science and Engineering at DGIST (President: Kuk Yang) jointly announced the development of solid electrolytes with improved atmospheric stability.
Electric cars and electronic devices frequently employ lithium-ion batteries as energy storage units. However, safety concerns have been persistently brought up recently due to the fact that it is prone to ignition because it is produced mostly with flammable organic liquid electrolytes.
On the other hand, the advantage of great thermal stability and the physical impediment to the creation of lithium dendrites are both present in oxide-based solid electrolytes. Among them, Li7La3Zr2O12 (hereinafter, “LLZO”) electrolyte is considered as a next-generation electrolyte due to its excellent lithium ion conductivity.
Despite these benefits, there is a drawback to LLZO electrolytes. When exposed to the atmosphere, moisture and carbon dioxide react to generate lithium carbonate on the surface. Lithium carbonate is created on the surface, grows along the grain boundaries, penetrates into the solid electrolyte, and interferes with the movement of lithium ions, reducing the solid electrolyte’s ability to conduct lithium ions.
By hetero-elemental doping, or adding gallium and tantalum to pure LLZO electrolytes, the study team was able to increase the LLZO electrolyte’s atmospheric stability.
It was proven that ‘LiGaO2,’ a third material created by the addition of gallium, inhibits the surface adsorption of moisture and carbon dioxide and encourages particle growth during thermal treatment, preventing the growth of lithium carbonate through grain boundaries and maintaining the lithium-ion conduction properties of LLZO electrolytes.
As a result, it was empirically verified that lithium-ion conductivity is maintained even when stored for a long time in the air, and stable performance was maintained even after repeated lithium electrodeposition/desorption.
DGIST Department of Energy Science and Engineering Professor Jong-Won Lee said, “I expect the solid electrolyte design concept presented by this research team to be helpful in developing high-performance/high-safety all-solid-state batteries incorporating solid electrolytes, which are stable in the atmosphere and have high lithium ion conductivity.”
In the meantime, Jung Woo-young, a student in the DGIST Master-Doctor Combined Program, took part in this study as the lead author, and the findings were presented online on November 2 in Energy Storage Materials, a global journal with a focus on energy.
It was also carried out with assistance from the ‘Nano and Materials Technology Development Project’ and ‘Engineering Research Center Project’ of the National Research Foundation of Korea.
