Development of World's Best-Performing 'Composite Solid Electrolyte' with No Fire or Explosion Risk

Daegu Gyeongbuk Institute of Science and Technology

Safe and world-class performance composite solid electrolyte simulation diagram.

[Asia Economy Reporter Kim Bong-su] A composite solid electrolyte with no risk of explosion or fire, flexible bending capability, and world-class performance has been developed, promising significant improvements in the performance and safety of batteries for wearable device power sources.

The Daegu Gyeongbuk Institute of Science and Technology (DGIST) announced on the 20th that the research team led by Principal Researcher Kim Jae-hyun of the Energy Convergence Research Division has fabricated such a composite solid electrolyte. Electrolytes are substances that dissolve in water or other solvents to ionize and conduct electricity, and are one of the four core materials of batteries. Currently, liquid electrolytes are widely used, structured with a separator dividing the anode and cathode. Due to this, if the separator is damaged by deformation or external impact, the liquid electrolyte can leak, causing the cathode materials to meet and vaporize, leading to risks of overheating or explosion accidents.

Replacing liquid electrolytes with solid electrolytes can prevent the risks of fire and explosion. Additionally, separators are no longer needed, and the overall battery volume can be reduced. However, solid electrolytes have much lower conductivity compared to liquids, necessitating research to compensate for this drawback.

The research team manufactured a new composite solid electrolyte by mixing a porous YNa zeolite, which forms the main framework with SiO2 and Al2O3 in a polymer, with lithium salt. Conventional zeolites had the disadvantage of not dispersing uniformly in polymers. By adjusting the concentration of lithium salt, the team succeeded in developing a technology that enables uniform dispersion of zeolite and suppresses the formation of lithium dendrites at the lithium metal anode interface of lithium-ion batteries. This overcomes both the low mechanical strength of existing polymer solid electrolytes and the inflexibility of oxide or sulfide solid electrolytes. The porous YNa zeolite with a large specific surface area enables effective lithium-ion transport, showing a world-class lithium-ion transference number of 0.84, an ionic conductivity of 1.66 × 10^-2 S cm^-1 at 60 °C, and a capacity retention rate of over 95% after 100 cycles. Furthermore, due to the absence of lithium dendrite formation, it demonstrated stable operation for over 1500 cycles at a high current density of 200 μA/cm^2 in lithium plating and stripping cycle tests.

Principal Researcher Kim said, “Although research on zeolite-based composite solid electrolytes was almost nonexistent, after numerous trials and errors and persistent efforts, we were able to produce a solid electrolyte with world-leading performance. Since this solid electrolyte is flexible, it can be very usefully applied in the future to batteries for wearable devices that have no risk of explosion or fire.”

This research result was published as a cover paper in the international journal 'Journal of Materials Chemistry A' on October 29.

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