The lithium-ion batteries (LIBs) that are currently available use flammable organic liquid electrolytes, posing a potential fire and explosion hazard.
This project sought to replace liquid electrolytes with safer solid electrolytes in lithium-ion batteries. This required the team to overcome low ionic conductivity and deterioration of performance characteristics due to high resistance in the degradation of contact with the anode and cathode that occurs during cell manufacturing.
A soft, half solid-state electrolyte material was designed that can be directly coated onto electrodes by mixing in a fluoropolymer, a ceramic solid electrolyte that features enhanced conductivity, with a small amount of liquid electrolyte, before making the mixture into a film.
The electric energy storage capacity of the new battery is about 95% of the capacity of the conventional LIB but with enhanced safety.
The ionic conductivity of a LLZO ceramic electrolyte was improved to as much as a fifth of the level found in conventional liquid electrolytes and separators. By applying this technology, an organic-inorganic hybrid solid electrolyte with enhanced ionic movement capability was designed and developed that is more than 50% better than the level found in conventional liquid electrolytes and separators.
Developing a lithium secondary battery that features high-safety solid electrolytes, which performs as well as organic liquid electrolytes, will enable LIB use in electric vehicles and energy storage systems, while ensuring public safety.