"Performance Unchanged Even in Cold"…Lithium Metal Battery 'Game Changer' Released

KAIST Research Team Develops Electrolyte Technology
"Solvent Performance Maintained from -20 to 60 Degrees Celsius"

A 'game changer' technology has emerged that can overcome the drawback of lithium secondary batteries, whose available capacity drops sharply in cold winter.

Changes in the solvation structure of the electrolyte and (below) schematic diagram of the operating mechanism of the developed electrolyte composition. Image source: Provided by KAIST

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 4th that the research team led by Professor Choi Nam-soon of the Department of Bio and Chemical Engineering has developed a world-class electrolyte technology that maintains high efficiency and energy of lithium metal batteries over a wide temperature range. The developed electrolyte formed a new solvation structure not previously reported and dramatically improved the lifespan characteristics of lithium metal batteries through additive technology that secures stable electrode-electrolyte interfacial reactions. The solvation structure generally refers to the formation of concentric shells by cations surrounded by charge-neutral solvents in electrolytes with low salt (ionic compound) concentration. It is a very important factor that expands the operating temperature range of batteries without increasing salt concentration.

With the acceleration of the electric vehicle era, the importance of developing high-capacity, high-energy-density secondary batteries that enable long driving distances on a single charge or can charge and discharge over a wide temperature range (-20 to 60 degrees Celsius), which corresponds to the global average temperature, is increasing.

The research team applied solvent composition technology and electrode interface protection technology that can operate stably over a wide temperature range (minus 20 to 60 degrees Celsius), unlike previously reported electrolytes with limited lithium ion mobility and restricted operating temperature ranges, achieving significantly improved coulombic efficiency compared to previous studies (minus 20 degrees Celsius 300 cycles 99.9%, room temperature 200 cycles 99.9%, high temperature 45 degrees Celsius 100 cycles 99.8%).

Also, battery life is considered as the number of cycles until 80% of the first cycle discharge capacity is reached under full charge-full discharge conditions. The developed electrolyte technology showed a high discharge capacity retention rate of 85.4% compared to the first cycle discharge capacity after 200 charge-discharge cycles at room temperature (25 degrees Celsius). Furthermore, it exhibited 91.5% retention after 100 cycles at high temperature (45 degrees Celsius) and 72.1% retention after 300 cycles at low temperature (minus 20 degrees Celsius), showing about 20% higher capacity retention under full charge-full discharge conditions compared to existing commercial technologies.

The research team explained, "We developed an electrolyte (PWSE) technology with a new solvation structure that maximizes performance over a wide temperature range from minus 20 to 60 degrees Celsius using lithium cobalt oxide cathodes," adding, "We also confirmed that storage performance is maintained even at high-temperature storage of 60 to 80 degrees Celsius. In particular, we presented a reference framework for lithium metal battery electrolytes, which will be a game changer in the lithium secondary battery electrolyte market."

This research result was published online on the 13th of last month in the international journal Energy & Environmental Science.

This content was produced with the assistance of AI translation services.