A research team from the Korea Advanced Institute of Science and Technology (KAIST) has made significant progress in developing anode-free lithium metal batteries, a promising technology for various applications such as electric vehicles, drones, and advanced energy storage systems.
Although these batteries are characterized by a much higher energy density than traditional batteries, their short lifespan has been the biggest obstacle to their widespread commercialization.
The research team, led by Professors Jino Lee and Sung Gap Im from the Department of Chemical and Biomolecular Engineering at KAIST, conducted a study aimed at modifying the electrode surface instead of focusing on modifying the electrolyte composition as is common. This approach resulted in the development of an anode-free lithium metal battery with a remarkably long lifespan.
The main challenge in developing this type of battery lies in the instability of the reaction at the interface between the electrolyte and the electrode. The team overcame this problem by applying an ultra-thin, manufactured polymer layer, no more than 15 nanometers thick, which significantly contributed to enhancing the battery’s durability, according to the results published in the journal “Joule.”
Anode-free batteries are characterized by their simplified design, which relies on a copper electrical conductor at the negative electrode instead of using traditional graphite or lithium metal, which provides an increase in energy density of between 30 and 50%, in addition to reducing production costs and simplifying the manufacturing process compared to traditional batteries.
It is known that the accumulation of lithium directly on copper during the first charging cycle leads to rapid consumption of the electrolyte and the formation of an unstable “SEI” layer, which significantly reduces the battery’s lifespan.
To overcome this problem, the KAIST team redesigned the surface of the copper conductor using the initiated chemical vapor deposition (iCVD) method to place a thin and homogeneous polymer layer that controls electrolyte reactions and directs the movement of lithium ions, which limits the undesirable decomposition of the electrolyte.
The study showed that the new layer prevents the electrolyte from mixing with the polymer film, and instead encourages the decomposition of salt anions, to form a solid “SEI” layer rich in inorganic materials, which reduces electrolyte loss and increases the thickness of the “SEI” irregularly.
The researchers confirmed, using techniques such as “operando Raman spectroscopy” and molecular dynamics simulations, that the coating creates an anion-rich region near the electrode, which enhances the formation of a strong and stable “SEI.”
Professor Jino Lee pointed out that this study is not limited to developing new materials, but also presents a design principle that demonstrates how to control electrolyte reactions and achieve interface stability through electrode surface engineering, which accelerates the potential for commercializing anode-free lithium metal batteries for use in future markets for electric vehicles and energy storage systems.
