A representational image of EV batteries.Getty Images
Researchers at the Korea Advanced Institute of Science and Technology (KAIST) have achieved a significant breakthrough in anode-free lithium metal batteries.
These batteries represent a promising evolution for electric vehicles, drones, and advanced energy storage systems. Though they promise substantially greater energy density than traditional lithium-ion batteries, their limited lifespan has so far impeded commercialization.
Now, a team from KAIST, led by Professors Jinwoo Lee and Sung Gap Im in the Department of Chemical and Biomolecular Engineering, has overcome a major hurdle toward widespread adoption. The team focused on modifying the electrode surface rather than repeatedly adjusting electrolyte formulations. The result is an anode-free lithium metal battery with a dramatically increased battery life.
Developing anode-free lithium metal batteries
The greatest problem when it comes to developing anode-free lithium metal batteries is interfacial instability. This refers to the chemical and mechanical instability at the interface between the electrolyte and the electrode.
The team overcame this problem by applying an extremely thin artificial polymer coating—just 15 nanometers thick—to the electrode. This innovation, detailed in a new paper published in the journal Joule, greatly improves battery durability.
Anode-free lithium metal batteries feature a streamlined design, employing only a copper current collector at the anode in place of conventional graphite or lithium metal. This configuration yields 30–50% greater energy density, reduced production expenses, and more straightforward manufacturing compared to standard lithium-ion batteries.
However, from the first charging cycle, lithium deposits directly onto the copper, quickly depleting the electrolyte and creating an unstable solid electrolyte interphase (SEI). This results in rapid performance degradation and the reduced lifespan that is so problematic for anode-free lithium metal batteries.
In their research, the KAIST team avoided electrolyte modifications by reengineering the copper current collector’s surface. Using initiated chemical vapor deposition (iCVD), the team deposited a consistent ultrathin polymer film. This coating manages electrolyte interactions, directing lithium-ion movement and limiting unwanted electrolyte breakdown.
Accelerating the commercialization of next-gen batteries
In traditional batteries, electrolyte solvents break down to produce soft, fragile organic SEI layers, leading to uneven lithium plating and the formation of sharp, dendritic structures that resemble needles.
The team’s new polymer layer resists mixing with electrolyte solvents, instead favoring decomposition of salt anions. This produces a firm, inorganic-rich SEI that curbs excessive electrolyte loss and uncontrolled SEI thickening.
Through techniques like operando Raman spectroscopy and molecular dynamics simulations, the researchers revealed how the coating creates an anion-enriched zone near the electrode during operation, fostering a robust inorganic SEI.
Notably, this solution involves merely adding a slim protective film without changing the electrolyte, ensuring strong alignment with current production lines and low additional costs. The iCVD method supports scalable, continuous roll-to-roll processing, ideal for commercial-scale output.
As Professor Jinwoo Lee pointed out in a press statement, “beyond developing new materials, this study is significant in that it presents a design principle showing how electrolyte reactions and interfacial stability can be controlled through electrode surface engineering. This technology can accelerate the commercialization of anode-free lithium metal batteries in next-generation high-energy battery markets such as electric vehicles and energy storage systems (ESS).”
