A team of scientists has found a surprisingly simple way to solve one of the biggest problems holding back next-generation lithium batteries.
By adding an ultrathin polymer coating—thousands of times thinner than a human hair—to a battery’s surface, researchers have dramatically extended the lifespan of anode-free lithium metal batteries, a technology widely seen as a game changer for electric vehicles, drones, and energy storage.
The breakthrough comes from researchers at KAIST and was published in the journal Joule.
The work was led by Professors Jinwoo Lee and Sung Gap Im from KAIST’s Department of Chemical and Biomolecular Engineering.
Anode-free lithium metal batteries are attractive because of their simple design. Instead of using a traditional graphite anode, they rely on a plain copper surface.
During charging, lithium metal forms directly on this copper.
This approach can boost energy density by 30 to 50 percent compared with today’s lithium-ion batteries, while also reducing manufacturing complexity and cost.
However, this simplicity comes with a serious drawback. When lithium first deposits onto the bare copper surface, it reacts aggressively with the battery’s liquid electrolyte.
This leads to rapid electrolyte consumption and the formation of an unstable layer known as the solid electrolyte interphase, or SEI.
Over time, this instability causes uneven lithium buildup and the growth of sharp structures called dendrites, which shorten battery life and can lead to failure.
Until now, most attempts to fix this problem focused on changing the electrolyte itself. The KAIST team took a different approach. Instead of repeatedly reformulating battery liquids, they redesigned the electrode surface where the damage begins.
Using a technique called initiated chemical vapor deposition, the researchers coated the copper surface with a uniform polymer film just 15 nanometers thick. This ultrathin layer subtly changes how the electrolyte behaves at the interface.
Rather than allowing solvent molecules to break down and form a weak, unstable SEI, the polymer layer encourages the decomposition of salt components in the electrolyte. This leads to the formation of a strong, inorganic SEI that protects the electrode.
Advanced tools such as real-time Raman spectroscopy and molecular dynamics simulations revealed what was happening at the atomic level. The polymer layer creates an environment rich in negatively charged ions near the surface, guiding lithium ions to deposit evenly and preventing runaway reactions.
As a result, lithium metal grows more smoothly, electrolyte loss is reduced, and the battery can operate reliably for much longer.
One of the most promising aspects of this discovery is its practicality. The method does not require new electrolytes or expensive materials. The coating process is compatible with existing battery manufacturing lines and can be scaled up using roll-to-roll production, making it realistic for industrial use.
Professor Jinwoo Lee said the study goes beyond introducing a new material. It offers a clear design principle for controlling chemical reactions inside batteries through surface engineering.
With further development, this approach could help bring anode-free lithium metal batteries out of the lab and into real-world applications, powering the next generation of electric vehicles and large-scale energy storage systems.
Source: KSR.
