Researchers in South Korea have developed a new battery technology that could help electric vehicles travel farther on a single charge while using smaller and lighter battery packs. Scientists at the Korea Advanced Institute of Science and Technology (KAIST) have found a way to address one of the biggest challenges facing anode-free batteries: their tendency to degrade as lithium builds up unevenly during charging.
The breakthrough combines precision manufacturing techniques borrowed from the semiconductor industry with an ultrathin protective coating. The approach encourages lithium to accumulate more evenly and helps form a stable protective layer, potentially extending battery life without adding significant weight or bulk.
The research, led by Professors Jinwoo Lee and Hee-Tae Jung from KAIST’s Department of Chemical and Biomolecular Engineering, also involved Kyungpook National University and the National NanoFab Center. The findings were published online on September 1 in Advanced Functional Materials.
Why Anode-Free Batteries Could Improve EV Range
Most conventional lithium-ion batteries use graphite or another material to form the anode, where lithium is stored during charging. Anode-free batteries take a different approach by eliminating this separate anode material and allowing lithium to deposit directly onto a thin copper current collector.
Removing the conventional anode can reduce battery weight and thickness while increasing the amount of energy stored within a given volume. For electric vehicles, this could eventually translate into more compact battery packs, improved driving range, or additional cabin and cargo space without increasing vehicle size.
However, anode-free batteries have a major weakness that has prevented their widespread commercialization.
During repeated charging and discharging, lithium can accumulate unevenly on the copper surface, forming sharp, branching structures known as dendrites. These formations can reduce battery efficiency, accelerate degradation, and, in severe cases, increase the risk of internal short circuits.
The protective layer that naturally develops around deposited lithium can also become unstable, further contributing to battery deterioration.
Previous approaches have attempted to solve these problems by adding extra lithium to compensate for material losses or applying thicker protective coatings. While these methods can improve performance, they also add weight and volume, undermining the principal advantage of anode-free battery designs.
The KAIST team instead focused on engineering the copper surface itself.
Semiconductor Manufacturing Helps Control Lithium Growth
The researchers developed a specially patterned copper foil designed to encourage lithium to deposit more uniformly. The surface features an array of microscopic tube-like structures that provide more locations for lithium to accumulate instead of allowing it to concentrate in isolated areas.
The team fabricated these structures using secondary sputtering lithography (SSL), a precision manufacturing technique adapted from semiconductor processing.
Each microscopic tube measured approximately 300 nanometers in diameter and 150 nanometers in height. The resulting surface offered roughly four times the available area for lithium deposition compared with conventional flat copper foil.
The increased surface area helps spread lithium across a larger number of deposition sites, reducing localized buildup that can contribute to dendrite formation.
This approach is significant because it targets a fundamental problem with anode-free batteries without requiring large quantities of additional electrode material.
Ultrathin MXene Coating Creates a More Stable Battery Interface
The researchers also applied an approximately 10-nanometer-thick coating of MXene, a two-dimensional material, to the engineered copper surface.
Rather than serving simply as a conventional protective barrier, the coating helps promote the formation of a more stable protective layer as the battery operates.
In the electrolyte used in the experiments, the MXene surface encouraged the development of a layer rich in lithium fluoride (LiF). This protective layer helps limit unwanted chemical reactions between lithium and the electrolyte while suppressing the growth of damaging lithium structures.
By combining more uniform lithium deposition with improved chemical stability, the design addresses two major causes of capacity loss and shortened battery life.
To investigate how the protective layer formed, the scientists examined the electrode’s surface and internal structure while minimizing exposure to air. They used advanced analytical techniques, including X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and transmission electron microscopy.
These analyses helped confirm the formation of a uniform, nanoscale protective layer and explain the role of the MXene coating in stabilizing the electrode.
What the Breakthrough Could Mean for Electric Cars
The research demonstrates a potential way to improve anode-free battery durability without sacrificing the technology’s main benefits: high energy density and reduced material requirements.
For electric vehicle manufacturers, longer-lasting anode-free batteries could eventually provide greater driving range from smaller battery packs. Reducing battery size and material use could also create opportunities to lower vehicle weight and potentially reduce manufacturing costs.
However, the findings do not mean that electric cars using this technology are ready to enter production. Further development and validation will be needed to determine how the engineered electrodes perform under practical conditions, including long-term cycling, different temperatures, fast charging, and large-scale manufacturing.
Battery performance also depends on factors such as the electrolyte, cell design, operating conditions, and manufacturing consistency. Laboratory improvements must translate into reliable performance at the full battery-cell and pack level before automakers can realize the potential benefits.
Professor Jinwoo Lee said the research demonstrates how ultrafine semiconductor manufacturing techniques can create uniform lithium deposition sites and a stable protective layer without changing the bulk electrolyte formulation or adding excess lithium.
The team hopes the findings will help accelerate the development of high-energy anode-free batteries for future applications, including electric vehicles.
KAIST researchers Eunji Kim, Hyunju Jung, and Jinuk Kim served as co-first authors. The project received support from South Korea’s National Research Foundation, the National NanoFab Center, and related semiconductor and battery technology development programs.
If the approach can be scaled successfully, it could help overcome one of the key barriers to anode-free batteries and bring lighter, more energy-dense battery systems closer to practical use in future electric cars.
[source: Science Daily, image credit: KAIST]
