%43%68%65%6d%69%63%61%6c%45%6e%67%69%6e%65%65%72%69%6e%67
-
KAIST Extends Lifespan of Graphite-Free Anode-Free Batteries That Could Make EV Batteries Smaller and Lighter
Korean researchers have developed a technology that could make electric-vehicle (EV) batteries smaller and lighter while helping EVs travel farther on a single charge. A KAIST research team has proposed a new solution to a persistent problem in anode-free batteries, which reduce weight and volume by eliminating anode materials such as graphite that normally store lithium during charging. In these batteries, lithium can grow into sharp, spike-like structures that shorten battery life. The key lies in using nanofabrication techniques employed in semiconductor manufacturing to create uniform sites for lithium deposition and promote the formation of a robust protective layer.
KAIST (President Choongsik Bae) announced on September 22 that a joint research team led by Professors Jinwoo Lee and Hee-Tae Jung from the Department of Chemical and Biomolecular Engineering, working with researchers from Kyungpook National University (President Heo Young-woo) and the National NanoFab Center (President Park Heung Soo), has developed a new technology that extends the lifespan of anode-free batteries by applying the ultrafine fabrication processes used in semiconductor device manufacturing to batteries.
Conventional lithium-ion batteries store lithium in an anode material such as graphite during charging. Anode-free batteries, by contrast, deposit lithium directly onto a thin copper foil without a separate anode material. Because they eliminate the weight and volume that the anode material would otherwise occupy, they are drawing attention as a next-generation technology capable of packing more energy into a battery of the same size.
However, repeated charging and discharging cause lithium to deposit unevenly on the copper foil, growing into branch- or spike-like structures known as dendrites. The protective layer over the lithium also becomes unstable, causing the battery’s performance and lifespan to deteriorate rapidly. This is one of the most significant obstacles standing in the way of commercializing anode-free batteries.
Some previous approaches to extending the lifespan of anode-free batteries involved adding excess lithium or applying a thick protective layer to the surface. These methods provide extra lithium to compensate for losses during use or coat the surface with a protective film. However, adding more material makes the battery heavier and thicker, undercutting the very advantage of a small, lightweight anode-free battery.
To minimize added weight and volume, the research team modified the copper foil on which lithium is deposited. Much like marking out closely spaced parking bays in a flat lot, the team created an array of microscopic tube-shaped structures on the copper surface so that lithium spreads out and deposits evenly rather than concentrating in one spot.
To do this, the team used a process called secondary sputtering lithography (SSL), used for the precise micromachining of semiconductors. Fabricating microscopic tubes about 300 nanometers in diameter and 150 nanometers in height on the copper foil increased the surface area available for lithium deposition to about four times that of flat copper foil, helping to reduce localized, spike-like lithium growth.
The team then coated the copper foil with a roughly 10-nanometer-thick layer of MXene, a two-dimensional material, forming an ultrathin film only a few thousandths the thickness of a human hair. Rather than serving as a finished protective layer itself, the MXene acts like a primer that draws together the components needed to form one. In the LiPF6-based electrolyte used in the study, the MXene surface promotes the formation of a robust protective layer rich in lithium fluoride (LiF) as the battery operates.
This protective layer reduces unwanted reactions between the lithium and the electrolyte and also suppresses the spike-like growth of lithium. By examining electrode surfaces and cross sections while minimizing air exposure, the research team confirmed that a nanoscale protective layer forms uniformly along the MXene and identified the mechanism behind its formation. The analysis employed X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and transmission electron microscopy (TEM), among other techniques.
Professor Jinwoo Lee said, “This study shows how ultrafine fabrication techniques used in semiconductor manufacturing can create both uniform sites for lithium deposition and a stable protective layer without changing the bulk electrolyte formulation or adding excess lithium.” He added that the technology is expected to serve as a foundation for accelerating the commercialization of high-energy anode-free batteries by extending battery life while minimizing increases in weight and volume.
KAIST researchers Eunji Kim, Hyunju Jung, and Jinuk Kim participated as co-first authors on the study. The findings were published online in the international journal Advanced Functional Materials on September 1.
Paper title: Anion-Interactive Anode Interfaces for Stable Anode-Free Lithium Metal Batteries,
DOI 10.1002/adfm.77931
Author information: Eunji Kim (KAIST/National NanoFab Center, co-first author), Hyunju Jung (KAIST, co-first author), Jinuk Kim (KAIST, co-first author), Hee-Tae Jung (KAIST, corresponding author), Yonghee Lee (Kyungpook National University, corresponding author), Jinwoo Lee (KAIST, corresponding author)
This research was supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (RS-2026-25542167), as well as the Global Semiconductor Advanced Fab Utilization Project through the National Nano Fab Center (NNFC). This work was also supported by Semiconductor-Secondary Battery Interfacing Platform Technology Development Project of NNFC.
2026.09.22 View 2837 -
KAIST Develops High-Efficiency, Eco-Friendly Hydrogen Separation Membrane That Filters Hydrogen Through a Molecular “Network”
For hydrogen to be widely used as a clean energy source in everyday life, technologies that can extract only hydrogen with high purity from mixed gases are essential. KAIST researchers have presented a new strategy for developing high-performance separation membranes that can selectively filter hydrogen for clean hydrogen energy production.
KAIST (President Choongsik Bae) announced on the 13th of August that a research team led by Professor Tae-Hyun Bae of the Department of Chemical and Biomolecular Engineering has successfully introduced hydrogen-selective transport pathways at the angstrom scale inside polymer membranes and clarified their separation performance through the concept of “network completeness.”
*Angstrom (Å): An extremely small unit of length used to measure wavelengths of light or the size of atoms and molecules. One angstrom is one hundred-millionth of a centimeter, or one ten-billionth of a meter, roughly one-millionth the thickness of a human hair.
Hydrogen is drawing attention as an eco-friendly energy source because it does not emit pollutants when used. However, separating hydrogen with high purity from mixed gases generated during production remains a key challenge for commercialization.
Crystalline porous materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are advantageous because their pores can be designed uniformly. However, they are difficult to fabricate over large areas without defects and have limitations in separating small molecules such as hydrogen. Polymer membranes, by contrast, are easier to process and scale up to large areas, but because their pore formation is difficult to control precisely, it has been challenging to raise their separation performance beyond a certain level.
To combine the advantages of both types of materials, the research team designed a modular network structure in which polymer chains are linked by crosslinkers. In this process, the team focused on the limitation that conventional indicators such as the degree of crosslinking (CD) and effective crosslinking degree (ECD), which have been used to describe the extent of crosslinking, cannot determine whether pores useful for separation have actually been formed.
The researchers therefore proposed a new metric called the Bridge Connectivity Degree (BCD), which refers to the proportion of crosslinkers that are connected at both ends to form complete pathways. This made it possible to quantitatively apply the concept of “complete framework connectivity,” which has been emphasized in inorganic porous materials, to polymer networks as well.
The newly developed membrane, ms-oDMB-DB50, achieved a high bridge connectivity degree of 73%, and both its hydrogen permeability and hydrogen/nitrogen selectivity improved significantly compared with the original material, DB50. Analysis showed that the membrane contains numerous ultramicropores smaller than 3 Å, which carbon dioxide cannot access. The research team also proposed a “density-probe method,” using helium molecules, which are smaller than hydrogen, as probes to experimentally verify the existence of these ultramicropores.
The newly developed membrane also operated stably for 100 hours without any loss of performance. Its tensile strength, the force the membrane can withstand without breaking, was about twice that of previously reported high-performance polymer membranes, confirming that it also has the robust durability needed for industrial processes.
Dr. Hongju Lee said, “There have been previous attempts to combine the advantages of these two types of materials, but this study is different in that it defines ‘how completely the network is connected’ as a quantitative value and directly links that value to separation performance,” adding, “We hope this study will serve as a starting point for extending reticular synthesis, a design principle used for inorganic molecular sieves, to polymer membranes.”
Professor Tae-Hyun Bae said, “By stitching polymer chains together with crosslinkers that fit together like Lego blocks, we formed a network inside the membrane that selectively allows only small hydrogen gas molecules to pass through.”
This paper was led by Dr. Hongju Lee, currently a postdoctoral researcher at the Korea Institute of Science and Technology, as first author, with Professor Tae-Hyun Bae as corresponding author. The research was published on July 23 in the international journal Nature Communications.
Paper title: Network completeness enables angstrom-scale transport pathways in polymer membranes,
DOI: https://doi.org/10.1038/s41467-026-73860-
Author information: Hongju Lee, formerly of KAIST and currently at the Korea Institute of Science and Technology, first author; Suhyeon Choi, KAIST, second author; and Tae-Hyun Bae, KAIST, corresponding author
This research was supported by the 2025 Global C.L.E.A.N. Project and the Mid-Career Researcher Program under the Basic Research Program, funded by the Ministry of Science and ICT.
2026.08.13 View 2883