Researchers suppress dendrite growth to extend lithium-metal battery life

- KAIST, Kyungpook National University and National NanoFab Center design copper current collector that distributes lithium evenly

- Dendrite suppression and stable protective layer formation expected to boost electric vehicle range

An AI-generated image illustrating research on anode-free lithium-metal batteries using ultra-fine nanofabrication processes. [Provided by KAIST]

South Korean researchers have developed a technology that suppresses dendrite formation and extends the lifespan of anode-free lithium-metal batteries, a next-generation energy storage technology drawing growing interest.

KAIST announced Tuesday that a joint research team led by professors Lee Jin-woo and Jeong Hee-tae of the Department of Chemical and Biomolecular Engineering, working with researchers from Kyungpook National University and the National NanoFab Center, had applied ultra-fine semiconductor fabrication processes to batteries to develop a new method for extending the life of anode-free cells.

Conventional lithium-ion batteries store charged lithium in anode materials such as graphite. Anode-free batteries, by contrast, deposit lithium directly onto a thin copper current collector without a separate anode material. By eliminating the weight and space occupied by the anode, the design allows more energy to be packed into a battery of the same size, making it a widely watched next-generation technology.

A persistent obstacle, however, is that repeated charging and discharging causes lithium to accumulate unevenly on the copper surface, forming needle- or branch-like growths known as dendrites. The protective layer around the lithium also becomes unstable, causing battery performance and lifespan to deteriorate rapidly — a key barrier to the practical adoption of anode-free batteries.

Previous approaches to extending anode-free battery life involved adding excess lithium or applying thick protective coatings to the surface — either pre-loading lithium to compensate for losses during use, or encasing the electrode in an external protective layer. Both methods add material, however, making the battery heavier and thicker and undermining the compact, lightweight advantages that make anode-free designs attractive.

Instead of adding more material, the research team redesigned the copper current collector itself. Drawing an analogy to marking out parking spaces on a flat lot, they etched fine tubular structures into the copper surface so that lithium would spread out and deposit evenly across a wide area rather than concentrating in one spot.

(Clockwise from top left) KAIST doctoral student Kim Eun-ji, doctoral student Jeong Hyeon-ju, doctoral student Kim Jin-wook, Kyungpook National University Professor Lee Yong-hee, and KAIST professors Jeong Hee-tae and Lee Jin-woo. [Provided by KAIST]

To achieve this, the team employed a semiconductor patterning technique called secondary sputtering lithography. Etching tubes roughly 300 nanometers in diameter and 150 nanometers in height into the copper surface increased the area in contact with lithium to about four times that of a flat copper collector.

The team then coated the structured copper surface with a roughly 10-nanometer-thick layer of MXene, a two-dimensional advanced material — a film thousands of times thinner than a human hair. Rather than acting as a finished protective barrier, the MXene layer functions as a primer that draws in the components needed to build one. Once the battery operates, a hard protective layer rich in lithium fluoride forms naturally on the MXene surface.

This layer reduces unwanted reactions between the lithium and the electrolyte and suppresses spike-like dendrite growth. The team examined the battery's surface and interior under air-free conditions, confirming that a uniform nanoscale protective layer formed along the MXene coating and identifying the mechanism behind its formation.

The researchers expect the technology to find use in next-generation batteries for electric vehicles, urban air mobility, drones and ESS applications, where high energy density and light weight are essential. They plan to pursue commercialization by securing the ability to scale up the ultra-fine nanofabrication process for large-area continuous production and by evaluating large-format pouch cells incorporating various electrolytes and high-capacity cathodes.

"We expect this to serve as a foundational technology that extends battery life while minimizing increases in weight and volume, accelerating the practical adoption of high-energy anode-free batteries," Professor Lee Jin-woo said.

The findings were published in the international journal Advanced Functional Materials.

nbgkoo@heraldcorp.com