Electric Vehicles Go 'Farther on a Single Charge'... Ultra Cost-Effective Battery Technology Even Tesla Would Covet

A dry-process manufacturing technology for thick-film electrodes has been developed that can extend the driving range of electric vehicles while reducing battery manufacturing costs.

On February 18, UNIST announced that a research team led by Professor Kwak Wonjin in the Department of Energy and Chemical Engineering, together with a team led by Professor Choi Junghyun at Gachon University and a team led by Professor Moon Janghyuk at Chung-Ang University, has developed a technology for dry-processed thick-film electrode batteries that can reduce both the initial capacity loss and the electrode manufacturing cost.

Research team, (clockwise from bottom right) Professor Kwak Wonjin, Researcher Lee Hyunwook (first author), Researcher Kim Dongha, Researcher Ji Hojung, Researcher Hwang Yuchan. Provided by UNIST

원본보기 아이콘

Thick-film electrodes are next-generation electrodes that increase battery capacity by increasing the thickness of the active material layer. Unlike conventional battery electrodes, they are manufactured using a dry process that does not use toxic solvents, offering the advantage of being environmentally friendly.

The problem is that they suffer from large initial capacity loss. All lithium-ion batteries inevitably experience lithium capacity loss during the initial charge-discharge cycles, but dry-processed thick-film electrodes show greater initial capacity loss because of the thick active material layer and the binder used to clump together the dry active material particles.

The research team developed an electrode that reduces initial capacity loss by inserting a thin lithium metal film between the active material layer of the anode and the copper foil (copper current collector layer) instead of a primer. A primer is originally a material that attaches the active material layer to the copper foil. The lithium metal inserted in place of the primer not only serves as a primer, but also pre-supplements the lithium that would otherwise be lost. The lithium in the thin film is drawn into the active material layer by the driving force of the potential difference.

In experiments, batteries using the developed dry thick-film electrodes showed an initial capacity loss approximately 75% lower than batteries using conventional electrodes. This translates into the potential to increase the driving range of electric vehicles by about 20% compared with current levels.

The cost of electrode manufacturing itself can also be reduced. Normally, even if the active material layer of the electrode is produced by a dry process, a separate wet process and drying step are still required to coat the primer layer, making the process complex. In this technology, the primer coating step is omitted altogether.

First author Researcher Lee Hyunwook explained, "This technology enables electrode adhesion and the pre-lithiation process, which replenishes lithium capacity, to be handled in a single step, and it can be directly integrated into the current roll-to-roll process, which is the standard for battery manufacturing." Roll-to-roll is a mass-production method in which copper foil in roll form is unwound, coated with electrode materials such as the active material layer, and then wound up again, similar to how a newspaper rotary press operates.

Professor Kwak Wonjin said, "Electrode thickening technology using dry processes is being aggressively developed by global companies such as Tesla," adding, "The anode technology developed in this study can be used regardless of the type of cathode, including high-nickel cathodes, and will help secure an advantage in the technology race."

Research figure: New battery thick-film electrode manufacturing technique (a, b) and electrode capacity enhancement effect (c).

원본보기 아이콘

This research was released online on January 21 in the world-renowned international journal Energy & Environmental Science and is awaiting formal publication.

The study was carried out with support from the Ministry of Trade, Industry and Energy's Materials and Components Development Program.

© The Asia Business Daily(www.asiae.co.kr). All rights reserved.