-Co-research with Stanford University, Selected for the cover paper of ‘Nano Letters’, a prestigious journal in the area of nanotechnology

-Proof of the core of the nanoelectrohydrodynamic phenomenon, Expected to maximize battery efficiency, etc.

▲(From left) SNU ECE Professor Sung Jae Kim, Stanford University Mechanical Engineering Professor Ali Mani, Korea Institute of Science and Technology Postdoctoral Researcher Hyekyung Lee, and Helmholtz-Zentrum Research Center M.D. Seoyun Sohn

The first study to prove the mechanism of accelerating ion transfer in batteries and seawater desalination devices has been published. This technology is attracting global attention as it can prevent the performance degradation or maximize the power efficiency of nanoporous membranes, which play a key role in such devices.

Seoul National University College of Engineering (Dean Kookheon Char) announced on the 1st that, Professor Sungjae Kim's team in ECE conducted joint research with Stanford University's Prof. Ali Mani team and proved the acceleration mechanism of electrolyte ion transfer through the nonporous membrane that occurs due to the recirculation current generated between nonuniformly arranged microstructures.

The research team theoretically/experimentally verified the recirculation current generated by connecting two microchannels that have a nanoporous membrane in between and installing microstructures at non-uniform intervals (Fig. a). They succeeded in using this current to drastically increase the iron current and to prevent the salt crystallization near the porous membrane.

The nanoporous membrane has pores of a size of 100 nanometers or less, and thus exhibit perm-selectivity, allowing only ions of polarity opposite of the surface charge of the membrane. In such a system, when an external electric field is applied, a nonlinear, over-limit current phenomenon occurs that greatly deviates from Ohm’s Law(law that dictates that current is proportional to the potential difference between two points and is inversely proportional to electrical resistance. This study is also attracting attention for the new mechanism for causing over-limit current.

The research team was able to obtain results after mimicking nature’s nonuniform microstructures and combining and thoroughly analyzing them. The results of this study hav key implications in the fields of energy and environment. In particular, it is expected to be useful for batteries and seewater desalination devices containing nanoporous membranes.

By applying this study, it is possible to maximize the charging efficiency in batteries by altering microstructures near nanoporous membranes to be nonuniform(Fig. b). In seawater desalination devices, it can minimize the generation of unwanted salts that degrades performance of the nanoporous membranes(Fig. c) and thus be applied for the prevention of membrane fouling.

Professor Sung Jae Kim of Seoul National University said, “We proved a mechanism that has great potential for industrial applications, as slight non-uniform distribution could elicit a significant power efficiency improvement. Currently, the joint research team is developing a platform that applies this technology to batteries and seawater desalination devices.”

The results of this study were published online on March 31 in 'Nano Letters', an authoritative journal in the field of nano science and technology. The paper was selected as the cover paper. This research was carried out with the support of the Ministry of Science and ICT's Mid-Range Researcher Support Project(중견연구자 지원 사업) and the Basic Research Lab Project(기초연구실 사업).

Fig. a. Micro fluid chip including microstructure of nonuniform distribution

Fig. b. Schematic diagram that shows the ion transfer acceleration when microstructures are nonuniformly arranged, in contrast to when arranged uniformly.

Fig. c. Experiment photo that shows the suppression of unwanted crystallization when microstructures are nonuniformly arranged, in contrast to when arranged uniformly

Source: http://ee.snu.ac.kr/community/news?bm=v&bbsidx=51187

Translated by: Jee Hyun Lee, English Editor of Department of Electrical and Computer Engineering, jlee621@snu.ac.kr