Research Field 1:

Direct Borohydride Feul Cell

2002 - 2007, LG Electronics Inc., Korea

2007 - Present, Nuclear, Plasma and Radiology Department, University of Illinois at Urbana-Champaign, IL

The Direct Borohydride Fuel Cell (DBFC) has been the subject of Dr. Kim's research since he began working as a chief research engineer in the Digital Appliance Lab at LG Electronics, South Korea, in 2002.
The DBFC is a relatively new type of fuel cell currently in the developmental stage, compared to hydrogen fuel cells, which have been introduced and utilized for several decades. The DBFC uses borohydride, a water-soluble chemical compound in solid form and an abundant natural resource in the U.S., as its fuel.

The design of the DBFC differs significantly from other types of fuel cells due to its electrochemical reaction, which requires the direct contact of fuel and catalytic electrodes, directly generating electrical energy. The DBFC has multiple advantages: borohydride can be stored as a chemically stable solid and dissolved in water to produce fuel on demand. Additionally, the DBFC offers higher energy density due to its double voltage—twice as strong as that of fuel cells using methanol or natural gas and twenty times stronger than wet cells commonly used in automobiles.

As a researcher, Dr. Kim has been dedicated to developing the DBFC for three key reasons. First, it is a relatively new field with significant potential and challenges. Second, Dr. Kim could apply his previous knowledge and experience with metal hydride application technology, which he gained during his doctoral research. Third, the DBFC is a highly competitive fuel cell from a mass production perspective because it utilizes non-precious metal hydride-based catalysts, unlike other fuel cells that rely on platinum or gold catalysts.

Dr. Kim's research on the development of the DBFC has included international collaborative efforts with research teams from Kogakuin University in Japan, the Korea Advanced Institute of Science and Technology in Korea, and the Kurchatov Institute in Russia. This collaboration led to the notable accomplishment of introducing a 1 kW portable DBFC system in 2004. This achievement resulted in the team securing forty-two patents and establishing confidence as pioneers in the field. The work was published as:

• C.H.Kim, K.J.Kim, M.Y.Ha, “Investigation of the characteristics of a stacked direct borohydride fuel cell for portable applications.” Journal of Power Sources, Volume 180, Pages 114-121, 2008, USA
• C.H.Kim, K.J.Kim, M.Y.Ha, “Performance enhancement of a direct borohydride fuel cell in practical running conditions.” Journal of Power Sources, Volume 180, Pages 154-161, 2008, USA

During his research on DBFC, Dr. Kim discovered that borohydride, used as an aqueous fuel solution, acts as an electrolyte that conducts ions and electrons. This characteristic must be carefully considered when designing the electrode, fuel channels, and fuel distribution manifolds. This discovery has made the DBFC design uniquely different from other types of fuel cells and has generated a considerable number of patent ideas.

One such idea involves designing the anode electrode with a corrugated shape to extend the fuel and catalyst contact surface area while eliminating the need for a complex fuel channel structure. This idea was applied for a patent and issued as:

• US 7318975, “Membrane electrode assembly of fuel cell,” Jan. 15, 2008
• KR 0806101, “Fuel cell,” Feb. 15, 2008

Moreover, many other discoveries from his DBFC research have led to the application of 46 additional patents, 7 of which have been issued in the U.S. and Korea to date. The related patents are:

• US 731658, “Fuel cell system,” Jan. 8, 2008
• US 7691501, “Fuel cell system and controlling method thereof,” Apr. 6, 2010
• US 7700206, “Fuel cell system,” Apr. 20, 2010
• US 7910251, “Fuel cell system,” Mar. 22, 2011
• KR 0565224, “Electrochemical battery, electrode thereof and method for manufacturing the same,” Mar. 22, 2006
• KR 0606978, “Fuel cell,” Jul. 24, 2006
• KR 0823924, “Structure for reducing internal circuit of fuel cell,,” Apr. 15, 2008

Dr. Kim firmly believes that the purpose of conducting research is not just to publish articles in scientific journals but also to drive innovations that can improve people's lives. With this conviction in mind, Dr. Kim began seeking opportunities to continue his research, even as his company shifted its focus to hydrogen fuel cells using natural gas reforming.

In 2006, while exploring further opportunities for DBFC research, Dr. Kim encountered a research team led by Prof. George H. Miley at the University of Illinois at Urbana-Champaign, which at the time was the only DBFC research team in the U.S. Consequently, Dr. Kim joined the team in 2007 through a mutual agreement. Since then, he has been active as a visiting research professor, working on the development of DBFCs for specialized applications where they may maximize their competitiveness.

Dr. Kim participated in the 2008 Wearable Power Pack Competition, organized by the Defense Research and Engineering division of the Department of Defense. Currently, he is developing a specialized DBFC system for unmanned underwater vehicles (UUVs), sponsored by the Mission and Unmanned Systems division of Lockheed Martin Corporation.

The performance and characteristics of direct borohydride/hydrogen peroxide (NaBH4/H2O2) fuel cells are being studied for potential applications in air-independent propulsion for outer space and underwater scenarios. With ocean water serving as a natural heat sink, this new fuel cell technology is particularly suited for underwater propulsion and power systems in small-scale, high-performance marine vehicles. The characteristics of this power system are compared with other options, specifically in underwater scenarios.

The potential of this fuel cell has been demonstrated through laboratory experiments, achieving a power density exceeding 1.5 W/cm² at 65°C and ambient pressure. This achievement was made possible through unique treatments of the fuel cell, including an in-situ electroplating technique. This technique results in electrodes with 20–40% higher power density than those produced by the conventional ex-situ electroplating method. Furthermore, this process simplifies the repair and reconditioning of the fuel cell.

The related paper is:

• N.Luo, G.Miley, K.J.Kim, R.Burton, X.Huang, “NaBH4/H₂O₂ fuel cells for air independent power systems.” Journal of Power Sources, Volume 185, Pages 685–690, 2008, USA

Dr. Kim is confident that his expertise, accumulated over the past ten years, is beneficial in various areas. In particular, it is a critical technology for the power source of robotic systems, which are expected to be widely adopted in national defense systems in the future.

Research Field 2:

Metal Hydride Thermal Energy Conversion System

1993 - 2000, Luikov Heat and Mass Transfer Institute, National Academy of Sciences, Belarus

2001 - 2002, DAC Lab of LG Electronics Inc., Korea

His expertise is not limited to fuel cells; it also encompasses metal hydride application as a thermal energy conversion technology. Dr. Kim conducted research on metal hydride application technology, a thermal energy conversion system, for nine years during his doctoral studies at the National Academy of Sciences, as a visiting researcher at the Luikov Heat and Mass Transfer Institute in Belarus, and as a senior research engineer at LG Electronics.

Metal hydride application technology enables the utilization of low-level thermal energy, such as waste heat, for cooling and heat upgrading, unlike refrigerators and air conditioners that consume electrical energy. This technology provides dual benefits:

1. Economic advantages: Waste heat from chemical or food processing industries can be used to operate refrigeration cycles without consuming electricity.

2. Ecological advantages: The global use of chlorofluorocarbons (CFCs), which are a primary cause of ozone layer depletion, can be reduced, as the technology uses hydrogen instead of CFCs.

A method of metal-hydride thermal energy conversion, proposed as an alternative to traditional vapor compression methods, has been investigated. Metal-hydride thermal energy converters, with varying thermo-physical properties, are arranged in pairs within parallel channels through which a heat-transfer agent flows. Thermal energy conversion occurs as a series of propagating heat waves. Numerical modeling demonstrates that the maximum thermal effect is achieved when the heat wave moves synchronously with the heat source (or sink) accompanying the phase transition in the metal-hydride thermal energy converter poles.

The research efforts, including the related paper and issued patent, are as follows:

• K.J.Kim, “Propagation of waves of metal-hydride thermal conversion in blown-through porous media.” Journal of Engineering Physics and Thermophysics, Vol.71, No.1, pp51~61, Minsk, Belarus, 1998
• G.A.Fateyev, M.A.Silenkov, K.J.Kim, “Experimental study of propagation of waves of energy conversion in blown- through porous media.” Journal of Engineering Physics and Thermo-physics, Vol.73, No.5, pp1093~1108, Minsk, Belarus, 2000
• KR 0442274, “Relief valve for airconditioner performing airconditioning by transmitting hydrogen,” Jul. 20, 2004
• S. Adamenko, A. Esaulov, B. Ulmen, V. Novikov, S. Ponomarev, A. Adamenko, V. Artyuh, A. Gurin, V. Prokopenko, V. Kolomiyets, V. Belous, K.-J. Kim, G. Miley, A. Bassuney, D. Novikov, "Exploring new frontiers in the pulsed power laboratory: Recent progress," Results in Physics 5, 62–68, 2015
• Ham, S.; Kang, S.; Kim, K.-J. A Numerical Study for Performance Prediction of a Metal Hydride Thermal Energy Conversion System Elaborating the Superadiabatic Condition. Energies 2020, 13, 3095.

Research Field 3:

Thermo-Dynamic Modeling of Internal Combustion Engine

1989 - 1991, Graduate school of INHA University, Korea

1991 - 1992, Korea Institute of Industrial Technology, Korea

Dr. Kim's journey as a scientific and engineering researcher began with his passion for understanding the physicochemical mechanisms of internal combustion engines during his graduate school years. These engines are mechanical systems that convert chemical energy directly into mechanical energy. Dr. Kim was particularly interested in Wankel-type rotary engines, which combine the mechanical advantages of two-cycle engines and the chemical advantages of four-cycle engines. Moreover, their unique geometrical structure results in lower friction loss compared to reciprocating engines.

Dr. Kim successfully developed a numerical model for the complex epitrochoidal motion of the engine, which accurately calculates the engine displacement in relation to the eccentric shaft angle. This model was later integrated into the thermodynamic model of internal combustion engines that Dr. Kim developed. The combined model not only predicts engine performance based on design parameters but also aids in designing and programming electronic engine management systems.

Dr. Kim's research and development experience in thermodynamic modeling significantly contributed to the development of electronic engine management systems and the evaluation of rotary engine performance for submarine applications during his tenure at the Korea Institute of Industrial Technology.

The efforts are introduced as:

• K.J.Kim, J.O.Chae, “A performance simulation of spark ignition Wankel type rotary engine.” The sixth international pacific conference of automotive engineers, Paper No. 912479, Seoul, Korea, 1991