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Recent Research Interests

Stress-Electrochemistry Coupling

Stress couples to various aspects of electrochemical reactions, including the electrochemical potential, diffusion, composition or phase behavior. This fundamental aspect of materials science has various exciting features that we can employ into device concepts. Some examples include the electrochemically driven mechanical energy harvesters or electrochemical actuators. However, understanding such behavior has been difficult to establish. We attempt to study the fundamental materials science aspects of stress-electrochemistry coupling by 1) designing novel device concepts and 2) in situ characterization techniques.

[References]

27. Strong Stress-Composition Coupling in Lithium Alloy Nanoparticles
Nature Communications 2019 10 3428
H.K. Seo, J.Y. Park, J.H. Chang, K.S. Dae, M.-S. Noh, S.S. Kim, C.-Y. Kang, K. Zhao, S. Kim*, J. Yuk*

21. Li Alloy-based Non-Volatile Actuators
Nano Energy 2019 57 653-659
M.-S. Noh, H. Lee, Y.G. Song, I. Jung, R. Ning, S.W. Paek, H.-C. Song, S.-H. Baek, C.-Y. Kang*, S. Kim*

5. Electrochemically driven Mechanical Energy Harvesting
Nature Communications 2016 7 10146
S. Kim, S.J. Choi, K. Zhao, H. Yang, G. Gobbi, S. Zhang, J. Li*

Design of Energy Harvesters

As more and more Internet of Things (IoT) devices get online, the power sources for them become a critical issue. Some devices may not have easy accessibility for frequent battery replacements. Thus, design of efficient energy harvesters that convert ambient energy sources such as vibrations, human walking or low-grade heat becomes a crucial technological challenge. Various types of energy harvesters such as thermoelectric, piezoelectric, triboelectric energy harvesters have been devised, however, none has claimed to be the most efficient yet. We aim to design various novel types of energy harvesters as well as hybridized energy harvesters, targeting specific ambient power sources.

[References]
28. Rational Design for Optimizing Hybrid Thermo-Triboelectric Generators Targeting Human Activities
ACS Energy Letters 2019 4 2069-2074
B. Seo, Y. Cha, S. Kim*, W. Choi*

19. Mechanical Fatigue Resistance of Piezoelectric PVDF polymers
Micromachines 2018 9 503
Y.-H. Shin, I. Jung, H. Park, J.J. Pyeon, J.G. Son, C.M. Koo, S. Kim*, C.-Y. Kang*

15. Metal-free, Flexible Triboelectric Generator based on MWCNT mesh film and PDMS layers
Applied Surface Science 2018 442 693-699
H. Hwang, K.Y. Lee, J.-H. Shin, S. Kim*, W. Choi*

14. Piezoelectric Polymer-based Roadway Energy Harvesting via Displacement Amplification Module
Applied Energy 2018 216 741-750
Y.-H. Shin, I. Jung, M.-S. Noh, J.H. Kim, J.-Y. Choi, S. Kim*, C.-Y. Kang*

Thermodynamics of Oxynitride Formation

Metal oxynitrides balance the exciting materials properties that oxides and nitrides possess. The compounds exhibit both the lowered band gaps of nitrides and the stability of the oxides. However, the known chemical space of oxynitrides is rather small compared to those of oxides or nitrides. Only a number of crystalline oxynitrides have been synthesized so far, and the thermodynamic driving force for their formation has not been fully understood; many of them have positive enthalpy of formation and configurational entropy has largely been considered to be the driving force for their formation. We attempt to study the chemical space of oxynitrides via density functional theory (DFT) calculations and machine learning algorithms.

[References]
18. A novel class of oxynitrides stabilized by nitrogen dimer formation
Scientific Reports 2018 8 14471
S. Kim*, H.J. Gwon, S.W. Paek, S.K. Kim, J.-W. Choi, J.-S. Kim, J.-H. Choi, C.-Y. Kang*, S.-H. Baek*

Recent Grants

3. Samsung Research Funding & Incubation Center for Future Technology
Role: PI
Amount: KRW 350,000,000/year (PI portion KRW 200,000,000/year)
Dates: 2019/12 – 2022/12

2. Samsung Research Funding & Incubation Center for Future Technology
Role: Co-PI
Dates: 2019/09 – 2022/08

1. KIST Institutional Grant
Role: PI
Amount: KRW 20,000,000/year
Dates: 2018/09 – 2019/08

External Computing Resources

1. KISTI Supercomputing Center (8,600,000 CPU hours 2019-2020)

2. KISTI Supercomputing Center (400,000 CPU hours Fall 2018)

 

Collaborators

Center for Electronic Materials (KIST)

Prof. Ju Li (MIT)

Prof. Kejie Zhao (Purdue University)

Prof. Sulin Zhang (Penn. State University)

Prof. Jong Min Yuk (KAIST)

Prof. Wonjoon Choi (Korea University)