Search

Your search keyword '"Im, Hyeon-Gyun"' showing total 118 results
Start Over Author "Im, Hyeon-Gyun"
118 results on '"Im, Hyeon-Gyun"'

5. Fluorine-Free Cycloaliphatic Epoxy-Based Siloxane Nanohybrid Binder with High Polar Hydroxyl Group Content Enabling LiFePO4-Type Battery with High Electrochemical Performance and Stability

Author

Jeong, Uktae, Jang, Junho, Hwang, Young Geun, Kang, Dong Jun, Kang, Min Jeong, Yoo, Jung-Keun, Oh, Youngseok, Yi, Jin Woo, Yoon, Jihee, and Im, Hyeon-Gyun

Abstract

LiFePO4-type (LFP) batteries have attracted significant attention in most battery manufacturing industries due to their long lifespan, high-temperature safety, and low cost of raw materials. However, as an active material, LFP still suffers from several intrinsic drawbacks, including poor conductivity, a low Li+diffusion coefficient, low capacity, and a lack of electrochemical stability, primarily due to conventional fluorine-based binders. Here, we report a simple yet effective approach to developing a fluorine-free binder based on a robust cycloaliphatic epoxy-based siloxane nanohybrid material (CES) to achieve high electrochemical stability in LFP batteries. The high content of silanol moieties in CES induces a strong affinity for the active material and conductive agent, significantly improving rheological (thixotropy) and mechanical (adhesion and cohesion) properties, which enable the formation of a uniformly coated electrode. As a result, we achieved superior electrochemical performance and stability in CES-applied electrodes compared to those with conventional fluorine-based binders. We investigate the reasons behind the contribution of CES to the electrochemical stability of LFP batteries through various analyses. The high thermal and oxidation stability of CES effectively prevents degradation of LFP-based active materials. Our binder development strategy offers a significant breakthrough in replacing conventional fluorine-based binders, advancing the development of high-performance and stable secondary batteries.

Published
2024
Full Text
View/download PDF

7. A Fluorine‐Free Binder with Organic–Inorganic Crosslinked Networks Enabling Structural Stability of Ni‐Rich Layered Cathodes in Lithium‐Ion Batteries.

Author

Jang, Junho, Ahn, Junho, Ahn, Jinho, Jeong, Uktae, Yoon, Jihee, Park, Jun Kyu, Shin, Woohyeon, Kang, Min Jeong, Cho, Min‐kyung, Kang, Dong Jun, Kim, Jongsoon, Yoo, Jung‐Keun, and Im, Hyeon‐Gyun

Subjects
POLYVINYLIDENE fluoride, SURFACE reactions, STRUCTURAL stability, TRANSITION metals, SURFACE structure
Abstract

Although the high‐energy Ni‐rich layered cathodes suffer from undesirable surface reactions with the electrolyte, the polyvinylidene fluoride (PVDF) binder has a limitation on surface stabilization because of its weak affinity and low adhesion/cohesion. Here, it is demonstrated that the novel fluorine‐free and hydroxyl‐rich siloxane nanohybrid (SNH) binder can enhance the electrochemical performances of LiNi0.8Mn0.1Co0.1O2 cathode (NCM811) via successful surface stabilization. The high silanol content in the SNH binder enhances the affinity to both NCM811 and conductive agent, facilitating uniform electron/ion pathways with high mass loading, improved shear thinning, and superior mechanical properties. Moreover, the fluorine‐free organic‐inorganic hybrid structure prevents the dissolution of transition metals, active material structural changes, and electrolyte interaction, leading to greatly enhanced cyclability of the SNH‐based NCM811 electrode (≈81.9% in half‐cell; ≈87.82% in full‐cell after 200 cycles) compared to PVDF‐based NCM811 electrode (≈58.8% in half‐cell; ≈61.24% in full‐cell after 200 cycles). Various analyses also indicate that the application of the fluorine‐free SNH binder successfully stabilizes both the surface and bulk structure of the NCM811 cathode during charge/discharge. The binder design represents a straightforward yet highly effective approach to achieving remarkably prolonged cyclability in lithium‐ion batteries, surpassing the performance of other fluorine‐based or polymer‐based binders. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

14. Corrigendum to ‘A novel organosilicon-type binder for LiCoO2 cathode in Li-ion batteries’ [Energy Storage Materials 49 (2022) 58–66]

Author

Ahn, Junho, primary, Im, Hyeon-Gyun, additional, Lee, Yongseok, additional, Lee, Dasom, additional, Jang, Hyekyeong, additional, Oh, Youngseok, additional, Chung, Kyeongwoon, additional, Park, Teahoon, additional, Um, Moon-Kwang, additional, Yi, Jin Woo, additional, Kim, Jongsoon, additional, Kang, Dong Jun, additional, and Yoo, Jung-Keun, additional

Published
2022
Full Text
View/download PDF

15. A novel organosilicon-type binder for LiCoO2 cathode in Li-ion batteries

Author

Ahn, Junho, primary, Im, Hyeon-Gyun, additional, Lee, Yongseok, additional, Lee, Dasom, additional, Jang, Hyekyeong, additional, Oh, Youngseok, additional, Chung, Kyeongwoon, additional, Park, Teahoon, additional, Um, Moon-Kwang, additional, Yi, Jin Woo, additional, Kim, Jongsoon, additional, Kang, Dong Jun, additional, and Yoo, Jung-Keun, additional

Published
2022
Full Text
View/download PDF

21. An exceptionally large energy cathode with the K–SO4–Cu conversion reaction for potassium rechargeable batteries.

Author

Lee, Yongseok, Yoo, Jung-Keun, Park, Hyunyoung, Ko, Wonseok, Kang, Jungmin, Jo, Jae Hyeon, Yoon, Gabin, Im, Hyeon-Gyun, Yashiro, Hitoshi, Myung, Seung-Taek, and Kim, Jongsoon

Abstract

Although layered-type cathode materials for lithium-ion batteries (LIBs) have received great attention due to their large gravimetric energy density, those for potassium rechargeable batteries (PRBs) just deliver small and limited energy density due to the large structural change and phase transition during de/intercalation of K+ ions with a large ionic size. Thus, a new approach is required for achieving high energy densities. A cathode material that results in ultrahigh energy density for potassium rechargeable batteries (PRBs) based on the conversion reaction of K–SO4–Cu in the system was developed. To maximize the electrochemical performance, a copper-sulfate/carbon nanocomposite (hereafter denoted as N-CSO/C) was prepared using a simple high-energy ball-milling process. At a current density of 12 mA g−1, the conversion reaction of K–SO4–Cu in the PRB system resulted in a specific capacity of ∼240 mA h g−1 with an average operating voltage of ∼2.8 V (vs. K+/K). This capacity and the resulting energy density are larger than those of other cathode materials for PRBs reported to date. After 200 cycles at 360 mA g−1, N-CSO/C retained ∼70% of the initial capacity. The overall reversible reaction mechanism of K–SO4–Cu in N-CSO/C in the PRB system was investigated through combined studies using first-principles calculation and various experimental techniques. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

22. Transparent Nanocomposites: Biomimetic Chitin–Silk Hybrids: An Optically Transparent Structural Platform for Wearable Devices and Advanced Electronics (Adv. Funct. Mater. 24/2018)

Author

Hong, Moo‐Seok, primary, Choi, Gwang‐Mun, additional, Kim, Joohee, additional, Jang, Jiuk, additional, Choi, Byeongwook, additional, Kim, Joong‐Kwon, additional, Jeong, Seunghwan, additional, Leem, Seongmin, additional, Kwon, Hee‐Young, additional, Hwang, Hyun‐Bin, additional, Im, Hyeon‐Gyun, additional, Park, Jang‐Ung, additional, Bae, Byeong‐Soo, additional, and Jin, Jungho, additional

Published
2018
Full Text
View/download PDF

23. Biomimetic Chitin–Silk Hybrids: An Optically Transparent Structural Platform for Wearable Devices and Advanced Electronics

Author

Hong, Moo‐Seok, primary, Choi, Gwang‐Mun, additional, Kim, Joohee, additional, Jang, Jiuk, additional, Choi, Byeongwook, additional, Kim, Joong‐Kwon, additional, Jeong, Seunghwan, additional, Leem, Seongmin, additional, Kwon, Hee‐Young, additional, Hwang, Hyun‐Bin, additional, Im, Hyeon‐Gyun, additional, Park, Jang‐Ung, additional, Bae, Byeong‐Soo, additional, and Jin, Jungho, additional

Published
2017
Full Text
View/download PDF

35. Hybrid crystalline-ITO/metal nanowire mesh transparent electrodes and their application for highly flexible perovskite solar cells

Author

Im, Hyeon-Gyun, primary, Jeong, Seonju, additional, Jin, Jungho, additional, Lee, Jaemin, additional, Youn, Doo-Young, additional, Koo, Won-Tae, additional, Kang, Sin-Bi, additional, Kim, Hyo-Joong, additional, Jang, Junho, additional, Lee, Daewon, additional, Kim, Han-Ki, additional, Kim, Il-Doo, additional, Lee, Jung-Yong, additional, and Bae, Byeong-Soo, additional

Published
2016
Full Text
View/download PDF

38. Biomimetic Chitin–Silk Hybrids: An Optically Transparent Structural Platform for Wearable Devices and Advanced Electronics.

Author

Hong, Moo‐Seok, Choi, Byeongwook, Kim, Joong‐Kwon, Jeong, Seunghwan, Leem, Seongmin, Kwon, Hee‐Young, Hwang, Hyun‐Bin, Jin, Jungho, Choi, Gwang‐Mun, Bae, Byeong‐Soo, Kim, Joohee, Jang, Jiuk, Park, Jang‐Ung, and Im, Hyeon‐Gyun

Subjects
BIOMIMETIC materials, WEARABLE technology, CHITIN, SILK, COMPOSITE materials, CONTACT lenses
Abstract

Abstract: The cuticles of insects and marine crustaceans are fascinating models for man‐made advanced functional composites. The excellent mechanical properties of these biological structures rest on the exquisite self‐assembly of natural ingredients, such as biominerals, polysaccharides, and proteins. Among them, the two commonly found building blocks in the model biocomposites are chitin nanofibers and silk‐like proteins with β‐sheet structure. Despite being wholly organic, the chitinous protein complex plays a key role for the biocomposites by contributing to the overall mechanical robustness and structural integrity. Moreover, the chitinous protein complex alone without biominerals is optically transparent (e.g., dragonfly wings), thereby making it a brilliant model material system for engineering applications where optical transparency is essentially required. Here, inspired by the chitinous protein complex of arthropods cuticles, an optically transparent biomimetic composite that hybridizes chitin nanofibers and silk fibroin (β‐sheet) is introduced, and its potential as a biocompatible structural platform for emerging wearable devices (e.g., smart contact lenses) and advanced displays (e.g., transparent plastic cover window) is demonstrated. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

47. Heat Transferable Thin Film Encapsulation Inserted Ag Thin Film to Improve Reliability of Flexible Displays.

Author

Kwon, Jeong Hyun, Im, Hyeon-Gyun, Bae, Byeong-Soo, Chang, Ki Soo, Park, Sang-Hee Ko, and Choi, Kyung Cheol

Subjects
HEAT transfer, METALLIC thin films, FLEXIBLE display systems
Abstract

In this study, thin film encapsulation (TFE) with an Ag thin film is proposed to improve the long-term reliability of flexible displays in terms of the barrier property, flexibility, and heat dissipation. By applying thin film encapsulation to bottom-emission organic light-emitting diodes (BEOLEDs) fabricated on glass, the lifetimes of OLED devices were improved, showing differences among TFE layers. The maximum temperatures measured from the backside of the glass substrate were 66.73, 64.15, 59.21 and 39.63 °C after the OLED was operated at a luminance of 10000 cd/m2, and an operational lifetime test results were remarkably consistent with the measurement results of infrared images. Efficient heat dissipation through thermally conductive TFE layers improved the OLED reliability in terms of lifetime. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results