https://scholarworks.bwise.kr/erica/handle/2021.sw.erica/94 2026-04-04T21:05:37Z 2026-04-04T21:05:37Z Lee, Boram Son, Mu Geun Song, Shin Ae Kim, Kiyoung Woo, Ju Young Choa, Yongho Kang, Joonhee Lim, Sung Nam https://scholarworks.bwise.kr/erica/handle/2021.sw.erica/121894 2026-01-08T10:02:57Z 2025-12-01T00:00:00Z

Title: Insights into the design of zincophilic artificial protective layers enabling uniform nucleation and deposition for stable dendrite-free Zn anodes Authors: Lee, Boram; Son, Mu Geun; Song, Shin Ae; Kim, Kiyoung; Woo, Ju Young; Choa, Yongho; Kang, Joonhee; Lim, Sung Nam Abstract: Aqueous zinc-ion batteries (AZIBs) are highly attractive as energy-storage systems owing to their inherent safety, low cost, and simple assembly processes. However, the growth of Zn dendrites and side reactions at the Zn metal anode significantly degrade their electrochemical performance. To address these challenges, this study introduces a surface modification that increases the lifespan and cycling stability of AZIBs by constructing an artificial zinc sulfide (ZnS) protective layer on the Zn anode. For the first time, the fundamental mechanism of uniform Zn plating underneath the ZnS protective layer is demonstrated through experiments and density functional theory simulations. In addition, the artificial ZnS protective layer of optimized thickness is formed using a simple, thickness-controllable coating method. Notably, the ZnS protective layer favors Zn atom adsorption while suppressing clustering, enabling uniform Zn deposition. In addition, defects within the thin ZnS coating modulate Zn2+ adsorption and diffusion, which facilitates Zn plating underneath the protective layer. This mechanism promotes uniform Zn nucleation and enhances the kinetics of Zn2+, preventing dendrite formation and side reactions and thereby improving the stability and electrochemical performance of the battery. The resulting Zn@ZnS||Zn@ZnS symmetric cell exhibits a cycle life of over 1600 h and excellent rate performance. Moreover, it maintains a high coulombic efficiency of 99.5 % and capacity retention of 80.1 % after 1500 cycles at a current density of 0.5 A g(-1), demonstrating exceptional long-term cycling stability. These insights into developing effective artificial protective layers that enable uniform nucleation will promote durable, dendrite-free Zn anodes for advanced AZIBs.

2025-12-01T00:00:00Z Im, Taehyeob Kim, Suyeon Kim, Juyong Kim, Minjong Ahn, Jonghyeok Lee, Kwiyoung Lee, Dongju Lee, Jai-Sung 김종렬 Lee, Caroline Sunyong https://scholarworks.bwise.kr/erica/handle/2021.sw.erica/122057 2026-01-09T15:03:00Z 2025-12-01T00:00:00Z

Title: Additive manufacturing of Fe-6.5Si cores with metal-insulator-metal structure via dual-nozzle material extrusion (MEX) technology Authors: Im, Taehyeob; Kim, Suyeon; Kim, Juyong; Kim, Minjong; Ahn, Jonghyeok; Lee, Kwiyoung; Lee, Dongju; Lee, Jai-Sung; 김종렬; Lee, Caroline Sunyong Abstract: This study proposes a novel approach for fabricating Fe-6.5 wt. %Si (Fe-6.5Si) soft magnetic cores using a dual-nozzle material extrusion (MEX) three-dimensional (3D) printing technology followed by a spark plasma sintering (SPS) process. A SiO2 insulator was printed between the Fe-6.5Si layers to fabricate metal-insulator-metal (MIM)-structured cores. Densified Fe-6.5Si soft magnetic cores (over 99%) were obtained owing to the resolution of the sintering problem with Fe-6.5Si because of its brittle nature using SPS. The magnetic core with a 0.2 mm-printed insulator (MC0.2) achieved a uniform insulator thickness of approximately 85 mu m. Despite MC0.2 being approximately three times thicker than the single Fe-6.5Si layer (magnetic core single layer, MCS), a SiO2 insulator used in the cores of MC0.2 and MCS, resulted in comparable eddy current losses at 1 kHz. This highlighted the effectiveness of the MIM structure in suppressing the eddy currents. Thus, the proposed approach offers a promising solution for overcoming the geometric limitations of traditional stamping processes and paves the way for advanced magnetic core applications in additive manufacturing.

2025-12-01T00:00:00Z Kim, Tae Sung Park, Geun Ho Kim, Dong Woon Park, Joo Hyun https://scholarworks.bwise.kr/erica/handle/2021.sw.erica/120519 2026-01-09T12:03:49Z 2025-08-01T00:00:00Z

Title: Evolution Mechanism of Nonmetallic Inclusions in Fe-1.5Al-xSi (x = 0.5–3.0 wt%) Alloyed Steels Authors: Kim, Tae Sung; Park, Geun Ho; Kim, Dong Woon; Park, Joo Hyun Abstract: The effects of Si content of steel melts containing 1.5% Al as well as alloying sequence of Si and Al on the evolution of inclusions are investigated. The SiO2 inclusion is primarily formed when Si (=0.5–3.0 wt%) is added to the melts at 1873 K, and the area fraction (AF) of the inclusions decreases over time. The subsequent addition of 1.5% Al to the Si-alloyed steel (i.e., 3.0Si→1.5Al) increases the AF of inclusions due to the formation of Al2O3. The population density function (PDF) analysis for the preferential Si alloying shows a fractal distribution, indicating that the inclusions grow by a collision mechanism. PDF analysis shows a lognormal distribution because Al2O3 inclusion is formed and grows after subsequent Al alloying. Alternatively, when 1.5% Al is preferentially added to steel, Al2O3 clusters are formed. The AF of Al2O3 cluster decreases over time. When 3.0% Si is subsequently added to the Al-alloyed steel (i.e., 1.5Al→3.0Si), singular Al2O3 particles are mainly observed. Because the Al alloying results in the formation of Al2O3 regardless of the alloying sequence and Si content, it is important to float up and separate Al2O3 cluster to improve the cleanliness of high-Si-Al-alloyed steels such as electrical steels. © 2024 The Author(s). Steel Research International published by Wiley-VCH GmbH.

2025-08-01T00:00:00Z Jun, Yeongjin Chung, Yongsug Park, Sungjin Kang, Suchang Paek, Min-Kyu Park, Joo Hyun https://scholarworks.bwise.kr/erica/handle/2021.sw.erica/122065 2025-09-05T01:30:32Z 2025-03-01T00:00:00Z

Title: Influence of tundish flux on reoxidation behavior of Al-killed Ti-containing stainless steel Authors: Jun, Yeongjin; Chung, Yongsug; Park, Sungjin; Kang, Suchang; Paek, Min-Kyu; Park, Joo Hyun Abstract: The cleanliness of Ti-containing ferritic stainless steel (Ti-FSS) has been improved via vacuum-oxygendecarburization (VOD) and ladle treatment (LT) processes. However, the reoxidation phenomena inevitably occur during melt transfer from ladle to continuous casting tundish, resulting in a loss of titanium yield in conjunction with the formation of reoxidative inclusions. Hence, the present work aims to systematically investigate the combinational effect of different tundish fluxes on the reoxidation behavior of Al-killed Ti-FSS melt. Rice husk ash (RHA) and MgO (M) insulation powders, and calcium aluminate, CaO-Al2O3 (CA) based flux were used for the experiments. When the molten steel was covered by M + CA fluxes, the average size of inclusions decreased. On the other hand, when the RHA + CA fluxes were added, the average size of inclusion decreased, whereas total number of inclusions significantly increased due to a reoxidation reaction by SiO2 in RHA. When the M + RHA + CA combinative fluxes were added, the size of inclusion decreased, and the number of inclusions exhibited a value between the M + CA and RHA + CA conditions. Consequently, a decrease in total oxygen content in Ti-FSS was most effective in the M + CA flux combination.

2025-03-01T00:00:00Z