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2024-03-15T11:00:36Z
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Artificial Li3N SEI-Enforced Stable Cycling of Li Powder Composite Anode in Carbonate Electrolytes
http://hdl.handle.net/20.500.11750/56528
Title: Artificial Li3N SEI-Enforced Stable Cycling of Li Powder Composite Anode in Carbonate Electrolytes
Author(s): Dzakpasu, Cyril Bubu; Gyan-Barimah, Caleb; Kang, Dongyoon; Song, Jihun; Jin, Dahee; Yu, Jong-Sung; Lee, Yong Min
Abstract: Lithium metal is considered one of the most attractive anode materials for next-generation batteries. However, the practical application of rechargeable Li-metal batteries has been hindered by the uncontrollable growth of Li dendrites and large volume changes during electrochemical cycling, leading to low Coulombic efficiency and safety concerns. This study reports a facile process of printing copper nitride nanowires (Cu3N NWs) onto Li metal powder (LMP) composite anode surface via a roll-pressing technique. Cu3N readily reacts with Li to form lithium nitride (Li3N), which is regarded as an excellent component for the interfacial layer on Li metal. The Li3N layer possesses a high ionic conductivity and ensures a homogeneous Li-ion flux, resulting in the suppression of dendrites. As a result, Li/Li symmetric cells assembled with the Li3N-LMP electrode exhibited lower overpotentials and superior cycling performance. Furthermore, NCM622/Li3N-LMP full cells demonstrated better capacity retention behavior (over 90% after 250 cycles) and higher discharge capacities during rate capability tests compared to the bare LMP cell. This study highlights the importance of a rational design of interfacial layers on LMP anodes for stable and long-term cycling. © 2024 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited
2024-01-31T15:00:00Z
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Development of Location-Data-Based Orchard Passage Map Generation Method
http://hdl.handle.net/20.500.11750/56529
Title: Development of Location-Data-Based Orchard Passage Map Generation Method
Author(s): Han, Joong-hee; Park, Chi-Ho; Jang, Young Yoon
Abstract: Currently, pest control work using speed sprayers results in increasing numbers of safety accidents such as worker pesticide poisoning and rollover of vehicles during work. To address this, there is growing interest in autonomous driving technology for speed sprayers. To commercialize and rapidly expand the use of self-driving speed sprayers, an economically efficient self-driving speed sprayer using a minimum number of sensors is essential. This study developed an orchard passage map using location data acquired from positioning sensors to generate autonomous driving paths, without installing additional sensors. The method for creating the orchard passage map presented in this study was to create paths using location data obtained by manually driving the speed sprayer and merging them. In addition, to apply the orchard passage map when operating autonomously, a method is introduced for generating an autonomous driving path for the work start point movement path, work path, and return point movement path. © 2024 by the authors.
2024-01-31T15:00:00Z
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Enhanced boiling heat transfer via microporous copper surface integration in a manifold microgap
http://hdl.handle.net/20.500.11750/56527
Title: Enhanced boiling heat transfer via microporous copper surface integration in a manifold microgap
Author(s): Kim, Kiwan; Kong, Daeyoung; Kim, Yunseo; Jang, Bongho; Cho, Jungwan; Kwon, Hyuk-Jun; Lee, Hyoungsoon
Abstract: Heat flux dissipation from electronic devices has increased with their miniaturization owing to the increasing performance demands and development of microfabrication technologies. Improving the heat transfer performance is crucial for enhancing heat dissipation. However, this often leads to an increase in pressure drop, which reduces energy efficiency. Microgap heat sink is a promising approach in this regard owing to its geometrical simplicity and facile fabrication while providing heat transfer performance comparable to that of microchannel heat sinks with substantially lower pressure drops. In this study, we develop a manifold microgap heat sink integrated with a porous copper surface that effectively enhances heat transfer while using significantly low pumping power. A three-dimensional liquid routing manifold is used to achieve better flow distribution and alleviate temperature non-uniformity while providing improved heat transfer by enabling jet impingement and mixing of the thermal boundary layer on the microgap surface with minimal additional pressure drop. Moreover, a microscale inverse opal structure is used to facilitate nucleate boiling on the microgap surface, which improves heat transfer while maintaining a relatively low flow resistance. A maximum heat flux of 322.8 W/cm2 was achieved at the mass flux of 472 kg/m2 s, and the corresponding pressure drop and maximum heater temperature were 0.6 kPa and 140 ℃, respectively. The coefficient of performance (COP) achieved herein was significantly higher than those reported in previous relevant studies, indicating that the proposed cooling technique can potentially be used for energy-efficient thermal management in electronics devices. © 2023 Elsevier Ltd
2024-02-29T15:00:00Z
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Ultrafast acousto-optic modulation at the near-infrared spectral range by interlayer vibrations
http://hdl.handle.net/20.500.11750/56526
Title: Ultrafast acousto-optic modulation at the near-infrared spectral range by interlayer vibrations
Author(s): Park, Tae Gwan; Kim, Chaeyoon; Oh, Eon-Taek; Na, Hong Ryeol; Chun, Seung-Hyun; Lee, Sunghun; Rotermund, Fabian
Abstract: The acousto-optic modulation over a broad near-infrared (NIR) spectrum with high speed, excellent integrability, and relatively simple scheme is crucial for the application of next-generation opto-electronic and photonic devices. This study aims to experimentally demonstrate ultrafast acousto-optic phenomena in the broad NIR spectral range of 0.77–1.1 eV (1130–1610 nm). Hundreds of GHz of light modulation are revealed in an all-optical configuration by combining ultrafast optical spectroscopy and light–sound conversion in 10–20 nm-thick bismuth selenide (Bi2Se3) van der Waals thin films. The modified optical transition energy and the line shape in the NIR band indicate phonon–photon interactions, resulting in a modulation of optical characteristics by the photoexcited interlayer vibrations in Bi2Se3. This all-optical, ultrafast acousto-optic modulation approach may open avenues for next-generation nanophotonic applications, including optical communications and processing, due to the synergistic combination of large-area capability, high photo-responsivity, and frequency tunability in the NIR spectral range. © 2024 the author(s), published by De Gruyter.