겹층구조의 LMO-NCM 복합양극을 통한 고온 사이클 수명개선 연구

유성태,류지헌,Yoo, Seong Tae,Ryu, Ji Heon 한국전기화학회 2022 한국전기화학회지 Vol.25 No.4

Spinel LiMn₂O₄ (LMO) and layered LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) are widely used as positive electrode materials for lithium-ion batteries. LMO and NCM positive electrode materials have a complementary properties. LMO has low cost and high safety and NCM materials show a relatively high specific capacity and better cycle life even at elevated temperature. Therefore, the LMO and NCM active materials are blended and used as a positive electrode in large-size batteries for electric vehicles (xEV). In this study, the cycle performance of a blended electrode prepared by simply mixing LMO and NCM and a bi-layer electrode in which two electrode layers aree sequentially coated are compared. The bi-layer electrode prepared by composing the same ratio of both active materials has similar capacity and cycle performance to the blend electrode. However, the LN electrode coated with LMO first and then NCM is the best in the full cell cycle performance at elevated temperature, and the NL electrode, in which NCM is first coated with LMO has a faster capacity degradation than the blended electrode because LMO is mainly located on the top of the electrode adjacent to electrolyte and graphite negative electrode. Also, the LSTA (linear sweep thermmametry) analysis results show that the LN bi-layer electrode in which the LMO is located inside the electrode has good thermal stability.

Fabrication of a three-electrode battery using hydrogen-storage materials

Roh, Chi-Woo,Seo, Jung-Yong,Moon, Hyung-Seok,Park, Hyun-Young,Nam, Na-Yun,Cho, Sung Min,Yoo, Pil J.,Chung, Chan-Hwa Elsevier 2015 Journal of Power Sources Vol.280 No.-

<P><B>Abstract</B></P> <P>In this study, an energy storage device using a three-electrode battery is fabricated. The charging process takes place during electrolysis of the alkaline electrolyte where hydrogen is stored at the palladium bifunctional electrode. Upon discharging, power is generated by operating the alkaline fuel cell using hydrogen which is accumulated in the palladium hydride bifunctional electrode during the charging process. The bifunctional palladium electrode is prepared by electrodeposition using a hydrogen bubble template followed by a galvanic displacement reaction of platinum in order to functionalize the electrode to work not only as a hydrogen storage material but also as an anode in a fuel cell. This bifunctional electrode has a sufficiently high surface area and the platinum catalyst populates at the surface of electrode to operate the fuel cell. The charging and discharging performance of the three-electrode battery are characterized. In addition, the cycle stability is investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We design new-concept three-electrode battery using hydrogen as energy carrier. </LI> <LI> Charging process is electrolysis of alkaline electrolyte. </LI> <LI> Discharging process is operation of alkaline fuel cell. </LI> <LI> Hydrogen is stored at bifunctional electrode as metal hydride with charging process. </LI> <LI> Bifunctional electrode acts as electrolysis cathode and fuel cell anode at same time. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

임피던스 변환 회로를 이용한 건식능동뇌파전극 개발

고덕원,이관택,김성민,이찬희,정영진,임창환,정기영 대한임상신경생리학회 2011 Annals of Clinical Neurophysiology Vol.13 No.2

Background: A dry-type electrode is an alternative to the conventional wet-type electrode, because it can be applied without any skin preparation, such as a conductive electrolyte. However, because a dry-type electrode without electrolyte has high electrode-to-skin impedance, an impedance-converting amplifier is typically used to minimize the distortion of the bioelectric signal. In this study, we developed an active dry electroencephalography (EEG) electrode using an impedance converter, and compared its performance with a conventional Ag/AgCl EEG electrode. Methods: We developed an active dry electrode with an impedance converter using a chopper-stabilized operational amplifier. Two electrodes, a conventional Ag/AgCl electrode and our active electrode, were used to acquire EEG signals simultaneously, and the performance was tested in terms of (1)the electrode impedance, (2) raw data quality, and (3) the robustness of any artifacts. Results: The contact impedance of the developed electrode was lower than that of the Ag/AgCl electrode (0.3±0.1 vs. 2.7±0.7 kΩ, respectively). The EEG signal and power spectrum were similar for both electrodes. Additionally, our electrode had a lower 60-Hz component than the Ag/AgCl electrode (16.64 vs. 24.33 dB, respectively). The change in potential of the developed electrode with a physical stimulus was lower than for the Ag/AgCl electrode (58.7±30.6 vs. 81.0±19.1 μV, respectively), and the difference was close to statistical significance (P=0.07). Conclusions: Our electrode can be used to replace Ag/AgCl electrodes, when EEG recording is emergently required, such as in emergency rooms or in intensive care units.

불용성 전극의 염소계 산화제 생성 특성

박미정,이택순,강미아 한국수처리학회 2017 한국수처리학회지 Vol.25 No.6

The electrochemical water treatment process using the insoluble electrode, the chemical reaction occurs through the electrode, which is the most important factor determining the water treatment ability and treatment efficiency of the electrode. The performance characteristics of the electrode vary greatly depending on various parameters of the manufacturing process, and the oxidant generation characteristics and the current efficiency are different depending on the material of the catalyst electrode layer of the electrode. The effects of the material and composition of the catalyst electrode layer on the chlorine oxidizer formation characteristics were evaluated in order to improve the utilization of the insoluble electrode as a water treatment electrode. The ruthenium dioxide (RuO₂) electrode, the iridium dioxide (IrO₂) electrode, the platinum (Pt) electrode, and the mixed metal oxide electrode (MMO) are used in the platinum-based insoluble electrode used in the water treatment. In this study, it was confirmed that the ruthenium-based catalyst electrode layer was the most effective, especially the electrode containing palladium was more excellent as a result of comparing the production characteristics of the chlorine-based oxidizing agent for the single material electrode and the composite material electrode. .

측면 게이트 전극을 이용한 스크린 프린트 되어진 탄소나노튜브 전계방출원의 연구

김창득,이형락,양기원,이영석,구교준,오의동,송창연,이민섭 한국물리학회 2017 새물리 Vol.67 No.3

A triode electrode field emitter having a lateral-gate electrode was fabricated, and its characteristics were confirmed. Generally, a gate electrode with a lateral-gate electrode structure is formed in proximity to the cathode electrode. The cathode and the gate electrodes were formed by using a one-step process with carbon nanotubes (CNTs). The field emission of the diode electrode structure was measured before that of the triode electrode structure was. The turn-on voltage of the diode electrode structure was 240 V. The turn-on voltage of the triode electrode structure was 40 V higher than that of the diode electrode structure. However, all field emitted currents of the triode electrode structure were confirmed to flow to the anode electrode. 측면에 게이트 전극을 가지는 삼극구조 전계방출원을 제작하여 그 특성을 확인하였다. 측면 게이트 전극의 구조는 음극 전극 측면에 게이트 전극이 형성 되어진 형태를 가진다. 음극 전극과 게이트 전극은 탄소나노튜브 (carbon nanotube, CNT)를 이용하여 한번의 스크린 프린트 공정을 이용하여 동시에 형성하였다. 이러한 측면 게이트 전극을 이용하여 수평 방향의 이극구조 전극에 대한 전계방출 특성을 확인하였다. 또한 양극 전극과 일정한 간격을 가지는 삼극구조의 전극에 대한 전계방출 특성을 확인하였다. 이극구조의 전계방출은 240 V에서부터 전계방출이 시작되는 것을 확인하였다. 삼극구조에서의 전계방출은 280 V에서부터 전계방출이 시작되어 이극구조에 비하여 40 V가 증가되어 전계방출이 시작됨을 확인하였다. 양극 전극을 이용한 삼극구조에서 게이트 전극으로 전계방출 되어진 전자들이 양극 전극 방향으로 전계방출됨을 확인하였다. 또한 삼극구조에서의 전계방출 특성 분석을 통하여 전계방출원으로의 적용가능성을 확인하였다.

Fabrication of Electrochemical Sensor with Tunable Electrode Distance

Yi, Yu-Heon,Park, Je-Kyun The Institute of Electronics and Information Engin 2005 Journal of semiconductor technology and science Vol.5 No.1

We present an air bridge type electrode system with tunable electrode distance for detecting electroactive biomolecules. It is known that the narrower gap between electrode fingers, the higher sensitivity in IDA (interdigitated array) electrode. In previous researches on IDA electrode, narrower patterning required much precise and expensive equipment as the gap goes down to nanometer scale. In this paper, an improved method is suggested to replace nano gap pattering with downsizing electrode distance and showed that the patterning can be replaced by thickness control using metal deposition methods, such as electroplating or metal sputtering. The air bridge type electrode was completed by the following procedures: gold patterning for lower electrode, copper electroplating, gold deposition for upper electrode, photoresist patterning for gold film support, and copper etching for space formation. The thickness of copper electroplating is the distance between upper and lower electrodes. Because the growth rate of electroplating is $0.5{\mu}m\;min^{-1}$, the distance is tunable up to hundreds of nanometers. Completed electrodes on the same wafer had $5{\mu}m$ electrode distance. The gaps between fingers are 10, 20, 30, and $40{\mu}m$ and the widths of fingers are 10, 20, 30, 40, and $50{\mu}m$. The air bridge type electrode system showed better sensitivity than planar electrode.

A6014-T4 합금 소재의 저항 점 용접 시 용융 거동 및 전극 열화에 미치는 전극 패터닝 효과

전현욱,김재훈,김재원,이은경,김양도,지창욱 대한금속·재료학회 2020 대한금속·재료학회지 Vol.58 No.12

In this study, the effects of electrode surface design on the resistance spot weldability and degradation of the electrode following resistance spot welding (RSW) of aluminum 6014-T4 alloy were investigated. A new patterning method that can be produced through repetitive pressurization was applied to the electrode, producing a lattice-like pattern shape on the resulting patterned electrode. When RSW was performed using the lattice patterned electrode, the contact resistance decreased because of the effective removal of the oxide film from the surface of the aluminum alloy. As a result, heat generated by resistance on the E/S interface was reduced. Moreover, the growth rate of the weld nuggets formed with the patterned electrode in the thickness direction was lower than that of the nuggets formed with the as-received electrode, and there was comparatively less Cu-Al alloying of the patterned electrode. In addition, a continuous RSW process was performed on the alloy to observe the effect of the electrode surface design on electrode sticking. The results indicated that electrode surface shape can significantly influence resistance heat generation and electrode cooling effects, as well as produce welds with different weld morphology and microstructure. Finally, it was proved that the patterned electrode suffered less electrode degradation through EPMA on the electrode surface after the continuous RSW was completed.

Effects of finite dimension on the electro-elastic responses of an interface electrode in a piezoelectric actuator

Li, Y.-D.,Lee, K.Y. WILEY-VCH Verlag 2010 Zeitschrift für angewandte mathematik und mec Vol.90 No.1

<P>All piezoelectric actuators are of finite dimension. The effect of finite geometry on the electro-elastic responses is of significance to the design of practical actuators. Electromechanical model is established for an interface electrode in a piezoelectric actuator with finite dimension. The methods of infinite series and Cauchy singular integral equation are employed to perform the electro-elastic analysis. The accuracy of numerical calculation is analyzed and the suitability of the present methods is discussed. Parametric studies on the electro-elastic intensity factors yield three conclusions. (a) A central electrode rather than an off-center one can help to enhance the structural reliability. (b) For an actuator with central electrode, it is better to make the interface twice as long as the electrode. For an actuator with periodical interface electrodes, the optimal allocation of electrodes is to make the space identical to the electrode length. (c) The thickness of the piezoelectric layer should be at least a quarter of the electrode length.</P> <B>Graphic Abstract</B> <P>All piezoelectric actuators are of finite dimension. The effect of finite geometry on the electro-elastic responses is of significance to the design of practical actuators. Electromechanical model is established for an interface electrode in a piezoelectric actuator with finite dimension. The methods of infinite series and Cauchy singular integral equation are employed to perform the electro-elastic analysis. The accuracy of numerical calculation is analyzed and the suitability of the present methods is discussed. Parametric studies on the electro-elastic intensity factors yield three conclusions. (a) A central electrode rather than an off-center one can help to enhance the structural reliability. (b) For an actuator with central electrode, it is better to make the interface twice as long as the electrode. For an actuator with periodical interface electrodes, the optimal allocation of electrodes is to make the space identical to the electrode length. (c) The thickness of the piezoelectric layer should be at least a quarter of the electrode length.</P> <img src='wiley_img/00442267-2010-90-1-ZAMM200900328-content328.gif' alt='wiley_img/00442267-2010-90-1-ZAMM200900328-content328'>

Embedded Metal Electrode for Organic–Inorganic Hybrid Nanowire Solar Cells

Um, Han-Don,Choi, Deokjae,Choi, Ahreum,Seo, Ji Hoon,Seo, Kwanyong American Chemical Society 2017 ACS NANO Vol.11 No.6

<P>We demonstrate here an embedded metal electrode for highly efficient organic inorganic hybrid nanowire solar cells. The electrode proposed here is an effective alternative to the conventional bus and finger electrode which leads to a localized short circuit at a direct Si/metal contact and has a poor collection efficiency due to a nonoptimized electrode design. In our design, a Ag/SiO2 electrode is embedded into a Si substrate while being positioned between Si nanowire arrays underneath poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), facilitating suppressed recombination at the Si/Ag interface and notable improvements in the fabrication reproducibility. With an optimized microgrid electrode, our 1 cm(2) hybrid solar cells exhibit a power conversion efficiency of up to 16.1% with an open-circuit voltage of 607 mV and a short circuit current density of 34.0 mA/cm(2). This power conversion efficiency is more than twice as high as that of solar cells using a conventional electrode (8.0%). The microgrid electrode significantly minimizes the optical and electrical losses. This reproducibly yields a superior quantum efficiency of 99% at the main solar spectrum wavelength of 600 nm. In particular, our solar cells exhibit a significant increase in the fill factor of 78.3% compared to that of a conventional electrode (61.4%); this is because of the drastic reduction in the metal/contact resistance of the 1 mu m-thick Ag electrode. Hence, the use of our embedded microgrid electrode in the construction of an ideal carrier collection path presents an opportunity in the development of highly efficient organic inorganic hybrid solar cells.</P>

Estimation of Electrode Consumption using Mast Position in Electric Arc Furnace

Kyuhwan Kim,Jae Jin Jeong,Taewon Kim,Sang Woo Kim 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

In order to automate the electrode replacement process, it is necessary to estimate the electrode consumption. Because the electrode controller lowers the electrode according to the electrode consumption, it is possible to estimate the consumption by measuring the position of the electrode. However, due to the structure of the electrode and the electrode arm, it is difficult to measure the electrode position directly. Thus we measured the position of the mast which holds up the electrode arm. In order to determine when to replace the electrode, it is necessary to know the consumption of the electrode per operation. So, we calculated the representative value of the mast position for every operation. Then, we analyzed the changing trend of the representative values of the mast position to estimate the electrode consumption. Also, because the arc length increases about 1 cm when the arc voltage increases 10 V, we modified the representative values and estimated the electrode consumption. The results which were obtained from the analysis of the mast position are in good agreement with the real operation pattern.