• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.209-209
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• 2003

The adventages of Li alloys have attracted the attention of many research groups, many of which have investigated tin-based alloys [1-2], Despite interesting performances of these, the irreversible capacity loss systematically observed on the first cycle for these compounds is a main drawback for their use as anode materials in lithium ion cells. Not only Sn is efficient in forming alloys with Li, Si can also react with Li to form alloys with a high Li/Si ratio, like Li$\_$22/Si$\_$5/ at 400$^{\circ}C$. It corresponds to a capacity of 4200mAh/g. Electrochemical Li-Si reaction occurs between 0 and 0.3 V against Li/Li$\^$+/, so that high-energy density battery can be realized. Despite the high theoretical capacity of elements like Si, however, particles of the alloys crack and fragment due to the repeated alloying and do-alloying which occurs as cell are charged and discharged. The research groups of Muggins [3] and Besenhard [4] have proposed that the volume expansion due to the insertion of Li can be reduced in micro- and submicro-structured matrix alloys. For this reason, the research group of J.R. Dahn investigated Sn/Mo sequential sputter deposition to prepare nanocomposites [5]. In this study, we investigated the characterization and the electrochemical characteristics of sequentially sputtered Si/Mo multilayer for microbattery anode.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1492-1501
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• 2015

This paper analyzes the effect of voltage sag on distribution systems due to the connection of Electric Vehicles (EVs). In order to study the impact of the voltage sag on the power system, two scenarios have been selected in this paper. The distribution system and EVs are modeled using the Electro Magnetic Transients Program (EMTP). The numbers of EVs are predicted based on the number of vehicles in distribution system of Seoul. In addition, the number of EVs is set up using real-time traffic in Seoul to simulate Scenario I and II. The simulation results show that voltage sag can occur if the distribution system has more than 30% of the total number of vehicles.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.324-330
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• 2006

In this study, carbothermal reduction method was employed to synthesis Sn-Sb alloy powders from chief metal oxides with ultrafine sizes. The Sn-Sb powders consisting of ultrafine particles were formed at $800{\sim}900^{\circ}C$ by reduction of oxides. Those powders have high initial discharge capacities ($570{\sim}637\;mAh/g$) and discharge capacities of those powders maintain initial capacity after 20 cycle due to existence of ultrafine particles in powders and alloying effect of Sn-Sb.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.249-254
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• 2008

Ag doping effect on $Li[Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode material was studied. Specially, we focused on rate performance of Ag doped samples. The $Li[Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ powder was prepared by simple combustion method and the Ag was doped using $AgNO_3$ during gelation process. Based on X-ray diffraction analysis, there was no structural change by Ag doping, but the 'metallic' form of Ag was included in the doped powder. Both bare and Ag 1 wt.% doped sample showed similar discharge capacity of 242 mAh/g at 0.2C rate. However, as the increase of charge-discharge rate to 3C, Ag 1 wt.% doped sample showed higher discharge capacity (172 mAh/g) and better cyclic performance than those of bare sample. The discharge capacity of Ag 5 wt.% doped sample was relatively low at all rate condition. However it displayed better rate performance than other samples.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1435-1440
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• 2013

To investigate the influence of the carbon matrix on the electrochemical performance of Si/C composites, four types of Si/C composites were prepared using graphite, petroleum coke, pitch and sucrose as carbon precursors. A ball mill was used to prepare Si/C blends from graphite and petroleum coke, whereas a dispersion technique was used to fabricate Si/C composites where Si was embedded in disordered carbon matrix derived from pitch or sucrose. The Si/pitch-based carbon composite showed superior Si utilization (96% in the first cycle) and excellent cycle retention (70% after 40 cycles), which was attributed to the effective encapsulation of Si and the buffering effect of the surrounding carbon matrix on the silicon particles.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1864-1873
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• 2018

Energy shifting is an innovative method used to obtain the highest profit from the operation of energy storage systems (ESS) by controlling the charge and discharge schedules according to the electricity prices in a given period. Therefore, in this study, we propose an optimal charge and discharge scheduling method that performs energy shift operations derived from an ESS efficiency model. The efficiency model reflects the construction of power conversion systems (PCSs) and lithium battery systems (LBSs) according to the rated discharge time of a MWh-scale ESS. The PCS model was based on measurement data from a real system, whereas for the LBS, we used a circuit model that is appropriate for the MWh scale. In addition, this paper presents the application of a genetic algorithm to obtain the optimal charge and discharge schedules. This development represents a novel evolutionary computation method and aims to find an optimal solution that does not modify the total energy volume for the scheduling process. This optimal charge and discharge scheduling method was verified by various case studies, while the model was used to realize a higher profit than that realized using other scheduling methods.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.224-226
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• 1996

The purpose of this study is to research and develop $Li_xNi_{2-x}O_2$ cathode for lithium rechargeable battery. We investigated XRD, cyclic voltammetry, AC impedance response and charge/discharge cycling of $Li_xNi_{2-x}O_2$/Li cells. The cell resistance was decreased much at initial charge process from 100% SOC to 0% SOC. The discharge capacity based on $Li_xNi_{2-x}O_2$ of 1st and 15th cycles was 135mAh/g and 108mAh/g, respectively. The $Li_xNi_{2-x}O_2$/Li cell had a good properties.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.131-138
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• 2019

To improve the performance of Si anodes in advanced Li-ion batteries, the design of the electrode plays a critical role, especially due to the large volumetric expansion in the Si anode during Li insertion. In our study, we used a simple fabrication method to prepare Si-based electrodes by grafting polyacrylic acid (PAA) to a carboxymethyl cellulose (CMC) binder (CMC-g-PAA). The procedure consists of first mixing nano-sized Si and the binders (CMC and PAA), and then coating the slurry on a Cu foil. The carbon network was formed via carbonization of the binders i.e., by a simple heat treatment of the electrode. The carbon network in the electrode is mechanically and electrically robust, which leads to higher electrical conductivity and better mechanical property. This explains its long cycle performance without the addition of a conducting agent (for example, carbon). Therefore, the partially carbonized CMC-g-PAA binder presented in this study represents a new feasible approach to produce Si anodes for use in advanced Li-ion batteries.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.441-447
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• 2022

Silicon-based materials are one of the most promising anode active materials in lithium-ion battery. A carbon layer decorated on the surface of silicon particles efficiently suppresses the large volume expansion of silicon and improves electrical conductivity. Carbon coating through chemical vapor deposition (CVD) is one of the most effective strategies to synthesize carbon- coated silicon materials suitable for mass production. Herein, we synthesized carbon coated SiOx via pilot scale CVD reactor (P-SiO_x@C) and carbon coated SiO_x via industrial scale CVD reactor (I-SiO_x@C) to identify physical characteristic changes according to the CVD capacity. Reduced size silicon domains and local non-uniform carbon coating layer were detected in I-SiO_x@C due to non-uniform temperature distribution in the industrial scale CVD reactor with large capacity, resulting in increased surface area due to severe electrolyte consumption.

• Electronics and Telecommunications Trends
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• v.39 no.1
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• pp.83-94
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• 2024

There have been continuous requirements for developing more reliable energy storage systems that could address unsolved problems in conventional lithium-ion batteries (LIBs) and thus be a proper option for large-scale applications like energy storage system (ESS). As a promising solution, aqueous metal-ion batteries (AMIBs) where water is used as a primary electrolyte solvent, have been emerging owing to excellent safety, cost-effectiveness, and eco-friendly feature. Particularly, AMIBs adopting mutivalence metal ions (Ca²⁺, Mg²⁺, Zn²⁺, and Al³⁺) as mobile charge carriers has been paid much attention because of their abundance on globe and high volumetric capacity. In this research trend review, one of the most popular AMIBs, zinc-ion batteries (ZIBs), will be discussed. Since it is well-known that ZIBs suffer from various (electro) chemical/physical side reactions, we introduce the challenges and recent advances in the study of ZIBs mainly focusing on widening the electrochemical window of aqueous electrolytes as well as improving electrochemical properties of cathode, and anode materials.