• 한국세라믹학회지
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• 제55권4호
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• pp.307-324
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• 2018

Rechargeable lithium-ion batteries (LIBs) have been rapidly expanding from IT based applications to uses in electric vehicles (EVs), smart grids, and energy storage systems (ESSs), all of which require low cost, high energy density and high power density. The increasing demand for LIBs has resulted in increasing price of the lithium source, which is a major obstacle to wider application. To date, the possible depletion of lithium resources has become relevant, giving rise to the interest in Na-ion batteries (NIBs) as promising alternatives to LIBs. A lot of transition metal compounds based on conversion-alloying reaction have been extensively investigated to meet the requirement for the anodes with high energy density and long life-time. In-depth understanding the electrochemical reaction mechanisms for the transition metal compounds makes it promising negative anode for NIBs and provides feasible strategy for low cost and large-scale energy storage system in the near future.

• 전력전자학회논문지
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• 제26권5호
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• pp.357-363
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• 2021

Eco-friendly hybrid railroad propulsion system with fuel-cell and battery was suggested to reduce carbon dioxide gas and replace retired diesel railroads. Lithium-ion battery with high energy/power density and long lifetime is selected as the energy source at the battery side due to its excellent performance. However, the performance of lithium-ion batteries was affected by temperature, current rate, and operating condition. Temperature is known to be the most influential factor in changing battery parameters. In addition, appropriate thermal management is required to ensure the safe and effective operation of lithium-ion battery. Electro-thermal coupled model with varying parameter depends on temperature, and state-of-charge (SOC) is suggested to estimate battery temperature. The electric-thermal coupled model contains diffusion current using parameter identification by adaptive control algorithm when considering thermal diffusion effect. An experiment under forced convection was conducted using cylindrical cell and 18 parallel-connected battery module to demonstrate the method.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.72-72
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• 2012

Lithium rechargeable batteries have been widely used as key power sources for portable devices for the last couple of decades. Their high energy density and power have allowed the proliferation of ever more complex portable devices such as cellular phones, laptops and PDA's. For larger scale applications, such as batteries in plug-in hybrid electric vehicles (PHEV) or power tools, higher standards of the battery, especially in term of the rate (power) capability and energy density, are required. In PHEV, the materials in the rechargeable battery must be able to charge and discharge (power capability) with sufficient speed to take advantage of regenerative braking and give the desirable power to accelerate the car. The driving mileage of the electric car is simply a function of the energy density of the batteries. Since the successful launch of recent Ni-MH (Nickel Metal Hydride)-based HEVs (Hybrid Electric Vehicles) in the market, there has been intense demand for the high power-capable Li battery with higher energy density and reduced cost to make HEV vehicles more efficient and reduce emissions. However, current Li rechargeable battery technology has to improve significantly to meet the requirements for HEV applications not to mention PHEV. In an effort to design and develop an advanced electrode material with high power and energy for Li rechargeable batteries, we approached to this in two different length scales - Atomic and Nano engineering of materials. In the atomic design of electrode materials, we have combined theoretical investigation using ab initio calculations with experimental realization. Based on fundamental understanding on Li diffusion, polaronic conduction, operating potential, electronic structure and atomic bonding nature of electrode materials by theoretical calculations, we could identify and define the problems of existing electrode materials, suggest possible strategy and experimentally improve the electrochemical property. This approach often leads to a design of completely new compounds with new crystal structures. In this seminar, I will talk about two examples of electrode material study under this approach; $LiNi_{0.5}Mn_{0.5}O_2$ based layered materials and olivine based multi-component systems. In the other scale of approach; nano engineering; the morphology of electrode materials are controlled in nano scales to explore new electrochemical properties arising from the limited length scales and nano scale electrode architecture. Power, energy and cycle stability are demonstrated to be sensitively affected by electrode architecture in nano scales. This part of story will be only given summarized in the talk.

• 한국세라믹학회지
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• 제53권3호
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• pp.306-311
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• 2016

Li-air batteries have received much attention due to their superior theoretical energy density. However, their sluggish kinetics on the cathode side is considered the main barrier to high performance. The rational design of electrode catalysts with high activity is therefore an important challenge. To solve this issue, we performed density functional theory (DFT) calculations to analyze the adsorption behavior of the $LiO_2$ molecule, which is considered to be a key intermediate in both the Li-oxygen reduction reaction (ORR) and the evolution reaction (OER). Specifically, to use the activity descriptor approach, the $LiO_2$ adsorption energy, which has previously been demonstrated to be a reliable descriptor of the cathode reaction in Li-air batteries, was calculated on $LaB_{1-x}B^{\prime}_xO_3$(001) (B, B' = Mn, Fe, Co, and Ni, x = 0.0, 0.5). Our fast screening results showed that $LaMnO_3$, $LaMn_{0.5}Fe_{0.5}O_3$, or $LaFeO_3$ would be good candidate catalysts. We believe that our results will provide a way to more efficiently develop new cathode materials for Li-air batteries.

• Journal of Electrochemical Science and Technology
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• 제13권1호
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• pp.32-53
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• 2022

Although lithium-ion batteries are currently the most reliable power supply system for various mobile applications, further improvement in energy density is still required as the need for batteries in large energy-consuming devices is rapidly growing. However, in the anode, the most widely commercialized graphite-based anode materials almost face theoretical limitations. In addition, sodium-ion batteries have been actively studied to replace expensive charge carriers with cheaper ones. Accordingly, conversion-based materials have been extensively studied as high-capacity anode materials in both lithiumion batteries and sodium-ion batteries because their theoretical capacity is twice or thrice higher than that of insertion-based materials. This review will provide a comprehensive understanding of conversion-based materials, including basic charge storage behaviors, critical drawbacks that should be overcome, and practical material design for high-performance.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권4호
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• pp.460-465
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• 2013

Electrical equipments of nuclear power plant are divided into class 1E and non-class 1E. Electrical equipment and systems that are essential to emergency reactor shutdown, containment isolation, reactor core cooling, and containment and reactor heat removal, are classified as class 1E. batteries of nuclear power plant are divided into four channels, which are physically and electrically separate and independent. The battery bank of class 1E DC power system of the nuclear power plant use lead-acid batteries in present. The lead acid battery, which has a high energy density, is the most popular form of energy storage. Kt factor of lead-acid battery is used to determine battery size and it is one of calculatiing coefficient for capacity. this paper analyzes Kt factor of lead-acid battery for the DC power system of nuclear power plant. In addition, correlation between Kt parameter and peukert's exponent of lead-acid battery for nuclear plant are discussed. The analytical results contribute to optimize of determining size Lead-acid battery bank.

• 한국응용과학기술학회지
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• 제40권6호
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• pp.1191-1200
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• 2023

The lithium ion battery has applied to various fields of energy storage systems such as electric vehicle and potable electronic devices in terms of high energy density and long-life cycle. Despite of various research on the electrode and electrolyte materials, there is a lack of research for investigating of the binding materials to replace polymer based binder. In this study, we have investigated petroleum pitch/polymer composite with various ratios between petroleum pitch and polymer in order to optimize the electrochemical and physical performance of the lithium-ion battery based on petroleum pitch/polymer composite binder. The electrochemical and physical performances of the petroleum pitch/polymer composite binder based lithium-ion battery were evaluated by using a charge/discharge test, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and universal testing machine (UTM). As a result, the petroleum pitch(MP-50)/polymer(PVDF) composite (5:5 wt % ratio) binder based lithium-ion battery showed 1.29 gf mm^-1 of adhesion strength with 144 mAh g^-1 of specific dis-charge capacity and 93.1 % of initial coulombic efficiency(ICE) value.

• 한국재료학회지
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• 제32권11호
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• pp.474-480
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• 2022

Lithium-ion batteries (LIBs) are powerful energy storage devices with several advantages, including high energy density, large voltage window, high cycling stability, and eco-friendliness. However, demand for ultrafast charge/discharge performance is increasing, and many improvements are needed in the electrode which contains the carbon-based active material. Among LIB electrode components, the conductive additive plays an important role, connecting the active materials and enhancing charge transfer within the electrode. This impacts electrical and ionic conductivity, electrical resistance, and the density of the electrode. Therefore, to increase ultrafast cycling performance by enhancing the electrical conductivity and density of the electrode, we complexed Ketjen black and graphene and applied conductive agents. This electrode, with the composite conductive additives, exhibited high electrical conductivity (12.11 S/cm), excellent high-rate performance (28.6 mAh/g at current density of 3,000 mA/g), and great long-term cycling stability at high current density (88.7 % after 500 cycles at current density of 3,000 mA/g). This excellent high-rate performance with cycling stability is attributed to the increased electrical conductivity, due to the increased amount of graphene, which has high intrinsic electrical conductivity, and the high density of the electrode.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권6호
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• pp.328-334
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• 2000

A lithium ion secondary battery using carbon as a negative electrode has been developed. Further improvements to increase the cell capacity are expected by modifying the structure of the carbonaceous material. There are hopes for the development of large capacity lithium ion secondary batteries with long cycle, high energy density, high power density, and high energy efficiency. In the present paper, needle cokes from petroleum were examined as an anode of lithium ion secondary battery. Petroleum cokes, MCL(Molten Caustic Leaching) treated in Korea Institute Energy Research, were carbonized at various temperatures of 0, 500, 700, $19700^{\circ}C$ at heating rate of $2^{\circ}C$/min for lh. The electrolyte was used lM liPF6 EC/DEC (1:1). The voltage range of charge & discharge was 0.0V(0.05V) ~ 2.0V. The treated petroleum coke at $700^{\circ}C$ had an initial capacity over 560mAh.g which beyond the theoretical maximum capacity, 372mAh/g for LiC6. This phenomena suggests that carbon materials with disordered structure had higher cell capacity than that the graphitic carbon materials.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.1129-1131
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• 2002

Zinc Air battery obtain their energy density advantage over the other batteries by utilizing ambient oxygen as the cathode materials, and reusing cathode as recycled form. And specific capacity of zinc powder is as high as 820mAh/g. When Zinc Air battery discharged by low rate current discharge voltage profile has very flat pattern until end of voltage. But, when Zinc Air battery discharged by high rate current discharge voltage and capacity become lower. Therefore, we focused on effects of catalyst size in cathode. So we examined performance of zinc air batteries, average discharge voltage, capacity, energy, resistance. And we also obtained resistance by the GSM pulse discharge. So we have got optimum size of catalyst for Zinc Air battery.