• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.735-737
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• 2017

An Off grid or remote solar electric systems are an energy supply to our home or to our companies without the utility of Grid at all. Off grid solar systems are very important for those who live in remote locations especially for developing countries where getting the electric grid is extremely expensive, inconvenient or for those who doesn't need to pay a monthly bill with the electric bill in general. The main critical components of any solar power system or renewable energy harvesting systems are the energy storage systems and its charge controller system. Energy storage systems are the essential integral part of a solar energy harvesting system and in general for all renewable energy harvesting systems. To provide an optimal solution of both high power density and high energy density at the same time we have to use hybrid energy storage systems (HESS), that combine two or more energy storage technologies with complementary characteristics. In this present work, design and simulation we use two storage systems supercapacitor for high power density and lithium based battery for high energy density. Here the system incorporates fast-response supercapacitors to provide power to manage solar smoothing and uses a battery for load shifting. On this paper discuss that the total energy throughout of the battery is much reduced and the typical thermal stresses caused by high discharge rate responses are mitigated by integrating supercapacitors with the battery storage system. In addition of the above discussion the off grid solar electric energy harvesting presented in this research paper includes battery and supercapacitor management system, MPPT (maximum power point tracking) system and back/boost convertors. On this present work the entire model of off grid electric energy harvesting system and all other functional blocks of that system is implemented in MATLAB Simulink.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1414-1417
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• 1996

The purpose of this study Is to research and develop $V_{6}O_{13}$ composite cathode for lithium thin film battery. $V_{6}O_{13}$ represents a class of cathode active material used in Li rechargeable batteries. In this study, we investigated cyclic voltammetry and charge/discharge characteristics of $V_6O_{13}$/SPE/Li cells. Cyclic voltammogram of $V_{6}O_{13}$/SPE/Li cell at scan rate 1mV/sec showed reduction peaks of 2.25V and 2.4V and oxidation peaks of 2.4V and 2.2V. The discharge curve of $V_{6}O_{13}$/SPE/Li cell showed 4 potential plateaus. The discharge capacity was decreased in the beginning of charge/discharge cycling. After 8th cycling, the discharge capacity was stable. The discharge capacity of 1st cycle and 15th cycle was 290mAh/g and 147mAh/g at $25^{\circ}C$, respectively.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.58-59
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• 2011

본 논문은 전류에 따른 NiMH 배터리의 성능 변화를 충 방전 실험을 통하여 비교 분석하였다. 따라서 실험을 통하여 NiMH 배터리의 데이터시트에 있는 충 방전 특성곡선과 실제 실험을 통한 충 방전 특성곡선을 비교 분석한다. 또한 충 방전 전류의 크기에 따라 변하는 특성곡선의 차이를 비교 분석한다. 전류 변화에 의한 배터리 분석을 위해 0.2C, 0.5C, 1C, 2C 정전류 충 방전 실험과 동일한 C-rate로 펄스전류로 충 방전 실험을 하였다. 실험을 통해서 얻은 데이터로 1차 Randles 등가회로를 통해 C-rate변화와 잔존용량 변화에 의한 파라미터 분석과 잔존용량-개로전압 곡선에서의 충 방전 히스테리시스를 알아보았다.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.194-195
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• 2019

배터리는 사용 기간과 회수가 증가함에 따라 수명이 점차 감소한다. SOH(State-Of-Health)는 배터리의 초기 상태와 현재 상태를 비교하여 배터리의 수명 상태를 나타내는 지표이며, 이는 배터리를 사용함에 있어서배터리의 현재 충전상태를 나타내는 SOC(State-Of-Charge)와 함께 정확한 추정을 필요로 한다. 본 논문에서는 리튬이온 배터리를 C-rate에 따라 노화시키며 각 C-rate별 SOH 추정 경향성을 분석하였다. 배터리의 SOC와 SOH는 확장 칼만 필터를 병렬적으로 사용하는 이중 확장 칼만 필터를 활용하여 추정한다. 배터리의 노화실험은 완전충전과 완전충전을 반복하는 전류 프로파일을 인가하였으며, 실험은 상온(25℃)에서 실행하였다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.413-414
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• 2012

본 논문에서는 C-rate, 온도, SOC (State-of-Charge, 잔존용량)를 고려하여 NiMH 배터리를 모델링하였고, 시뮬레이션 결과를 배터리 실험 결과와 비교하였다. 제안한 배터리 모델은 1차 테브난 등가회로를 기반으로 구성하였으며 Matlab/Simulink 환경에서 구현하였다. 모델을 구현하기 위한 실험으로는 정전류, 펄스전류 실험을 하여 가변온도와 다양한 C-rate에서 변하는 파라미터를 도출하였고, 도출한 파라미터는 룩업 테이블을 이용하여 배터리 모델에 적용하였다. 제안된 배터리 모델을 짧은 시간동안 불규칙하게 변하는 전류 패턴에 대한 시뮬레이션과 실험 파형을 통하여 배터리 모델의 성능을 검증하였다.

• Carbon letters
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• v.1 no.3_4
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• pp.170-177
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• 2001

Lithium intercalated carbon (LIC) are basically employed as an anode for currently commercialized lithium secondary batteries. However, there are still strong interests in modifying carbon surface of active materials of the anode because the amount of irreversible capacity, charge-discharge capacity and high rate capability are largely determined by the surface conditions of the carbon. In this study, the carbonaceous materials were coated with tin oxide and copper by fluidized-bed chemical vapor deposition (CVD) method and their coating effects on electrochemical characteristics were investigated. The electrode which coated with tin oxides gave the higher capacity than that of raw material. Their capacity decreased with the progress of cycling possibly due to severe volume changes. However, the cyclability was improved by coating with copper on the surface of the tin oxides coated carbonaceous materials, which plays an important role as an inactive matrix buffering volume changes. An impedance on passivation film was decreased as tin oxides contents and it resulted in the higher capacity.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.320-326
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• 2018

In this study, Graphite/Silicon/Carbon (G/Si/C) composites were synthesized to improve the electrochemical properties of Graphite as an anode material of lithium ion battery. The prepared G/Si/C composites were analyzed by XRD, TGA and SEM. Also the electrochemical performances of G/Si/C composites as the anode were performed by constant current charge/discharge, rate performance, cyclic voltammetry and impedance tests in the electrolyte of $LiPF_6$ dissolved inorganic solvents (EC:DMC:EMC=1:1:1 vol%). Lithium ion battery using G/Si/C electrode showed better characteristics than graphite electrode. It was confirmed that as the silicon content increased, the capacity increased but the capacity retention ratio decreased. Also, it was shown that both the capacity and the rate performances were improved when using the Silicon (${\leq}25{\mu}m$). It is found that in the case of 10 wt% of Silicon (${\leq}25{\mu}m$), G/Si/C composites have the initial discharge capacity of 495 mAh/g, the capacity retention ratio of 89% and the retention rate capability of 80% in 2 C/0.1 C.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.31-38
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• 2006

There are two types of metal hydride electrodes as a negative electrode in a Ni-MH battery, $AB_2$ Zr-based Laves phases and $AB_5$ LM(La-rich mischmetal)-based alloys. The $AB_5$ alloy electrodes have characteristic properties such as a large discharge capacity per volume, easiness in activation, long cycle life and a low cost of alloy. However they have a relatively small discharge capacity per weight. The $AB_2$alloy electrodes have a much higher discharge capacity per weight than $AB_5$ alloy electrodes, however they have some disadvantages of poor activation behavior and cycle life. Therefore, in order to improve the discharge capacity of the $AB_5$ alloy electrode the Zr, Ti and V which are the alloying elements of the $AB_2$ alloys were added to the $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}$ alloy which was chosen as a $AB_5$ alloy with a high capacity. The addition of Zr, Ti and V to $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}$ alloy improved the activation to be completed in two cycles. The discharge capacities of Zr 0.02, Ti 0.02 and V 0.1 alloys in $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}M_y$ (M = Zr, Ti, V) were respectively 346, 348 and 366 mAh/g alloy. The alloy electrodes, Zr 0.02, Ti 0.05 and V 0.1 in $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}M_y$ (M = Zr, Ti, V), have shown good cycle property after 200 cycles. The rate capability of the $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}M_y$ (M = Zr, Ti, V) alloy electrodes were very good until 0.6 C rate and the alloys, Zr 0.02, Ti 0.05 and V 0.1, have shown the best result as 92 % at 2.4 C rate. The charge retention property of the $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}M_y$ (M = Zr, Ti, V) alloys was not good and the alloys with M content from 0.02 to 0.05 showed better charge retention properties.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.348-355
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• 2023

Magnesium secondary batteries are attracting much attention due to their potential to replace conventionally used lithium ion batteries. Magnesium secondary battery cathode material Mo₆S₈ were synthesized by molten salt synthesis method and PVC as a carbon materials were added to improve electrochemical properties. Crystal structure, size and surface of the synthesized anode materials were measured through XRD and SEM. Charge-discharge profiles and rate capabilities were measured by battery test system. 2.81 wt% PVC coated sample showed the best rate capabilities of 85.8 mAh/g at 0.125 C-rate, 69.2 mAh/g at 0.5 C-rate, and 60.5 mAh/g at 1 C-rate.

• Clean Technology
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• v.24 no.4
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• pp.332-338
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• 2018

Currently graphite is used as an anode active material for lithium ion battery. However, since the maximum theoretical capacity of graphite is limited to $372mA\;h\;g^{-1}$, a new anode active material is required for the development of next generation high capacity and high energy density lithium ion battery. The maximum theoretical capacity of Si is $4200mA\;h\;g^{-1}$, which is about 10 times higher than the maximum theoretical capacity of graphite. However, since the volume expansion rate is almost 400%, the irreversible capacity increases as the cycle progresses and the discharge capacity relative to the charge is remarkably reduced. In order to solve these problems, it is possible to control the particle size of the Si anode active material to reduce the mechanical stress and the volume change of the reaction phase, thereby improving the cycle characteristics. Therefore, in order to minimize the decrease of the charge / discharge capacity according to the volume expansion rate of the Si particles, the improvement of the cycle characteristics was carried out by pulverizing Si by a dry method with excellent processing time and cost. In this paper, Si is controlled to nano size using vibrating mill and the physicochemical and electrochemical characteristics of the material are measured according to experimental variables.