• Title/Summary/Keyword: Battery Discharge Rate

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A SOC Coefficient Factor Calibration Method to improve accuracy Of The Lithium Battery Equivalence Model (리튬 배터리 등가모델의 정확도 개선을 위한 SOC 계수 보정법)

  • Lee, Dae-Gun;Jung, Won-Jae;Jang, Jong-Eun;Park, Jun-Seok
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.4
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    • pp.99-107
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    • 2017
  • This paper proposes a battery model coefficient correction method for improving the accuracy of existing lithium battery equivalent models. BMS(battery management system) has been researched and developed to minimize shortening of battery life by keeping SOC(state of charge) and state of charge of lithium battery used in various industrial fields such as EV. However, the cell balancing operation based on the battery cell voltage can not follow the SOC change due to the internal resistance and the capacitor. Various battery equivalent models have been studied for estimation of battery SOC according to the internal resistance of the battery and capacitors. However, it is difficult to apply the same to all the batteries, and it tis difficult to estimate the battery state in the transient state. The existing battery electrical equivalent model study simulates charging and discharging dynamic characteristics of one kind of battery with error rate of 5~10% and it is not suitable to apply to actual battery having different electric characteristics. Therefore, this paper proposes a battery model coefficient correction algorithm that is suitable for real battery operating environments with different models and capacities, and can simulate dynamic characteristics with an error rate of less than 5%. To verify proposed battery model coefficient calibration method, a lithium battery of 3.7V rated voltage, 280 mAh, 1600 mAh capacity used, and a two stage RC tank model was used as an electrical equivalent model of a lithium battery. The battery charge/discharge test and model verification were performed using four C-rate of 0.25C, 0.5C, 0.75C, and 1C. The proposed battery model coefficient correction algorithm was applied to two battery models, The error rate of the discharge characteristics and the transient state characteristics is 2.13% at the maximum.

Optimal Capacity Determination of BESS for Customer using Investment Cost and Electric Cost (투자비용과 전기요금을 반영한 수용가 BESS의 최적용량 산정)

  • Park, Jin-Kyung;Baek, Young-Sik;Jeong, Ki-Seok;Park, Ji-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.2
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    • pp.208-213
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    • 2015
  • This study presents the estimation method for the optimal capacity of BESS(Battery Energy Storage System) in order to reduce the electric charges of common consumer. The daily optimal charge and discharge plan of BESS which satisfies the given constraints is established using linear programming through the change of rated output/rated capacity of the time that shows the electric charges in the highest reduced rate has been selected. There will be a problem to compare only reduced rate because the bigger the rated capacity, the more reduced rate is increased. Therefore, rated output/rated capacity of the time when the reduced amount of electric charges for a year is higher than the investment cost of BESS was selected.

Impedance Estimation for Lithium Secondary Battery According to 1D Thermal Modeling (리튬 2차 전지의 1차원 열적 특성을 고려한 임피던스예측)

  • Lee, Jung-Su;Lim, Geun-Wook;Kim, Kwang-Sun;Cho, Hyun-Chan;Yoo, Sang-Gil
    • Journal of the Semiconductor & Display Technology
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    • v.7 no.2
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    • pp.13-17
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    • 2008
  • In this paper, in order to get the characteristics of the lithium secondary cell, such as charge and discharge characteristic, temperature characteristic, self-discharge characteristic and the capacity recovery rate etc, we build a thermal model that estimate the impedance of battery by experiment & simulation. In this one-dimensional model, Seven governing equations are made to solve seven variables c, $c_s,\;\Phi_1,\;\Phi_2,\;i_2$, j and T. The thermal model parameters used in this model have been adjusted according to the experimental data measured in the laboratory. The result(Voc, Impedance) of this research can be used in BMS(Battery Management System), so an efficient method of using battery is developed.

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Preparation of Expanded Graphite using Perchloric Acid and It's Application as Anode Materials for High Power Li-ion Secondary Battery (과염소산을 이용한 팽창흑연의 제조 및 고출력 리튬이온전지 음극재로의 응용)

  • Park, Yul-Seok;Zheng, Hua;Kim, Myung-Soo
    • Journal of the Korean Applied Science and Technology
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    • v.28 no.1
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    • pp.85-94
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    • 2011
  • Expanded graphites were used as anode materials of high power Li-ion secondary battery. The expanded graphite was prepared by mixing the graphite with $HClO_4$ as a intercalation agents and $KMnO_4$ as a oxidizing agents. The physical and electrochemical properties of prepared expanded graphites through the variation of process variables such as contents of intercalation agent and oxidizing agent, and heat treatment temperature were analyzed for determination of optimal conditions as the anode of high power Li-ion secondary battery. After examing the electrochemical properties of expanded graphites at the different preparing conditions, the optimal conditions of expanded graphite were selected as 8 wt.% of oxidizing agent, 400 g of intercalation agent for 20 g of natural graphite, and heat treatment at $1000^{\circ}C$. The sample showed the improved charge/discharge characteristics such as 432 mAh/g of initial reversible capacity, 88% of discharge rate capability at 10 C-rate, and 24 mAh/g of charge capacity at 10 C-rate. However, the expanded graphite had the problems of potential plateaus like natural graphite and lower initial efficiency than the natural graphite.

The Effect of Electrochemical Performance and Safety by Surface Modification of Anode Materials for Lithium Secondary Battery (리튬 이차 전지를 위한 음극 활물질 표면의 코팅으로 인한 전기화학적 특성 및 안전성)

  • Heo, Yoon-Jeong;Ko, Sung-Tae
    • Journal of the Korean Electrochemical Society
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    • v.12 no.3
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    • pp.239-244
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    • 2009
  • This paper aims to report the effect of surface treatment on graphite and its effect on the improvement of $Al_2O_3$ and $nano-Li_4Ti_5O_{12}$. The structure and property of surface treatment on graphite were determined by scanning electron microscopy, transmission electron microscopy and electrochemical property and safety were determined by charge/discharge cycler, accelerating rate calorimeter. The composite with different metallic oxide exhibited the first efficiency of 82.5% and specific capacity of 350 mAh/g. Although the composite showed same efficiency and specific capacity at first cycle, surface treatment on graphite by $nano-Li_4Ti_5O_{12}$ exhibited a higher charge/discharge rate, cycle life and thermal stability.

A Study on Electrochemical Characteristics of LiCoO2/LiNi1/3Mn1/3Co1/3O2 Mixed Cathode for Li Secondary Battery (리튬2차전지용 LiCoO2/LiNi1/3Mn1/3Co1/3O2계 복합정극의 전기화학적 특성 연구)

  • Kim Hyun-Soo;Kim Sung-Il;Eom Seung-Wook;Kim Woo-Seong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.1
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    • pp.64-70
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    • 2006
  • In this study, the $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ mixed cathode electrodes were prepared and their electrochemical performances were measured in a high cut-off voltage. As the content of $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ increased in a mixed cathode, the reversible specific capacity and cycleability of the electrode enhanced, but the rate capability was deteriorated. On the contrary the rate capability of the cathode enhanced, but the reversible specific capacity and cycleability were deteriorated, increasing the content of $LiCoO_2$ in the mixed cathode. The cell of $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ ($50:50 wt\%$) mixed cathode delivered a discharge capacity of ca. 168 mAh/g at a 0.2 C rate. The capacity of the cell decreased with the current rate and a useful capacity of ca. 152 mAh/g was obtained at a 2.0 C rate. However, the cell showed very stable cycleability: the discharge capacity of the cell after 20th charge/discharge cycling maintains ca. 163 mAh/g.

Ag Doping Effect on Li[Ni0.2Li0.2Mn0.6]O2 Cathode Material (Li[Ni0.2Li0.2Mn0.6]O2 양극물질의 Ag 도핑(Doping) 효과)

  • Ryu, Jea-Hyeok;Kim, Seuk-Buom;Park, Yong-Joon
    • 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.

The Electrochemical Performance of Li3V2(PO4)3/Graphene Nano-powder Composites as Cathode Material for Li-ion Batteries

  • Choi, Mansoo;Kim, Hyun-Soo;Lee, Young Moo;Jin, Bong-Soo
    • Journal of Electrochemical Science and Technology
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    • v.5 no.4
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    • pp.109-114
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    • 2014
  • The $Li_3V_2(PO_4)_3$/graphene nano-particles composite was successfully synthesized by a facile sol-gel method. The addition of a graphene in $Li_3V_2(PO_4)_3(LVP)$(LVP) showed the high crystallinity and influenced the morphology of the $Li_3V_2(PO_4)_3$ particles observed in X-ray diffraction (XRD) and scanning electron microscopy (SEM). The LVP/graphene samples were well connected, resulting in fast charge transfer. The effect of the addition graphene nano-particles on electrochemical performance of the materials was investigated. Compared with the pristine LVP, the LVP/graphene composite delivered a higher discharge capacity of $122mAh\;g^{-1}$ at 0.1 C-rate, better rate capability and cyclability in the potential range of 3.0-4.3 V. The electrochemical impedance spectra (EIS) measurement showed the improved electronic conductivity for the LVP/graphene composite, which can ensure the high specific capacity and rate capability.

A Study on Optimization of Manufacturing Condition for LiNi1/3Mn1/3Co1/3O2-based Cathode Electrode (LiNi1/3Mn1/3Co1/3O2계 정극활물질을 적용한 전극 제조조건 최적화 연구)

  • Kim Hyun-Soo;Kim Sung-Il;Lee Chang-Woo;Moon Seong-In;Kim Woo-Seong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.2
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    • pp.139-144
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    • 2006
  • A fabrication condition of the cathode electrode was optimized in a lithium secondary battery. The $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ powders were used as a cathode material. The $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$/Li cells were prepared with a certain formulation and their cycleability and rate-capability were evaluated. Optimum electrode composition simulated from the evaluated value was 86.3: 5.6: 8.1 in mass $\%$ of active material: binder: conducting material. Discharge capacity decreased markedly as the press ratio exceeded $30\%$ during preparation of the electrode. Discharge performance at a high current rate deteriorated abruptly as the electrode thickness was over $120{\mu}m$.

Dispersion of Li[Ni0.2Li0.2Mn0.6]O2 Powder by Surfactant for High-power Li-ion Cell

  • Yun, Su-Hyun;Park, Yong-Joon
    • Bulletin of the Korean Chemical Society
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    • v.30 no.7
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    • pp.1598-1602
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    • 2009
  • The particle size of Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode powder was controlled effectively by dispersion using lauric acid as a surfactant. The samples treated by lauric acid showed smaller particles of approximately half the original size compared to the particles of a pristine sample. A structural change due to the dispersion of Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ powder was not detected. The rate performance of the Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode was improved by dispersion using lauric acid, which was likely due to the decrease of the particle size. In particular, a sample dispersed pristine powder using lauric acid (L2) presented a greatly enhanced discharge capacity and capacity retention at a high C rate. The discharge capacity of a pristine sample was only 133 m$Ahg^{-1}$ (3C rate) and 96 m$Ahg^{-1}$ (12C rate) at the tenth cycle. In contrast, the L2 electrode delivered higher discharge capacities of 160 m$Ahg^{-1}$ (3C rate) and 129 m$Ahg^{-1}$ (12C rate) at the tenth cycle. The capacity retention at a rate of 12C/2C was also enhanced from ~ 45% (pristine sample) to 57% (L2) by treatment with lauric acid.