• Title, Summary, Keyword: Lithium iron phosphate

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A study on thermal performance of batteries using thermal imaging and infrared radiation

  • Kim, Hee-Jung;Lee, Joon-Hyun;Baek, Dong-Ho;Lee, Jin-Kyung
    • Journal of Industrial and Engineering Chemistry
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    • v.45
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    • pp.360-365
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    • 2017
  • This study attempted to improve the performance of pouch-type lithium iron phosphate battery ($LiFePO_4$) through analysis on its degradation mechanism at a high rate (10 C) for the purpose of observing resistance and electrochemical changes in each material when a battery was manufactured considering the low electrical conductivity and of lithium iron phosphate and properties of cathode materials. For this, the life and safety of lithium batteries are evaluated after forming dendrites through the reduction of lithium at the negative electrode (graphite) as resistance in $LiFePO_4$. The components of $LiFePO_4$, which generate this kind of resistance includes tab, electrolytes, cathode active materials, anode active materials, binders and conductive materials. The main cathode (lithium-ion phosphate) and anode (natural graphite) materials were fabricated in 90% and 96% respectively, using conductive materials and binders. For a case, a 20 Ah Al pouch was fabricated. A full cell was fabricated with the best materials and components through analysis on resistance characteristic. Then, $LiFePO_4$ was thermally safer with a long lifespan than the conventional high-rate output. For analysis on materials, in addition, basic material analysis was performed through impedance, X-ray diffraction (XRD), X-Scan and field emission scanning electron (FESEM). After tracing heat generated within the battery using infrared radiation (IR), the degree of degradation was examined. Then, the degradation rates of lithium batteries and reliability of measurements were comparatively assessed. When analyzed with an infrared camera, temperature rapidly rose up to over $80^{\circ}C$ during charge and discharge. A battery was fabricated using an industrial engineering method which can secure internal resistance-lowering slurry and coating dispersion processes and reduce resistance in the binder and tab joint. As a result, it was able to substitute conventional $LiFePO_4$ with high internal resistance, disperse heat inside the cell and increase its lifespan.

A novel OCV Hysteresis Modeling for SOC estimation of Lithium Iron Phosphate battery (리튬인산철 배터리를 위한 새로운 히스테리시스 모델링)

  • Nguyen, Thanh Tung;Khan, Abdul Basit;Choi, Woojin
    • Proceedings of the KIPE Conference
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    • pp.75-76
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    • 2016
  • The relationship of widely used Open circuit Voltage (OCV) versus State of Charge (SOC) is critical for any reliable SOC estimation technique. However, the hysteresis existing in all type of battery which has been come to the market leads this relationship to a complicated one, especially in Lithium Iron Phosphate (LiFePO4) battery. An accurate model for hysteresis phenomenon is essential for a reliable SOC identification. This paper aims to investigate and propose a method for hysteresis modeling. The SOC estimation is done by using Extended Kalman Filter (EKF), the parameter of the battery is modeled by Auto Regressive Exogenous (ARX) and estimated by using Recursive Least Square (RLS) filter to tract each element of the parameter of the model.

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Development of ESS Based on VRFB-LFPB Hybrid Batteries (VRFB-LFPB 하이브리드 배터리 기반의 ESS 개발에 관한 연구)

  • Cheon, Young Sik;Park, Jin Soo;You, Jinho;Lee, Jin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.31 no.1
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    • pp.61-67
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    • 2018
  • High-power lithium batteries are suitable for equipment with high power output needs, such as for ESS's initial start-up. However, their management cost is increased by the installation of air-conditioning to minimize the risk of explosion due to internal temperature rise and also by a restriction on the number of charge/discharge cycles. High-capacity flow batteries, on the other hand, have many advantages. They can be used for over 20 years due to their low management costs, resulting from no risk of explosion and a high number of charge/discharge cycles. In this paper, we propose an ESS based on hybrid batteries that uses a lithium iron phosphate battery (LiFePO) at the initial startup and a vanadium redox flow battery (VRFB) from the end of the transient period, with a bi-directional PCS to operate two batteries with different DC voltage levels and using an efficient energy management control algorithm.

Development of LiFePO4/FePO4 Electrode for Electro-Osmotic Pump using Li+ Migration

  • Baek, Jaewook;Kim, Kyeonghyeon;Shin, Woonsup
    • Journal of Electrochemical Science and Technology
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    • v.9 no.2
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    • pp.85-92
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    • 2018
  • Olivine structure of $LiFePO_4$ (LFP) is one of the most commonly used materials in aqueous rechargeable lithium batteries (ARLBs), and can store and release charge through the insertion/de-insertion of $Li^+$ between LFP and FP. We have fabricated LFP and LFP/FP electrodes on titanium paper and studied their electrochemical properties in 2 M $Li_2SO_4$. The LFP/FP electrode was determined to be a suitable electrode for electo-ostmotic pump (EOP) in terms of efficiency in water and 0.5 mM $Li_2SO_4$ solution. Experiments to determine the effect of cations and anions on the performance of EOP using LFP/FP electrode have shown that $Li^+$ is the best cation and that the anion does not significantly affect the performance of the EOP. As the concentration of $Li_2SO_4$ solution was increased, the current increased. The flow rate peaked at $4.8{\mu}L/30s$ in 1.0 mM $Li_2SO_4$ solution and then decreased. When the EOP was tested continuously in 1.0 mM $Li_2SO_4$ solution, the EOP transported approximately 35 mL of fluid while maintaining a stable flow rate and current for 144 h.

Electrochemical Performance of Lithium Iron Phosphate by Adding Graphite Nanofiber for Lithium Ion Batteries

  • Wang, Wan Lin;Jin, En Mei;Gu, Hal-Bon
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.3
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    • pp.121-124
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    • 2012
  • Olivine type $LiFePO_4$ cathode material was synthesized by solid-state reaction method including one-step heat treatment. To improve the electrochemical characteristics, graphite nanofiber (GNF) was added into $LiFePO_4$ cathode material. The structure and morphological performance of $LiFePO_4$ were investigated by X-ray diffraction (XRD); and a field emission-scanning electron microscope (FE-SEM). The synthesized $LiFePO_4$ has an olivine structure with no impurity, and the average particle size of $LiFePO_4$ is about 200~300 nm. With graphite nanofiber added, the discharge capacity increased from 113.43 mAh/g to 155.63 mAh/g at a current density of 0.1 $mA/cm^2$. The resistance was also significantly decreased by the added graphite nanofiber.

Li Ion Diffusivity and Rate Performance of the LiFePO4 Modified by Cr Doping

  • Park, Chang-Kyoo;Park, Sung-Bin;Shin, Ho-Chul;Cho, Won-Il;Jang, Ho
    • Bulletin of the Korean Chemical Society
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    • v.32 no.1
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    • pp.191-195
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    • 2011
  • This study reports the root cause of the improved rate performance of $LiFePO_4$ after Cr doping. By measuring the chemical diffusion coefficient of lithium ($D_{Li}$) using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the correlation between the electrochemical performance of $LiFePO_4$ and Li diffusion is acquired. The diffusion constants for $LiFePO_4$/C and $LiFe_{0.97}Cr_{0.03}PO_4$/C measured from CV are $2.48{\times}10^{-15}$ and $4.02{\times}10^{-15}cm^2s^{-1}$, respectively, indicating significant increases in diffusivity after the modification. The difference in diffusivity is also confirmed by EIS and the $D_{Li}$ values obtained as a function of the lithium content in the cathode. These results suggest that Cr doping facilitates Li ion diffusion during the charge-discharge cycles. The low diffusivity of the $LiFePO_4$/C leads to the considerable capacity decline at high discharge rates, while high diffusivity of the $LiFe_{0.97}Cr_{0.03}PO_4$/C maintains the initial capacity, even at high C-rates.

Electrochemical Characteristics of Carbon-coated LiFePO4 as a Cathode Material for Lithium Ion Secondary Batteries

  • Shin, Ho-Chul;Lee, Byung-Jo;Cho, Won-Il;Cho, Byung-Won;Jang, Ho
    • Journal of the Korean Electrochemical Society
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    • v.8 no.4
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    • pp.168-171
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    • 2005
  • The electrochemical properties of $LiFePO_4$ as a cathode for Li-ion batteries were improved by incorporating conductive carbon into the $LiFePO_4$. X-ray diffraction analysis and SEM observations revealed that the carbon-coated $LiFePO_4$ consisted of fine single crystalline particles, which were smaller than the bare $LiFePO_4$. The electrochemical performance of the carbon-coated $LiFePO_4$ was tested under various conditions. The carbon-coated $LiFePO_4$ showed much better performance in terms of the discharge capacity and cycling stability than the bare $LiFePO_4$. The improved electrochemical performances were found to be attributed to the reduced particle size and enhanced electrical conductivity of the $LiFePO_4$ by the carbon.

High safety battery management system of DC power source for hybrid vessel (하이브리드 선박 직류전원용 고 안전 BMS)

  • Choi, Jung-Leyl;Lee, Sung-Geun
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.7
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    • pp.635-641
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    • 2016
  • In order to drive a hybrid propulsion device which combines an engine and an electric propulsion unit, battery packs that contain dozens of unit cells consisting of a lithium-based battery are used to maintain the power source. Therefore, it is necessary to more strictly manage a number of battery cells at any given time. In order to manage battery cells, generally voltage, current, and temperature data under load condition are monitored from a personal computer. Other important elements required to analyze the condition of the battery are the internal resistances that are used to judge its state-of-health (SOH) and the open-circuit voltage (OCV) that is used to check the battery charging state. However, in principle, the internal resistances cannot be measured during operation because the parallel equivalent circuit is composed of internal loss resistances and capacitance. In most energy storage systems, battery management system (BMS) operations are carried out by using data such as voltage, current, and temperature. However, during operation, in the case of unexpected battery cell failure, the output voltage of the power supply can be changed and propulsion of the hybrid vehicle and vessel can be difficult. This paper covers the implementation of a high safety battery management system (HSBMS) that can estimate the OCV while the device is being driven. If a battery cell fails unexpectedly, a DC power supply with lithium iron phosphate can keep providing the load with a constant output voltage using the remainder of the batteries, and it is also possible to estimate the internal resistance.