• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.4
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• pp.1-11
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• 2022

In this study, the thermal runaway of NCM and LFP batteries were compared and analyzed through numerical analysis under various conditions. Comparing the thermal runaway of the NCM622 (18650) battery cell and the LFP (18650) battery cell through oven test simulation, the LFP battery did not show thermal runaway, whereas the NCM622 battery temperature increased to 710℃ in 12 minutes. To observe the thermal runaway and propagation of the prismatic LFP battery cell, the internal temperature was set at 200℃ and the oven test simulation was conducted. It was found that thermal runaway occurred at 391℃ after 47 minutes. As a result of observing thermal runaway propagation by placing five NCM622 and LFP battery cells, the thermal runaway propagation was clearly observed in the case of the NCM622 battery, but in the case of the LFP battery, thermal runaway was not observed after the first cell. From the third battery cell, it was confirmed that the temperature change was very insignificant, and through this, it is considered that the LFP battery is relatively safe compared to the NCM battery in terms of the thermal runaway propagation of the battery.

• Journal of Electrochemical Science and Technology
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• v.13 no.4
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• pp.472-478
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• 2022

Solar energy harvesting is practiced by various nations for the purpose of energy security and environment preservation in order to reduce overdependence on oil. Converting solar energy into electrical energy through Photovoltaic (PV) module can take place either in on-grid or off-grid applications. In recent time Lithium battery is exhibiting its presence in on-grid applications but its role in off-grid application is rarely discussed in the literature. The preliminary capacity and Peukert's study indicated that the battery quality is good and can be subjected for life cycle test. The capacity of the battery was 10.82 Ah at 1 A discharge current and the slope of 1.0117 in the Peukert's study indicated the reaction is very fast and independent on rate of discharge. In this study Lithium Iron Phosphate battery (LFP) after initial characterization was subjected to life cycle test which is specific to solar off-grid application as defined in IEC standard. The battery has delivered just 6 endurance units at room temperature before its capacity reached 75% of rated value. The low life of LFP battery in off-grid application is discussed based on State of Charge (SOC) operating window. The battery was operated both in high and low SOC's in off-grid application and both are detrimental to life of lithium battery. High SOC operation resulted in cell-to-cell variation and low SOC operation resulted in lithium plating on negative electrode. It is suggested that to make it more suitable for off-grid applications the battery by default has to be overdesigned by nearly 40% of its rated capacity.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.455-456
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• 2017

본 논문에서는 리튬 인산철 배터리($LiFePO_4$)의 내부 파라미터 추출 방법으로 전기화학적 기반인 정전류식 간헐적 적정 테크닉(galvanostatic intermittent titration technique;GITT)을 사용하였다. 배터리 관리 시스템(battery management system;BMS) 알고리즘의 기본적으로 들어가는 충방전 저항을 미세 구간으로 나누어 볼 수 있다. SOC(state-of-charge)에 맞는 저항 성분을 찾을 수 있고, 미소 용량 정보를 알아내어 특정 SOC 구간에서의 LFP 배터리 최적 운용 구간을 알 수 있다.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.4
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• pp.46-58
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• 2021

As accidents with thermal runaway (TR) of lithium-ion batteries occur sporadically, the safety concern is the main obstacle that hinders the large-scale applications of lithium ion batteries. In most accidents, the TR of a single cell occurred first, and then dissipated the heat to the surroundings and triggered the TR of adjacent cells, resulting in TR propagation. Therefore, it is important to understand the mechanism of TR propagation and determine the key parameters during TR propagation in a battery pack. In this study, we performed a numerical analysis on the thermal runaway phenomenon by cathode active materials and appearance sizes in cylindrical lithium-ion batteries using a two-dimensional analysis model. The model results showed that the TR propagation of 21700 type cells (21 mm diameter, 70 mm height) occurs more rapidly than 46800 type cells (46 mm diameter, 80 mm height) and the LFP cell has higher thermal safety than the NCM cell. Especially, we found that the effect of the separator on the occurrence of TR is negligible.

• 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.

• Resources Recycling
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• v.32 no.3
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• pp.9-17
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• 2023

Efforts are currently underway to develop a method for efficiently recovering lithium from the cathode material of waste lithium iron phosphate batteries (LFP). The successful application of lithium battery recycling can address the regional ubiquity and price volatility of lithium resources, while also mitigating the environmental impact associated with both waste battery material and lithium production processes. The isomorphic substitution leaching process was used to recover lithium from spent lithium iron phosphate batteries. Lithium was leached by the isomorphic substitution of Fe²⁺ in LFP using a relatively inexpensive ferric chloride etching solution as a leaching agent. In the study, the leaching rate of lithium was compared using the ferric chloride etching solution at various multiples of the LFP molar ratio: 0.7, 1.0, 1.3, and 1.6 times. The highest lithium leaching rate was shown at about 98% when using 1.3 times the LFP molar ratio. Subsequently, to eliminate Fe, the leachate was treated with NaOH. The Fe-free solution was then used to synthesize lithium carbonate, and the harvested powder was characterized and validated. The surface shape and crystal phase were analyzed using SEM and XRD analysis, and impurities and purity were confirmed using ICP analysis.

• Journal of Electrochemical Science and Technology
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• v.14 no.4
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• pp.320-325
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• 2023

In Li-ion batteries, a thick electrode is advantageous for lowering the inactive current collector portion and obtaining a high energy density. One of the critical failure mechanisms of thick electrodes is inhomogeneous lithiation and delithiation owing to the axial location of the electrode. In this study, it was confirmed that the top layer of the composite electrode contributes more to the charging step owing to the high ionic transport from the electrolyte. A high-loading multilayered electrode containing LiFePO₄ (LFP) and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) was developed to overcome the inhomogeneous electrochemical reactions in the electrode. The electrode laminated with LFP on the top and NCM811 on the bottom showed superior cyclability compared to the electrode having the reverse stacking order or thoroughly mixed. This improvement is attributed to the structural and interfacial stability of LFP on top of the thick electrode in an electrochemically harsh environment.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.179-180
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• 2016

본 논문은 차량 시동 시 발생하는 급격한 배터리 전압강하를 예측하여, SLI용 리튬이온 배터리의 시동가능 여부를 판단하는 SOF 추정 알고리즘을 제안한다. 제시하는 알고리즘은 전압강하를 묘사하는 배터리 등가 저항을 분석하고, 주파수 분석을 이용한 실시간 파라미터 추정을 통해 추정 정확도를 향상시킨다. 알고리즘 정확도는 MATLAB 시뮬레이션으로 검증한다.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.121-122
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• 2018

리튬 인산철(LFP, $LiFePo_4$) 배터리의 경우 다른 종류의 배터리에 비해 내부 파라미터가 비선형적인 단점이 있다. 일반적인 배터리 등가회로 모델을 적용 시, 비선형성으로 인해 추정 성능이 감소한다. 배터리 등가회로 모델을 기반인 확장 칼만 필터(EKF, Extended Kalman Filter)를 통해 SOC (State of Charge) 추정 시 추정성능이 감소할 수 있다. 따라서 본 논문은 LFP 배터리의 SOC 추정 성능 향상을 위해 실시간 파라미터 관측기를 통한 배터리 등가회로 모델을 기반으로 EKF의 내부 파라미터를 분석하고 이에 따른 차등 모델을 제안한다.

• Clean Technology
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• v.30 no.1
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• pp.28-36
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• 2024

As demand for electric vehicles increases, the market for lithium-ion batteries is also rapidly increasing. The battery life of lithium-ion batteries is limited, so waste lithium-ion batteries are inevitably generated. Accordingly, lithium was selectively preleached from waste lithium iron phosphate (LiFePO₄, hereafter referred to as the LFP) cathode material powder among lithium ion batteries, and iron phosphate (FePO₄) powder was recovered. The recovered iron phosphate powder was mixed with alkaline sodium carbonate (Na₂CO₃) powder and heat treated to confirm its crystalline phase. The heat treatment temperature was set as a variable, and then the leaching rate and powder characteristics of each ingredient were compared after water leaching using Di-water. In this study, lithium showed a leaching rate of approximately 100%, and in the case of powder heat-treated at 800 ℃, phosphorus was leached by approximately 99%, and the leaching residue was confirmed to be a single crystal phase of Fe₂O₃. Therefore, in this study, lithium, phosphorus, and iron components were individually separated and recovered from waste LFP powder.