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NCM622과 LFP 리튬이온 배터리의 주변 온도와 셀 크기에 따른 열폭주 현상에 대한 수치해석적 연구
김우영,김남진 한국 지열 · 수열에너지학회 2021 한국지열에너지학회논문집 Vol.17 No.4
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.
동일 형태의 NCM/LFP 배터리의 열폭주 현상에 대한 수치해석적 비교 연구
강명보,김우영,김남진 한국 지열 · 수열에너지학회 2022 한국지열에너지학회논문집 Vol.18 No.4
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°C in 12 minutes. To observe the thermal runaway and propagation of the prismatic LFP battery cell, the internal temperature was set at 200°C and the oven test simulation was conducted. It was found that thermal runaway occurred at 391°C 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.
박혜진(Hye-Jin Park),심성주(Seong-Ju Sim),진봉수(Bong-Soo Jin),김현수(Hyun-Soo Kim) 한국전지학회 2021 한국전지학회지 Vol.1 No.2
본 논문은 양극활물질인 LiFePO₄에 관한 것으로 우수한 안정성을 가진 반면 낮은 전자전도도와 확산계수로 인한 낮은 충방전 특성 및 큰 부피가 단점이다. 이러한 특성을 해결할 수 있는 방법들에 대해 본 논문에서 소개할 예정이며, LiFePO₄를 합성하는 다양한 방법들과 이에 대한 장점 및 단점, 그리고 전기적 특성에 대해 다룰 예정이다. 이후 LiFePO₄의 특성을 향상시킬 수 있는 방법들에 대해 논의할 예정이며 향후 활용 전망에 대해서 간략히 논할 예정이다. Even, LiFePO₄ as a cathode active material has the obvious advantages (good stability), there are still facing some problems such as poor electronic conductivity, slow charging/discharging from slow diffusion coefficient, and large volume. To overcome this, in this paper we will introduce a various methods and review the various LiFePO₄ synthesis methods including advantage/disadvantage points and way to improve the electrical performance of LiFePO₄ more. Finally, we will briefly discuss the prospects for future use.