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재료불확실성에 의한 고장률 감소를 고려하여 비에너지 최대화를 위한 리튬 이온 배터리 셀의 신뢰성 기반 최적설계
최이재(Yijae Choi),유동현(Donghyeon Yoo),박진환(Jinhwan Park),김창완(Chang-Wan Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Lithium-ion batteries (LIBs) are being used in various fields from portable electronic devices to transportation, military and aviation due to their high energy density and long lifespan. Development and demand for high-power/high-density LIB cells are increasing due to the development of the electric vehicle industry. In this paper, using the LIB electrochemical numerical model, considering the material uncertainty of the LIB cell, RBDO was performed to improve reliability and maximize specific energy density. As a result of the optimization, the specific energy increased by 34.8% from the initial 172.4 Wh/kg to 232.9 Wh/kg without any change in the specific output performance of the battery. Also, in the case of the initial design, there is a failure rate of 83.2%, but as a result of the RBDO design, the failure rate is 0.6%.
리튬이온 배터리 셀의 제작 불확실성에 의한 불량률 및 성능 편차 저감을 위한 신뢰성 기반 강건 최적설계
박진환(Jinhwan Park),유동현(Donghyeon Yoo),김창완(Chang-Wan Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Lithium-ion batteries (LIBs) have been widely used in electric vehicles (EVs) and large-capacity energy storage systems (ESSs) due to their advantages such as high energy density and high power density. However, the manufacturing uncertainty of the LIB cell increases the failure rate and causes cell-to-cell variation, which reduces the performance of the battery. In this paper, Reliability-Based Robust Design Optimization (RBRDO) was used to improve the reliability and robustness of LIB cell manufacturing uncertainty. Using RBRDO, the energy density of the LIB cell was maximized, while the failure rate and cell-to-cell variation were reduced. To verify the superiority of RBRDO, Deterministic Design Optimization (DDO) and Reliability-Based Design Optimization (RBDO) were performed and compared with the results of RBRDO.
대형 리튬이온 배터리의 온도분포 균일화를 위한 탭 타입, 탭 사이즈 및 탭 부착위치 최적화
장혁균(HyukKyun Chang),박진환(Jinhwan Park),유동현(Donghyeon Yoo),김창완(Chang-Wan Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Large vehicle LIBs tend to have increased dimension for battery cell capacity as demand increases. Increasing the dimension of a LIB cell forms an uneven temperature distribution within the cell. Uneven temperature distribution can reduce battery performance and life. This study uses a 3D thermal-electrochemical model to analyze the temperature distribution by tap size and attachment location with the three tap-types of 55Ah LFP/graphite pouch cells. The width of the positive and negative tabs, the attachment positions of the positive and negative tabs, and the height of the tabs were used as design variables. To analyze the temperature distribution, we calculated the maximum temperature, minimum temperature, and the difference between maximum temperature and minimum temperature (Tdiff) inside the cell. By minimizing the temperature difference inside the cell, the initial design and the optimized design were compared with the potential gradient and temperature difference. As a result of optimization, the temperature difference at the Optimized CT-type, where the two tabs are located in the center, was 3.97℃ lower than that of the Optimized NT-type and 2.22℃ lower than that of the Optimized LT-type. In addition, the potential gradient was lower in order of Optimized CT-, Optimized LT-, and Optimized NT-type, indicating the lowest heat generation due to internal Joule Heat in the Optimized CT-type