Thermal Material Properties of Commercial NMC111-LMO / Graphite Lithium-Ion Battery Cell

A commercial 20 Ah pouch cell (SPB58253172P2, Enertech International, Inc.), which consists of a NMC111-LMO cathode blend and a graphite anode[1] is characterized thermally. The cell opening is performed at a State of Charge (SoC) of 0 % in an inert environment in a glove box. After disassembly, the anode and cathode sheets were triple washed with DMC and left to dry. For the density and heat capacity measurements, the coatings of both anode and cathode sheets were scraped off. For the thermal diffusivity measurements 18 mm double coated coins were punched from the sheets. All probes were exposed to air only very shortly before inserting them into the measurement devices. The experimental analysis is performed according to Oehler et al.[2]. The density measurement is done with a Micro Ultrapyc 1200e Gas (Quantachrome Instruments) pycnometer in nitrogen gas. The heat capacity is measured in a Q2000 (TA Instruments) differential scanning calorimeter in a temperature range from -40 °C to 60 °C. The thermal diffusivity measurement of the double coated coins is performed in helium atmosphere in a LFA 467 Hyperflash (NETZSCH-Gerätebau GmbH) in a temperature range from -20 °C to 60 °C. To calculate the thermal conductivity of the coatings via a serial connection[3], additional knowledge of the layer thicknesses, porosities of the coatings and the thermal material properties of the current collectors are needed. The thicknesses of the coatings and current collectors are measured with a Micromar 40 EWR (Mahr GmbH). A Balance XPE206DR precision scale (Mettler Toledo) was used to measure the mass of the coating probes. The porosity of the coating was then determined gravimetrically. All measurements were conducted at least three times. Error propagation of the standard deviation was performed for the calculated values. The measurement of the density and heat capacities of the current collectors as well as pouch foil and separator were performed as previously described. The current collector materials are assumed to be copper and aluminum and the thermal conductivities at 0 °C are taken from literature[4]. [1] L. Cloos, J. Langer, M. Schiffler, A. Weber, Th. Wetzel, J. Electrochem. Soc. 2024, 171, 040538. [2] D. Oehler, P. Seegert, T. Wetzel, Energy Technol. 2021, 9, 2000574. [3] A. Loges, S. Herberger, D. Werner, T. Wetzel, Journal of Power Sources 2016, 325, 104–115. [4] P. Stephan, S. Kabelac, M. Kind, D. Mewes, K. Schaber, T. Wetzel, Eds. , VDI-Wärmeatlas: Fachlicher Träger VDI-Gesellschaft Verfahrenstechnik und Chemieingenieurwesen, Springer Berlin Heidelberg, Berlin, Heidelberg, 2019.本研究对一款商用20 Ah软包电池（SPB58253172P2，Enertech International, Inc.）开展热特性表征，该电池采用NMC111-LMO混合正极与石墨负极[1]。电池拆解在惰性气氛手套箱中以0%荷电态（State of Charge, SoC）下进行。拆解完成后，正、负极极片经碳酸二甲酯（DMC）三重洗涤后自然晾干。针对密度与热容测试，需刮除正、负极极片的活性涂层；针对热扩散率测试，则从极片上冲压出直径18 mm的双面涂层圆片试样。所有试样仅在放入测试设备前极短时间暴露于空气中。本实验分析参照Oehler等人[2]的方法开展。密度测试采用Micro Ultrapyc 1200e型气体比重瓶（Quantachrome Instruments），以氮气为测试介质。热容测试在Q2000型差示扫描量热仪（TA Instruments）中进行，测试温度范围为-40 ℃至60 ℃。双面涂层圆片的热扩散率测试在LFA 467 Hyperflash型激光闪射仪（NETZSCH-Gerätebau GmbH）中开展，测试气氛为氦气，温度范围为-20 ℃至60 ℃。若通过串联模型[3]计算活性涂层的导热系数，还需获取涂层厚度、涂层孔隙率以及集流体的热物性参数。涂层与集流体的厚度采用Micromar 40 EWR型测厚仪（Mahr GmbH）进行测量。采用XPE206DR型精密电子天平（Mettler Toledo）测量涂层试样的质量，随后通过重量法计算涂层的孔隙率。所有测试均至少重复三次，对计算得到的结果进行了标准偏差的误差传递分析。集流体、软包铝塑膜与隔膜的密度及热容测试按照前述方法开展。本研究假设集流体材料分别为铜与铝，其在0 ℃下的导热系数取自文献[4]。 [1] L. Cloos, J. Langer, M. Schiffler, A. Weber, Th. Wetzel, J. Electrochem. Soc. 2024, 171, 040538. [2] D. Oehler, P. Seegert, T. Wetzel, Energy Technol. 2021, 9, 2000574. [3] A. Loges, S. Herberger, D. Werner, T. Wetzel, Journal of Power Sources 2016, 325, 104–115. [4] P. Stephan, S. Kabelac, M. Kind, D. Mewes, K. Schaber, T. Wetzel, Eds. , VDI-Wärmeatlas: Fachlicher Träger VDI-Gesellschaft Verfahrenstechnik und Chemieingenieurwesen, Springer Berlin Heidelberg, Berlin, Heidelberg, 2019.