Physics-informed full-field strain reconstruction in large-format lithium-ion batteries using distributed optical fiber sensing

Entropy measurement of a large format lithium ion battery and its application to calculate heat generation

Comparative study on the influence of incident heat flux on thermal runaway fire development of large-format lithium-ion batteries

Thermal runaway propagation in large format lithium ion battery modules under inclined ceilings

Mitigating overcharge induced thermal runaway of large format lithium ion battery with water mist

Large-format lithium-ion batteries (LIBs) suffer from problems in terms of their product life and capacity due to large temperature differences in LIB cells. This study analyzes the effect of design factors on temperature distribution using a 3D electrochemical–thermal model. The design of experiments methodology is used to obtain the sampling points and analyze the effect of the cell aspect ratio, negative tab attachment position, and positive tab attachment position. These were considered as design factors for the maximum and minimum temperatures, as well as their difference, in large-format LIB cells. The results reveal that the cell aspect ratio, negative tab attachment position, and positive tab attachment position considerably influence temperature distribution. The cell aspect ratio has the most significant effect on the temperature distribution by changing the longest current pathway and the distance between tabs and the lowest temperature point in the LIB cell. A positive tab attachment position affects the maximum temperature, minimum temperature, and the temperature difference due to the heat generation caused by the high resistance of aluminum, which the positive tab is made. Furthermore, a negative tab attachment position affects the minimum temperature due to low resistance.

Design optimization of tab attachment positions and cell aspect ratio to minimize temperature difference in 45-Ah LFP large-format lithium-ion pouch cells

Thermally and electrochemically driven imbalances might reduce the overall net energy within large format lithium-ion batteries. In this study, we designed a proprietary multi-tab pouch cell for investigation of these imbalances depending on cell design and temperature. The cell consists of a single-layered NMC/graphite electrode pair with a length of 50 cm and a width of 10 cm. 22 equidistantly distributed tabs are connected to each electrode giving insight to local potentials within the current collector domain (Fig. 1). Temperature variation is negligible due to the comparably small heat generation of the cell and the global influence of temperature can be analyzed. A high precision measurement setup is prepared for a μV resolution between tab pairs. By that, the internal current density distribution can be assessed. The cell is operated at 5, 25 and 40 °C and 0.1, 0.5, 1 and 2C current rate, whereby three different tab patterns are applied: Standard pouch cell, counter-tab and center-tab design. It turns out that higher potential drops along the cell as well as larger potential variation occur at elevated temperature. Further, the differentiation of potential difference between the tabs indicates a larger state of charge inhomogeneity at higher temperature, even at low current rates. It might be concluded that the interaction of an increased current collector resistance and an increased electrochemical performance in between the collector foils provokes a more distinct inhomogeneity in current density at higher temperature. Corresponding to our previous work [1,2], we apply a multi-dimensional modeling approach to the presented multi-tab cell to describe the temperature dependent current spread for purpose of optimized cell design. Based on these simulations, a maximum tab-to-tab distance depending on temperature can be estimated under the objective of an acceptable potential drop along the current collectors.

Our focus is on large-format lithium-ion batteries, used in electric vehicles today and in the foreseeable future, which are charged at high rates. In order to fully charge the battery, we employ a protocol often referred to as cc-cv (constant current followed by constant voltage). We compare and contrast results for cocurrent and countercurrent tab locations. We show how the pseudo three-dimensional (P3D) model can be used to assess temperature and current distributions and determine if Li plating is expected. We demonstrate the advantages of countercurrent tab locations to (i) obtain more uniform current and temperature distributions and (ii) lower the propensity for Li plating. Sensitivity analyses include the influence of ambient temperature and cell length. The methodology laid out in this work can facilitate rational battery-cell design and robust operation, including high-rate charging.

Thermal and stoichiometry inhomogeneity investigation of large-format lithium-ion batteries via a three-dimensional electrochemical-thermal coupling model

Enhancing the estimation accuracy in low state-of-charge area: A novel onboard battery model through surface state of charge determination

With growing demands for low-cost, large-format lithium-ion batteries mainly for electric vehicles (EVs) and energy storage system (ESS), escalating price and unsustainable supply of cobalt have become increasingly acute.1 Moreover, owing to the toxic nature and an increasing concern for child labor used in ore mining, significant research is being devoted to decrease the share or completely removing cobalt from the current cathode families, particularly in high-capacity Ni-rich layered cathodes which have sufficiently high potential for commercialization.2-5 This study involves a systematic investigation on the Ni-rich Li[Ni0.9Co0.1-xMnx]O2 (x = 0, 0.05, and 0.1) layered cathodes by variation of the Mn to Co content. Remarkably, Co-free Li[Ni0.9Mn0.1]O2 (NM90) exhibits outstanding mechanical and microstructural stability resulted in excellent cycling performance, which outperformed its Co-containing Li[Ni0.9Co0.1]O2 and Li[Ni0.9Co0.05Mn0.05]O2 counterparts. Alongside observations of high voltage and high-temperature stability, Co-free NM90 demonstrate substantially higher capacity retention, increasing the attractiveness of this material for practical application.To elucidate the impact of the Mn content in Ni-rich cathodes, the characterization techniques such as in-situ XRD, TEM and micro-compression analysis as well as electrochemical measurements have conducted and provided valuable information regarding the intrinsic properties of individual cathode components and their effects on electrochemical performance of the cathode materials. References Y.-K. Sun, D. J. Lee, Y. J. Lee, Z. Chen and S.-T. Myung, ACS Appl. Mater. Interfaces 2013, 5, 11434.U.‐H. Kim, D.‐W. Jun, K.‐J. Park, Q. Zhang, P. Kaghazchi, D. Aurbach, D. T. Major, G. Goobes, M. Dixit, N. Leifer, C. M. Wang, P. Yan, D. Ahn, K.‐H. Kim, C. S. Yoon and Y.‐K. Sun, Energy Environ. Sci. 2018, 11, 1271.K.-J. Park, M.-J. Choi, F. Maglia, S.-J. Kim, K.-H. Kim, C. S. Yoon and Y.-K. Sun, Adv. Energy Mater. 2018, 8, 1703612.U.‐H. Kim, H.‐H. Ryu, J.‐H. Kim, R. Mücke, P. Kaghazchi, C. S. Yoon and Y.‐K. Sun, Adv. Energy Mater. 2019, 9, 1803902.U.‐H. Kim, L.-Y. Kuo, P. Kaghazchi, C.S. Yoon and Y.-K. Sun, ACS Energy Lett. 2019, 4, 576.

An investigation of heat transfer and capacity fade in a prismatic Li-ion battery based on an electrochemical-thermal coupling model

The use of lithium-ion batteries in many of today's electronic consumer products has increased significantly due to the advantages of high energy density, high cell voltage, and longer shelf life over that of comparable battery chemistries. The cell chemistry of conventional lithium-ion batteries has been limited by the choice of suitable lithium liberating cathode materials i.e. the three oxide electro active materials: LiMn/sub 2/O/sub 4/, LiCoO/sub 2/ and LiNiO/sub 2/ (lithium-manganese, lithium-cobalt, and lithium-nickel respectively). These materials are generally found to offer high electrochemical performance at the expense of poor thermal stability. The three lithium oxide's thermal instability when over-charged has limited the application of these materials to small and relatively low capacity lithium-ion batteries. The novel use of a phosphate-based material in the cathode has been found to offer many of the advantages of traditional lithium-ion chemistries without sacrificing the safety necessary in a large format application. In this paper, the results of safety testing comparing phosphate-based cells and the most popular of the three lithium oxide materials (lithium-cobalt), is presented. Test data will show that the safety circuitry used in popular lithium-cobalt 18650 cylindrical cells will not prevent an event or propagation of an event if thermal runaway occurs within one cell in a battery pack. In contrast, abuse testing of phosphates based cells shows no thermal events under identical conditions.

A comprehensive investigation on the thermal and toxic hazards of large format lithium-ion batteries with LiFePO4 cathode

Although lithium ion batteries (LIBs) as an energy storage device have been identified as the most promising candidate for large scale automotive and aerospace applications, safety issues still remain to be secured. Hence in order to improve the safety of LIBs, we introduce a new gel polymer electrolyte (GPE) containing the frame retardant material, magnesium hydroxide (Mg(OH)2). First, a dense polymer film of the thickness of 20 µm is prepared by casting the precursor solution consisting of poly(vinylidene fluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) as a polymer matrix, dibutyl phthalate (DBP) as a pore generation agent, and Mg(OH)2 as a flame retardant agent, in acetone. And then, DBP is extracted in the methanol bath to make pores in the polymer film. They are gelled with additional liquid electrolyte, 1.15M LiPF6 in ethylene carbonate/ethyl methyl carbonate (EC/EMC, 3/7 by vol). Mg(OH)2 composited GPE exhibits a distinguished fire-retardant properties, which results in a relevant self-extinguishing time (SET) reduction. The ionic conductivity is also greatly enhanced in the GPEs with increasing ratio of Mg(OH)2. Due to the hydrophilic properties of Mg(OH)2, unit cells employing LiCoO2 cathode, the composite GPE, and graphite anode achieve significant improvements in rate capability and cycle performance that were closely associated with their improved uptake for liquid electrolyte. The electrochemical stability of the GPE with Mg(OH)2 is comparable to that without Mg(OH)2. This results imply that Mg(OH)2composited GPE can provide the large-format LIBs with greatly improved safety. Acknowledgements This work was supported by the Energy Technology Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20142010102980) Refernces 1. Daeyong Yeon , Yunju Lee , Myung-Hyun Ryou , Yong Min Lee, Electrochimica Acta 157 (2015) 282-289 2. Myung-Hyun Ryou, Yong Min Lee, Jang Wook Choi, Jung-Ki Park, Electrochemistry Communications 17 (2012) 18-21 3. Yong Min Lee, Dong-Hyun Ko, Jun Young Lee, Jung-Ki Park, Electrochimica Acta 52 (2006) 1582–1587