Browsing by Subject "LITHIUM-ION BATTERIES"

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  • Vepsäläinen, Jari; Ritari, Antti; Lajunen, Antti; Kivekäs, Klaus; Tammi, Kari (2018)
    Uncertainty in operation factors, such as the weather and driving behavior, makes it difficult to accurately predict the energy consumption of electric buses. As the consumption varies, the dimensioning of the battery capacity and charging systems is challenging and requires a dedicated decision-making process. To investigate the impact of uncertainty, six electric buses were measured in three routes with an Internet of Things (IoT) system from February 2016 to December 2017 in southern Finland in real operation conditions. The measurement results were thoroughly analyzed and the operation factors that caused variation in the energy consumption and internal resistance of the battery were studied in detail. The average energy consumption was 0.78 kWh/km and the consumption varied by more than 1 kWh/km between trips. Furthermore, consumption was 15% lower on a suburban route than on city routes. The energy consumption was mostly influenced by the ambient temperature, driving behavior, and route characteristics. The internal resistance varied mainly as a result of changes in the battery temperature and charging current. The energy consumption was predicted with above 75% accuracy with a linear model. The operation factors were correlated and a novel second-order normalization method was introduced to improve the interpretation of the results. The presented models and analyses can be integrated to powertrain and charging system design, as well as schedule planning.
  • Visuri, Aku; Hamberg, Jonatan; Peltonen, Ella (2022)
    While the use of smartphones in extreme temperatures does not necessarily occur every day nor in all parts of the world, numerous use cases can be highlighted where the use of smartphones in cold temperatures is mandatory. Modern smartphones are designed to function in a wide range of temperatures, but when exposed to extreme cold temperatures the performance and reliability can significantly suffer. This paper presents a controlled laboratory experiment, using a clinical cold chamber to expose seven smartphone models to both medium cold (0 degrees C to -20 degrees C) and extreme cold (-30 degrees C) environments. The results showcase the smartphones' sensing software's lack of awareness of the cold environment, as well as reliability issues in the form of device crashes across the whole range of tested devices. We present a strategy for implementing monitoring application designs to both appropriately sense the effect of cold environments, as well as predicting device shutdowns in extreme cold. (C) 2021 The Authors. Published by Elsevier B.V.
  • Srur-Lavi, Onit; Miikkulainen, Ville; Markovsky, Boris; Grinblat, Judith; Talianker, Michael; Fleger, Yafit; Cohen-Taguri, Gili; Mor, Albert; Tal-Yosef, Yosef; Aurbach, Doron (2017)
    In this paper, we studied the influence of LiAlO2 coatings of 0.5, 1 and 2 nm thickness prepared by Atomic Layer Deposition onto LiNi0.8Co0.15Al0.05O2 electrodes, on their electrochemical behavior at 30 and 60 degrees C. It was demonstrated that upon cycling, 2 nm LiAlO2 coated electrodes displayed similar to 3 times lower capacity fading and lower voltage hysteresis comparing to bare electrodes. We established a correlation among the thickness of the LiAlO2 coating and parameters of the self-discharge processes at 30 and 60 degrees C. Significant results on the elevated temperature cycling and aging of bare and LiAlO2 coated electrodes at 4.3 V were obtained and analyzed for the first time. By analyzing of X-ray diffraction patterns of bare and 2 nm coated LiNi0.8Co0.15Al0.05O2 electrodes after cycling, we concluded that cycled materials preserved their original structure described by R-3m space group and no additional phases were detected. (c) The Author(s) 2017. Published by ECS. All rights reserved.
  • Holopainen, Jani; Heikkilä, Mikko J.; Salmi, Leo D.; Ainassaari, Kaisu; Ritala, Mikko (2018)
    Electroblowing was used to prepare ZnO and aluminum doped zinc oxide (AZO, 1–3 cation-% of Al) fibers. The as-blown fibers were calcined at 500 °C to obtain the target material. The average fiber diameters ranged from 240 ± 60 nm for ZnO fibers to 330 ± 80 nm for AZO with 3% Al. Smaller crystallite size was measured with the x-ray diffraction for the Al doped fibers. Electroblowing was found out be an effective method to increase the fiber productivity over electrospinning and other methods reported in literature to prepare AZO fibers as a high production rate of 0.32 g/h was achieved. The ZnO and AZO fibers could be converted to zeolitic imidazole framework-8 [ZIF-8, zinc(2-methylimidazolate)2] by a solvent free thermal treatment in an autoclave under 2-methylimidazole (HmIM) vapor at 150 and 200 °C while preserving the fibrous structure. The conversion process to ZIF-8 occurred faster at higher temperatures and on fibers with smaller crystallite size. Depending on the conversion treatment time either ZnO/ZIF-8 and AZO/ZIF-8 core/shell fibers or ZIF-8 fibers could be obtained. At best the prepared ZIF-8 fibers had a very high BET specific surface area of 1340 m2/g.