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Now the lithium ion batteries are widely used in electric vehicles (EV). The cycle life is among the most important characteristics of the power battery in EV. In this report, the battery cycle life experiment is designed according to the actual working condition in EV. Five different commercial lithium ion cells are cycled alternatively under 45 °C and 5 °C and the test results are compared. Based on the cycle life experiment results and the identified battery aging mechanism, the battery cycle life models are built and fitted by the genetic algorithm. The capacity loss follows a power law relation with the cycle times and an Arrhenius law relation with the temperature. For automotive application, to save the cost and the testing time, a battery SOH (state of health) estimation method combined the on-line model based capacity estimation and regular calibration is proposed. [ABSTRACT FROM AUTHOR]

The lithium titanium oxide (LTO) anode is widely accepted as one of the best anodes for the future lithium ion batteries in electric vehicles (EVs), especially since its cycle life is very long. In this paper, three different commercial LTO cells from different manufacturers were studied in accelerated cycle life tests and their capacity fades were compared. The result indicates that under 55 °C, the LTO battery still shows a high capacity fade rate. The battery aging processes of all the commercial LTO cells clearly include two stages. Using the incremental capacity (IC) analysis, it could be judged that in the first stage, the battery capacity decreases mainly due to the loss of anode material and the degradation rate is lower. In the second stage, the battery capacity decreases much faster, mainly due to the degradation of the cathode material. The result is important for the state of health (SOH) estimation and remaining useful life (RUL) prediction of battery management system (BMS) for LTO batteries in EVs. [ABSTRACT FROM AUTHOR]

This paper proposes a total cost of ownership (TCO) model for battery sizing of plug-in hybrid electric vehicles (PHEVs). The proposed systematic TCO model innovatively integrates the Beijing driving database and optimal PHEV energy management strategies developed earlier. The TCO, including battery, fuel, electricity, and salvage costs, is calculated in yearly cash flows. The salvage cost, based on battery degradation model, is proposed for the first time. The results show that the optimal battery size for PHEVs in Beijing is 6-8 kWh. Several additional scenarios are also analyzed: (1) 10% increase in battery price or discount rate leads to an optimal battery size of 6 kWh, and 10% increase in fuel price shifts the optimal battery size to 8 kWh; (2) the longer and more dispersive daily range distribution in the U.S. increases the optimal battery size to 14 kWh; (3) the subsidy in China results in an optimal battery size of 13 kWh, while that in the U.S. results in 17 kWh, and a fuel savings rate based subsidy policy is innovatively proposed; (4) the optimal battery size with Li4Ti5O12 batteries is 2 kWh, but the TCO of Li4Ti5O12 batteries is higher than that of LiFePO4 batteries. [ABSTRACT FROM AUTHOR]

A general approach is proposed to address the cylinder-to-cylinder air-fuel ratio (AFR) balancing control problem using a single universal exhaust gas oxygen (UEGO) sensor. Using the multirate sampling technique, a control-oriented engine model, well combining the fuel delivery dynamics and exhaust gas dynamics, is established. Gas mixing phenomena is characterized by a gas mixing matrix, which is valid both for equal-length and unequal-length exhaust runners. Based on the developed model, the observability of the individual cylinder AFR estimation problem is analyzed using the input observability concept. An input observer using the one-step forward feedback is proposed to design the estimator. Using the estimated AFR, a decoupled PI compensator is designed for each cylinder to compensate the cylinder-by-cylinder variations. Finally, the proposed approach is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

Despite the widespread utilization of Lithium-ion batteries (LIBs), concerns regarding safety during operation persist owing to accidents and potential risks of fires and explosions. To comprehend the thermal dynamics that underlie severe LIB incidents, calorimetry tests have been prevalently employed for over three decades to examine the exothermic/endothermic behavior, reaction kinetics, and thermal interactions among LIB materials. There exists a substantial volume of calorimetry test results on various LIB electrodes, electrolytes, and other components. However, this data showcases low consistency, yielding an unreliable database that obstructs a thorough understanding of LIB thermal behavior. In this research, a comparative analysis of differential scanning calorimetry (DSC) results from materials utilized in the most commercialized LIB systems is conducted. The analysis unveils notable discrepancies in DSC data amassed by different researchers, identifies five predominant causes of data inconsistency, proposes a standardized DSC operational procedure, and generates a set of self-consistent data. Subsequently, an intrinsic safety spectrum is delineated and compared with X-ray diffraction (XRD) outcomes to elucidate the correlation between the crystal lattice structure and the thermal behavior of the material. This work aids in the formation of a comparative DSC database, utilizing the vast but inconsistent literature data. Moreover, it clarifies the linkage between the material structure and thermal behavior, facilitating data-driven thermal analysis of LIBs. [ABSTRACT FROM AUTHOR]

The article discusses a 2022 study on the interfacial void evolution principles in solid-state batteries. Topics covered include the building of a solid-state void nucleation and growth model, an analogy with the bubble formation in liquid phases, and lithium metal batteries' determination of the morphological instabilities that lead to battery failure. Also noted are the morphological evolutions' revelation of void defects under different stripping circumstances.

Owing to the scope of large-scale use of hydrogen energy in future technology, addressing safety issues like leakage and diffusion in all steps of production, storage, transportation, etc., will become inevitable. This paper focuses on the volume change of the combustible area after double ferrule joint leaks. First, a calibrated computational fluid dynamics (CFD) model was built and calibrated for accuracy through a hydrogen horizontal jet process. Second, the schlieren method was used to observe the hydrogen leakage morphology when the pipe was scratched. The CFD model was used to investigate the morphology and combustible volume changes under different wind directions and speeds. Third, critical wind speed (CWS), representing the disturbance wind speed when the combustible volume generated by the hydrogen jet was reduced to 85% of the non-disturbed environment, was proposed. Fourth, the scratch leakage behavior with the double ferrule joint placed horizontally was simulated. This research found that forced convection in the hydrogen system reduced the combustible volume produced by the hydrogen jet, and the typical value of CWS here was 1.5 mls. [ABSTRACT FROM AUTHOR]