Automotive Science and Engineering

Improving energy harvesting in automotive applications: comparative analysis of ZnO Nanostructures for flexible piezoelectric devices

Isa Koranian

Fueled by their potential for energy harvesting, ZnO nanorods (NRs) have sparked considerable enthusiasm in the development of piezoelectric nanogenerators in the last decade. This is attributed to their exceptional piezoelectric properties, semiconducting nature, cost-effectiveness, abundance, chemical stability in the presence of air, and, the availability of diverse and straightforward crystal growth technologies. This study explores and compares the piezoelectric properties of two promising nanostructured ZnO architectures: thin films deposited via radiofrequency (RF) magnetron sputtering and well-aligned nanorod arrays grown using a hydrothermal process. Both structures are fabricated on flexible polyethylene terephthalate (PET) with an indium tin oxide (ITO) electrode (PET-ITO substrate), presenting valuable options for flexible piezoelectric devices. By directly comparing these distinct morphologies, we provide insights into their respective advantages and limitations for energy harvesting and sensor applications. The investigation into the piezoelectric properties of ZnO NRs involved the construction of an actual piezoelectric nanogenerator. This device demonstrated a direct correlation between applied mechanical forces and the resultant voltage outputs. It was observed that when the same external force was applied to both devices, the ZnO NRs-based piezoelectric nanogenerator (PENG) exhibited a higher output voltage compared to the other device.

Evaluating Electrolyte Solvent Effects on Low-Temperature Performance of Lithium-ion Batteries Using Electrochemical Impedance Spectroscopy

Mohammad Zarei-Jelyani

The global transition towards renewable energy necessitates efficient energy storage solutions to address the intermittency of renewable sources. Lithium-ion batteries (LIBs), widely utilized in electric vehicles (EVs) for their high energy density and efficiency, yet their performance at low temperatures remains a challenge. This study investigates the influence of electrolyte solvent composition on LIB performance under low-temperature conditions. Three electrolytes were studied: a standard electrolyte (STDE) comprising 1 M LiPF₆ in ethylene carbonate (EC) and diethyl carbonate (DEC), a low-temperature electrolyte (LTE) consisting of 1 M LiPF₆ in EC, ethyl methyl carbonate (EMC), and ethyl acetate (EA), and a long-cycle-life electrolyte (LCLE) containing 1 M LiPF₆ in EC/EMC. The EIS results revealed significant differences in resistance values among the electrolytes at varying temperatures. Specifically, at 0 °C, the STDE exhibited a charge transfer resistance (R_ct) of 1055.3 Ω and a solid electrolyte interface resistance (R_SEI) of 803.4 Ω, whereas the LTE showed a substantially lower R_ct of 507.4 Ω and R_SEI of 64.2 Ω, indicating superior low-temperature performance. Similarly, at -20 °C, the R_ct values for STDE, LTE, and LCLE were 8878.6 Ω, 854.2 Ω, and 15622 Ω, respectively, with corresponding R_SEI values of 172.1 Ω, 92.4 Ω, and 2364 Ω. Notably, the addition of EA in the LTE formulation contributed to enhanced low-temperature performance, likely by lowering the overall viscosity of the electrolyte mixture and improving ionic mobility. This study demonstrates the critical role of solvent composition, particularly EA, in optimizing LIB performance for cold climate applications.

Design modification of shifting blocker of vehicle gearbox for strength improvement

Abbas Soltani

In this paper, the strength of the gear shifting blocker for Peugeot gearbox is investigated. A hardened steel sheet is used inside the plastic part of shifting blocker to strengthen it. According to the feedback from the customer that this part fails in some conditions, some suggestions for its improvement are presented. In this research, two proposed correction designs are presented to increase the strength of the gear shifting locker by changing on the considered steel sheet. Abaqus software has been used to model the gear shifting blocker and analyze the stress of parts by finite element method. In order to validate the analytical results and choose the proper proposed design to strengthen the blocker part, some experimental tests are performed on the tension-compression test device. By comparing the results of the numerical analysis, it can be observed that the first and second modification designs have improved the stresses of blocker plastic part by 18% and 45%, respectively.

High-entropy oxides with a spinel structure as lithium-ion battery anode materials

Hadi Arabi

High-entropy oxides (HEOs) are single-phase crystal structures composed of multiple metal elements that provide great potential for energy storage applications due to the synergistic eﬀect of various metal species. They are considered effective anode materials for high-performance lithium-ion batteries (LIBs) because of their structural stability, high electronic conductivity, and ability to create anode materials with novel structures using several elemental compounds. Because the effects of different types of electrochemically active elements on the properties of anode materials are unknown, it is necessary to develop HEOs and investigate their properties. Herein, to explore the electrochemical properties of HEOs by changing the content of cations with various mechanisms for storing lithium, we prepared three samples of HEOs with spinel structure using the solid-state method, one of which is equimolar ((MgNiTiFeZn)_0.6O₄) and two numbers are near-equimolar ((Mg_0.6Ni_0.6Ti_0.3Fe_0.9Zn_0.6)O₄ and (Mg_0.6Ni_0.6Ti_0.3Zn_0.9Fe_0.6)O₄)). For structural properties determination, X-ray diffraction analysis was used. The results confirmed the formation of three single-phase high-entropy oxides.
Electrochemical tests indicated the structural stability of three compounds of high entropy oxides, and the composition of (MgNiTiFeZn)_0.6O₄, relative to the others, has better rate capability (163 mAhg⁻¹ at 1000 mAg^–1) and higher discharge capacity (220 mAhg⁻¹ at 200 mAg^–1) after 200 cycles.

Design of a brake kinetic energy recovery system using flywheel for a passenger car

Mohsen Esfahanian

The objective of developing kinetic energy recovery systems for vehicles is to repurpose energy otherwise dissipated during braking. Brake energy recovery and storage are achieved through two broad methods: electrical and mechanical, contingent on the energy storage type and the traction system's operational approach. Utilizing a rotating flywheel emerges as a practical, cost-effective, safe, and environmentally friendly means of storing energy, offering an extended service life. This study, synthesizing insights from various theories, aims to devise a prototype brake energy recovery system compatible with Samand car, employing the flywheel tank. Additionally, considerations for the power transmission system and clutch involve designing their type and dimensions, taking many factors into account for the selection. The initial design undergoes simulation and evaluation using MATLAB_SIMULINK and the ADVISOR plugin. The investigation delves into the influence of various design parameters on the efficiency of the system. Subsequently, attempts are undertaken to clarify the factors contributing to varied outcomes. The simulation results indicate a notable decrease in fuel consumption and emissions for a Samand car during urban driving cycles characterized by frequent braking. This improvement is realized through the utilization of a steel flywheel with an incomplete cone geometry and a specified radius. Suggestions are put forth for refining the controller to potentially enhance reductions in fuel consumption and pollution.

Effect of Input Heat of Resistance Spot Welding (RSW) Process on the Mechanical Behavior of Welded Joint of SS-316L Steel

Moslem Mohammadi Soleymani

In the automobile sector, stainless steel and resistance spot welding (RSW) are often used. In this work, RSW was used to join five samples of 316L stainless steel joints at currents of 15, 20, 25, 30, and 35 kA while the heat input parameters varied. The welded joints' microstructure, hardness, and mechanical properties were examined and evaluated. The base metal, heat-affected zone (HAZ), and weld areas' microstructures were all examined using optical microscopy. The mechanical characteristics of the joints were assessed using room-temperature tensile-shear testing and hardness testing. The microstructure findings revealed ferrite in many weld regions and an austenitic structure overall. In the samples with welding currents of 15, 20, 25, 30, and 35 kA, the average hardness of the weld zone was 329, 258, 251, 238, and 235 Vickers, in that order. The hardness of the weld zone exhibited an inverse connection with the welding current, as an increase in welding current resulted in a drop in the resistance spot welded area's hardness. Furthermore, when heat input increased, the hardness of the HAZ reduced and increased relative to the 316L steel. The joint strength of the RSW increased with increasing welding current, as demonstrated by the tensile-shear test results for all five welded samples with varying currents. As a result, the samples with 30 and 35 kA currents failed at the weld with a force greater than 3 kN, while the other samples with lower welding currents had a failure force of less than 2 kN.