We are presenting our recent research results about the Ni-NiO nanoparticles on poly-(diallyldimethylammonium chloride)-modified graphene sheet (Ni-NiO/PDDA-G) nanocomposites prepared by the hydrothermal method at 90°C for 24 h. The Ni-NiO nanoparticles on PDDA-modified graphene sheets are measured by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) pattern for exploring the structural evidence to apply in the electrochemical catalysts. The size of Ni-NiO nanoparticles is around 5 nm based on TEM observations. The X-ray diffraction (XRD) results show the Ni in the (012), (110), (110), (200), and (220) crystalline orientations, respectively. Moreover, the crystalline peaks of NiO are found in (111) and (220). The thermal gravimetric analysis (TGA) result represents the loading content of the Ni metal which is about 34.82 wt%. The electron spectroscopy for chemical analysis/X-ray photoelectron spectroscopy (ESCA/XPS) reveals the Ni⁰ to Ni^II ratio in metal phase. The electrochemical studies with Ni-NiO/PDDA-G in 0.5 M aqueous H₂SO₄ were studied for oxygen reduction reaction (ORR).

Traditional high power constant current‐constant voltage (CC−CV) charging leads to the degradation of Li‐ion batteries. Thus, aging due to charging is a primary issue to be overcome in application technology. This study proposes the impacts of a sinusoidal waveform charging strategy for charging Li‐ion batteries. Specifically, a negative voltage is introduced in the charging process to reverse passivation layer formation. After few cycles of sinusoidal waveform charging, aged cells can be revived. Tests reveal that the available capacity of an aged cell can be improved by a maximum of 18.7 % relative to the original rated power. After 600 charging‐discharging cycles of new cells, the cells charged using the sinusoidal waveform strategy possess approximately 15 % more electrical capacity than do cells charged using the conventional CC−CV method, indicating an increase in battery cycle life. The suppression of interfacial resistance is characterized by electrochemical impedance spectroscopy. Sinusoidal waveform charging can reduce charging time by half and the maximum rise in temperature by 6 °C compared with the CC−CV charging method.

This study investigated the matching designs between a power integration mechanism (PIM) and transmission system for single-motor parallel hybrid electric vehicles. The optimal matching design may lead to optimal efficiency and performance in parallel hybrid vehicles. The Simulink/Simscape environment is used to model the powertrain system of parallel hybrid electric vehicles, which the characteristics of the PIM, location of the gearbox at the driveline, and design of the gear ratio of a gearbox influenced. The matching design principles for torque-coupled–type PIM (TC-PIM) parameters and the location of the gearbox are based on the speed range of the electric motor and the internal combustion engine. The parameters of the TC-PIM (i.e., $k_1$ and $k_2$ ) are based on the $k$ ratio theory. Numerical simulations of an extra-urban driving cycle and acceleration tests reveal that a higher $k_{ratio}$ has greater improved power-assist ability under a pre-transmission architecture. For example, a $k_{ratio}$ of 1.6 can improve the power-assist ability by 8.5% when compared with a $k_{ratio}$ of 1. By using an appropriate gear ratio and $k_{ratio}$ , the top speed of a hybrid electric vehicle is enhanced by 9.3%.

Charging methods that were employed earlier provided constant energy to a battery, but the negative impact was the activation of chemical reactions that lead to battery passivation. Thus, in order to mitigate the battery aging, moderate energy for charging a lithium‐ion battery has been theoretically calculated using density functional theory. The charging process was associated with a Li‐ion transfer model between two electrodes. When charging, Li‐ions from the positive electrode, pass through a separator/electrolyte, transfer via a solid electrolyte interface (SEI), and intercalate into the negative electrode. Calculations provided activation energies of migration through the SEI and intercalation of graphite. The inverse reaction of electrolyte reduction was introduced in the process to prevent impedance formation. The unit of power of the external charger can be converted to voltage. Therefore, the proposed novel charging strategy used positive voltage for migration and negative voltage for the inverse reaction of reduction. The charging strategy can be approximated to a sinusoidal waveform, which is effective in reviving Li‐ion battery and prolonging the cycle life.

In recent years, hybrid electric vehicles (HEVs) have increased significantly due to climate change and the demand for high-efficiency power sources. HEVs that combine an internal combustion engine (ICE) and an electric motor (EM) can improve the power output of the ICE and overcome the challenges of the insufficient battery life of electric vehicles. In this study, a parallel HEV with a power distribution mechanism is developed for energy saving and carbon reduction. The driver′s power demands are used as input sources, and a rule-based control strategy is used to determine the power distribution of the generator, EM, and ICE. The NEDC2000 driving cycle is used as the test benchmark to demonstrate the performance of the HEV. In comparison to ICE vehicles, the fuel efficiency of HEVs significantly improved. In addition, other parameters, including the average brake-specific fuel consumption (BSFC), brake-specific carbon monoxide emission (BSCO), and brake-specific hydrocarbons (BSHCs), were lower, which can effectively save fossil fuel and reduce air pollution.