Lithium-ion batteries are the backbone of novel energy vehicles and ultimately contribute to a more sustainable and environmentally friendly transportation system. Taking a 5 Ah ternary lithium-ion battery as an example, a two-dimensional axisymmetric electrochemical–thermal coupling model is developed via COMSOL Multiphysics 6.0 in this study and then is validated with the experimental data. The proportion of different types of heat generation in a 26,650 ternary lithium-ion battery during the charge/discharge cycle is investigated numerically. Moreover, the impact of essential factors such as charge/discharge multiplier and ambient temperature on the reaction heat, ohmic heat, and polarization heat are analyzed separately. The numerical results indicate that the total heat generated by the constant discharge process is the highest in the charging and discharging cycle of a single battery. The maximum heat production per unit volume is 67,446.99 W/m³ at 2 C multiplier discharge. Furthermore, the polarization heat presents the highest percentage in the charge/discharge cycle, reaching up to 58.18% at 0 C and 1 C multiplier discharge. In a high-rate discharge, the proportion of the reaction heat decreases from 34.31% to 12.39% as the discharge rate increases from 0.5 C to 2 C. As the discharge rate rises and the ambient temperature falls, the maximum temperature increase of the single-cell battery also rises, with a more pronounced impact compared to increasing the discharge rate.

Riblet and superhydrophobic surfaces are two typical passive control technologies used to save energy. In this study, three microstructured samples—a micro-riblet surface (RS), a superhydrophobic surface (SHS), and a novel composite surface of micro-riblets with superhydrophobicity (RSHS)—were designed to improve the drag reduction rate of water flows. Aspects of the flow fields of microstructured samples, including the average velocity, turbulence intensity, and coherent structures of water flows, were investigated via particle image velocimetry (PIV) technology. A two-point spatial correlation analysis was used to explore the influence of the microstructured surfaces on coherent structures of water flows. Our results showed that the velocity on microstructured surface samples was higher than that on the smooth surface (SS) samples, and the turbulence intensity of water on the microstructured surface samples decreased compared with that on the SS samples. The coherent structures of the water flow on microstructured samples were restricted by length and structural angles. The drag reduction rates of the SHS, RS, and RSHS samples were −8.37 %, −9.67 %, and −17.39 %, respectively. The novel established RSHS demonstrated a superior drag reduction effect and could improve the drag reduction rate of water flows.