[Objective] Owing to the airplane requirements for lightweight, simple system structures and easy maintenance, air cooling is the primary thermal management for airplane power batteries. Previous studies have explored the impact of air-cooled thermal management on battery performance, but the research combining the effect on performance with the underlying mechanism is limited. [Methods] To investigate the impact of air cooling on the performance of ternary lithium batteries in airplanes, a lithium battery thermal management test platform was developed, with a wind speed-adjustable power. The platform is independently designed and consists of a check valve, inlet connecting section, battery placing middle section, outlet connecting section, cooling fan, and pulse width modulator (PWM) speed control module, among other components. The system includes four main functions: rectification, insulation, stability, and high-precision wind speed control. The rectification function regulates the airflow direction for uniformity. The insulation function is achieved by installing adiabatic check valves at the entrance and exit. The airflow stability is ensured by utilizing the Venturi effect to maintain low inlet pressure and pulsation. Finally, the high-precision wind speed is controlled by a PWM speed control module. The platform has the additional benefit of a stable and uniform wind speed, which strongly correlates with the current and enables precise wind speed control by adjusting to the current size. Based on this platform, experiments were conducted to study the impact of air cooling on the performance of lithium batteries, including thermal, electrical, and material performance, and explore the relationship and impact mechanisms among them. [Results] The experimental results indicate the following: (1) applying air cooling can effectively reduce the surface temperature of the cell body, maintaining it within a suitable working temperature of 45 °C and a temperature difference of 5 °C. Concurrently, air cooling significantly minimizes temperature fluctuations, resulting in lower temperature stresses throughout the battery and greater stability of its internal structure; (2) the thermal performance of the battery is improved to weaken its impact on material performance, preventing the fragmentation of cathode particles in ternary lithium batteries, maintains a stable and orderly layered structure, and suppresses the loss of cathode active material and active lithium; (3) under suitable wind speed conditions, such as 6 m/s, the battery material maintains a stable and significant inhibition of resistance growth, impeding the decline in battery capacity and effectively extending the service life of the battery. The capacity degradation rate of air cooling is significantly lower than that of the no-air-cooling condition under the same number of cycles. [Conclusions] Herein, we address the research gap on the effect of air cooling on the performance of ternary lithium batteries in airborne power batteries. Experimentally, we investigate the impact of air cooling on the thermal, electrical, and material performance of ternary lithium batteries, providing insights into the intrinsic mechanism of air cooling on battery performance. The results can guide the design of power battery systems for airplane operations. Additionally, it offers data support and a theoretical basis for developing next-generation power battery thermal management systems. © 2024 Tsinghua University. All rights reserved.
