Abstract
The development of better electrochemical energy storage systems has sparked significant interest in using Li-ion batteries for electric vertical takeoff and landing (eVTOL) applications. To ensure the optimal performance and safety of onboard batteries, their behavior under different charging/discharging protocols and environmental conditions must be understood. This paper presents a comprehensive evaluation of commercial Li-ion batteries for eVTOL applications, focusing on their responses to varying charging/discharging strategies and mechanical vibrations experienced during flight. Through controlled experiments, the effects of rapid cycling on battery performance were investigated, including effects on lifespan, capacity, and internal resistance. Additionally, the impact of mechanical vibrations on battery behavior was assessed to identify potential challenges for onboard batteries. The results of this study revealed intriguing insights into the interplay between temperature, vibration, and battery performance. This work contributes to the broader adoption of electric aerial transportation, promising a greener and safer future for urban mobility.
| Original language | English |
|---|---|
| Article number | 234335 |
| Journal | Journal of Power Sources |
| Volume | 602 |
| DOIs | |
| State | Published - May 15 2024 |
Funding
After temperature variations were introduced to the system, a notable decrease in capacity was observed, as depicted in Fig. 3. This outcome was expected because the system's internal resistance tends to increase with lower temperatures, negatively affecting its capacity. However, an interesting finding emerged when vibration was introduced to the system at lower temperatures. Above 0 °C, the system's retained capacity for vibration was comparable to that under the nonvibrating condition. Surprisingly, below 0 °C, the capacity began to increase, surpassing the capacity in the non-vibration scenario. These results are visualized in Fig. 3a and b as the polarization curves of the cells by varying temperature with and without vibration. These findings are further supported by the EIS spectra presented in Fig. S1. Above 0 °C, the EIS spectra showed comparable behavior for both the vibrating and nonvibrating setups. However, below 0 °C, a synergistic effect of vibration on the system became evident, resulting in lower cell resistance and possibly contributing to the observed capacity enhancement. The temperature and vibration variations in the system had distinct effects on its capacity, with vibrations having a unique influence at lower temperatures. The results suggest a potential avenue for further exploring the optimization of the system's performance. Table S3 lists the discharge capacities of the cells at different temperatures with and without vibration, and the trend of discharge capacity is plotted in Fig. S2. Until 0 °C, both systems showed identical responses, and below 0 °C, the difference in capacity was quite significant. We note here that the experiments were carried out in environmental chambers to regulate the overall temperature of the measurement system. We do not anticipate the surface temperature of the batteries to change significantly due to this engineering control within our experiments. Further, there is a significant body of literature pertaining to vibration-induced heating in solid materials [22–26]. We anticipate that such vibration-induced heating will result in improved performance at lower temperatures. Dedicated experimental and modeling efforts to elucidate this behavior are needed to understand this behavior in lithium-ion batteries completely.This research at Oak Ridge National Laboratory, managed by UTBattelle, LLC, for the USDepartment of Energy under contract DE-AC05- 00OR22725, was sponsored by the USArmy DEVCOM Army Research Laboratory and was accomplished under Support Agreement 2371-Z469-22. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the DEVCOM Army Research Laboratory or the U.S. Government. This research at Oak Ridge National Laboratory , managed by UT Battelle , LLC, for the US Department of Energy under contract DE-AC05- 00OR22725, was sponsored by the USArmy DEVCOM Army Research Laboratory and was accomplished under Support Agreement 2371-Z469-22. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the DEVCOM Army Research Laboratory or the U.S. Government. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purp oses. DOE will provide public access to these results of federally sponsored research in accordance with the Public Access Plan ( https://www.energy.gov/doe-public-access-plan ). DOE
Keywords
- 18650 cells
- Impedance spectroscopy
- Lithium-ion batteries
- Rate performance
- Vibration
- eVTOL