A team of researchers from the American Drexler University has designed an innovative optimization and cooling system that helps prevent electric vehicle batteries from overheating. As a consequence, these batteries increase their performance parameters so that its useful life is extended so that it can be used for a longer time without degrading. The system provides a cooling network inspired by the microvascular network of humans.
The result of the research is a system that balances numerous factors based on the use of carbon fiber. It provides optimal specifications for the design of the cooling system for structural batteries, which serve a dual function in electric vehicles: as a structural component and as an energy store. From composite materials, the system provides a microvascular cooling network which can help prevent devices from getting too hot, malfunctioning, and even catching on fire.
The method has been developed under the direction of Ahmad Najafi, assistant professor in the university’s Faculty of Engineering. As he explained, it balances the factors that improve battery performance, such as capacity and conductivity, by reducing other variables that add complexity, such as weight and overheating, which work against performance and can cause malfunctions.
The general objective of the project is to provide the best specs of a battery pack tailored to any EV design, says the research team in an article published on their work in the journal Composites Part B: Engineering. They get it by calculating the best pattern, size and number of microvascular channels to quickly dissipate heat from the batteries, as well as optimizing the design for the efficiency of the flow of coolant moving through the channels.
“The proposed optimization scheme aims to maximize the range of electric vehicles while ensuring that the battery pack does not overheat during operation and shows promising mechanical integrity,” the researchers state in the article.
Najafi compares the system to cooling a radiator-based internal combustion engine vehicle: “The coolant draws heat away from the battery compound as it moves through the network of microchannels.”
Weight reduction: carbon and solid batteries
The researchers worked with a carbon fiber battery, which already reduces the weight of batteries in proportion to the energy they carry, a key factor that inhibits performance. For this reason, scientists and automakers have been considering the use of solid carbon-fiber-based batteries, as a slimmed-down version of the larger lithium-ion batteries typically used in electric vehicles, to reduce the vehicle weight. According to the researchers’ estimates, reducing the weight of a car by just 10% can increase efficiency and increasing autonomy between 6 and 8%.
Therefore, the use of a carbon fiber composite in a structural battery that plays a dual role as a structural component of the vehicle and an energy store can reduce the overall weight of the vehicle and improve its ability to store energy.
The cooling system: inspiration from nature
The heating of lithium batteries is one of the great handicaps when it is used in electric vehicles. The increase in temperature not only has repercussions on the performance of the vehicle but also causes its degradation to accelerate.
In solid-state batteries, in which the liquid electrolyte is replaced by a solid (ceramic type) or polymeric material, this heating tendency will be even more pronounced, Najafi assures. This is because the conductivity of the polymer electrolyte is much lower than that of the liquid electrolytes used in lithium-ion batteries. As a consequence, bottlenecks are created in the movement of electrons that generate heat.
For create your thermal management system, the researchers were inspired by the vascular system of the human body, which is nature’s own cooling method of dissipating heat. To achieve this, they modified a custom design tool to create an optical microvascular network that can aid in the design of cooling compounds. These materials can be integrated into the packaging of structural batteries currently being tested by companies such as Tesla, Volvo and Volkswagenthe researchers said.
They also integrated parameters into the system for the use of carbon fiber in the battery, such as the thickness and directions of the fibers in each layer, the volume fraction of the fibers in the active materials, and the number of microvascular composite panels needed. for thermal regulation.
The system under test
Once the parameters were established, the researchers tried various combinations to ensure they met vehicle structural integrity standards. They then simulated the energy demand of a vehicle at various speeds for several minutes, while recording the battery temperature and the expected range of the vehicle.
This research showed that the system could improve the autonomy of a Tesla Model S up to 23%. However, the real application of it is aimed at helping discover the best combination of battery size and weight along with optimizing enough cooling capacity to keep it going in any current or future vehicle, Najafi said.
“While we know that every little weight saving can help improve the performance of an electric vehicle, thermal management can be just as important, perhaps more so, when it comes to making people feel comfortable driving it,” the statement said. of press. “Our system strives to integrate improvements in both areas, which could play an important role in advancing electric vehicles.”