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Helps EVs keep cool during the act of balancing the weight of the battery-ScienceDaily

Packing batteries with enough energy to power a car has put a lot of pressure on storage devices that have been primarily tasked with running small appliances and electronics for the past century or so. .. They are under stress-they manifest themselves in malfunctions, poor performance, and even meltdowns. Researchers at Drexel University are trying to help by removing literal heat from batteries and planning more sustainable routes for use in electric vehicles.

In a recently published paper in the journal Composite Material Part B: EngineeringResearchers led by Drexel’s Ahmad Najafi, PhD, an assistant professor of engineering, reveal a design optimization system for incorporating vascular-like cooling networks into the packaging of a new generation of carbon fiber-based batteries used in electric vehicles. Did. Their method balances performance-enhancing factors such as battery capacity and conductivity with problematic variables such as weight and thermal activity that can reduce performance and cause malfunctions in the design of any electric vehicle. We provide the best battery package specifications for you.

“One of the main obstacles to EV development and the resulting increase in market share is the low specific energy of the battery, especially for long-distance designs, which makes the EV heavier,” the author writes. ..

Multi-faceted battery

Demand for electric vehicles has been driven by increasingly imminent air quality and climate change concerns, as well as rising gas prices, but of the electric vehicles that drew much attention last year for durability and safety. The market has been constrained by recalls of their batteries in question.

As a result, more companies are using solid-state batteries (thin carbon fiber-based versions of large lithium-ion batteries widely used in electric vehicles) because they can be skillfully incorporated into the physical structure of the vehicle chassis. I am considering. As a way to reduce weight.

A carbon fiber composite that functions part of the car’s frame, as reducing the weight of the car by only 10% could increase mileage efficiency between charges by 6-8%, according to some estimates. Can be replaced with. both As a structural component and as a battery, it can not only reduce the gross vehicle weight, but also increase the energy storage capacity.

heating

For the success of these structural or “massless” batteries, designers must face the challenges posed by using solid polymers rather than liquid electrolyte solutions as the medium of electron transport.

“Structural batteries generate significantly more heat than standard lithium-ion batteries,” explains Najafi. This is because the conductivity of polyelectrolytes is much lower than that of liquid electrolytes used in lithium-ion batteries. This means that as electrons move through the polymer, they face more bottlenecks. They are forced to move slowly, resulting in more heat as the battery releases its energy.

“Structural battery composites are a promising technology for reducing the weight of electric vehicles, but their design could certainly benefit from the addition of thermal management systems,” says Najafi. “This not only improves the range of the EV, but also significantly reduces the possibility of thermal runaway reactions.”

Keep cool

Najafi’s research group has been developing special composites for thermal management for many years. Their work utilizes the vasculature, a unique cooling method of nature, to dissipate heat. By modifying the design tools invented to plot the optimal “microvascular” network, researchers will function as part of the structural battery package currently being tested by companies such as Tesla, Volkswagen, and Volkswagen. I was able to design a cooling composite material.

The design system, presented in a recent study by the Najafi team, calculates the optimal pattern, size, and number of microvascular channels to quickly dissipate heat from the battery and improve the flow efficiency of coolant as it travels through the channels. It can be optimized.

“These composites act like radiators for internal combustion engine vehicles,” says Najafi. “The coolant draws in heat and pulls it away from the battery composite as it travels through the network of microchannels.”

By sandwiching a structural battery between layers of cooling microvascular composites, it is possible to stabilize the temperature during use and extend the working time and power range.

Perfect fit

As reported in the paper, the team’s structural battery optimization process involves the thickness and orientation of each layer of carbon fiber, the volume fraction of the fiber in the active material, and the number of microvascular composite panels required for temperature control. Some design parameters are considered, such as.

To test each combination, the group measured the stiffness of each structural battery-cooled composite laminate and confirmed that it met the structural integrity criteria of the vehicle. Next, we simulated the energy demand of the vehicle at various speeds over a period of minutes, recording the battery temperature, which is the predicted range of the vehicle.

Studies have shown that a computer model of one optimized system can improve the Tesla Model S’s driving range by as much as 23%. However, the team said that the true value of their work includes the best combination of battery size and weight (sufficient cooling capacity to maintain functionality) for electric vehicles currently in production and future designs. ) Is the ability to collect.

“We know that even a little lighter weight can improve EV performance, but thermal management is just as important. Perhaps even more important for people to drive comfortably.” Said Najafi. “Our system strives to integrate improvements in both of these areas, which may play an important role in the advancement of electric vehicles.”

https://www.sciencedaily.com/releases/2022/05/220516104641.htm Helps EVs keep cool during the act of balancing the weight of the battery-ScienceDaily

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