The new optimization system for EV batteries can control thermal activity

Drexel University researchers have created an optimization system for electric vehicle batteries to manage endurance, weight and thermal activity.

As carmakers increasingly explore carbon-fiber structural batteries as lithium-ion alternatives, researchers at Drexel University in Pennsylvania have developed a system to optimize the design of electric vehicle (EV) batteries to maximize their range. and reliability.

Packing enough energy into a car battery puts a lot of pressure on storage devices, which in the last century or so have been mainly responsible for controlling small appliances and electronics. Stress can lead to malfunctions and reduced productivity.

In an article published recently in the magazine Composites Part B: EngineeringA research team led by Dr. Ahmad Najafi of Drexel, an assistant professor at the College of Engineering, developed a design optimization system to include a blood vessel-like cooling network in the packaging of a new generation of carbon-based batteries used in EVs.

Their method balances performance factors – such as battery capacity and conductivity – against problematic variables, including weight and thermal activity, to ensure optimal EV battery specifications.

A new generation of batteries for electric vehicles

As demand for electric vehicles has been affected by growing concerns about climate change and rising gas prices, the market has been dampened by growing concerns about the safety and durability of electric car batteries.

As a result, more and more companies are considering the use of solid-state batteries – a thin, carbon-fiber version of larger lithium-ion batteries widely used in electric vehicles – as they can be skillfully incorporated into the physical structure of a vehicle’s chassis. to lose weight.

In addition, reducing the car’s weight by only 10% can increase the efficiency of mileage between charges by up to 6-8% according to some estimates. Thus, replacing parts of the car frame with a carbon fiber composite that functions as both a structural component and a battery can reduce the overall weight of the vehicle as well as improve its energy storage capacity.

Control of the thermal activity of the EV battery

To succeed in these structural or “massless” batteries, designers must face the challenge of using a solid polymer – rather than a liquid electrolyte solution – as its electron transfer medium.

“Heat production will be significantly higher in structural batteries than standard lithium-ion batteries,” Najafi explained.

This is because the conductivity of the polymer electrolyte is much lower than that of the liquid electrolytes used in lithium-ion batteries. This means that the electrons face a bigger obstacle as they move through the polymer, which leads to slower movement and generating more heat while the battery discharges its energy.

“While structural composite batteries are a promising technology for reducing the weight of electric vehicles, their design can certainly benefit from the addition of a heat management system,” Najafi added. “This could not only improve the range of EV, but also significantly reduce the chances of a thermal reaction.

To solve this problem, Najafi’s research team used the natural method of cooling the vascular system to dissipate heat. Thus, by modifying a design tool they invented to design the optimal “microvascular” network, researchers were able to design cooling composites to work as part of the structural packaging of the battery, which is currently being tested by companies such as Tesla. , Volvo and Volkswagen.

The design system presented by the Najafi team in their latest study can calculate the best model, size and number of microvascular channels for rapid heat dissipation from batteries. This also means that the design flow is optimized for the efficiency of the flow of the coolant moving through the ducts.

“The coolant attracts heat and draws it out of the battery composite as it travels through the microchannel network,” Najafi explained. Placing structural batteries between layers of cooling microvascular composites can stabilize their temperature during use and expand the range of time and power in which they can operate.

Optimizer system for EV batteries

The process of optimizing the structural battery of the research team takes into account several design parameters, such as fiber thickness and directions in each layer of carbon fiber, the volume of fiber in the active materials and the number of microvascular composite panels required for thermal regulation.

According to the study, the computer models of an optimized system reveal that it can improve the driving range of the Tesla Model S by as much as 23%. However, the team noted that the real value of their work is its ability to put together the best combination of battery size and weight – including enough cooling capacity to keep it running – for each electric vehicle currently in production and any future projects.

“While we know that any part of saving weight can help improve EV performance, heat management can be just as important – perhaps more so when it comes to making people feel comfortable driving them.” said Najafi. “Our system seeks to integrate improvements in both areas that could play an important role in EV’s progress.