Understanding Thermal Runaway – and Solutions for Designing Safer Batteries

Posted by Casey Cephas | 11/2/21 9:30 AM

According to the classic TV show, The Jetsons, we’re a mere four decades away from driving flying cars. While that may be science-fiction, the era of electronic vehicles (EV) is much more realistic. The global EV market increased 43% from 2019 to 2020 – and hit the 10 million stock milestone in the process. Considering that this growth occurred during the COVID-19 pandemic, it’s safe to say that the future is now when it comes to electric vehicles.

One key driver of the growth and mainstream consumer adoption of EVs is advancements in battery technology. Today’s batteries (and therefore vehicles) offer higher capacity, extended driving range, improved motor performance, and faster charging. However, one drawback to high-powered batteries that can present a design challenge – and even potential safety hazard – is thermal runaway.

What is thermal runaway?

Thermal runaway (or TR, for short) is a phenomenon that can affect rechargeable energy storage systems, including lithium-ion (Li-ion) batteries and valve-regulated acid (VRLA) batteries. The dangerous condition occurs when the temperature rapidly rises inside one of the battery cells. The excess heat combined with lower internal resistance to the charging current enables the temperature to rise quickly even further and affect other cells. This pattern will repeat until the battery is removed or fails – hence the “runaway” of thermal runaway.

Several factors can influence thermal runaway, including:

  • High ambient temperature
  • Age of battery
  • Excessive float charging voltage
  • Overcharging

Risks of thermal runaway

Once the thermal runaway process begins, it is very unlikely that the condition will stop on its own. If the temperature increases and isn’t effectively dispelled, the inevitable result will be the battery overheating. The heat will cause significant damage to the battery and its compartment. In some cases, the battery may leak toxic chemicals or gas.

Beyond battery damage, thermal runaway poses severe risks to the product’s users and surroundings, including sudden system failure and dangerous events such as fire or explosions. While traditional combustion vehicles can also experience these hazardous situations, fires with EVs can be more extreme. As a newer technology, issues with EVs also tend to attract more media attention and can harm a company’s reputation.

Addressing and preventing thermal runaway

Based on the dangers and costs associated with thermal runaway, there’s no surprise that prevention has been a top priority for EV manufacturers and regulators. One approach to minimizing the possibility of TR is with preventative maintenance, including adjusting the charging voltage, ensuring proper ambient air temperature surrounding the battery, and replacing older batteries before failure is likely to occur.

There are two main downsides to this maintenance approach. First, it requires an experienced technician who has the proper training and equipment to work with these advanced batteries. Second, it doesn’t address real-world demand, such as enabling faster charging to accelerate the adoption of EVs.

Thankfully, there are effective thermal management solutions that can be incorporated into the design of a battery system. Thermal interface material can be inserted between two components to enhance thermal coupling. These materials are suited to delay the onset of thermal runaway, and offer characteristics such as high-temperature resistance, thin and lightweight form factors, and flexibility.

For example, there are conductive tapes and pads specifically designed for thermal runaway and fire propagation protection within EV batteries. These materials are designed to maintain optimal conditions and slow down thermal runaway. Furthermore, they have been tested with a high-temperature flame and exposure to the metal particulates typically present during thermal runway in EV batteries.

In addition to thermal management, additional solutions can be designed to improve the safety and reliability of batteries, including:

  • EMI shielding
  • Anti-propagation
  • Seals and gaskets
  • Spaces and compression pads
  • Dielectric barriers and insulators

Custom materials converting for thermal runaway prevention

While the materials technology for thermal management is quite impressive, it only works if it can fit precisely into your design. That’s where your material converting partner comes in.

At Tapecon, we are here to help you prevent thermal runaway and improve the performance and safety of your product. As a 3M Preferred Converter and converter of other reputable material suppliers, we can help you source the leading materials and products for thermal management and other battery protection solutions. Our expert team then uses various converting techniques to create a component that precisely fits your specifications.

Let’s make something great

With over 100 years of manufacturing experience, Tapecon works with product teams to solve challenges, create products, and enhance lives. Learn more about our custom materials converting services.

Topics: Electronics Materials, Custom Converting

Written by Casey Cephas

Casey is the Marketing Coordinator at Tapecon Inc.

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