Fires are a risk in lithium-ion batteries, because they’re sensitive to high operating temperatures and are inherently flammable. Battery packs tend to degrade much faster due to heat. If a battery fails, it can burst into flames and cause widespread damage.

However, sensors used in battery management systems can monitor their health and performance to help make electric vehicles safer.

One of the companies at the forefront of developing state-of-the-art sensors is Honeywell International Inc. The company is a leading supplier to both the automotive and aerospace industries. It supplies EV manufacturers with aluminum brazing fluxes, corrosion protection fluorides, and thermal management systems for batteries and power electronics.

In 2020, Honeywell formed a strategic partnership with Nexceris to address lithium-ion battery system safety for energy storage applications. It combines Honeywell’s very early warning smoke detection system and Li-ion Tamer gas detection technology from Nexceris.

"As the world transitions to electric-powered vehicles, automakers are faced with the need to provide lithium-ion batteries that function properly and safely during all stages of their lifecycle,” says Victor Verissimo, general manager of the transportation line of business at Honeywell Sensing and Safety Technologies. “We are supporting this transition with ready-now products to help our customers mitigate safety risks as they expand their EV portfolios.

“By collaborating with Nexceris to develop an enhanced suite of battery monitoring sensors, we will help automotive manufacturers strengthen their battery health monitoring systems with the ability to detect thermal runaway conditions even earlier,” claims Verissimo.

Autonomous and Electric Mobility recently asked Verissimo to explain why thermal management is critical to EV performance.

AEM: What is “thermal runaway”? How does it affect the performance of lithium-ion batteries?

Verissimo: Thermal runaway is one of the main safety risks associated with the use of lithium-ion batteries. It is a phenomenon that causes extremely high temperatures within the battery cell where it no longer functions properly and may eventually lead to vehicle failure, smoke and fire. It can be caused by a variety of factors, including internal defects, an external short circuit or over-charging.

AEM: Why is thermal management a critical issue in EVs?

Verissimo: Thermal management extends the life of batteries and impacts the overall drivability and safety of electric vehicles. Batteries can go into thermal runaway while the vehicle is being operated or when a car is parked and unattended, which is why proper battery safety sensing technology is critical. Without it, the vehicle becomes at risk for fire hazards.

AEM: What makes thermal management challenging?

Verissimo: Thermal management or battery safety sensing can be challenging because not all lithium-ion batteries are manufactured the same. Across manufacturers, lithium-ion batteries can be made using various chemistries and formulas, which means different concentrations of gases may be released prior to thermal runaway. This is referred to as off-gassing. This requires advanced sensing technology to detect those harmful gases at early stages.

Through our partnership with Nexceris, we have a proprietary solution that can detect conditions that lead to thermal runaway and help solve this challenge, regardless of the makeup of the battery and its thermal runaway profiles.

AEM: How do sensors help address thermal management issues in EVs?

Verissimo: Sensors play an important role in thermal management and battery safety, because their functionality can determine temperature regulation issues such as overheating or off-gassing from the lithium-ion batteries powering EVs.

In the U.S., there are regulations pending that would require electric vehicle manufactures to provide drivers with a minimum five-minute warning to exit the vehicle in the case of a thermal event in the battery. Putting these sensors into EV batteries proactively helps protect the life cycle of the battery and, ultimately, keeps people safe. Through our collaboration with Nexceris, we will help automakers strengthen their battery health monitoring systems with the ability to detect thermal runaway conditions at early stages.

AEM: What new types of sensors has Honeywell developed specifically for EV thermal management?

Verissimo: In partnership between Honeywell and Nexceris, this new sensing technology for EV battery safety helps prevent conditions that lead to thermal runaway, as well as other lithium-ion battery issues, to help protect the lifecycle of the battery, prevent car breakdowns and other safety hazards.

AEM: What other types of EV battery management sensors does Honeywell produce?

Verissimo: This new sensing technology extends our existing battery safety portfolio, which includes automotive-grade pressure and aerosol sensors that detect thermal runaway. We also produce high-amperage current sensors used in battery management systems, which monitor conditions related to the state of charge and state of health of the EV battery. These sensors enable the safe operation of EVs and improve battery life and vehicle performance, thereby allowing vehicle manufacturers to optimize driving range.

We also have a wide portfolio of gas detection devices for use in EV battery manufacturing facilities to protect workers from exposure to harmful, toxic and flammable gases.

AEM: Are these sensors any different than devices used in traditional ICE vehicles?

Verissimo: While internal combustion engine vehicles do not require lithium-ion battery sensors, sensing technology is still critical to the safety and operation of the vehicle. For example, both battery and ICE vehicles rely on sensors to optimize motion, position and speed over various temperature ranges.