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Can NASA Tech Stop Lithium-Ion Thermal Runaway?

May 30, 2024 by Kevin Clemens

A NASA-derived technology helps characterize battery thermal runaway and could lead to safer battery packs.

Since lithium-ion batteries can contain a large amount of energy in a small space, their charging and discharging characteristics must be carefully controlled to maintain thermal integrity. When a cell releases stored energy and heat builds more rapidly than it can be dissipated, the result is thermal runaway. If a lithium-ion battery goes into thermal runaway due to improper handling, it can release huge amounts of gas and heat, potentially causing a significant fire.

In 2023, NASA’s Johnson Space Center revealed the Small Fractional Thermal Runaway Calorimeter (S-FTRC), designed to measure a small-format lithium-ion cell's total thermal energy yield during thermal runaway. The S-FTRC measures the heat of chemical reactions when a lithium-ion cell enters thermal runaway. 

The invention also considers the energy leaving the cell via conduction and through vented gases and effluents. The effects of these toxic, hot, and corrosive gases can be significant. During a thermal runaway, a lithium-ion cell can release as much as 3 liters per amp-hour (Ah).  A large 200 Ah cell could produce up to 600 liters of gases released in as little as 3-5 seconds.

 

NASA’s Johnson Space Flight Center's cell thermal runaway calorimeter.

NASA’s Johnson Space Flight Center's cell thermal runaway calorimeter. Image used courtesy of NASA 

 

Larger Format Cells

The S-FTRC has been expanded to allow testing and characterization of larger format cells (L-FTRC) during thermal runaway. San Diego, California-based KULR Technology Corporation, an energy management platform company, licensed L-FTRC technology from NASA. KULR’s device uses NASA’s technique to examine the largest lithium-ion battery cell formats and characterize total energy yield, fractional energy yield, and mass ejection distributions. It can also extract gas samples and submit them for third-party analyses. KLUR can now undertake L-FTRC experiments for any capacity cylindrical, pouch, and prismatic cells.

KULR has completed L-FTRC tests on 200-amp-hour (Ah) high-energy nickel manganese cobalt prismatic-format lithium-ion battery cells for an unnamed global automotive OEM customer.

 

Testing the L-FTRC

Testing the L-FTRC. Image used courtesy of KULR

 

No two thermal runaway events are the same. To improve battery safety, engineers must know a thermal event’s total energy yield and how the energy leaves the lithium-ion cell. The FTRC, originally developed by NASA, is the only known calorimeter method providing these data. 

 

KULR Enhancements

To support mid-sized lithium-ion cells (30 Ah to 70 Ah) and very large cells (up to 200 Ah), KULR modified the original S-FTRC design to be modular. The company found that the larger the cell, both in size and capacity, the more difficult it was to test. They have undertaken additional research and development to allow flow measurement of the gases produced during thermal runaway events. One such highly toxic gas is hydrogen fluoride, which, in concentration, is critical to achieving certification for lithium-ion cells used around people. 

A better understanding of the characteristics of thermal runaway will result in safer and more resilient battery systems