Scientists determined how particles released by lithium-ion batteries can affect lung health.
Introduction
Batteries power our world. They store and release energy via chemical reactions. Lithium-ion batteries use lithium and other metals to store energy. Cell phones, laptops, tablets, and even electric vehicles use these batteries. Why? They can store a large amount of energy in a small space. They hold their charge for a long time. They can also recharge quickly, many times over. That is why these batteries are also used to store energy made by renewable energy sources.
But lithium-ion batteries can be dangerous if they experience thermal runaway. During thermal runaway, the battery becomes very hot. Then the energy stored in the battery is released suddenly. The result is fire and potential explosions. The batteries also release tiny solid particles known as particulate matter. Some of these particulates are large enough to see with the unaided eye. Others are very small.
When you inhale or breathe in particulates, they can hurt your lungs. During a thermal runaway event, people like first responders may breathe in these particles. We wanted to know the health effects of particulate matter and metals released by lithium-ion batteries. We focused on how the particulate matter and metals affect lung cells.
Methods
We tested two different types of lithium-ion batteries. Type A contained lithium, iron, and phosphate. Type B contained lithium, manganese, and cobalt.
We placed the batteries in a chamber. We then heated them to cause thermal runaway. We used probes to measure the number and size of particles. We also analyzed the composition of the particles.
We used a computer model to calculate the amount of particulates that would represent very high or worst-case scenario exposure levels. To achieve this, the model assumed people inhaled the particles through their nose for two hours a day, five days a week, for 52 weeks (one year) or 260 weeks (five years).
Then, we grew lung cells and exposed them to our modeled amount of particulate matter. We exposed Group A cells to the particulates produced by Type A batteries and Group B cells to those made by Type B batteries. We used two doses of particulates from each battery type. The low dose modeled exposure for one year. The high dose represented modeled exposure for five years.
We analyzed the amount of cell stress and DNA damage and repair compared to a control group. We determined the amount of cell stress or oxidative stress by measuring a molecule known as reactive oxygen species, or ROS.
Results
Particulate Characteristics
We learned that the two battery types release similar metals during thermal runaway (see Fig 1). The main metals released were sodium (Na), calcium (Ca), and lithium (Li). The batteries also released aluminum (Al) and the heavy metals nickel (Ni), cadmium (Cd), and lead (Pb). Type B released the heavy metal manganese (Mn) as well. We found that the Type B batteries had higher particulate concentrations. These particles had a larger average diameter compared to Type A.
Cell Stress
Group A cells produced the same amount of ROS as the control cells at both doses. Group B cells produced more ROS than the control cells when there was a high dose of particulate matter. There was no change in ROS at the low dose.
DNA Damage and Repair
Cells in Group A did not show an increase in DNA damage at either dose. But they did show a decrease in the substances used to repair DNA. This decrease occurred at both doses.
Cells in Group B showed DNA damage at both doses. They also showed a decrease in DNA repair chemicals, but only at the higher dose.
Discussion
We found that emissions from thermal runaway of lithium-ion batteries may cause harmful effects in the body. Both battery types produced particulate matter, including heavy metals. Cadmium and lead are dangerous heavy metals that can cause health hazards.
The Type B batteries released the heavy metal manganese, which can damage the lungs. This might explain why Type B batteries caused more cells to experience stress and DNA damage than Type A batteries did.
Many of the changes we observed in Group A and Group B cells can cause lung disease. Cell stress and DNA damage can cause inflammation in the lungs. This inflammation and injury can lead to diseases such as long-term bronchitis and pulmonary fibrosis.
Our research also showed that battery chemistry is important. Particulate matter from Type A batteries had harmful effects on lung cells. But the particulate matter from Type B batteries caused more harmful effects. This means that the type of battery affects the level of risk that first responders experience. They are often called out to fires and explosions, so their exposure risk is higher.
Conclusion
Thermal runaway in lithium-ion batteries can be dangerous. That is why it is important to use devices with these batteries carefully. Only charge a device with a lithium-ion battery with its own charger. You also want to make sure that the device does not experience temperatures that are very hot. In addition, never cover a device with a blanket or other items. These items trap heat, making thermal runaway more likely. Lastly, keep charging devices away from pets, as damage from pets can cause thermal runaway.
