Many electronic devices use lithium-ion batteries. These include laptops, cellphones, tablets, cameras and power tools. Electric vehicles as well as micro-mobility devices such as hoverboards, E-scooters and E-bikes have become increasingly popular and use this type of battery.  Compared with traditional battery technology, lithium-ion batteries charge faster, last longer and have a higher power density for more battery life in a lighter package. While these batteries provide an effective and efficient source of power, the likelihood of them overheating, catching fire and even leading to explosions increases when they are damaged or improperly used, charged, or stored.

Recently the news reported that a fire broke out in the overhead storage bin of an Air China flight. The fire was caused by a lithium-ion battery undergoing a thermal runaway event. Thermal runaway is a chain reaction of damaged power cells in a battery and can be caused by a short circuit due to a manufacturing defect, mechanical damage, exposure to extreme heat/cold or overcharging. Thermal runaway has telltale signs such as an increase in battery temperature, off-gassing (venting gas, vapor, or smoke) or a fire. Fires caused by thermal runaway can produce chemical hazards that may release hydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen cyanide (HCN), phosphoryl fluoride (POF3), carbon monoxide (CO), carbon dioxide (CO2), and black carbon.¹

Lithium-ion batteries exposed to thermal, physical and operational “abuse” are more likely to suffer breakdown (short circuit) and the potential for thermal runaway and fire. Let’s explore these three common causes of lithium-ion battery failure and thermal runaway.

Thermal Abuse: Thermal abuse refers to the condition where lithium-ion batteries are exposed to temperatures, either from the surrounding environment or internal chemical reactions, outside their designed operating range. If not controlled, elevated environmental temperatures may lead to internal cell damage, internal short-circuits and thermal runaway. This could theoretically occur, for example, when the lithium-ion battery of an AED stored outside is exposed to direct sunlight. While controlling ambient temperatures is important, batteries also generate their own heat and aggressive charging or discharging operations increase heat generation. High current charging can especially lead to rapid lithium-ion movement, generating significant heat and causing a dramatic increase in a battery’s temperature.²

Physical Abuse: When lithium-ion batteries are subjected to physical stress, including puncture, crushing, penetration, impact or immersion, it can lead to the breakdown of the separator inside the battery and result in short circuiting and fire. In some cases, physical damage allows the direct reaction of anode and cathode in the electrolyte, leading to internal short circuits. Exothermic side reactions including electrolyte decomposition may also trigger thermal runaway.²

Operational Abuse: Excessive charging and discharging at a battery’s maximum current rate would be considered an aggressive operational mode and could damage the system. When batteries break down due to operational abuse, short circuits can develop which increase the risk for thermal runaway. Repetitively and rapidly charging and discharging in low-heat-transfer environments can cause internal heating which can lead to thermal runaway.²

Most DVT members have some type of exposure to lithium-ion batteries: from cell phones to battery powered tools and EV vehicles. Familiarize yourself with the signs of failing lithium-ion batteries and use best practices to protect the battery integrity:

• Read Manufacturer Instructions: Always follow the manufacturer’s instructions for the battery, charger, and tool.
• Use Original Components: Use only original manufacturer-approved batteries, chargers and tools to ensure compatibility and safety.
• Avoid Damage: Regularly inspect batteries for damage and avoid using them if they are punctured, crushed or show signs of malfunction.
• Avoid Modifications: Never modify or disassemble a lithium-ion battery.
• Prevent Short Circuits: Avoid storing batteries with loose metal objects and cover battery terminals when not in use.
• Monitor Battery Behavior: Look out for unusual behavior such as prolonged charging times or reduced performance.
• Proper Storage: Store batteries in a cool, dry place away from direct sunlight or high temperatures.

Sources:

• “Weekly Safety Meeting – Safety with Lithium-Ion Batteries.” Safety Matters Weekly, 3 Jan. 2022, safetymattersweekly.com/weekly-safety-meeting-safety-with-lithium-ion-batteries/.
• Lavin, Shaun E.; Kyeremeh, Kwabena A.; Nemeh, Elias; Beyerle, David S.; Alkire, Chad; Kelty, Samuel; Srinivasan, Lakshmi, Shaw, Stephanie; Minear, Erin; Kamath, Haresh; Ionel, Dan M.; and Patrick, Aron, “Causes and Prevention of Thermal Runaway in Lithium-Ion Batteries — a U.S. Utility Perspective” (2024). Power and Energy Institute of Kentucky Faculty Publications.