Is thermal runaway more likely with older lithium batteries?

Battery Aging and Thermal Runaway

Thermal runaway is a catastrophic event where a battery’s self-heating cycle accelerates uncontrollably, resulting in a fire. Older lithium batteries are more likely to experience thermal runaway due to internal changes that occur as the battery ages. These changes can include the degradation of the separator material, which can lead to increased electrical resistance and heat generation. As the battery cycles, the separator can become brittle and prone to cracking, allowing electrical shorts to occur and triggering thermal runaway.

Factors Contributing to Thermal Runaway

Several factors contribute to the increased risk of thermal runaway in older lithium batteries. These include the battery’s state of charge, internal resistance, and storage conditions. For example, storing a lithium battery in a hot environment (above 25°C or 77°F) can accelerate aging and increase the risk of thermal runaway. Additionally, charging a battery to high states of charge (above 90%) can also contribute to thermal runaway. In contrast, storing a lithium battery in a cool, dry environment and keeping it charged between 20% and 80% can help mitigate the risk of thermal runaway.

Preventing Thermal Runaway

To prevent thermal runaway in older lithium batteries, it’s essential to follow proper storage and usage guidelines. This includes storing the battery in a cool, dry environment and keeping it away from heat sources. Additionally, monitoring the battery’s state of charge and internal resistance can help identify potential issues before they become catastrophic. Regular inspections of the battery’s physical condition can also help identify signs of aging and thermal runaway. By taking these precautions, you can minimize the risk of thermal runaway and ensure safe battery operation.