Understanding the Risk of Fire in Discharged Lithium Batteries
Although the risk is significantly lower for a discharged lithium battery to catch fire compared to a charged one, it is important to understand the potential hazards. Lithium batteries, whether fully charged or discharged, can still pose a risk under certain conditions. This article will explore the reasons why discharged lithium batteries can still catch fire and provide guidance on how to handle and store these batteries safely.
Internal Short Circuits
One of the primary reasons a discharged lithium battery can still catch fire is the possibility of internal short circuits. These can occur due to damage to the battery or manufacturing defects. When an internal short circuit happens, it can lead to overheating and, ultimately, ignition. Even though the battery is discharged, it can still retain enough electrical activity to create an internal short circuit if there are any flaws in the battery's design or materials.
Chemical Reactions
Another risk comes from the residual chemicals within the battery. Even when a lithium battery is discharged, there can be residual chemical reactions that under certain conditions can result in a fire.
External Factors
External factors such as exposure to high temperatures, physical damage, or improper disposal methods can also increase the risk of fire in discharged batteries. It is crucial to handle, store, and dispose of lithium batteries properly, regardless of their charge state, to minimize these risks.
Handling and Storage of Lithium Batteries
To further ensure the safety of lithium batteries, it is important to avoid exposing them to extreme temperatures and to handle them gently. Store batteries in a cool, dry place and avoid stacking them or placing heavy objects on top of them. If you need to charge a discharged lithium battery, it is advisable to use a trusted battery charger to minimize the risk of damage or fire.
The Dangers of Lithium Batteries
Lithium, similar to sodium, can react explosively when it comes into contact with air. If this reaction happens inside a lithium battery, the battery can fill with high-pressure explosive gas. While this gas might not necessarily ignite, it will eventually lead to the bursting of the battery container, often in an explosive manner.
Fire Safety for Lithium Batteries
The electrolyte in lithium-ion (Li-ion) batteries is flammable, regardless of the cell's charge state. If you apply a flame to a discharged Li-ion cell, it can heat up to the point where the electrolyte vaporizes through the pressure relief valve. If the flame is nearby, the electrolyte vapor can ignite. For pouch cells, the polymer/aluminum film can melt, exposing the electrolyte and leading to a fire. In these cases, a Class-D extinguisher is recommended for use.
Proper Charging Techniques
For the safest charging of Li-ion batteries, it is crucial to charge at the lowest possible rate. This minimizes cell heating and maximizes the battery's cycle life. If you must use fast charging, ensure that the device is on a cool surface to prevent overheating. In vehicles, placing the phone near the air vent and turning on the air conditioning can help cool the battery effectively.
Always prioritize safety when dealing with lithium batteries. Understanding the risks and taking appropriate precautions can significantly mitigate the chance of a fire or explosion. By following these guidelines, you can ensure that your lithium batteries remain safe and reliable, providing power without danger.