Why do Lithium-ion Batteries Catch Fire? How to Avoid the Mishap?

Lithium-ion batteries have become the backbone of every technology that needs battery support in the current space for innovations . With a wide range of areas of applications — from smartphones to electric cars (EVs) to even the International Space Station — li-ion batteries support them all. This is largely thanks to the high energy density and efficiency that the technology offers.

However, there’s a flip side to this otherwise sweet story. If manufacturing or safety checks miss any anomaly, the batteries’ high energy bank may risk catching fire and even exploding in the worst-case scenario. The Lithium-ion battery technology is also infamous for some of the most dreadful industrial mishaps, even in recent times. This brings us to the following question:

Why do Lithium-ion batteries catch fire?

Technically, a Lithium-ion battery stores and releases its electrical energy through electrochemical reactions. Lithium ions move from one electrode to the other when the electric energy is derived from the battery. This happens through a liquid medium, known as electrolyte, in which the electrodes are submerged. The electrolyte consists of lithium salt and organic solvents. The organic solvents are responsible constituents for fire hazards in Li-ion batteries. Besides, the fire gets endorsed in the presence of oxygen. Notably, the positively charged electrode (cathode) in the battery contains oxygen. When the battery undergoes any specific stresses, e.g., internal short, excessive heat, and more, it may result in the release of oxygen from the cathode. In conclusion, Lithium-ion batteries may not only catch fire but are also able to self-sustain that fire.

Apart from that, in intense thermal incidents, the flammable electrolyte, along with various flammable/toxic gases such as hydrogen (H2), methane (CH4), carbon monoxide (CO) and hydrofluoric acid (HF), may escape the Li-ion battery. The release of these flammable gases causes fires and explosions.

The Various Causes

From a non-technical point of view, lithium-ion batteries catch fire as they are extremely sensitive to high temperatures, even degrading much faster than ordinary ones due to heat. They are highly flammable on the inside. In addition, when the battery is under any kind of external pressure, there’s a risk of the battery becoming very hot and exploding from over-pressure. Furthermore, when the current surges, the battery overheats. Lithium-ion cells also undergo self-discharge as the batteries lose their stored charge in case of the electrodes or the external circuit not being connected. Elevated self-discharge can cause temperatures to rise, which may lead to a Thermal Runaway also known as ‘venting with flame’. During a thermal runaway, the heat generated by a failed cell may move to the next cell, causing it to become thermally unstable as well. Thus, a chain reaction can destroy the entire pack within a few short seconds.

There may be several conditions leading to battery failures and, eventually, the fires. Low-quality components and manufacturing defects remain one of the main causes of battery failure. Keeping the batteries exposed to heat sources can be extremely dangerous as this may lead to an explosion. Another less common reason may be battery penetration, which may cause a short-circuit and, eventually, fire. Further, high voltage charging, or excessive discharging damages the pack. And so does the use of non-recommended or poorly-insulated chargers.

Minimizing the Risk of Lithium-ion battery Fires

It may be extremely difficult to discern how and when a battery may catch fire. But here’s a breather – the risk of mishaps can be minimized by taking a few precautions.

• Avoid storing at high temperatures. The batteries, or any equipment using one, must be kept away from high temperatures. This may include precautions against keeping in hot vehicles, covering a laptop with a blanket, cell phone in a warm pocket, etc.
• Avoid keeping all items containing lithium-ion batteries together. Now, having lithium-ion batteries close to each other does not increase the risk of a fire. But, if there is an accident and one battery catches fire or explodes, the other batteries may catch fire and make the situation worse.
• Avoid overcharging. Lithium-ion batteries are severely affected if they are completely drained before being recharged or if they are over-charged. Further, using any charger other than the one intended for the battery may increase the risk of damage. Instead, charge before the battery drains out completely and stop charging it before it regains full battery capacity. Make it a rule to charge between 20 and 80 per cent of battery capacity. Apparently, lithium-ion batteries do not suffer the “memory effect” as badly as other types of rechargeable batteries. Hence, feel free to discharge and recharge many times nearly back to their original charge.
• Keep EV under a shade. This way the battery will be at lower temperatures. Standing under the sun too long will naturally increase the risk of high temperature.
• Store dry. Store the battery, the equipment or the gadget using one, in a clear and dry place, away from flammable and corrosive substances.
• Let it cool. After using, do not immediately charge the battery. In that case, let it cool down first.