Introduction

The most popular form of battery in use today is the lithium-ion battery. Sony was the first to develop lithium-ion batteries way back in the 1970s. Sony used these batteries in their handheld video recorders. Today, batteries power everything in our lives, from cell phones to electric vehicles. Even the International Space Station needs batteries for power. Our dependence on batteries forces us to ask, can batteries blast due to rising temperatures?

In 2008, Tesla became the first car company to commercialize a battery-powered car. Industry experts predict that by 2050, the lithium-ion (Li-ion) battery market will reach USD 100.4 billion.

Li-ion batteries are currently popular because of the amount of power they can provide at a given size and weight. A typical 1 kg Li-ion battery can store around 150 watt-hours of electricity. A lead-acid battery would require 6 kg of battery to hold the same amount of energy. However, Li-ion batteries are susceptible to high temperatures. They are also flammable. Under high temperatures, these batteries degrade much faster than they do under normal conditions. A Li-ion battery pack failure will cause the battery to erupt in flames.

We’ve all heard about the recent fire incidents involving Li-ion batteries. In 2019, a vessel in the Arabian Sea, COSCO Pacific, caught fire after Li-ion batteries onboard spontaneously combusted. Fires caused by Li-ion batteries are difficult to extinguish. The batteries also allow the fire to spread quickly. As more and more people buy electric vehicles, we can expect to see an increase in the number of fire incidents involving these vehicles.

Before we go on to understand why can batteries blast due to rising temperatures, let us first understand how the batteries work.

Li-ion Batteries: Working Principle

Like any other battery cell, the Li-ion cells have a positive electrode, called a cathode, and a negative electrode called an anode. Between the cathode and anode is a chemical solution called an electrolyte. The battery pack consists of cells of lithium-ion stacked together in modules, a voltage tap, temperature sensors, and an onboard computer for the management of the individual cells. The anode is usually made of graphite. The cathode can be made with different lithium materials, including Lithium Nickel Manganese Cobalt and Lithium Cobalt Oxide.

Source

When we provide the cell with a charging current, lithium ions travel from the cathode, through the electrolyte, to the anode. During discharge, electrons flow in the opposite direction. The flow of electrons powers the device to the battery cell has been connected to. The cell is completely discharged when all the ions have moved back to the cathode. At this point, the cell will need to be charged again to power your device.

The safety measures incorporated into the design of lithium-ion cells include:

1. Pressure-sensitive vent holes

Batteries are pressurized. There is a high chance that the battery can become hot and explode from overpressure. Therefore, the outer metal wall of the battery needs vent holes. These vent holes will let out the excess pressure, preventing other battery cells from catching fire.

2. Positive Temperature Coefficient (PTC)

The PTC is essentially a switch that protects it from current surges and overheating.

Lithium-ion battery cells undergo self-discharge. Self-discharge refers to the battery losing its stored charge without being connected to an external circuit or even without the cathodes being connected. Self-discharge increases with age and temperature. Chemical reactions inside the cell are responsible for self-discharge.

Damage to the cell causes impurities to penetrate the cell. The impurities create a short circuit, allowing a large current to flow between the positive and negative electrodes. A sudden temperature rise accompanies this current flow, making the battery release its stored energy within milliseconds.

The heat generated within one cell is fully capable of travelling to the next adjacent cell. The chain reaction destroys the entire battery pack in a few seconds.

Ways In Which Li-ion Batteries Can Catch Fire

1. Manufacturing Defects

During manufacture, defects in the production process cause small metallic particles, also called impurities, to escape into the Li-ion battery cells. Li-ion battery manufacturers need to ensure that battery production occurs inside controlled ‘cleanrooms.’

2. Flaws in Design

Car buyers want to purchase cars with sleek, slim bodies. This puts pressure on manufacturers to design thin-bodied vehicles with high performance and maximum range. To achieve this, manufacturers need to develop compact designs for the batteries. This forces them to pack high capacity cells into a small body, messing with the battery’s original design.

Changing the design can damage the electrodes. Damaged electrodes could cause a short circuit. If not controlled, the chain reaction of cell failures could spiral out of control very quickly.

3. Improper Usage

Placing the battery near a heat source or fire will cause it to explode. Puncturing the battery pack through an accident or deliberately will allow a short circuit to develop, causing the battery to catch fire. This is why warranties lapse when people carry out unauthorized battery disassembly. Even overcharging the battery can damage it.

4. Issues with Charging

The use of improperly insulated chargers damages the battery. The battery could undergo enough damage to fail if the charger generates heat near it. That being said, lithium-ion batteries do come with built-in protections against overcharging. But, using chargers not authorized for the battery will damage it in the long run.

What Do You Do When A Battery Catches Fire?

Based on all we’ve learned about Li-ion batteries so far, we can safely conclude that the answer to the question can batteries blast due to rising temperatures? YES, they can. So here are some safety precautions to remember if you ever find yourself in an unfortunate situation.

Move the device away from flammable substances if you notice that the Li-ion battery is starting to overheat. Additionally, cut off its current supply. If you’re in an electric vehicle, evacuate the automobile immediately. You should never try to extinguish the fire by yourself.

In case of a fire caused by batteries, always use a type ABC or type BC dry fire extinguisher. Fires caused by lithium-ion batteries are class B fires. A common misconception among people is that Li-ion batteries actually contain lithium metal. It is not true, which is why you should never use a class D fire extinguisher for such kinds of fires.

Lastly, if you can, make sure you isolate the fire and prevent it from expanding. Fires from batteries can burn for days because of all the stored energy.