In a study published in Nano Energy, researchers discovered that lithium-ion batteries release harmful gases after they combust. Lithium-ion batteries, found in digital cameras, laptops and smartphones, are often abused through overcharging and overheating. Since smartphones are among the most frequently used handheld devices, researchers sought to shed light on how these batteries could potentially be ruining public health, especially when considering their abundance and their unknown disadvantages.
First invented in the 1980s, lithium-ion batteries have earned their popularity through their low price tag, energy efficiency and light weight. Lithium-ion batteries are also effective in using their maximum capacity and do not lose efficiency in colder weather, as compared to similar rechargeable batteries. These advantages, however, are put into perspective when considering their harmful gaseous emissions and their ability to overheat.
Following battery combustion, over 100 organic compounds are released into the air, along with possibly emitted gases including carbon, carbon dioxide, ethane, ethylene, hydrogen, hydrogen fluoride methane and propane, among others. While some of these gases are more harmful than others, nearly all of them are toxic, cause skin irritation and damage the environment. Some of the released gases, such as ethylene, methane and propane, may give more insight into incidents regarding battery explosions, like those experienced in Samsung Galaxy Note7 phones that were prone to battery exhaustion and overheating. Other batteries emit gases, such as methane, which can be fatal when released in areas lacking ventilation.
In the experiment, researchers examined the overheating of four kinds of 18,650 lithium-ion batteries and two types of pouch batteries. Using nearly 200,000 lithium-ion batteries charged at 0, 50, 100 and 150 percent, researchers placed the single batteries inside of a cubic stainless steel combustion chamber and exposed them to a small flame until they combusted. Using a chemical identification system along with other processes, researchers were able to determine the gases that were emitted as well as their toxicity, graded based on China National Standards, and created a thorough spectrum detailing them.
The batteries were found to differ in their combustion rates depending on their capacity, cathode, charge and material composition. Researchers concluded that the denser the volume and the higher the charge of the battery, the more likely the batteries were to release these toxic gases that are especially fatal in closed spaces.
While lithium-ion batteries have become much safer, they still require a great deal of improvement to ensure the safety of their users. Overcharging remains one of the researchers’ biggest concerns as it is the main perpetrator of combustion and the subsequent gas emission. Researchers urge manufacturers to test lithium-ion batteries for the risk of combustion so they can formulate comprehensive safety plans for users.