Why Do Smartphone Batteries Explode? New Study Reveals

Battery problems have been a common issue with devices such as smartphones and laptops. But battery injury risks gradually emerged as a prominent concern when several incidents of the explosion of Samsung Galaxy Note 7 smartphone batteries were reported last year. The explosions were blamed on the faulty batteries getting exposed to ambient air.

High-energy lithium-ion batteries are generally fragile and if the chemical composition of these batteries gets affected by the electric charge passing through them, it can cause a chemical reaction resulting in an explosion. But why do batteries explode? A new team of researchers has used a technique called cryo-electron microscopy to examine what happens inside batteries during this process.

The scientists, working on battery development, blame the growth of dendrites for battery explosions. But what are dendrites? They are microscopic crystalline structures that form due to chemical reactions that occur when an excess electric charge passes through a lithium-ion battery.

The research team, which presented its findings in a paper titled, “Atomic structure of sensitive battery materials and interfaces revealed by cryo–electron microscopy” published Friday in the Science Journal, presented the first atomic-scale observations of dendrites.

The research shows how dendrites can break through the barriers in different segments of a battery, which ultimately causes a short circuit. The research shows that dendrites are actually six-sided crystals and not the irregular shaped crystals as previously observed using electron microscopes.

Researchers froze high-density batteries at different points in their discharge cycles and removed various components to see the effect. Using a high-intensity microscope, they were able to examine how the battery responded at an atomic level.

"With cryo-EM, you can look at a material that's fragile and chemically unstable and you can preserve its pristine state — what it looks like in a real battery ­— and look at it under high resolution. This includes all kinds of battery materials. The lithium metal we studied here is just one example, but it's an exciting and very challenging one," professor and research leader Yi Cui in a statement.

The findings of the research are important as they may actually lead to designing of safer batteries in the future. Once we know how and why dendrites form, we can actually work on avoiding their formation and thereby making devices safer. Since lithium-ion batteries are being used not just in smartphones and laptops, but even in electric cars such as Nissan Leaf and Tesla Model 3, safer batteries are the need of the hour.

Technology companies such as Samsung are working on new battery concepts such as solid-state batteries, which have a lesser chance of active dendrite formation due to their solid state, which can delay chemical reactions inside the battery. Some scientists are even working on device prototypes which might not be dependent on batteries.

However, since such solutions are still far away from commercial application, as scientists probe further, we can hope for safer batteries in the near future.