How battery explorer

An exploding phone seems like a freak accident

but the same chemical properties that make batteries work also make them likely to catch fire. Samsung is learning this the hard way, as it becomes the latest company to recall a device  in this case, its new Galaxy Note 7 phone because the batteries could be dangerous.

When batteries explode, it’s often the failure of manufacturers to make sure no explosion will happen. Exploding batteries can be the consequence of overeager companies pushing technology to the limit. As our screens gets bigger and phones more powerful, they need more energy, but most of us are unwilling to give up battery life or charging speed.

We’ve already achieved almost 90 percent of the maximum battery life theoretically possible from the lithium-ion battery, according to Lynden Archer, a materials scientist at Cornell University, so manufacturers are pushing the limits more and more to eke out only a little bit more energy. "There’s been a bit of an arms race where every manufacturer of a smartphone wants to get the highest battery life," he says. "This trend in the field is producing more and more of a tendency for overcharging so all these models of failure are becoming more commonplace."

Samsung blames the Galaxy Note recall on the fact that, in some devices, two parts of the battery that should not have touched came together. But there are many common ways for rechargeable lithium-ion batteries to break, and this usually happens because we keep demanding more from the devices. (Lithium-ion batteries are the type used in almost all smartphones and electronics. Engineers use lithium because it’s light and can hold a lot of energy.)

As we reported earlier, Samsung has stressed that reports of problematic batteries account for less than 0.1 percent of the entire volume sold; but there’s no doubt that this global recall is more than just a minor snafu for the consumer electronics giant. The Note 7 launched just a few weeks ago and was met with mostly positive reviews, including our own.

More importantly, Samsung managed to make waves in the smartphone market weeks before Apple launched its highly anticipated new iPhone. Now, Samsung’s successful launch has been marred by exploding batteries.

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To understand what makes a battery safe, it’s helpful to know how they work. There are two electrodes, or electrical conductors, on opposite sides. One electrode holds positively charged ions and is called the cathode. The cathode is filled with lithium and that is where the "fuel" is stored. The opposite electrode holds negatively charged ions and is called the anode.

During charging, lithium ions move from the cathode to the anode. When the battery is in use, the lithium moves in the opposite direction. In between are chemicals called electrolytes that conduct the current by helping ions move more easily between the two sides. But even though ions need to move from side to side, the anode and the cathode themselves should never touch because they’ll redirect energy to the electrolytes. To prevent this from happening, battery makers insert separators in between.