Building a Battery that Won’t Explode

It’s been a hard few weeks for batteries. After reports that their Galaxy Note 7 phones were catching on fire, Samsung announced that they would be pulling phones from the shelves, effective yesterday. The source of spontaneous combustion was discovered to be the phone’s ultra-high capacity Lithium Ion (Li-Ion) batteries – a technology that’s used in a huge range of consumer goods from your laptop computer to your car.

This isn’t the first time that Li-Ion batteries have gotten into trouble – earlier this year, half a million hoverboards were recalled for occasionally bursting into flames.

Small, cheap, and safe. Pick two.

Batteries are a particularly tricky engineering challenge. They’re one of those technologies that’s so important to our daily lives – when they work well, nobody notices, and when they don’t the consequences can range from annoying to downright dangerous.

In today’s ever-shrinking consumer devices especially, creating a battery that’s small, cheap, and safe is very difficult. Even some of the world’s biggest companies don’t get it right every time. Small and cheap devices are increasingly popular, but as we’ve seen with the Note 7 and the hoverboard before it, without a strong safety record, a product is doomed for recall. 

“Without a strong safety record, a product is doomed for recall”

Building a Safer Battery

When it comes to battery safety, engineers can make choices in a few different categories to help improve a battery’s stability:

1) Battery Chemistry
The choice of the type of battery or battery chemistry sets a baseline for portability, safety, and performance. There are dozens of available chemistries – we’ll take a look at the most common.

  • Lead Acid batteries are one of the oldest types of battery still in use today. When used properly, lead acid batteries can be safe and reliable, but they aren’t used in most modern tech like phones and laptops because they tend to be heavy, inefficient, and short-lived. Lead acid batteries are extremely toxic when not disposed of properly. They are still found in cars and other vehicles, but most modern batteries use a type of Lithium Ion battery.
  • Lithium Ion is the most popular type of battery chemistry used in modern battery systems. All Lithium Ion batteries are not created equal, and there are a wide variety of chemistries that fall under the Lithium Ion umbrella. Within the world of lithium ion batteries, there are two chemistry types common in portable batteries.
    • Lithium Cobalt technology is the most widely used battery chemistry in consumer electronics, powering your phone, laptop, and smartphone. Although it’s widely used and has the highest energy density of any mass-market battery technology available, it’s the least safe battery chemistry available, responsible for the majority of battery-related fires.
    • Lithium Iron Phosphate batteries trade some of the energy density and portability of the lithium cobalt batteries, for greater stability and safety. LiFePO4 batteries have a long lifespan and are much more stable than lithium cobalt batteries – and thus less susceptible to fire. These benefits come at a price, though – LiFePO4 batteries are heavier than Lithium Cobalt batteries, which is why they’re mostly used in heavier-duty equipment like the Gridless CORE and other portable battery systems.

2) The Battery Management System (BMS)
Though battery chemistry plays a role in safety, especially when it comes to a certain technology’s potential to spontaneously catch fire, the BMS is an even more important factor. The BMS is a system that monitors each cell of a battery in real time, watching for any signs of over- or under-charging, changes in temperature, and short circuiting. If a battery cell shows signs of damage, the BMS is responsible for disabling it. This is especially important with Li-Ion batteries, since they are much more volatile and overly reactive to changes in condition. A poorly designed BMS can allow a faulty cell to spark a fire, destroying the entire battery (and your gear) in the process.

3) Mechanical Protection
This solution is the simplest, but also the most vital. When lithium-based batteries are compressed, crushed, punctured, or sometimes just dropped, they can burst into flame. So, designing a robust case for the battery that protects against these things is the first line of defense in avoiding fire. This is why it’s vital for even the most stable batteries to have rugged cases that can handle the elements and can withstand weight being placed on top of them.

Lots of factors go into determining whether a battery is safe. And though the perfectly small, cheap, and safe battery has yet to be invented, carefully balancing the three elements above can help battery engineers get as close as possible to that ideal.