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E-cigarettes. Hoverboards. Samsung phones. All of these have been in the headlines over the last several months because of exploding batteries. Most recently, a woman’s noise-canceling headphones burst into flames while she was on a flight from Melbourne to Beijing.

Sometimes these explosions cause fires that lead to serious injuries. In the headphone story above, for example, the woman suffered from burns on her neck. What makes these batteries so volatile?

New Technology Challenges Lithium-Ion Batteries

Each of these products is powered by a lithium-ion battery. These batteries are popular because they store a lot of energy in a small space, and can keep our gadgets going all day long without creating bulk or weight. The first rechargeable versions came out about 25 years ago in Sony’s Handycams, but today dozens of manufacturers supply them to technological product companies.

Products like cell phones, e-cigarettes, laptops, music players, and other portable devices are now overwhelmingly powered by lithium-ion batteries. As technology continues to move forward at breakneck speed, consumers demand more power and longer life in ever-smaller spaces. This is challenging to these lithium-ion batteries, which can be sensitive to short-circuiting, over-charging, and even physical abuse.

Lithium-Ion Batteries by Nature Dangerous

Inside a lithium-ion battery is a thin piece of polypropylene between the electrodes that keeps them from touching together. If something goes wrong with that little piece of plastic, the electrodes come into contact with each other, which results in overheating.

The batteries are filled with a flammable substance that can explode when it gets too hot, and that liquid is mixed with a skin-burning compound. Add oxygen to the mix and the danger grows. This basic design makes lithium-ion batteries a little touchy

A production flaw can increase the risk that the electrodes will come into contact with one another (as was the case in recalled Samsung phones). A lack of proper insulation can also increase the risk of explosion or short-circuiting. Forcing the battery into an extra-small space can increase the risk of damage to the electrodes. If the product does not have adequate venting or heat management, an explosion may result.

Lithium-ion battery chargers can create additional risks. Cheap cables that users may purchase for travel or other reasons may be poorly made, which can increase the risk of fires. They can actually “overcharge” the battery, which increases the pressure inside the cell, potentially leading to rupture. Also, marketing pressures to make product prices competitive may compel companies to cut corners on important safety factors like insulation or quality control. Knock-off hoverboards frequently ended up in the news for causing fires.

Even regular use can increase the risk of problems. If a consumer drops the phone, it can damage the power source, but because the battery is sealed inside most products, that damage may be hidden from the user.

The other issue is that once overheating is present, it tends to snowball. The flammable substance inside creates a “thermal runaway” situation that is difficult to stop.

Manufacturers Have Several Safety Options

Manufacturers can take steps to make their batteries safer. A Positive Thermal Coefficient (PTC)—which is a temperature sensitive current-limiting switch—can protect against short-circuiting. Proper protection within the battery can reduce the risk of over-charging.

A Protection Circuit Module (PCM)—an electronic circuit—can protect against several possible risks:

  1. Overcharging
  2. Short-circuiting
  3. Over-current (when the battery is exposed to higher currents during charging than it is designed for)
  4. Over-discharge (when the product is stored in a discharged state and starts to break down)

The PCM monitors the battery cell and disconnects it when it senses that current or voltage have reached their limits.

A Current Interrupt Device (CID) is made to disconnect the battery under conditions of excessive pressure (often present during over-charging), and mechanical protection helps increase the product’s resistance to the common drops and bumps associated with regular use.

The point is that these batteries can be made to be safer if companies follow the proper procedures and use the right materials. Cutting corners, or failing to implement successful quality control processes, can result in risky batteries that may explode, harming consumers and sometimes causing devastating injuries.

One Comment

  1. Gravatar for Gerald Flood

    lithium ion and lithium are not interchangeable terms Each chemistry is significantly different. I would expect an article like this to have been proof read.

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