Lithium-ion batteries have helped to drive technological advances in mobile devices, and no other battery technology is yet able to take its place. Why are Lithium-Ion batteries problematic, why is Fitbit recalling some of their products, and what technologies could replace lithium-ion?

Why Lithium-Ion batteries problematic?

The impact that lithium-ion batteries have had on the mobile world cannot be understated. Their substantial energy density (compared to existing battery technologies) allows them to be made extremely small and lightweight, enabling mobile devices to be reduced in size considerably. Furthermore, their high-energy density also allowed for designs to use more powerful processors given a specific battery weight and expected battery life between charges, leading to smarter devices.

But for all their positives, Lithium-Ion batteries come with some very serious flaws that must be addressed very carefully. Their extremely high-energy density combined with low resistance allows for large amounts of instantaneous current to flow, and thus a short circuit can lead to a fire. But to make matters worse, the chemistry behind Lithium-Ion batteries can generate hydrogen gas if too much current is drawn from the battery, leading to the battery swelling and eventually rupturing.

Finally, the swelling and subsequent rupturing of the battery cause internal short circuits to form between different layers. Not only does this accelerate the rate of the hydrogen gas being formed, but it also creates an ignition source that can ignite the generated hydrogen gas. Thus, a lithium-ion battery that fails does so catastrophically.

Trying to put out a lithium-ion battery fire with water doesn’t do much for two reasons; firstly, pouring water onto a lithium-ion battery can generate hydrogen gas, which can worsen the fire. Secondly, a lithium-ion battery fire that is extinguished can restart later as short circuits are still present, which generate hydrogen gas, and the evaporated water allows for the battery temperature to rise again. There are problems with lithium-ion batteries in cars and It is not uncommon to see electric vehicles reignite themselves hours after a crash.

Thus, when integrating lithium-ion technology into designs, precautions must be taken to ensure that short circuits are prevented and that the battery’s integrity is assured.

Fitbit recalls Ionic devices after reports of failing batteries

Recently, Fitbit (now owned by Google) has had to issue a recall on some of their products (specifically, the Ionic FB503CPBU, Ionic FB503GYBK, Ionic FB503WTGY, and Ionic FB503WTNV) after many customers have reported overheating issues. While over one million of these devices have been manufactured and distributed, the Consumer Product Safety Commission (CPSC) in the United States has received well over 100 complaints of failing devices.

While many customers have reported minor burns and overheating devices, others have received burns as bad as third-degree, which require skin grafts to repair. Despite the small size and capacity of the batteries used on the Fitbit, their ability to fail catastrophically under high short-circuit currents demonstrates the power that lithium-ion batteries have. Fitbit has announced that anyone with a recalled device can get a full refund, but it also insisted that the failure rate for such devices is less than 0.01% (of course, being the 0.01% is not going to be pleasant).

What technologies could replace lithium-ion?

While there are many battery technologies in development, none are ready to pick up the mantle of lithium-ion. It should be understood that it is unlikely for any battery technology to exist that has the same energy density capabilities of lithium-ion and be inherently safe because energy is energy; if it is all released at the same time, the resulting reaction will be catastrophic either way. A battery technology with a high-energy density that doesn’t allow for energy to be released fast would be safer, but at the cost of not being able to charge/discharge quickly and therefore may not be appropriate for current uses of lithium-ion batteries.

So, this leads us to what alternatives are being developed? One contender is hydrogen which could replace lithium in vehicles. The high energy density of hydrogen combined with its storage as a liquid makes it an ideal fuel source for cars. Furthermore, transferring hydrogen in liquid fuel via a pump can see vehicles refuelled in seconds, while electric vehicles can take hours.

An additional advantage of liquid hydrogen is that it is a very portable source of fuel ideal for use in trucks and haulage vehicles. Simply put, doubling the size of a hydrogen fuel tank does not significantly increase the vehicle’s weight while increasing the size of a battery for an electric vehicle does. This means that hydrogen-powered vehicles can carry more goods than electric vehicles for a given range.

Supercapacitors are another contender that could replace lithium-ion batteries as they offer a high energy density without the use of potentially flammable materials such as lithium. While supercapacitors have been in use for years, they are not ready to take on the role of batteries as their energy storage capacity is still very limited, and they are costly compared to lithium-ion batteries.

Many other technologies exist, but they are all in their infancy and may not be ready commercially for decades. It is clear that lithium-ion presents significant challenges, but considering how widespread it is used, it would seem that they will be sticking around for decades to come.