The recent fiasco involving the Samsung Galaxy Note 7’s batteries turning into little explosives has had the company scrambling to do some serious damage control. Samsung did state that the cause of the phones catching fire was a fault in the battery, which can be traced back to a lapse in quality control during the manufacturing process. This isn’t the first time batteries have exploded within their host phones, with plenty of stories in the last several months surfacing of phones catching fire while being charged. What is it that makes these otherwise docile entities go up in flames? There’s plenty going on inside that little plastic case of chemicals that you should probably know.
Lithium is the most reactive element known to man. It reacts to the oxygen in the air in a rather violent fashion, requiring the metal to be stored in air-tight jars containing vegetable oil. Such a reactive element is being used as battery fodder simply because besides being the lightest metal, it also has the highest electrochemical potential (ECP). Essentially it’s the metal that has the potential to move its ions around the most, to generate current. Today’s batteries don’t use lithium metal as in, but a Lithium-Metal-Oxide (usually lithium-cobalt-oxide) which is far more stable, but has slightly lower ECP, but enough to power your cellphones.
How does the battery work
Inside a lithium ion battery, there are four distinct components; the cathode (lithium on the positive electrode), the anode (graphite on the negative electrode), an electrolyte (acts as a catalyst and electron barrier) and an outer circuit (through which electrons move). When the battery is in use, the ions move from the anode to the cathode, forcing the electrons to do the same, in effect supplying the power needed to power your device. When you plug the battery in for charging, the flow of ions (and hence electrons) reverses and they move from the lithium cathode to the graphite anode where the charge is stored.
The charge game
We know that the Lithium Ion batteries have been pushed to the limit in terms of how much charge they can hold for a particular size. In order to address the issue of phones needing to be charged all the time, a Fast Charge technology was created in order to be able to push the phone’s battery from 0-60 in under 30 minutes. In order to be able to charge batteries faster, batteries are being built with a voltage regulation chip that speaks to the charger in some ways. The charger pushes more current till the phone’s battery reports reaching a certain percentage and then the charges starts to lower the current so as to prevent battery damage. Pushing more current means more heat being generated, which could potentially endanger the battery, however, manufacturers are using sturdier materials to account for the increased heat.
Don’t believe the hype
While it’s great that a phone’s battery can reach 60% charge capacity in a fraction of the time, the load it puts on the battery itself should not be ignored. Lithium fatigue can occur sooner on such devices in comparison to the non-quick charge enabled phones. Additionally, just because you use a Quick-Charge certified charger with a phone may not make it charge faster. As mentioned, each battery has a built in safety circuit which regulates how much current and voltage are going into the battery. When a phone and a charger are capable of fast charging, the phone’s safety circuit still regulates the voltage going in based on the charge percentage of the battery. The charger isn’t pushing 3A at 5V (or whatever the rating) at all times. Conversely, plugging your old phone into a fast charger wont charge it any faster because the phone’s circuitry probably only allows a certain amount of current in.
So what’s the problem?
There are plenty of things that can go wrong with the use of a lithium ion battery. If not manufactured right, deposits can develop on the cathode, generating heat which eventually will cause the battery to explode. Beyond that, if voltage is continually applied to the battery after it reaches 100% charge, it can again heat up and explode. To prevent this, manufacturers have built in a circuit that regulates and cuts off voltage as and when needed. With excessive and improper use, the electrolyte can develop oxygen bubble, causing the lithium to have a raging reaction also resulting in a fiery spectacle. Any physical damage to the battery can also cause unwanted disruption in the chemical balance inside, resulting in, you guessed it, a fire.
While it is nice to be able charge a phone’s battery from 0-100 in a fraction of the time, there is still the concern that frequent and rigorous charging of the battery may result in a shorter lifespan for these cells. Given that phones these days come with non-replaceable batteries, we could see the cellphone batteries becoming incapable of holding charge effectively a lot sooner. Being able to charge faster is nowhere near the same thing as a battery being able to just last longer.
Why do we still use these mini grenades?
As dangerous as it may sound to use Li-Ion based batteries, the manufacturing process has been almost perfected over the last two decades so that all conceivable safety features are built in to prevent a mini-fireworks show. Voltage regulation chips, sturdier seals and casing along with a stringent purification and manufacturing process is what ensures that these batteries don’t go around exploding. In the case of the Note 7, one of these safety features got neglected, resulting in a massive number of faulty batteries. It is essential to remember that besides having the highest ECP, lithium is also a very soft metal, allowing it to be sandwiched into that ever-so-slim thing you call a cellphone. At a time when “space is at a premium,” lithium is probably the only metal we can use for powering devices.
Is this the best we can Do?
Ever since Sony announced the patent on Li-On batteries in 1991, they have become the go-to solution for powering portable devices. Everything from cellphones to tablets to RC cars and drones are being powered by Lithium Ion (or Lithium Polymer) batteries. We are seeing 4000mAh batteries being crammed into some phones, while others are removing essential hardware just to be able to accommodate larger batteries. What is evident is the fact that we’ve hit a ceiling point on just how much power we can draw from the Li-On technology. While we have spent a better part of the last two decades making them safer to use, not a lot of work has been done to look at developing alternate sources of power. With a limit on maximum capacity and the dangers it poses if not manufactured correctly, are lithium ion batteries ready to power the devices of the future? Will they be able to meet the needs for phones that don’t die halfway through the day?