It is a story as common as it is known. We bought a new mobile phone, and for a while the battery works like a charm. We go out into the street, with the phone fully charged, we spend the whole day at work and, even so, we still have more than enough charge for the trip home.
However, after a few months (about a year, approximately), everything seems to have changed: we can practically begin to see how the battery meter decreases more and more, and faster, being common that we maintain the saving mode of energy activated for most of the time.
Clearly, something has changed. But why do smartphone batteries seem to fail so quickly? In some respects, the truth, the problem is that these types of devices require more energy than ever thanks to the fact that they have more complex processors and larger screens, while batteries are getting smaller as companies design. slimmer phones.
How does a mobile phone battery work?
Smartphones, as with most portable electronic devices, use lithium ion batteries , because they are quite a bit lighter and lighter than other batteries. And because, in addition, they maintain their load for much longer.
They work by moving lithium ions between two electrodes: a lithium-cobalt oxide cathode and a carbon (graphite) anode. When we charge the battery, ions tend to accumulate at the anode. And, when it is discharged (to power a device), the ions end up returning to the cathode. This is known as a “cycle,” and it is an accepted and common part of lithium-ion battery design.
If this process were one hundred percent efficient, the battery would never get worse. But, as it is not, each time we charge it, a film of lithium atoms remains attached to the anode, reducing its capacity. If the ions cannot move, they cannot transfer their charge, so they cannot provide energy. Thus, the next time we reload the device, a new layer will end up being deposited.
In this way, once the process is repeated a few hundred times, it is the moment in which we will begin to observe a noticeable drop in the amount of energy that the battery can store.
The same would happen with the cathode, where a similar layer could also develop due to what experts call “electrolyte oxidation”. The hotter a battery heats up (or, for example, the higher its voltage), the faster and more damaging the reaction will be. In turn, the reactive capacities of the cathode are immediately reduced, causing a sudden and irreversible loss of capacity.
Is it appropriate to recharge the battery without fully discharging it?
At this point, it is normal for us to wonder if it is advisable to completely discharge the battery of our mobile phone before recharging it again. And it makes sense to think that, by waiting until the moment when the battery is completely discharged to plug it back in, the number of charge cycles that the battery must withstand decreases.
However, the reality is quite different: the lithium-ion batteries that are used by almost all consumer electronic products (including smartphones) do not “like” very much when they are completely discharged.
There is actually a lot of action inside the battery case as electrons pass from the anode to the cathode through a series of electrolyte buffers that regulate the flow. As long as there is a relatively constant amount of charge inside the battery, this cycle will cause little wear on the battery’s internal architecture.
What’s more, by some estimates, frequently and completely discharging a battery can reduce its capacity by 70 percent in 300 to 500 charge cycles .
And the problems start when a battery is completely discharged (or when it is kept at one hundred percent charge). Forcing the cathode to fully charge from zero causes degradation of physical materials, as well as potentially adverse reactions within the electrolyte solution.
So how could we extend the battery life?
The safe operating range of a lithium-ion battery ranges from 30 to 80 percent, so, ideally, it is to prevent our mobile phone battery from completely discharging and we control its charge level to reduce the risk of shutting down.
But it is also advisable not to charge the battery to 100% . It may seem counterintuitive, but unless we need a full charge, the battery will perform much better with a partial charge .
The same would happen with those devices that we are not going to use for a while. Ideally, keep them partially charged.
