In late November, Apple launched a program of free replacement batteries for some iPhone parties because of the problem of sudden disconnection of the smartphones even with a charged battery. Claims show the iPhone 6s is released in September-October last year. What is the source of the problem battery iPhone and why the power of smartphones die so early?
The death of the battery in the iPhone, iPad, MacBook and other electronic gadgets the process is painful and — if lucky — slow. Over time, lithium-ion battery that once fueled your smartphone for hours (and even days!) gradually loses its ability to hold a charge. In the end you accept, perhaps, curse Apple and then buy a new battery, and even a new iPhone model.
But why is this happening? What is happening in the battery that makes it give up the Ghost? The answer lies in the fact that due to damage from a large number of cycles of charging and discharging and exposure to high temperatures eventually begins to disrupt the process of moving the lithium ions between the electrodes.
In conventional lithium-ion battery, we find the cathode (or negative electrode) made of lithium oxides such as lithium oxide with cobalt. We also find an anode, or positive electrode, which today is usually made of graphite. A thin porous separator keeps the two electrodes apart to prevent short circuits. And an electrolyte made of organic solvents and on the basis of lithium salts, which allows lithium ions to move inside the cell.
During charging, electric current moves lithium ions from the cathode to the anode. During discharge (in other words, when using the battery), the ions move back to the cathode.
Corey Protin from Businessinsider compared this process with water in the hydropower system. Moving up water requires energy, but it is very easy to flows down. In fact, it delivers kinetic energy, said Protein, in a similar way, the lithium-cobalt oxide at the cathode “does not want to give your lithium”. Like moving up water requires energy to move atoms of lithium from the oxide and move them to the anode.
During charging, ions are placed between the sheets of graphite included in the anode. But, says the expert, “they don’t want to be there at the first opportunity they will move back.” This is the discharge.
Over time, the battery is degraded in several ways, which can affect capacity, and on power until, in the end, it just won’t be able to perform basic functions. Think of it another analogy related to the water: charging a battery as filling buckets with water from the tap. The volume of the bucket is a capacity of the battery, or capacity. The speed with which you can fill it — turning the faucet on full blast or a thin stream is power. But time, high temperatures, multiple cycles, and other factors that ultimately form a hole in the bucket.
In analogy with the bucket of water leaks. In the battery, lithium ions are removed or “bound”. In the end, they lose the ability to move between the electrodes.
If you charge your iPhone almost every day, then after a year we get about 300 charge cycles. The battery in the mobile device loses 20% capacity after 400 cycles. Thus, within a year after buying the iPhone 7 or any other smartphone you may notice a deterioration of battery life. Sooner or later, too much lithium ions “attached” and the battery won’t hold any useful charge. The bucket will cease to hold water.