When checking out the specifications of mobile phones, you see the capacity of the battery, whether it’s removable or not, and what is the maximum supported power for a charger. However, there is more to a battery than meets the eye.
As you must be already aware, cellphone batteries are rechargeable, unlike the double-A batteries that you use in your TV remotes. This indicates that they are made of different materials, are of different shapes, and are designed for different purposes.
In the past, mobile phones have had their fair share of different types of batteries. They came in different shapes and sizes, some were removable and some weren’t, but most importantly, the battery technology changed over time and so did the materials.
This guide tells you about the different types of mobile phone batteries, how they work, their advantages and disadvantages, and basically everything there is to know about them. By the end of this post, you should be able to differentiate between the different types of batteries, what their ratings and values mean, and which one is best suited for your needs and requirements.
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How batteries work
All batteries, whether big or small, whether single-use or rechargeable, work using the same basic principles.
A battery’s purpose is to convert the stored chemical energy into electrical energy. One end of the battery becomes negatively charged and the other is positively charged due to a chemical process that occurs within. Electrons move across the circuit to which the battery is attached as a result of this difference in charge, known as “potential difference“.
A battery contains two conduction metals, each on one end of a cell, and an electrolyte. An electrolyte is the medium (liquid or gel) through which the charged ions are carried between the electrodes. When a negative charge is produced on one end, which is the “cathode,” a positive charge is created on the other electrode, known as the “anode.”
The anode attracts negative ions, whereas the cathode attracts positive ions. This difference in charge pushes the electrons in the circuit’s wires around, transferring energy to the other components in the circuit.
The potential difference between the two electrodes is the actual functional voltage the battery can provide. The rest of the circuit is usually designed around the battery voltage – so that it can make the other components function as they should. Normally, most smartphone batteries are designed to provide 3.8 Volts (V).
You may be now wondering that most chargers only provide a voltage of 5V, so how is the phone operating on 3.8V? This is because to charge a cellphone battery, there must be a potential difference between the voltage being supplied and the voltage at the other end – only then will the ions (current) flow, and the battery be charged.
Characteristics of mobile batteries
Other than the voltage rating, other characteristics of a mobile phone battery also need to be considered. Here are a few things you ought to know before we discuss the different types of batteries:
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Cut-off voltage: The lowest voltage that may be used by the battery is called the cut-off voltage. This voltage often designates the battery’s “empty” status.
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State Of Charge (SOC): State Of Charge is the battery capacity, expressed in percentages, that represents how much charge is remaining inside the battery. This is the same battery percentage that we see on our mobile screens.
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Coulometric capacity: Derived from the word “Coulomb,” which is the unit of electric charge, this is the battery capacity a battery can provide from when it is 100% charged till it reaches the cut-off voltage (dies). In simple words, it is the battery capacity you see in the specifications of any mobile phone, represented with MilliAmpere-Hour, or “mAH.”
Nowadays, most flagship phones have a coulometric capacity of 5000mAH or above.
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C-rate: It is the rate of time it takes for the battery to discharge or recharge completely. For example, if a battery has a rating of 1C, it means that the battery will be drained in 1 hour. If it has a rating of 0.5C, it will take 2 hours, and if the rating is 2C, it will take 30 minutes for the battery to drain.
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Degradation: If you have used a gadget with a rechargeable battery for a long time, you would know degradation is a real thing. This is also why Apple provides an overall battery health (in percentage) on their iOS devices.
Battery degradation can occur from charge and recharge cycles, as well as improper charging habits, like leaving it to charge overnight. Also, time is a crucial factor in natural battery degradation, which is why all cells and batteries also have a shelf life.
Types of mobile phone batteries
Now that you understand what the different terms and characteristics of a battery mean, here are the 4 types of mobile phone batteries that have been introduced to mobile phones over time:
- Nickel-Cadmium (NiCad)
- Nickel-Metal Hydride (NiMH)
- Lithium-ion (Li-ion)
- Lithium-Polymer (Li-Po)
These are the 4 rechargeable cell phone batteries that have been used over time in mobile phones. The latter 2; Li-ion and Li-Po are the ones we see in all modern phones today. Other than these, you may find cells and batteries of other types as well, such as Alkaline batteries, but those are only single-use batteries and cannot be used for cell phones.
Let us now discuss the properties of the 4 different mobile phone battery types.
Nickel-Cadmium (NiCad)
NiCad batteries are practically Lithium Ion batteries, but these are affected by the “memory effect.” This means that it gets difficult for these batteries to store the charge over time after a certain number of charging and discharging cycles. As a result, the battery’s overall capacity decreases, reducing its run time and shortening its lifespan.
The battery needs to be completely depleted before being recharged to prevent this. Of course, this is not always possible. Therefore, NiCad batteries will eventually degrade.
Furthermore, hazardous and non-environmentally friendly elements are used in the production of nickel-cadmium batteries. As such, they have to be disposed of properly after their useful life is up, which is a growing issue.
For the reasons mentioned above, this type of battery is no longer used by cell phone manufacturers and has been replaced by Lithium-Ion and Lithium-Polymer batteries.
Nickel-Metal Hydride (NiMH)
The dimensions and form factor of NiMH batteries are identical to those of nickel-cadmium batteries but can hold up to twice the energy capacity, and have a 30 to 40% longer operating life. In addition, they are less harmful to the environment because they are not manufactured with hazardous materials or chemicals.
Although NiMH batteries also suffer from the memory effect, they are less prone to it, therefore making them cheaper and safer to manufacture. However, one major caveat of these batteries is the significantly faster depleting time. Voltage dips may occur after a few hundred charging cycles, which will make the crystals within coarser.
Even though NiMH batteries were popular for a certain time, they cannot hold the charge for prolonged periods, resulting in battery depletion, and therefore needed frequent changing. Hence, mobile phone manufacturers shifted to other, more efficient, alternatives.
Lithium-ion (Li-ion)
Li-ion is another type of rechargeable battery that offers more charging cycles than NiMH batteries while having a prolonged operating life.
In a Lithium-ion battery, the cathode is composed of a composite substance called “intercalated lithium compound,” and lithiated graphite is used for the anode. The electrolyte is a liquid that carries the charges between the electrodes. Because of its porosity, the separator, which is the 4th element inside the battery, allows lithium ions to pass through while preventing thermal runaway and short-circuiting of the cell.
Li-ion batteries have a high energy density, which means that they can hold more charge. They do not suffer from the memory effect and have low self-discharge. Additionally, Lithium-ion batteries can be charged quickly.
One caveat of this technology is it is expensive to manufacture. However, since it offers more charging cycles and a relatively prolonged lifespan, the battery pays for itself in the long run.
That said, Lithium-ion batteries pose a threat to the users if damaged. The liquid electrolyte is highly flammable, resulting in third-degree burns if comes directly in contact with the skin.
Lithium-Polymer (Li-Po)
Compared to other battery types, Lithoum-ion batteries are safer, smaller, lighter, and have a plastic casing instead of a metal one. Similar to Lithium-ion batteries, these are not affected by the memory effect and do not lose capacity between charges if the battery is not completely drained.
Li-Po batteries superseded Lithium-ion batteries since they retain the battery charge even better, and are the most advanced technology in the battery sector yet. However, they offer less energy density, but the manufacturers of the phones prefer the quality of the charge, instead of its quantity.
A Lithium-Polymer battery uses a polymer electrolyte rather than a liquid one. The electrolyte in all Li-Po batteries is a gel polymer with excellent conductivity.
Lithium-ion vs. Lithou-Polymer batteries
The main difference between a Li-ion and Li-pol battery is that the latter uses a Solid Polymer Electrolyte (SPE) such as PolyEthylene Oxide (PEO), PolyAcryloNitrile (PAN), PolyMethyl MethAcrylate (PMMA), or PolyVinylidene Fluoride (PVdF), while a Li-ion battery uses a liquid Lithium-Salt Electrolyte (such as LiPF6) held in an organic solvent.
Depending on factors such as temperature, age, and Depth of Discharge (DoD), Lithium-ion batteries can last up to two years when used properly and charged up to 2,500 times before their performance starts to decline; batteries with 100% DoD will only retain 70-80% of their original capacity after 300-500 cycles.
In contrast, Lithium-Polymer batteries can last up to 3 years before the charge capacity starts to deplete.
Removable vs. non-removable batteries
A phone with a removable battery signifies that the phone can be opened by a user, without the user’s special tools, and the battery can be removed easily. Such phones used to come to the market in the past, but not so much in the last decade.
Removable batteries allowed users to replace the batteries when their performance declined. All they had to do was open the phone, pull out the old battery, and replace it with a newer one. However, one disadvantage to this architecture was, that the manufacturers, had to design the device so that the battery was accessible. this meant that the design had to accommodate the user and not the functionality of the phone.
Manufacturers then shifted to non-removable battery designs, where the phone was enclosed from all sides, and the battery was unreachable. If a battery has to be replaced, you need to go to a specialist, who opens the phone using special tools and replaces the battery for you after pulling out a number of different components and accessing the battery.
Non-removable batteries allowed manufacturers to better utilize the space around the battery and incorporate a better design with more features, like the wireless charging coil.
Best practices for keeping phone battery healthy
If you are looking to store your phone away for some time, or simply want to prolong the life of your battery (since they are so difficult to replace now), here are a few pointers for you:
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Install the latest OS update
Operating system updates usually optimize battery usage by making the OS better. Therefore, do not be lazy when a new update rolls out for your phone.
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Avoid extreme operating temperatures
While there is a large range of ambient temperatures in which your device can function properly, the optimal comfort zone is between 16° and 22°C. It’s crucial to keep your device out of environments hotter than 35°C since this might permanently degrade the battery. In other words, a given charge won’t power your smartphone for as long as it used to.
The device may sustain further harm if it is charged in a hot environment. Some operating systems may restrict charging when battery temperatures are higher than 80 percent of the acceptable range. One can irreparably destroy a battery even by keeping it in a hot environment.
You can also see a brief drop in battery life while using your smartphone in extremely cold temperatures. In such scenarios, when the battery’s temperature returns to its normal operating range, its performance will return to normal too.
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Half-charge the phone when storing
When storing away your device, whether for a few days or a long time, two factors need to be considered:
- The ambient temperature
- The initial charge of the battery when putting it away
To overcome these, make sure to leave your phone charged to about 50% SOC only. A device’s battery may enter a deep depletion condition, making it unable to retain a charge, if it is stored with its battery completely depleted. On the other hand, if you keep it fully charged for a long time, the battery can lose part of its capacity and reduce its lifespan.
Moreover, make sure to shut down the device so the battery doesn’t deplete any further. Also, make sure to store the device in a cool, dry place, away from moisture.
Additionally, if you are leaving the phone for more than 6 months, it is recommended that you recharge it to nearly 50 percent every 6 months.
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Do not wait to recharge at 0%
Waiting for your phone’s battery to reach 0 percent before recharging it only means completing a recharge cycle. Each battery has a tentative number of charging cycles, and if you recharge your phone daily only after it reaches 0% it means that the battery will only last equal to the number of the total charging cycles.
Therefore, it is recommended that you recharge your phone at around 20 percent.
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Do not charge all the up to 100%
The optimal battery operating range is between 20 and 80 percent, and it is recommended that you charge your phone between these ranges as well. this means that when your battery’s SOC reaches 20 percent, charge it to 80 percent, and then unplug it.
You may charge it to 100% occasionally, but always charging it to that capacity can reduce its lifespan.
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Avoid using phone while charging
Using the phone while charging puts it under parasitic load – when the battery is being drained during charging. Parasitic load adds higher voltage stress to the battery, increases heat, and can cause parts of the battery to continually cycle and deteriorate faster than the rest of the cell.