Li-Ion Vs Li-Po For Smartphones? What to choose and how to use them?

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The Li-Ion battery was the popular choice of battery in every Smartphone up to the year 2018. But In 2019 and 2020, the smartphone manufacturers have been pushing Li-Po batteries in their Budget and Flagship smartphones.

Therefore, it is about time that we understand which is the better battery technology (Li-Ion Vs Li-Po). Even Samsung has switched from Li-Ion to Li-Po this year (2020) in the Samsung Galaxy S20 series instead of Li-ion in the Samsung Galaxy S10.

The answer is not just a yes or no. Both battery technologies (Li-Ion and Li-Po) has its advantages and disadvantages. This is why I am going to compare in different sections like Lifetime, Power Density, Energy Density and Cycle count, etc.

This Article would cover:

  • What to choose between Li-Ion vs Li-Po for a smartphone.
  • How to use each battery type for a long life
  • Comparison between each battery type in different aspects.

This Article would not cover:

  • Internal Working of Li-Ion or Li-Po Battery.
  • Chemical Composition of both batteries.
  • Production of Li-ion or Li-Po batteries.

Background Of Li-Ion, Li-Po Batteries:

Li-Ion batteries are being used in electronic components since 1991 when Sony commercialized it that year. Since then, its usage and applications have been increasing from Electric Cars to iPods.

A big misunderstanding is that the Li-Po is another and separate battery technology which is not true. Li-Po is actually the third generation or third type of Li-Ion Battery.

These are the three types of Li-Ion and a basic comparison as to why the other two generations even exist.

Li ion vs Li poly vs li prismatic

The first type is in the Cylindrical shape and is normally called Li-ion batteries. The cylindrical shape is mostly used in Electric vehicles and Laptop batteries.

The Prismatic form factor of Li-Ion batteries is used in smartphones and it sits right in between Li-ion cylindrical form and Li-Po batteries in terms of energy density, size, and weight.

The Li-Po could be manufactured in different sizes and shapes unlike Li-ion for their application in toys, headphones, computer mouse, etc.

Energy Density:

Energy Density is measured as Energy/Volume which means Watt-Hour(wh)/Volume, WH/m³, or Joule/m³. Since Joule and Watt-hour are both units of energy.

It means that how much Energy can be packed in some space or volume. The more energy in a small space means more density or vice versa.

Energy density is sometimes confused with Energy/KG or WH/Kg. The Energy/Kg is called specific energy and not Energy Density. These two concepts are often mixed with one another and it is really important to understand them.

The energy density (Wh/m³) of Li-ion batteries is higher than Li-Po batteries. The specific energy (Wh/Kg) of Li-Po batteries is higher than the Li-ion batteries.

For example, if we have 1kg of each battery type (Li-ion and Li-Po), the 1 KG Li-Po battery would provide more Energy or Wh. Now, if we have a volume of 1 Litre for each battery type (Li-ion and Li-Po), the 1 Litre of Li-ion would provide more Energy or Wh.

This is a really important factor for smartphones as we don’t have a lot of space inside a smartphone. So, we have to decide whether we want a Li-Po battery with low weight to keep the overall weight of the smartphone low. The alternate is to get a Li-ion battery with low volume if there is not enough space for a bulky battery.

The Li-Po is usually 35% lighter than a Li-ion with a steel shell and the Li-Po is 20% lighter than a Li-ion battery for an aluminum shell. So if weight or mass is the concern, the Li-Po wins easily.

But in terms of volume, the Li-ion consumes 15-20% less space than Li-Po for the same energy density.

For smartphones, the long-lasting battery is really important, especially for small size smartphones. The iPhone SE(2020) has an 1821 mAh Li-ion battery. If it had the same capacity with a Li-Po battery, it would not last as long as it would with Li-ion, as Li-ion has higher energy density than Li-Po battery. For the smartphones having battery capacity up to 3000mah, I would suggest using only Li-ion battery only.

But on the other hand, for smartphones with batteries above 4000 mAh, it is fine to choose Li-Po because of the huge size of the battery, the energy density would be plenty even for a Li-Po battery for one day use.

Power Density:

The maximum power available per unit volume (Power/Volume), W/m³, or W/L. A battery with higher power density can discharge large quantities of currents in a short time compared to a battery with low power density.

Li-Po batteries are more power-dense than Li-ion batteries for the same volume.

Energy density vs power density graph-whaddafudge
Inverse Proportion

The applications such as drilling, acceleration of a car, RC Quadcopters, or a high-end gaming laptop running at peak CPU frequency requires high power density.

One important application of high power density in smartphones is fast charging. The Li-Po are known for their faster discharge rates as well as faster charge rates. It is due to the Li-Po batteries that we now have smartphones charging in about 35 minutes.

The power density and energy density of lithium batteries are inversely proportional to each other. Meaning, if a battery has higher power density, it would have lower energy density and a higher energy density battery will have lower power density. But it is also possible to have a battery (balanced) with a mediocre power density as well as energy density.

The graph on the right image roughly explains the relation between Energy density and Power density. At the center, the energy density and power density are almost the same or balanced.

This is why Li-ion has higher density and low power density, and the Li-Po has higher power density and low energy density.

For example, assume we have two cars with the same engine and horsepower but with different batteries. The car with a high power density battery would be able to accelerate faster while the car with a low power density battery would be able to cover more distance on one charge because of higher energy density.

The smartphones do not really need a lot of power density for like 90% of the tasks and, therefore, Li-ion power density is enough for now. But as the era of software produced images (artificial bokeh or portrait mode), videos (artificial bokeh, low light modes), liquid-cooled smartphones, gaming smartphones with 240Hz displays, 4 speakers, overclocked chipsets are coming in the near future, Li-Po high power density would play a huge role in smartphones.

Size and Shape:

The shape and size are really important factors when it comes to picking a smartphone battery because of how little space is available inside a smartphone.

There is not a lot of comparison between Li-ion and Li-Po when it comes to creating different sizes and shapes for each application. The Li-ion cell’s shapes are limited to a cylindrical shape and rectangular shape (prismatic).

The Panasonic batteries on the right image is an example of different shapes and sizes obtained by Li-ion batteries. Sadly, there i8s not a lot of flexibility in shape and size when it comes to Li-ion.

The Li-Po, on the other hand, is on another level if we compare the shapes and sizes of Li-Po with Li-ion.

Source: Contrel.com

All of the shapes in the picture above are available for a Li-Po battery. Not just the shape, the size is also really impressive. A Li-Po battery could be as thin as 0.5mm and 0.6g.

Due to the flexibility of their sizes and shapes, the Li-Po batteries are widely used in portable devices such as Bluetooth headphones, Bluetooth mouse, Electric toys, Remote control cars, helicopters, and quadcopters, etc.

Source: Bluetooth Headphone Batteries

The shape of a Li-Po battery inside a Bluetooth is shown in the above picture. The flexible shapes, design, and sizes are a double-edged sword too. While they provide batteries of different sizes and shapes for different applications but they also make it extremely difficult and expensive to design and manufacturer batteries separately for each device.

Cost:

The lack of different shapes and sizes for Li-ion batteries makes it really cheap for mass production. Generally speaking, the cost of Li-ion batteries for a smartphone is a lot cheaper than Li-Po.

This graph should give you an idea about the cost of Li-ion batteries.

li-ion cost curve (cost vs capacity)
Source: qnovo.com

The flexible size and shape of a Li-Po is really handy for small and weird shaped products but this also increases the complexity. The design and production of different size products become really expensive. This is why the cost of Li-Po is at least twice the cost of Li-ion.

The cost of Li-ion batteries right now is 0.1-0.3$ per Wh depending on the production capacity. The Li-Po costs at least twice of this.

Nowadays, most of the smartphones from budget to flagship contain Li-Po batteries. This is why the cost has dropped significantly for Li-Po batteries because of the production of large quantities reduce prices. The reason for using the Li-Po batteries even in Mid-Range smartphones is because of the flexible size and shape of Li-Po batteries over Li-ion.

Smartphone Manufacturer’s main goal is to save cost above everything. By using shape and size-specific Li-Po battery in a smartphone, the manufacturer is able to save some space for other components and also get maximum capacity for the weight of the battery, this ends up saving money.

Which is Safer?

The Li-ion is relatively more unstable than a Li-Po battery. There are a lot of reasons for this. But I feel like a video would be much better for the demonstration of the safety of Li-ion and Li-Po.

The Li-ion battery is definitely more dangerous than Li-Po when it comes to short circuits or leaking but the build of Li-ion is more sturdy and can handle more drops than Li-Po.

This video is for the testing of Li-ion batteries, short circuit tests, drop test, puncture test, and much more.

Li-ion Endurance

The next video is to test the endurance of Li-Po batteries.

Li-Po Endurance

After watching both of these videos, one can easily decide that the Li-Po batteries are way better than Li-ion batteries in terms of safety. Even after getting punctured or short-circuiting, the Li-Po battery does not explode like the Li-ion battery.

Lifetime:

The lifetime of a battery is explained in charge/discharge cycles. If you charge your smartphone from 0-100% and discharge it back to 100-0%, this is one charge/discharge cycle. But what if we don’t charge our phone to 100% always and we also do not discharge it to 0% always.

To keep things simple, if you charge your phone from 50-100% and then discharge it back to 50% before charging again, this would count as half or 0.5 charge/discharge cycle.

This lifetime of a battery is not explained properly anywhere as it changes from one battery model to another even for the same technology (Li-ion or Li-Po).

If we have to compare the best quality Li-ion battery with the best quality Li-Po battery, the Li-ion would win in the charge/discharge cycle or lifetime.

It is simple really, a flagship smartphone would have a flagship-grade battery with charge/discharge of 1500+ which can last from 3-5 years. The Mid-range smartphones batteries with charge/discharge cycles around 1000+ last for around 2-4 years. Budget smartphone batteries with charge/discharge cycles of around 600-750 last for around 2-3 years.

But everything is not black and white. Some mid-range smartphones use flagship-grade batteries and some budget smartphones use mid-range batteries, so this can vary from smartphone to smartphone.

These values are based on hit and trial method, they are not accurate, and please do not quote me on this. But these values should give you a good idea of battery life in different smartphones and why they are not the same.

Best Practices to optimize Battery life:

At the end of the day, if you do not properly use and charge your smartphone’s battery, it will die out before you expect it. The Li-ion and Li-Po are almost the same when it comes to using and optimizing them. This is why all of the important points in this heading will apply to both batteries.

The following are the best practices to maintain if you want to get the best performance and durability out of your smartphone battery:

  1. Always keep your smartphone battery between 20% and 80%. The battery suffers the most amount of pressure or strain at extreme ends i.e. below 20% and above 80%. All of the ions should not be at the cathode or anode at once. This is why it is not recommended to charge your smartphone overnight and not because it wastes charge/discharge cycles.
  2. Drain your smartphone battery from 100% to 1% once a month. This avoids any discrepancies in the state of charge or percentage and also keep all of the cells in the battery pack refreshed.
  3. Charge your phone battery slowly (avoid faster charging). This might sound strange but the fast charging does shorten battery life as it pushes a lot of power in a short time. A lot of power is dissipated as heat which reduces the power conversion and in return reduces the battery life a little. To be honest, the slowest you charge your smartphone battery, the more life it would have.
  4. Heat is the battery’s biggest enemy. The battery temperature should not increase above 40°C while charging. If it does go above 40°C using the original charger, make sure it does not go above 45°C. If it does, turn off the Radios (Wifi, Bluetooth, etc) or turn off your smartphone.
  5. Use the original charger that came with the smartphone or a charger that uses the same technology. For example, the OnePlus and Oppo charger uses the same technology although they do use different names. Also, the Power Delivery supported devices would work fine with any PD certified charger. But if you don’t have any option and you need to charge your phone with other chargers, choose the charger with the lowest amount of power like 5W or 10W and avoid using higher power chargers that are based on other technologies.
  6. Do not use your smartphone while charging. If you must, try to use only light applications and avoid high power draining applications such as audio call, video call, gaming, benchmarks, camera, and restarting the smartphone.
  7. If the battery is not in use, charge it at least once every 6 weeks.

Li-Ion Vs Li-Po (In Practical):

ExamplesBetter BatteryReason
For Small Size Smartphones
(1000-3000mAh)
iPhone SE, iPhone 11 Pro, Samsung S10e, Google Pixel, etcLi-ionLi-ion packs more energy density (Wh/m³) which is necessary for long lasting battery.
For Mid Size Smartphones
(2500-4000mAh)
Samsung A50, Mi A3, Pixel 4XL, iPhone 11 Pro Max, LG G8.Both would work depending on the smartphonePixel 4XL needs Li-Po for heavy image processing which draws a lot of current, A50 would be fine with either.
For Huge Phones
(4000-6000mAh)
Mi Note 9 Pro, Asus ROG Phone 2, Samsung Note 10+, Mi Note 10Li-PoBigger Li-Po batteries have enough energy density to last a long time. With more power density in them, they are definitely the better choice here.
For Power BanksAny power bankLi-PoDue to being safer in extreme conditions and also lighter, Li-Po are better for portable items.
ApplicationBetter BatteryReason
GamingLi-PoLi-Po can provide a lot more power to keep the chipset running at peak performance for stable frame rates.
General ConsumersLi-IonLi-Ion are perfect for normal tasks, as they provide longer battery life than Li-Po. Also, the charge/discharge cycle count is greater for Li-ion which means the smartphone will last longer.
Video Editing and Image ProcessingLi-ion for Midrange, Li-Po for FlagshipMidrange smartphones do not focus on video editing performance and extreme post image processing which is why Li-ion is enough. But Flagships heavily rely on real time and post image processing which requires a lot of power.

Summary:

If the goal is a battery that will last longer throughout the day, lasts longer over the years, and should consume less space, then Li-ion is better.

If the goal is a battery that will charge faster, outputs a lot of power for demanding applications, have flexible shape and size, is light, then Li-Po is better.

I am going to summarize everything in this article by making a table of comparison between Li-ion and Li-Po battery.

Li-IonLi-Po
Energy Density (Wh/m³)High15-20% lower than Li-ion
Power Density (W/ )LowHigh
Size Larger than Li-Po, No comparison hereCould be as thin as 0.5mm
ShapeCylindrical and rectangularavailable in so many shapes
Cost0.1-0.3$/Whdouble the cost of Li-ion
Charge/Discharge CyclesHighLower than Li-ion
SafetyMore volatile compared to Li-PoBetter than Li-ion
Conversion RateThe capacity to convert battery to actual power is 85-95%75-85%
WeightRelatively HeavierLight
Charging speedNormalFaster than Li-ion

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