Choosing the right LFP battery for your RVs, boats, or solar homes can be challenging without knowing the differences in battery construction, performance, and durability. Therefore, it's essential to understand the significance of battery cell packing type when selecting a Lithium Iron Phosphate (LiFePO4) battery. The cell packing type plays a vital role in the battery's overall performance and longevity, making it a crucial factor to consider.

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In this blog, we'll explore why understanding battery cell is critical when choosing the right battery for your specific application, and take an in-depth look at pouch and prismatic LiFePO4 batteries.

Part 1: What are Prismatic Cells

Prismatic LiFePO4 batteries are named for their rectangular, prism-like shape. They typically have a hard plastic casing that protects the battery cells and can be stacked together to create larger battery packs. Prismatic LiFePO4 batteries are commonly used in electric vehicles, solar power systems, and other applications that require high-performance and long life. Most of LiTime LiFePO4 batteries are made of prismatic cells.

Benefits of Prismatic Cells

• Space Efficiency: Prismatic cells have a rectangular or square shape, which allows for efficient use of space in battery packs, making them ideal for certain applications with specific space constraints.
• Stackability: They can be stacked more easily than cylindrical cells, simplifying the construction of larger battery packs.
• Ease of Assembly: Prismatic cells can be easier to assemble into battery modules or packs due to their uniform shape.

Part 2: What are Pouch LiFePO4 Cells

These cells are thin and flexible, making them ideal for use in portable devices. They offer higher energy density than other types of LiFePO4 cells but are still highly reliable and long-lasting.

Benefits of Pouch Cells

• Flexibility: Pouch cells are lightweight and flexible, making them suitable for applications where space and weight are critical factors.
• Customization: They can be manufactured in various sizes and shapes, allowing for greater design flexibility.
• Cost-Effectiveness: Pouch cells are often cost-effective to produce and can offer a good balance between performance and cost.

2.1 Pouch Cell Swelling? Satety Concerns of Pouch Cells

Pouch cell swelling, also known as "pouch ballooning," is a phenomenon commonly observed in lithium-ion pouch cells. It occurs due to several factors related to the cell's construction and operation:

• Gas Formation: During the normal operation of a lithium-ion cell, especially during charging, a small amount of gas can be generated as a byproduct of the electrochemical processes occurring within the cell. This gas primarily consists of oxygen and hydrogen, which can lead to the buildup of internal pressure.
• Electrolyte Decomposition: Over repeated charge-discharge cycles, the electrolyte within the cell can undergo decomposition. This decomposition can produce gases, such as carbon dioxide, which contribute to the internal pressure buildup.
• Formation of Solid-Electrolyte Interphase (SEI) Layer: The formation and growth of the SEI layer on the electrodes during cycling can also contribute to the generation of gases within the cell, leading to increased internal pressure.
• Volume Changes in Electrodes: During charging and discharging, the electrodes within the pouch cell undergo volume changes as lithium ions are inserted and extracted. These volume changes can lead to mechanical stress on the pouch packaging, potentially causing it to swell.
• Heat Generation: Heat generated during charging and discharging can also contribute to the expansion of the cell components, including the electrodes and the electrolyte, leading to swelling.

The combination of these factors can lead to the expansion of the pouch cell, causing it to swell. Pouch cell swelling can affect the performance and safety of the cell, potentially leading to mechanical stress on the internal components, degradation of the electrode materials, and compromise of the cell's structural integrity.

Although LiFepo4 Pouch Cells are considered safer than other lithium-ion battery technologies, it remains crucial to handle them with care. Choosing a reputable supplier is a key factor to guarantee the cells' quality and reliability. Additionally, following proper handling and storage protocols, minimizing the risk of physical damage or puncture, and conducting regular monitoring for any signs of malfunction are essential practices. Lastly, it's important for customers to plan for the safe disposal or recycling of batteries and prevent exposure to extreme temperatures or moisture.

Ensuring that LiFePO4 Pouch Cells adhere to regulatory standards such as UL, CE, and RoHS is vital. These safety certifications confirm that the batteries meet stringent safety and environmental criteria and have undergone thorough testing and quality control procedures.

All of LiTime LiFePO4 lithium batteries have passed the test of UL, CE, and RoHS.

LiTime 12V 100Ah Mini is made of pouch cells, here's the battery cell drill test. 

Part 3: Prismatic VS Pouch Cells: Key Differences

Basic Differences

Shape

Prismatic cells are rigid and rectangular. Pouch cells are flexible and flat. Prismatic cells are bulkier, while pouch cells offer more design flexibility, adapting to various shapes and sizes.

Packaging

Prismatic cells use a metal casing for durability and thermal control. Pouch cells are wrapped in a flexible pouch, typically made from laminated materials like aluminum and polymer. This makes pouch cells lighter and more space-efficient.

Size

Prismatic cells are larger and thicker due to their rigid design. Pouch cells are thinner and more compact, perfect for devices with limited space.

Weight

Prismatic cells are heavier, thanks to their metal casing. Pouch cells are lighter, benefiting from their flexible packaging.

Cell Voltage & Capacity

Both types can offer varying voltages and capacities based on chemistry and design. While their voltage ranges are similar, their capacity depends on size and construction.

Durability

Prismatic cells are more durable and resistant to external stress due to their metal casing. Pouch cells are more vulnerable to damage, requiring extra safety measures.

Cost

Prismatic cells are pricier to produce because of their complex metal casing. Pouch cells, with their simpler construction, are generally cheaper.

Performance

Prismatic cells provide higher energy density, making them ideal for high-energy applications like electric vehicles. Pouch cells offer higher power density, suited for devices that need quick bursts of power, such as smartphones and tablets.

Applications of Prismatic VS Pouch Cells

1. Prismatic Cells: Built for Tough Tasks

Prismatic cells are robust and durable, designed for high-performance applications that need reliability. Here’s where they excel:

• Electric Vehicles (EVs): Prismatic cells are the backbone of EV battery packs. Their metal casing protects against damage, ensuring safety and long-term performance.
• Power Tools: For tools that demand high power, like drills and saws, prismatic cells provide the endurance and output needed for extended use.
• Energy Storage Systems (ESS): In large-scale energy storage projects, prismatic cells’ strength and capacity make them ideal for stabilizing renewable energy grids.

2. Pouch Cells: Light and Flexible

Pouch cells are lightweight and customizable, perfect for portable devices and space-constrained applications. Key uses include:

• Consumer Electronics: Smartphones, tablets, and wearables benefit from the thin, compact form of pouch cells. They fit snugly into small spaces while providing sufficient power.
• Medical Devices: Pouch cells are used in pacemakers and insulin pumps, where their small size and light weight are essential for implantable technologies.
• Aerospace & Drones: In the aerospace industry, where weight is critical, pouch cells help power drones and aircraft systems, optimizing fuel efficiency and extending flight time.

Feature Prismatic Cells Pouch Cells Shape Rigid, rectangular or square Flexible, flat Packaging Metal casing for durability and thermal control Flexible pouch made of laminated materials Size Larger and thicker Thinner and more compact Weight Heavier due to metal casing Lighter, benefiting from flexible packaging Cell Voltage & Capacity Similar voltage range; capacity varies with design Similar voltage range; capacity varies with design Durability More durable, resistant to external stress More vulnerable, requires extra safety measures Cost Higher production cost due to metal casing Lower production cost due to simpler design Performance Higher energy density, ideal for high-energy tasks Higher power density, suitable for quick power bursts Applications EVs, power tools, energy storage systems (ESS) Consumer electronics, medical devices, aerospace & drones

Part 4: Frequently Asked Questions

1. What is a Pouch LiFePO4 battery, and how does it work?

A Pouch LiFePO4 battery cell is typically made up of a thin Aluminum plastic pouch that contains the battery components, including the electrodes, electrolyte, and separator. The pouch is then sealed to prevent leakage and protect the cell from moisture and damage. The battery works by transferring lithium ions between the cathode and the anode during charging and discharging.

2. What are the advantages of using a Pouch LiFePO4 battery?
The advantages of using a Pouch LiFePO4 battery include long cycle life, fast charging, high energy density, low self-discharge rate, and improved safety features.

3. Why are prismatic cells better than other types of cells?

Prismatic cells were developed to enhance manufacturing efficiency, as they are larger while still being more compact than cylindrical cells.

4. 

5. Can I overcharge or over-discharge a LiFePO4 battery?
No. Over charge or over discharge the battery will damage the lifespan of using. Therefore, many LiFePO4 battery manufactures like LiTime have  installed battery management system to prevent the batteries from overcharging or over-discharging, ensuring the battery's safety and longevity.

Visit LiTime user-stories and youtube reviews for more information about LiTime batteries.

6. Can I use a Pouch LiFePO4 battery in place of a lead-acid battery?
Yes, Pouch LiFePO4 batteries can be used as a direct replacement for lead-acid batteries in many applications, including electric vehicles, off-grid solar systems, and marine applications.

7. How fast can a LiFePO4 battery charge?
A LiFePO4 battery can be charged at a faster rate than a traditional lead-acid battery, and in some cases, can be charged up to 80% in less than an hour. We suggest you using LiFePO4 battery charger in order to keep the battery in good conditions.

8. How do I store a LiFePO4 battery properly?
It is recommended to store LiFePO4 batteries in a cool and dry place, away from direct sunlight and heat sources. It is also recommended to keep them charged to about 50% of their capacity during storage. 

Conclusion

In summary, when selecting a LiFePO4 battery for specific applications such as RVs, boats, or solar homes, it is crucial to understand the significance of battery cell packing type. Pouch and prismatic LiFePO4 batteries are two different types of cells with their advantages and disadvantages.

Pouch batteries offer higher energy density, flexibility, improved thermal management, and reduced risk of internal short circuits and swelling. They are ideal for portable electronics, solar-powered lighting, electric vehicles, marine applications, off-grid systems, RVs, and camping applications.

On the other hand, prismatic batteries are typically used in larger applications such as electric vehicles, solar power storage systems, and backup power supplies for buildings. The choice between the two depends on the specific needs of the application.

All Things You Need to Know about Li-ion Battery Package Forms

All Things You Need to Know about Li-ion Battery Package Forms

Li-ion batteries are widely used in many aspect, nowadays.

Have you noticed that？There are many kinds of Li-ion batteries’ shapes, for example, square and cylindrical.

How many kinds of shapes are there？
Do you know their differences?
Do you know why engineers design that?

Read on and make your own mind up.
According to different packaging forms, there are mainly three kinds of Li-ion batteries: Cylindrical lithium ion battery, Prismatic lithium ion battery, and Pouch lithium ion battery.

cylindrical  rechargeable lithium ion battery

prismatic lithium battery

pouch lithium battery

Different package structures refer to different characteristics. Let’s break them down one by one.

Content

1.What is Cylindrical Lithium Battery?
2.Advantages and Disadvantages of Cylindrical Lithium Battery
3.What is Prismatic Lithium Battery?
4.Advantages and Disadvantages of Prismatic Lithium Battery
5.What is Pouch Lithium Battery?
6.Advantages and Disadvantages of Pouch Lithium Battery
Q&A 1: Are pouch batteries better than cylindrical batteries?
Q&A 2: Do cylindrical batteries swell?
Q&A 3: Why battery shell is important? What’s function?
Q&A 4: What is the advantage of aluminum shell?
Q&A 5: What is the difference between cylindrical and prismatic battery cells?
Q&A 6: Naming Rules for batteries

What is Cylindrical Lithium Battery?

The structure of a typical cylindrical lithium battery : shell, cap, positive electrode, negative electrode, diaphragm, electrolyte, PTC element, washer, safety valve, etc.

Generally, the battery shell is the negative electrode of the battery, the cap is the positive electrode of the battery.

Different kinds of Li-ion batteries can be formed into cylindrical, for example, LiFePO4 battery, NMC battery, LCO battery, LTO battery, LMO battery and etc.

structure of cylindrical lithium battery

For more information, please visit Aluminum Prismatic LFP Cell.

reasons of high market penetration rate

Cylindrical shells divided into two types: steel or alloy material.

Generally speaking, the main battery is cylindrical cylindrical lithium iron phosphate batteries which is based on steel shell.

The earliest cylindrical Li-ion battery was the Li-ion battery which was invented by SONY in .

There are many models of cylindrical lithium batteries,such as common ones: ‘lithium ion cylindrical battery 3.7V mAh ″, “lithium ion  battery ”, “lithium rechargeable battery ″, ‘”lithium battery ”,etc.

Cylindrical lithium batteries are more popular among lithium battery companies in Japan and South Korea, and there are also large-scale companies in China that produce cylindrical lithium batteries.

Application of  cylindriacal lithium battery: Electrical vehicle, Laptop, digital camera, solar lamps, lawn lamps, backup energy, power tools, and toy models, pneumatic tools, portable energy transfer and etc.

Advantages of Cylindrical Lithium Battery:

1.Good Consistency: with mature technology and producing standard, manufacturers can produce productions in large quantity and high quality.

2.Safe: Withstand high voltageand generally sealed batteries, NO SWELLING
3.Goodheat dissipation effect→ Large specific surface area of the cylinde
4.High capacity, such as 15Ah cylindrical lithium ion battery, 20Ah cylindrical lithium battery
5.High output voltage
6.Stable output voltagel
7.Stable electric chemical performance
8.High current discharge
9.Good charge and discharge cycle performance
10.Wide operating temperature range
11.Environmentally friendly
12.Low PACK cost
13.Replaceable battery suppliers

flexible design for cylindrical cell battery pack

Cylindrical battery array with liquid cooling tubes

(A simple lithium battery pack)

Disadvantages of Cylindrical Lithium Battery:

• Small energy density increasing room
• The probability of alienation of the characteristics increases
• High production cost for battery system software level
• Low packing density because of its shape: can’t fully utilize space in the battery pack
• Battery performance reaches its limit

Want More Details: Download our battery design ebook.

Lithium Battery Design Design Ebook Download(2M, 20 pages, PDF)

What is Prismatic Lithium Battery?

Structure:  Laminated or wound top cover, housing, positive electrode plate, negative electrode plate, diaphragm, insulating parts, safety components, etc.

Although there are steel shell and aluminum shell battery, the aluminum shell one has generally become the mainstream with the market’s pursuit.

Prismatic cells have many anodes, cathodes and separators which of them are rolled up and then pressed into a metallic or hard-plastic shells.

Layer stacking and jelly rolling are both assemble for prismatic electrodes. That is the reason why there are thousands optional types of prismatic cells.

Application of prismatic lithium battery: small electronic devices such as mobile phones.

structure of prismatic lithium battery

Advantages of Prismatic Lithium Battery

• Flexible Design
• High reliability in package
• High energy efficiency in battery system
• Monitor cells one by one because of simple system composition
• Simple structure and easily to expand energy density and battery capacity by connecting single cells.

Prismatic battery array with a heat sink conduction matrix

(A simple lithium battery pack)

Disadvantages of Prismatic Lithium Battery:

• Not easier to find replaceable batteries compared with cylindrical batteries because of large amount of battery models.
• Cell inconsistency problem is relatively big because there is no very mature standard.
• Battery pack has shorter life than single cells inside.
• Relatively expensive model cost.
• Vulnerability to swelling
• Lower energy density

What is Pouch Lithium Battery

Structure: Liquid lithium-ion batteries with a layer of polymer shell. The package material is aluminum-plastic composite film which is the most critical and technically difficult material in pouch Li-ion batteries.

Packaging materials have three layers:
Outer barrier– outer protective layer composed of nylon BOPA or PET
Permeable layer– intermediate layer made of aluminum foil
Inner layer–Multifunctional high barrier layer

Application of Pouch lithium battery: Consumer, military, as well as automotive industries.

Mainly used in equipment which has equipment weight requirement or compact space. Pouch batteries are suitable for conditions where the working environment is relatively stable and there are no complex road conditions to ensure the structural stability and service life of lithium battery packs.

structure of pouch lithium battery

Pouch battery array with a heat sink

(A simple lithium battery pack)

Disadvantages of Pouch lithium battery:

1. High model developing cost of new designed battery
2. The quantity of existing pouch batteries models can not meet market’s demand
3. Exposure to high humidity and hot temperature can shorten service life.
4. Lack of producing standardization

Advantages of Pouch lithium battery:

• Good Safety Performance

Packed with aluminum-plastic film. In safety hazards, the pouch lithium battery will only swell and crack at most, unlike the steel-shell or aluminum-shell battery, which will explode.

• Light Weight

40% lighter than that of the steel-shell lithium battery of the same capacity,
20% lighter than that of the aluminum-shell lithium battery of the same capacity.

• Large Capacity

10 to 15% higher than that of steel-shell batteries of the same specification and size 5 to 10% higher than that of aluminum-shell batteries.

• Small Internal Resistance

The internal resistance is small, which greatly reduces the self discharge

• Flexible Design

The shape of the pouch lithium battery can be customized according to customer needs, and new battery models can be developed.

These are all details about cylindrical, prismatic and pouch batteries.

Looking forward, with pouch cells’ optimism , it will move to higher producing efficiency and better performance. Pouch and prismatic formats will be the most used, especially for automotive and energy storage use.

However, it does not means that cylindrical battery will disappear, it will also exist with less dominant stake in the battery market.

Q&A

• Are pouch batteries better than cylindrical batteries?

Yes. Pouch lithium battery is well kown for its  LIGHTER weight, BETTER safety performance, LARGER lithium battery capacity and SMALLER internal resistance.

At present, if you have other requirement, you can consider pouch batteries. If you do not have weight, space and cost requirements, cylindrical is the optimal choice to save your money and time.

• Do cylindrical batteries swell?

No, it rarely swell. Because its shell is made by steel or alloy material which is very hard, it can withstand high gas pressure and voltage. Thus cylindrical lithium battery will not swell. While pouch battery has possibility to swell.

• Why battery shell is important? What’s function?

The following are functions of battery shell

1. Suppress battery polarization
2. Reduces thermal effects
3. Improves magnification performance
4. Reduce the internal resistance of the battery
5. Significantly reduce the dynamic internal resistance of the cycle process
6. Improves consistency and increases the cycle life of the battery
7. Improve the adhesion of the active substance to the collector fluid
8. Reduce the manufacturing cost of the pole piece
9. Protects the collector fluid from being corroded by the electrolyte
10. Improve the high and low temperature properties of lithium batteries
11. Improve the processing properties of lithium iron phosphate and lithium titanate materials.

• What is the advantage of aluminum shell?

1.The lightweight space is large, because the density is 1/3 of steel；
2.Good thermal conductivity,5 times of steel’s；
3.Absorbs twice as much energy per unit weight as steel；
4.Good extension performance；
5.Strong plasticity, good weld-ability, and good productivity；
6.Good casting performance, can be processed into different shapes；
7.Corrosion-resistant, easy to recycle and regenerate

• What is the difference between cylindrical and prismatic battery cells?

shape cylindrical lithium cell pristimatic lithium cell pouch lithium cell Electrode Arrangement wound wound stacked Mechanical Strength very hard ++ hard + not hard - Heat Management not bad- good+ good+ Specific Energy high + high+ very high ++ Energy Density high + very high ++ high +

From the chart below, we can easily gain:

1. Pouch battery is formed by stacking. Whie the other two are formed by wounding
2. Cylindrical battery is the hardest one among these three kinds of lithium cell
3. Pouch battery is soft.
4. Cylindrical battery is poor in heat management. While the other two are good.
5. Pouch lithium ion battery has the highest specific energy among them.
6. Prismatic lithium cell has the highest energy density among them.

Want More Details: Download our battery design ebook.

Lithium Battery Design Design Ebook Download(2M, 20 pages, PDF)

• Naming Rules for batteries

Some may confused about numbers mentioned above:, , , …
Let’s have a look about these numbers.
All of them are names of cylindrical cells.According to name of cylindrical battery given by manufacturers, we can easily know its basic information.

How？

For cylindrical lithium cells,

Naming Rule:  Three letters+Five numbers+ normal capacity

Five Letters refer to main electrode materials of cell
The first letter: anode material
            “I”– lithium ion
            “L”– lithium or lithium alloy
The second letter: cathode electrode material
            “C”– Cobalt electrode
            “N”– Nickle electrode
            “M”– Manganese electrode
            “V”– Lead electrode
The third letter：“R”– cylindrical cell   

Five numbers refer to its outer dimensions
The first and second number: the diameter of cell(mm)
The third and fourth number :the height of battery (mm)
The last number “0”: cylindrical battery

The normal capacity: usually use milliampere( mAh) as unit

For prismatic lithium battery, here is a subtly different point

Naming Rule:  Three letters+ Six numbers+ normal capacity
Six numbers refer to its outer dimensions
The first two numbers: the thickness of cell(mm)
The third and fourth numbers :the width of battery (mm)
The last two numbers: the height of battery (mm)

Pay attention!!

1. Thickness, width, height≥100mm, must add “/”among three sizes

  ICP35/78/131         INP34/63/110

2. One of Thickness, width, height≤1mm, the letter “t”should be add before this size

  ICPt            INP35t968

 IMPt: a square secondary lithium-ion battery, the cathode material is Manganese, its thickness is about 0.7mm, the width is about 34mm and the height is about 48mm.

For example

ICP： a prismatic secondary lithium-ion battery, the cathode material is Cobalt, its thickness is about 10mm, the width is about 34mm, and the height is about 50mm.

INPO8/34/150 : a prismatic secondary lithium-ion battery, the cathode material is Nickle, its thickness is about 8mm, the width is about 34mm and the height is about 150mm.

Want More Details: Download our battery design ebook.

Lithium Battery Design Design Ebook Download(2M, 20 pages, PDF)

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