A Comprehensive Guide to Cylindrical Lithium-Ion Cells

Everything You Need to Know about Cylindrical Lithium-Ion Battery Cells

Cylindrical lithium-ion battery cells are a type of rechargeable battery commonly used in a wide range of electronic devices, electric vehicles, and energy storage systems. They are characterized by their cylindrical shape, standardized sizes, and high energy density, making them versatile and suitable for various applications.

Cylindrical Lithium-ion Cells – A Legacy of Innovation

The story of cylindrical lithium-ion battery cells traces back to the 1990s, when researchers pioneered the development of rechargeable lithium-ion batteries. The cylindrical form factor emerged as a practical and efficient design, offering high energy density and standardized dimensions. Over the years, advancements in materials science, manufacturing techniques, and electrode designs have propelled cylindrical lithium-ion batteries to the forefront of energy storage technology.

Structure

Cylindrical lithium-ion battery cells typically consist of several key components:

  • Cathode: The positive electrode or the cathode, usually made of a lithium metal oxide compound such as lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), or lithium nickel cobalt manganese oxide (LiNiCoMnO2, NMC), and Lithium Nickel Cobalt Aluminum Oxide (or NCA).
  • Anode: The negative electrode or the anode, commonly composed of graphite or other carbon-based materials capable of intercalating lithium ions during charging.
  • Separators:A porous membrane that separates the cathode and anode while allowing the flow of lithium ions. The separator is typically made of polyethylene or polypropylene.
  • Electrolyte:A conductive solution containing lithium ions that facilitates the movement of ions between the cathode and anode during charging and discharging. The electrolyte is typically a lithium salt dissolved in a solvent such as ethylene carbonate (EC) and dimethyl carbonate (DMC).
  • Current Collector:Thin metal foils (often made of aluminum for the cathode and copper for the anode) that collect and conduct electrical current to and from the electrodes.
  • Casing:A cylindrical metal or plastic housing that encloses the electrodes, separator, and electrolyte, providing physical support and protection for the internal components.

Working Principle

  • During charging, lithium ions are extracted from the cathode and intercalated into the graphite anode, creating a lithium-ion battery cell.
  • During discharging, the process is reversed, with lithium ions migrating back to the cathode, releasing energy that can be used to power electronic devices or electric motors.

Naming Rules

As we all know, understanding the naming rules of cylindrical lithium-ion batteries is crucial for identifying and selecting the right battery for specific applications. In order to help you better understand its naming rule, let’s break the details down as follows.

The naming rules for cylindrical lithium-ion battery cells follows a standardized format based on the cell’s dimensions, and usually represented by a five-digit code, where each digit provides specific information about the cell’s dimensions. Here’s a breakdown of the representation:

First and Second Digits: These digits represent the diameter of the cell in millimeters. For example, “18” indicates an 18mm diameter.
Third and Fourth Digits: These digits denote the height or length of the cell, also in millimeters. For instance, “65” represents a height of 65mm.
Fifth Digit: The fifth digit indicates the cylindrical shape of the cell. Typically, it’s “0” for cylindrical cells.

By following this naming convention, we can easily identify the size and shape of cylindrical lithium-ion battery cells. Putting it all together, let’s take an example:

21700 Cell:

  • The first and second digits, “21,” represent the diameter (21mm).
  • The third and fourth digits, “70,” represent the height or length (70mm).
  • The fifth digit, “0,” indicates the cylindrical shape.
  • So, an “21700” cell is 21mm in diameter, 70mm height, and cylindrical in shape.

This standardized format ensures clarity, consistency, and compatibility across different manufacturers and applications, making it easier for consumers and engineers to select the appropriate battery cells for their needs.

Benefits

Cylindrical lithium-ion batteries are the cornerstone of modern electronics, powering everything from smartphones and laptops to electric vehicles and renewable energy storage solutions. Their cylindrical shape, standardized size and high energy density make them versatile and suitable for a wide range of applications. Let’s explore some of these key benefits:

  1. High energy density(up to 270Wh/kg).
  2. Wide operating voltage range from 2.5V to 4.2V, nominal voltage 3.7V or 3.65V.
  3. Good cycle life, 500-1000 Cycles.
  4. Low self-discharge~ 1% per month.
  5. Wide Operating Temperature Range:approximately -20°C to 60°C (-4°F to 140°F)
  6. Quick chargeis possible (>=2C).
  7. Standard sizes: 18650, 21700, 26650, 32650, 46800.
  8. Highly sophisticated production processes: Automatic mass production lines ensure high qualified rate and consistencyand reduce costs.

Applications

  • Consumer Electronics: Smartphones, laptops, tablets, cameras, and other portable electronic devices.
  • Electric Vehicles: Electric cars, electric bicycles, scooters, and other forms of transportation.
  • Energy Storage Systems: Grid-scale energy storage, residential and commercial backup power, and renewable energy integration.
  • Aerospace and Defense: Satellites, unmanned aerial vehicles (UAVs), and military applications.
  • Medical Devices: Implantable medical devices, portable diagnostic equipment, and patient monitoring systems.

Conclusion

Cylindrical lithium-ion battery cells have become indispensable in powering the technologies that drive our modern world, offering a reliable and efficient energy storage solution for a wide range of application.

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