Topic 3 - How Does a Li-ion Cell Work?

Objective: By the end of this topic, you will understand the detailed charging and discharging process of Li-ion cells, including the movement of ions and electrons, and the role of electrodes and electrolyte.

Unveiling the Inner Workings of Li-ion Cells

Lithium-ion (Li-ion) cells are the backbone of modern technology, but have you ever wondered what happens inside a Li-ion cell when it's charging or discharging? Let's dive into the fascinating world of Li-ion cell chemistry and explore the detailed explanation of the charging and discharging process.

A Li-ion cell is a type of rechargeable battery that stores energy through electrochemical process. It's made up of three key components: a positive cathode (typically lithium cobalt oxide) that releases lithium ions, a negative anode (usually graphite) that absorbs them, and an electrolyte (a lithium salt dissolved in an organic solvent) that facilitates the flow of ions between them. Additionally, there is a separators, one between the cathode and anode, which prevent them from touching and causing a short circuit. 

When Li-ion cell is charged, lithium ions move from the cathode, through the electrolyte, and are stored in the anode along with an electrons. This process is reversed during discharge, allowing the anode to release the electron and generate current. This might seem a bit confusing at first, so let’s break it down and understand it clearly:

During the charging process of a Li-ion cell:

• At the cathode (positive electrode), lithium ions (Li+) are released and electrons (e-) are absorbed.
• The electrons flow back through the external circuit (like a wire) to the anode (negative electrode).
• At the anode, the electrons combine with the lithium ions (Li+) that have traveled through the electrolyte, forming neutral lithium atoms.
• These lithium atoms are stored in the anode material (typically graphite) between its layers.

In summary, during charging:

• Lithium ions (Li+) move from the cathode to the anode through the electrolyte.
• Electrons (e-) flow from the cathode to the anode through the external circuit.

This process is reversed during discharge, allowing the cell to generate current.

The Intricate Dance of Ions and Electrons

Understanding the charging and discharging process of Li-ion cells reveals the intricate dance of ions and electrons that enables our devices to function. By grasping this fundamental knowledge, we can appreciate the remarkable technology that powers our modern world.

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Section: All about Lithium ion Batteries 

Articles: Introduction to Batteries | Lithium ion batteries | Disadvantages of LIBs | Working Principle of Lithium ion Batteries | Lithium ion battery - Materials & Components