What is a battery cell?

A battery cell stores electrical energy through an electrochemical process and is the basic unit of a battery. Typically, one electrochemical system composes two electrodes, the cathode (positive electrode) and the anode (negative electrode). An electrolyte is a substance that separates the electrolytes allowing the movement of ions while preventing direct contact between the anode and cathode.

The charging process causes the lithium ions to travel from their storage, that is, the cathode to the anode, due to the electrochemical reaction of the battery cell. When the discharging process takes place, the reverse of the former happens as the stored lithium ions travel from the negative electrode and back to the positive electrode, which results in the generation of an electric current that powers various devices.?

Battery cells are usually in various chemistries, each with distinct advantages, limitations, and characteristics. The commonly known battery cells include Lithium-polymer (Li-polymer), Nickel-Metal Hydride (NiMH), Lithium-ion (Li-ion), Lead-Acid, and Nickel-Cadmium (Ni-Cd), among others.?

What is a battery cell made of?

A battery cell is made of the following components;

Electrodes: the battery cell contains two electrodes- the cathode and anode. They consist of different materials for facilitating ion movement during the charging and discharging cycles.?The electrolyte is a chemical substance separating the electrodes in a battery cell. Depending on the battery type, it can either be in gel, solid or liquid form and allows the movement of ions between the anode and cathode.

Separator: to prevent direct contact with electrodes, a porous material called a separator is used. It ensures battery safety during operation and helps maintain the proper flow of ions within the cell.

Current collectors: the facilitation of electric current flow between the external circuit of the battery cell and the electrodes is done by the conductive materials called current collectors.

Enclosure: It depends on the battery type; the cell is contained within an enclosure made of different materials. Also called the housing, it prevents external influences from affecting the battery's performance while protecting the internal components.

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Terminal: the battery cell consists of two terminals (the positive terminal and negative terminal) which provide the points of connection for the external circuit to get power from the cell during the discharge cycle.?

Difference between cell and battery

When referring to or describing electrochemical devices used in the storage of electrical energy, the terms cell and battery are commonly used in the topic of energy storage. The two concepts are related but with distinct meanings.

Cell

The basic unit of an electrochemical energy storage device is called a cell. It is made up of two electrodes and an electrolyte. The cathode is the positive electrode, the anode is the negative electrode, and the electrolyte is the medium separating them. An electrochemical reaction occurs during the charging process of the cell, causing the ions to move from the cathode to the anode. The reverse happens during discharge as the stored ions travel back to the cathode resulting in electric currents. Cells are not directly suitable for most practical applications as they are typically small, low in capacity, and relatively low in voltage.

Battery

On the other hand, the collection of multiple cells connected in a specified arrangement or configuration is called a battery. Batteries are suitable for use in devices and applications as they can achieve higher capacity levels and voltage by combining the individual electrical outputs of the cells. A battery pack can have hundreds or thousands of cells, like in an electric vehicle, or a few cells, like in a laptop or smartphone battery. They are available in different sizes and shapes and are widely used in applications ranging from small electronic devices to large-scale industrial uses.?

What does a battery cell look like?

The physical appearance of a battery cell is dependent on the design and type of the battery. Various types of battery cells come in different sizes, shapes, and appearances. The common types of battery cells and their appearances include,

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1.Cylindrical Lithium-ion cell

It is among the most common battery cell types. It is often used in consumer electronics and devices, such as power tools and laptops. It has a metal casing and is cylindrical. The positive and negative terminals are located at the cap or top of the cell.

2.Prismatic Lithium-ion (Li-ion) Cell

These have a more square or rectangular shape, allowing for efficiency in space utilization in certain devices. They are commonly found in slim electronic devices like tablets and smartphones. The positive and negative terminals here are located on opposite sides of the cell.?

3.Pouch (Li-polymer) cell

Pouch cells use aluminum-plastic film or a flexible polymer as their outer casing. They are commonly used in lightweight and slim devices and can be custom-shaped. They are common in smartwatches, smartphones, and some portable electronics.

4.Lead-Acid Cell

These are commonly found in uninterruptible power supplies and automotive applications. They are large and rectangular, mainly used in lead-acid batteries. A lead-acid battery contains lead plates submerged in sulfuric acid, and multiple cells are connected.?

5.Button cell

These are small and round batteries common in calculators, watches, and other small electronic gadgets. They have a metal casing in a compact cylindrical shape. The negative terminal is at the bottom, while the positive terminal is at the top.

6.Nickel-Cadmium (Ni-Cd) and Nickel-Metal Hydride (NiMH) Cells

These cells are mainly used in older rechargeable batteries and applications such as cordless power tools. Often, they are prismatic or cylindrical. However, they are becoming less common as days go by due to the major adoption of Li-ion batteries.

Conclusion

In conclusion, a cell is the basic building block in an electrochemical energy storage device. It is composed of the cathode, anode, and an electrolyte. A battery is a collection of connected cells, forming a higher capacity and voltage energy storage unit. The two provide electrical energy storage and delivery for various applications and devices. Battery technology keeps evolving, and new form factors and designs might emerge.