Batteries have become an essential part of modern technology. You can find them in phones and laptops, as well as in cars and even in renewable energy storage. We often see a battery as a single unit. However, its foundation lies in a smaller component called a battery cell. Hence, a question usually arises: What are battery cells, and how do they function?
Actually, each cell is a compact unit that stores and delivers energy. These small multiple cells create the batteries we rely on in daily life. That’s why it’s essential to understand the basics of a cell to know how a battery performs. If you are new to battery cells, don’t worry! This detailed guide will provide a clear look at battery cells. So, let’s begin!
What is a Battery Cell?
Let’s first grasp the basics of what battery cells actually are!
A battery cell is a smaller unit of a battery that stores energy and turns it into electricity. It has two ends, called electrodes, and a medium in between, called an electrolyte. When connected to a circuit, the chemicals inside the cell react and generate an electric current. This current is what powers your devices.
In simple words, a battery cell is a powerhouse that makes modern portable technology possible. These cells are the reason why energy can be carried around and used anytime, anywhere. However, it is crucial to note that a single cell can power small devices. However, larger machines typically require multiple cells to be connected to form a battery pack.
This is why the performance of a battery directly depends on the quality and capacity of its cells. In other words, the stronger the cells, the better the battery performs. Moreover, not all the battery cells are the same. They come in a variety of shapes and sizes to meet different energy needs. This variety makes their usability wide across several industries.
The Basic Parts of a Battery Cell
I hope you have a basic understanding of battery cells from the above section. Every battery cell may appear to be a simple object from the outside. However, inside it has a carefully designed structure. Each part of the cell has a specific role, and together they enable the cell to store and release energy. So, let’s dive in and explore some common battery cell components.
- Anode: The anode is the negative end of the cell. It is typically made of materials such as graphite, lithium, or zinc, depending on the type of battery. Its main job is to release electrons when the battery is in use. So it is the starting point where electricity begins to flow.
- Cathode: The cathode is the positive end of the cell. It is often made from metals such as lithium cobalt oxide or manganese oxide. The cathode’s role is to receive the electrons that come from the anode. Together, the anode and cathode create the pathway for electricity to flow.
- Electrolyte: Between the anode and cathode lies the electrolyte. This is a chemical substance that can be in liquid, gel, or solid form. It allows tiny charged particles called ions to move between the two sides. Without the electrolyte, the movement of charges would not happen.
- Separator: The separator is like a safety wall between the anode and cathode. It stops them from touching each other directly, which can cause a short circuit. However, it still allows ions to pass through.
- Current Collectors: The function of a current collector is to ensure electricity can flow from the battery and power a device. These are thin metal layers attached to the anode and cathode. They collect the electrons and send them out through the external circuit. This enables you to power your device.
How Does a Battery Cell Work?
As I mentioned earlier, a battery cell converts chemical energy into electrical energy. However, this process is not as simple as it sounds. This occurs through a comprehensive, step-by-step process. So let’s dive in and explore how a battery actually works!
Step 1: Chemical Reaction Begins
As you know, inside the cell, there are two ends called the anode and the cathode. Both of these electrodes are dipped into a gel-like material called electrolyte. When you connect a battery to a device, the materials inside the anode begin reacting with the electrolyte. This reaction forces the anode to release tiny charged particles called electrons. These electrons are now ready to move. However, they cannot pass directly through the inside of the battery.
Step 2: Electron Flow
Since electrons cannot cross through the electrolyte, they take the only available path. That path is an external circuit containing a wire. This means they leave the anode, travel through the wire or the device connected to it, and move towards the cathode. This movement of electrons from anode to cathode creates electrical energy. This is what we refer to as the current that powers your device.
Step 3: Ions Movement
While electrons move outside the battery, something else happens inside. Actually, there are other tiny particles inside the electrolyte known as ions. These ions carry an electrical charge. They move through the electrolyte from the anode to the cathode. This movement maintains the chemical reaction’s balance and enables it to run smoothly. Without this ion movement, the battery would quickly cease to function.
Step 4: Electricity Powers the Device
As the electrons travel through the external circuit, they pass through the device connected to the battery. Their movement provides the energy that powers the device. For example, in a remote control, the electrons light up the small circuit. This sends a signal to your device, such as a TV. In a phone, they run the screen, apps, and other features. In simple words, the movement of electrons is what brings your device to life.
Step 5: Charging and Discharging
Discharging of battery cells occurs when you use the battery to power an electrical device. During discharge, the chemicals react in a way that causes electrons to flow from the anode to the cathode. Those electrons travel through a wire, powering your device. On the flip side, charging occurs only in rechargeable batteries, such as LiFePO4 and Lead-Acid batteries.
It is the opposite of discharging. How? When you plug the battery into an electrical source, the current pushes electrons back to where they formed. At the same time, ions inside the battery also return to their original positions. This process resets the battery’s chemistry, making it ready for use again.
Types of Battery Cells
Battery cells are not always built in the same shape. Their design and structure change depending on where they will be used. Hence, based on these factors, there are five main types of battery cells. Let’s break down their details and specialties in this section.
1- Alkaline Cells
Alkaline cells are one of the most common and widely used battery cells in daily life. They are called “alkaline” because they use an alkaline electrolyte, usually potassium hydroxide. This electrolyte is what allows them to last longer and provide more power than older zinc-carbon batteries. However, these cells are non-rechargeable. This means once they are fully used, they cannot be charged again. You can find them in remote control cars, clocks, flashlights, and other similar devices.
2- Lead-Acid Cells
Lead-acid cells are one of the oldest and most reliable types of battery cells. They are still widely used today because of their low cost, durability, and ability to deliver high power. These cells are made using lead plates and an electrolyte of sulfuric acid. Due to this combination, they provide a steady and reliable power source. Remember, the non-rechargeable lead-acid batteries cannot be charged. So they create more waste compared to rechargeable batteries.
3- Nickel-Cadmium (NiCd) Cells
Nickel-cadmium cells, often referred to as NiCd batteries, are a type of rechargeable battery. These batteries use nickel oxide hydroxide and metallic cadmium as their primary materials. They have become popular due to their ruggedness, long-lasting nature, and ability to handle a wide range of temperatures. Moreover, these cells can also deliver strong, steady power output. This makes them suitable for household and industrial use.
4- Nickel-Metal Hydride (NiMH) Cells
Nickel-Metal Hydride (NiMH) battery cells are an advanced version of nickel-based cells. Instead of cadmium, battery cell manufacturers use a metal hydride material as the negative electrode. However, the positive electrode remains nickel oxide hydroxide. This change makes NiMH batteries safer for the environment because they don’t contain toxic cadmium. They also offer a higher energy density. Therefore, they can store more energy in the same size as NiCd cells. This is why NiMH cells became popular for consumer electronics, digital cameras, and even hybrid cars.
5- Lithium-Ion Cells
Lithium-ion cells are the most common and advanced rechargeable cells used today. These cells work by moving lithium ions between the cathode and anode during charging and discharging. Due to this design, they are highly efficient and can store a significant amount of energy in a compact size.
This makes them not only lightweight but also powerful. Another benefit of lithium-ion cells is their high energy density. This means they last longer before needing a recharge compared to older batteries. That’s why these cells are commonly used in high-rate batteries.
常見問題
What is the difference between a cell and a battery?
A cell is the basic single unit that produces electricity from a chemical reaction. For example, an AA battery used in a remote is actually a single cell. However, a battery is composed of one or more cells connected in series. For example, the battery in your smartphone or car has many small cells.
How many cells make up a battery?
The number of cells in a battery depends on the amount of voltage and power required. For instance, an AA or AAA battery typically consists of only one cell. However, a 9V battery has six tiny cells inside, each about 1.5V. All those cells are connected to give a total of 9 volts.
Can dead cells in batteries be reused?
No, the dead cells in the batteries cannot be reused. The reason is that the chemical reaction inside the cell has already been used, and they are non-rechargeable. So trying to recharge them can be unsafe.
總結
Battery cells are the foundation of modern energy storage. They power everything from household electronics to large-scale renewable energy systems. However, these cells generate energy with a basic working principle. For example, they convert chemical energy into electrical energy with the movement of electrons.
Moreover, depending on the usability, battery cells come in various types. Each of those types has its own advantages and disadvantages. Some of these are rechargeable, while others are non-rechargeable but have an extended lifespan. This variety enables industries to select the best option based on cost, performance, and reliability.