Lithium manganese battery and its structure principle
2021 Dec 10 By admin 0 comment

Lithium manganese dry battery is abbreviated as lithium manganese battery. Lithium manganese battery is a chemical power source that has not yet been widely used, and it is a high-quality product among primary batteries.

Lithium-manganese batteries cannot be recharged repeatedly, but their specific capacity is much larger than that of zinc-manganese dry batteries, so they are commonly used in computers, cameras, video cameras and other electrical appliances. This chapter specifically introduces the characteristics and applications of lithium manganese batteries.

1. Graphics of common lithium manganese batteries
The appearance of common lithium manganese batteries is shown in Figure 1. Figure 1 (a) shows a large button type lithium manganese battery, and its view is like a coin. Its smooth upper part is the negative electrode, and the bottom is engraved with characters as the positive electrode. The engraved characters are the battery model (CR2025), positive mark (+), rated voltage, and production company name. The CR2025 lithium manganese battery has a rated voltage of 3V and a rated capacity of 150mA·h. It is commonly used on the motherboard of a desktop computer. It uses a weak current as the power supply for the CMOS circuit. Generally, it can be used normally for about 3 years without replacement.

Lithium manganese battery and its structure principle
Figure 1 Graphic of Lithium Manganese Battery

As shown in Figure 1(b), it is a cylindrical lithium manganese battery, the model is CR1123A, its rated voltage is 3V, and its rated capacity is 1300mA·h. It is commonly used in cameras.

There is also a CR1425 No. 2 lithium manganese battery, which has a rated voltage of 3V and has pins on both electrodes. This kind of lithium manganese battery is convenient for soldering on circuit boards of computers and the like.

2. Classification of lithium manganese batteries
They are often divided into button, cylindrical, and rectangular batteries according to their shape.

3. Composition and structure of lithium manganese battery
The structure of the button lithium manganese battery is shown in Figure 2. It is mainly composed of positive metal shell, positive manganese dioxide material, electrolyte, negative metal lithium material, negative metal cover, diaphragm, plastic sealing ring and so on.

Lithium manganese battery and its structure principle
Figure 2 Schematic diagram of the button type lithium manganese battery

The positive electrode of the button type lithium manganese battery is composed of heat-treated manganese dioxide and the metal shell that contains it. The negative electrode is composed of lithium metal (or lithium alloy) and a metal cover. The positive and negative electrodes have a very fine and penetrating property. A strong polyethylene film is used as a diaphragm to isolate, and the electrolyte uses an anhydrous lithium perchlorate organic solution. Because this battery uses lithium and manganese dioxide as electrode materials, it is called a lithium manganese dioxide (Li-MnO2) battery, or lithium manganese dioxide for short.

When manufacturing lithium manganese batteries, metal lithium is used, and lithium is a very active metal. It can chemically react with many substances at room temperature, especially when it comes into contact with water, it will have a violent chemical reaction. Release a large amount of heat energy, which is easy to produce high temperature and even cause combustion. Therefore, the production of lithium manganese batteries requires operation in a dry environment with a humidity ≤ 1%. Not only that, there are strict requirements for the storage, transportation and use of lithium manganese batteries, and safety requirements must be strictly followed. Otherwise, there may be danger, fire, or even explosion. Obviously, users should know more about the safe application of lithium manganese batteries.

The electrolyte used in lithium manganese batteries is not an aqueous solution, but a non-aqueous organic solution. It has a strong ionization tendency and a large voltage difference between the positive and negative electrodes, which improves the voltage and working efficiency of the lithium manganese battery.

Lithium manganese batteries can be made into different dimensions to meet the requirements of different occasions. Common ones are button-shaped, cylindrical and rectangular.

4. The basic principle of lithium manganese battery
The electrochemical principle of lithium manganese battery is determined by its internal material structure.

Lithium manganese battery and its structure principle
Figure 3 principle of lithium manganese battery

After the lithium-manganese battery is assembled and injected with anhydrous organic electrolyte, the manganese dioxide of the positive electrode and the metal lithium of the negative electrode participate in the internal chemical reaction. Without charging, it can generate a rated voltage of 3V, which is the battery’s chemical energy conversion For electrical energy.

When the lithium manganese battery is connected to a load and discharged, the internal chemical reaction will continue to proceed, and the contents of the battery will undergo the following changes.

Lithium manganese battery and its structure principle
Lithium manganese battery discharge formula

During the discharging process, the metal lithium is slowly consumed to generate MnOOLi compound, and at the same time, chemical energy is converted into electrical energy for use by external electrical loads, and the battery voltage is gradually reduced.

Lithium-manganese batteries will continue to consume lithium metal safely after a period of discharge. When the metal lithium is safely depleted and the battery voltage drops from 3V to 2V, the lithium manganese battery is also discharged, announcing the end of its life.