Button battery (also known as button battery) is a small battery with a button like appearance, widely used in various micro electronic devices. The following are its core knowledge points:
structure and classification

Button batteries can be divided into:

Disposable batteries: including silver oxide batteries (CR series) and lithium manganese batteries (CR series), with a voltage of mostly 3V;
Rechargeable battery: Lithium ion battery (LIR/ML series), voltage 3.6V, supports repeated charging

Model Naming Rules

Common models such as CR2032, SR626, etc. have the first two digits representing diameter (mm) and the last two digits representing thickness (mm). For example, CR2032 represents a diameter of 20mm and a thickness of 3.2mm

Common application scenarios

Electronic devices: electronic watches, calculators, remote controls, toys;
Medical equipment: pacemakers, electronic hearing aids;
Others: electronic scales, lighters, car keys

The size numbering of lithium batteries usually uses the new numbering method of IEC, where the first two digits are diameter (unit: mm) and the last two digits are thickness (unit: 0.1 mm), whichever is closer. For example, the approximate size of CR2032 is a diameter of 20 mm and a thickness of 3.2 mm

silver oxide

This button battery has the characteristics of long service life and large capacity, and is widely used, with the largest application volume. This type of battery uses silver oxide as the positive electrode, zinc powder as the negative electrode, and potassium hydroxide or sodium hydroxide as the electrolyte. Electricity is generated through the chemical reaction between zinc and silver oxide. The thickness (height) of silver oxide button batteries comes in five specifications: 5.4mm, 4.2mm, 3.6mm, 2.6mm, and 2.1mm, and their diameters come in four specifications: 11.6mm, 9.5mm, 7.9mm, and 6.8mm. When selecting, one should choose one based on the size of its location. Its commonly used models include AG1, AG2, AG3, AG1O, AG13, SR626, etc. Its model AG is a Japanese standard and SR is an international standard model

silver peroxide

The structure of this battery is basically the same as that of the silver oxide button battery, with the main difference being that the anode (bowl electrode) of the battery is made of silver peroxide

Alkaline Manganese

This battery has a large capacity, excellent low-temperature performance, inexpensive materials, and can meet the requirements of continuous discharge with high current demand. Its shortcomings are insufficient energy density and unstable discharge voltage. The positive electrode of the alkaline manganese button battery is manganese dioxide, the negative electrode is zinc, and the electrolyte is potassium hydroxide, with a nominal voltage of 1.5V

Charging precautions

Rechargeable button batteries require the use of a constant current and constant voltage charger, with a charging current not exceeding 0.2C (such as 40mA for 200mAh batteries), a cut-off voltage controlled at 4.2V, and ensuring that the ambient temperature is between 10-40 ℃. If the battery expands beyond 0.5mm or the surface temperature exceeds 50 ℃, the power must be immediately cut off