What is the working principle of cylindrical lithium-ion batteries? The working principle and characteristics of cylindrical lithium ion battery

Cylindrical lithium ion battery refers to a secondary battery composed of two compounds that can reversibly insert and extract lithium ions as the positive and negative electrodes.

When the battery is charged, the lithium atoms in the cathode ionize into lithium ions and electrons, and the lithium ions move to the anode to synthesize lithium atoms with the electrons. During discharge, lithium atoms are ionized from the anode surface in the graphite crystal into lithium ions and electrons, and lithium atoms are synthesized at the cathode.

Cylindrical lithium-ion batteries are an alternative to metal lithium storage batteries. The main components of the battery are positive electrode, negative electrode, electrolyte, separator and casing. Among them, the most important positive electrode, negative electrode, electrolyte, and separator are also known as the four main materials of lithium batteries.

Cathode---Using a carbon electrode that can absorb lithium ions. When discharging, lithium becomes lithium ions, leaving the anode of the battery to reach the cathode of the cylindrical lithium ion battery.

Negative electrode----The material is to choose the lithium compound that can be inserted as close as possible to the lithium potential. For example, various carbon materials include natural graphite, synthetic graphite, carbon fiber, mesosphere carbon, etc. and metal oxides.

Electrolyte---a mixed solvent system that uses LiPF6 ethylene carbonate, propylene carbonate and low-viscosity diethyl carbonate and other alkyl carbonates.

Diaphragm---Using polyolefin microporous membranes such as PE, PP or their composite membranes, especially the PP/PE/PP three-layer membrane not only has a low melting point, but also has high puncture resistance, which plays a role in heat insurance.

The outer shell is made of steel or aluminum, and the cover assembly has the function of explosion-proof and power-off.

The working principle of cylindrical lithium-ion battery refers to the principle of charge and discharge: when the battery is charged, lithium ions are generated on the positive electrode of the battery, and the generated lithium ions move to the negative electrode through the electrolyte. The carbon as the negative electrode has a layered structure. It has many micropores. The lithium ions that reach the negative electrode are embedded in the micropores of the carbon layer. The more lithium ions are inserted, the higher the charging capacity.

In the same way, when the battery is discharged (that is, the process when we use the battery), the lithium ions embedded in the carbon layer of the negative electrode are released and move back to the positive electrode. The more lithium ions returned to the positive electrode, the higher the discharge capacity. What we usually call battery capacity refers to the discharge capacity.

It is not difficult to see that during the charging and discharging process of cylindrical lithium-ion batteries, lithium ions are in a state of movement from positive → negative → positive. If we compare the cylindrical lithium-ion battery to a rocking chair, the two ends of the rocking chair are the two poles of the battery, and the lithium ion is like an excellent athlete running back and forth on both ends of the rocking chair. Therefore, the experts gave the cylindrical lithium-ion battery a lovely name, rocking chair battery.