18650 is the ancestor of lithium-ion battery. It is a standard lithium-ion battery model. 18 means 18mm in diameter, 65 means 65mm in length, and 0 means cylindrical battery.
Lithium ion battery is a kind of rechargeable battery, which mainly relies on the movement of lithium ions between the positive and negative electrodes. During charging and discharging, lithium ions are intercalated and de intercalated back and forth between the two electrodes: during charging, lithium ions are de intercalated from the positive electrode and embedded into the negative electrode through the electrolyte, and the negative electrode is in a lithium rich state; The reverse is true when discharging.
The working principle of lithium-ion battery refers to its charge and discharge principle. When the battery is charged, lithium ions are generated on the positive pole of the battery, and the generated lithium ions move to the negative pole through the electrolyte. The carbon as the negative electrode has a layered structure, which has many micropores. Lithium ions reaching the negative electrode are embedded into the micropores of the carbon layer. The more lithium ions embedded, the higher the charging capacity.
Similarly, when the battery is discharged (i.e. the process of using the battery), the lithium ion embedded in the carbon layer of the negative electrode will come out and move back to the positive electrode. The more lithium ions returned to the positive electrode, the higher the discharge capacity. The battery capacity we usually refer to is the discharge capacity.
It is not difficult to see that during the charging and discharging process of lithium-ion batteries, lithium ions are in a moving state from positive pole to negative pole to positive pole. If we compare the 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 at both ends of the rocking chair. Therefore, experts gave lithium-ion battery a lovely name rocking chair battery.