Lithium ion batteries are a type of secondary battery (rechargeable battery) that primarily relies on the movement of lithium ions between the positive and negative electrodes for operation.

During the charging and discharging process, Li+is intercalated and disembedded back and forth between the two electrodes: during charging, Li+is disembedded from the positive electrode, embedded into the negative electrode through the electrolyte, and the negative electrode is in a lithium rich state; When discharging, the opposite is true.

Lithium ion batteries use carbon materials as the negative electrode and compounds containing lithium as the positive electrode. There is no metallic lithium present, only lithium ions. This is the lithium-ion battery. Lithium ion batteries refer to batteries that use lithium ion embedded compounds as the positive electrode material.

The charging and discharging process of lithium-ion batteries is the process of lithium ion insertion and removal. During the insertion and removal of lithium ions, there is also the insertion and removal of equivalent electrons such as lithium ions (the positive electrode is traditionally represented by insertion or removal, while the negative electrode is represented by insertion or removal). During the charging and discharging process, lithium ions are inserted/removed and inserted/removed back and forth between the positive and negative electrodes, which is vividly referred to as a "rocking chair battery".

When charging the battery, lithium ions are generated on the positive electrode of the battery. The generated lithium ions move through the electrolyte to the negative electrode, and the carbon used as the negative electrode has a layered structure with many micropores. The lithium ions that reach the negative electrode are embedded in the micropores of the carbon layer, and the more lithium ions embedded, the higher the charging capacity.

Similarly, when discharging the battery (i.e. during the process of using the battery), the lithium ions embedded in the negative carbon layer detach and move back to the positive electrode. The more lithium ions return to the positive electrode, the higher the discharge capacity.

Generally, the charging current of lithium batteries is set between 0.2C and 1C. The higher the current, the faster the charging, and the greater the heat generated by the battery.

Moreover, if the current is too high, the capacity will not be full. Because the electrochemical reaction inside the battery takes time, just like pouring beer, pouring too fast will produce foam, which will lead to dissatisfaction.