How Lithium-Ion Batteries Work

Lithium-ion batteries use carbon materials as the negative electrode and lithium-containing compounds as the positive electrode. There is no lithium metal, only lithium ions. This is the lithium-ion battery. Lithium-ion battery refers to the general term for batteries with lithium-ion intercalation compounds as positive electrode materials. The charging and discharging process of lithium-ion batteries is the intercalation and deintercalation process of lithium ions. In the process of intercalation and deintercalation of lithium ions, it is accompanied by the intercalation and deintercalation of electrons equivalent to lithium ions (the positive electrode is customarily represented by intercalation or deintercalation, while the negative electrode is represented by insertion or deintercalation). During the charging and discharging process, lithium ions intercalate/deintercalate and intercalate/deintercalate back and forth between the positive and negative electrodes, which is vividly called "rocking chair battery".
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 used as the negative electrode has a layered structure, and it has many micropores. Lithium ions that reach the negative electrode are embedded in the micropores of the carbon layer. The more lithium ions are embedded, the higher the charging capacity. Similarly, when the battery is discharged (that is, the process in which we use the battery), the lithium ions embedded in the carbon layer of the negative electrode come out and move back to the positive electrode. The more lithium ions returned to the positive electrode, the higher the discharge capacity.
Generally, the charging current of lithium batteries is set between 0.2C and 1C. The larger the current, the faster the charging, and the greater the heat generation of the battery. Moreover, the capacity is not full enough for charging with an excessive current, because the electrochemical reaction inside the battery takes time. Just like pouring beer, if you pour it too quickly, it will produce foam, which will make you dissatisfied.