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The mechanism of action of Li-ion Battery

2022-04-07

Li-ion Battery uses carbon material as the negative electrode and a lithium-containing compound as the positive electrode. There is no metal lithium, only lithium ions. This is a lithium-ion battery. Lithium-ion battery refers to a general term for batteries with lithium-ion intercalation compounds as cathode materials. The charging and discharging process of lithium ion batteries is the process of intercalation and deintercalation 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 (usually the positive electrode is represented by intercalation or deintercalation, and the negative electrode is represented by intercalation or deintercalation). During the charging and discharging process, lithium ions are intercalated/deintercalated and intercalated/deintercalated 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 as the negative electrode has a layered structure, and it has many micropores. The lithium ions reaching the negative electrode are embedded in the micropores of the carbon layer. The more lithium ions are embedded, the higher the charging capacity. Likewise, 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 higher the current, the faster the charging, and the greater the battery heat. Moreover, if the current is too large for charging, the capacity is not full, because the electrochemical reaction inside the battery takes time. Just like pouring beer, if you pour it too fast, it will produce foam and become dissatisfied.