Learn about lithium ion battery in close range

- 2021-03-10-

Lithium ion battery is a kind of rechargeable battery, which mainly depends on the lithium ion moving between the positive and negative electrodes. In the process of charging and discharging, Li + is intercalated and de intercalated between the two electrodes: Li + is de intercalated from the positive electrode and inserted into the negative electrode through the electrolyte, and the negative electrode is in a lithium rich state; in the process of discharging, the opposite is true. Generally, the battery with lithium as electrode is the representative of modern high-performance battery.

Working principle of lithium ion battery

Lithium ion batteries use carbon materials as the negative electrode and lithium compounds as the positive electrode. There is no metal lithium, only lithium ion. This is called lithium-ion batteries. Lithium ion battery is a general term for batteries with lithium ion intercalation compounds as cathode materials. The charge and discharge process of lithium-ion battery is the process of lithium ion intercalation and de intercalation. In the process of lithium ion intercalation and de intercalation, it is accompanied by the intercalation and de intercalation of equivalent electrons with lithium ion (traditionally, the positive electrode is represented by intercalation or de intercalation, while the negative electrode is represented by intercalation or de intercalation). In the process of charge and discharge, lithium ion is intercalated / de intercalated and intercalated / de intercalated between positive and negative electrodes, which is vividly called "rocking chair battery".

When the battery is charged, lithium ion is generated on the positive electrode of the battery, and the generated lithium ion moves to the negative electrode through the electrolyte. As a negative electrode, carbon has a layered structure with many micropores. The lithium ions that reach the negative electrode are embedded into the micropores of carbon layer. The more lithium ions are embedded, the higher the charging capacity is. Similarly, when the battery is discharged (i.e. when we use the battery), the lithium ion embedded in the negative carbon layer comes out and moves 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 battery is set between 0.2C and 1C. The higher the current is, the faster the charging is, and the higher the battery heating is. Moreover, if the battery is charged with too much current, the capacity is not full enough, because the electrochemical reaction inside the battery takes time. Just like pouring beer, it will produce bubbles when it is too fast, but it will be dissatisfied.