Will fast charging affect battery life?

Quickly understand lithium-ion batteries

First of all, we must understand the charging and discharging principle of lithium-ion batteries. The battery has two poles: the positive electrode is a lithium compound, and the negative electrode is graphite.

Both charging and discharging are the mutual conversion of electrical energy and chemical energy. During the movement of positive and negative electrodes, lithium ions are also changing into different compounds.

We can think of lithium ions as a small car with electric charge: when charging, the electric field uses the electric field to drive the car to the negative electrode to store a certain amount of energy (lithium ions are inserted into the micropores of the graphite carbon layer of the negative electrode); when discharging, These charged lithium-ion carts ran to the positive electrode due to a chemical reaction (the deintercalation of lithium ions makes the positive electrode in a lithium-rich state). In this process, a current supply is formed.

In an ideal state, as long as the chemical structure of the positive and negative materials basically does not change, and the reversibility of the battery charge and discharge is very good, the lithium ion battery can guarantee a long-term cycle.

Fast charging is important to ensure that lithium ions are quickly inserted from the positive electrode and quickly inserted into the negative electrode, without causing lithium ion deposition.

However, when the current increases, the semi-permeable membrane (SEI membrane) on the surface of the negative electrode (graphite) of the electrode will rupture to a certain extent, causing the electrode material and the electrolyte to react with each other. In addition, the increase in temperature will also cause secondary effects inside the battery. The reaction destroys the chemical substances on the battery, resulting in a decrease in reversibility (that is, the lithium-ion car cannot be driven back and forth), and the battery capacity will continue to decrease.