The charging and discharging of a lithium battery involves the movement of lithium ions between the negative electrode and the positive electrode. During the charging stage, the electrical energy is converted into chemical energy. The amount of energy that the cell can store is called its “power.” The process of charging and discharging a lithium-ion battery can be complicated, but it is generally simple.
The lithium battery is charged by a charger that maintains a constant current. The charge is slow and gradual, so that it will not cause the battery to overheat. The first phase of charging is known as the pre-charge phase, and the voltage of the battery will be below three volts during this period. After that, the battery will begin to gain energy and will eventually reach its maximum potential.
The first phase of charging is called the constant-voltage phase. This phase involves applying a constant voltage that is equal to the maximum voltage of the cells in the series. Top-charging is necessary to maintain a higher voltage than that of the battery’s self-discharge rate. Once the voltage reaches four to five volts, the battery is full-charged.
The second stage is called the discharge cycle. This stage occurs when a negative electrode is overcharged. The discharge cycle stops when the battery is discharged. A discharged battery will not be able to store any energy, so it is important to discharge and charge it properly. Increasing the current can reduce the life of a lithium-ion battery. However, unrestricted high-current charging can embed ions into the negative electrode.
As the lithium-ion battery is fully discharged, the lithium ions move to the cobalt-oxide electrode. The lithium-ion batteries contain various types of materials, so their weight and energy content will vary. In some cases, a lithium-ion battery is heavier than the lead-ion batteries. When fully discharged, the lithium-ion battery is overcharged.
When a lithium-ion battery is being recharged, the current gradually increases. The charging current will decrease if the current is too high. Therefore, a higher charge current will result in a full charge in less time. During Stage one, the current is increased, but it takes more than a year to reach a saturation. For stage two, the current is reduced.
Lithium-ion batteries contain electronic controllers. The chargers will help the battery charge and discharge cycle without overheating. For example, the cellular energy is equal to the voltage multiplied by the charge. This is called the electrochemical equilibrium. The formula is as follows: The higher the current, the higher the voltage. If the voltage is too high, the lithium-ion cell is overcharged.