1. Polymer lithium battery charging method
The current polymer lithium battery charging method generally adopts constant current constant voltage charging: the battery is first charged with constant current CC, when the battery voltage rises to a certain value (4.2 v), the voltage remains constant CV, the current in the circuit decreases to very small, and finally tends to 0.
2. The electrochemical principle of polymer lithium battery
Polymer lithium-ion battery refers to Li + intercalated compound as a positive, negative secondary battery. Lithium compounds LiCoO2, LiNiO2 or LiMn2O4 were used for the Cathode, and lithium-carbon interlayer compounds LixC 6 were used for the Cathode, the typical battery system is:
positive reaction: LiCoO2=Li1-xCoO2+xLi++xe————(2．1)
negative reaction: 6C+xLi++xe-=LixC6———–(2．2)
battery reaction: LiCoO2+6C=Li1-xCoO2+LixC6———–(2．3)
3. Consequences of overcharge of polymer lithium batteries
The Polymer Lithium battery can not be overcharged. If the battery is overcharged, the performance of the battery will be greatly affected, and the negative electrode will deposit metal lithium, which may cause the battery to explode or catch fire, at the same time, the solvent in the electrolyte was decomposed, which led to the serious destruction of the battery performance.
4. Over-discharge of polymer lithium battery
It should be noted that the polymer lithium-ion battery may be in a state of over-discharge due to its self-discharge characteristics during long periods of inactivity. In order to prevent the occurrence of over-discharge, the cell should be regularly charged to maintain its voltage above 3.0v. Over-discharge will lead to the loss of cell performance and battery function. It is required to add qualified Lithium Battery Protection Circuit Board in concrete application.
5. Selection of charging voltage for polymer lithium battery
At present, Commercial Lithium Batteries (high-voltage Polymer batteries) use cathode materials, cathode materials, and electrolyte electrochemical windows basically above 4.5v, that is to say, the battery is stable when the charging voltage reaches 4.5v. However, if the battery charging voltage is too low (such as less than 4.15 v), it will seriously affect the battery charging capacity. If the battery charging voltage is controlled at 4.13v, the battery charging capacity is about 60-80% of the battery capacity, which greatly affects the performance of the battery.
6. Charging voltage of polymer lithium ion battery
The charging current and charging voltage of ordinary polymer lithium battery should not exceed the following standards.
If the charging current exceeds the prescribed value, it may damage the charging and discharging performance, mechanical performance, and safety of the battery cell, and may cause heat generation and leakage. Polymer lithium-ion battery chargers must be able to charge at constant current and voltage; the charge current of the single battery must be below 1C5A; the temperature range must be 0 ~ + 45 °c when charging, and the voltage must not exceed 4.23v when charging.
In fact, the battery charging voltage and the battery system, and the battery discharge rate has nothing to do.