Lithium-ion Polymer Battery is a new kind of rechargeable battery which contains polymer electrode or electrolyte. It has no less than one kind of polymer materials in the main battery configuration system. There are many kinds of Lithium-ion Polymer Battery, to determine by the different types of cathode /anode materials.
Lithium-ion Polymer Battery has many advantages, such as higher energy density, thinner format, lighter weight, better safety performance, lower cost, etc, as to other kinds of secondary batteries.
The thickness, size and shape of Lithium-ion Polymer Battery can be designed according to the requirements freely. Lithium-ion Polymer Battery applies carbon as anode, which is rich in earth, and is capable of fast discharge. Also, Li+ intercalate into carbon layer during charge, which improves the safety problem of Li-ion battery. Thirdly, the whole performance is better, it can afford fast charge.
The shape of Lithium-ion Polymer Battery is fictile. It is super light, thin, high energy density, does not have leakage problem. Also it contains no poisonous substance like Lead, Cadmium, Hydrargyrum; it is a Green power sources.
Lithium-ion Polymer Battery applies gelled electrolyte with more stable discharge characteristics and higher discharge plateau. Also the battery can afford high power output. Even high rate charge /discharge, high frequency service, the battery can endure fast charge, does not has any memory effect. The charge /discharge efficiency of every cycle is about 99.8%.
Lithium-ion Polymer Battery has excellent capacity retention, low self-discharge rate, which is less than 5% per month at room temperature. That’s to say, the capacity retention rate is more than 95% per month. The battery has very good coherence of inner structure, which assures coherence of every charge /discharge process and the longer service life.
As Lithium-ion Polymer Battery utilizes aluminum package film as the shell, and once safety problems arise, there is no explosion but only expansion. The safety requrements are as follows:
Short Circuit: No fire, no explosion.
Over Charge: No fire, no explosion.
Thermal Test: No fire, no explosion. (150℃ 10min)
Puncture Test: No explosion. (Nail dia. 3mm)
Impact Test: No fire, no explosion. (A 10kg bar dropped from a height of 1m on the cell)
Fire-exposure: No explosion. (Use gas to burn the cell)
Charging Mothod of Lithium-ion Polymer Battery
Generally speaking, Constant Current /Constant Voltage charging method is used to charge Lithium-ion Polymer Battery. For example, first supply constant current to charge the battery to 4.2V, then supply constant voltage (4.2V) to charge till charge current decline to about 0mA.
Electrochemistry Principles of Lithium-ion Polymer Battery
Lithium-ion Polymer Battery consists of lithium oxide cathode (such as LiCoO2, LiNiO2, LiMn2O4,etc), graphite anode, organic solvent electrolyte including lithium salt and separator. Typical battery system and reaction of charge and discharge are as follows:
(-) C | LiPF6—EC+DEC | LiCoO2 (+)
Positive Electrode: LiCoO2=Li1-xCoO2+xLi++xe-
Positive Electrode: 6C+xLi++xe-=LixC6
Overall: LiCoO2+6C=Li1-xCoO2+LixC6
Bad Effect of Overcharge
Overcharge is forbidden when charging Lithium-ion Polymer Battery. Overcharge will cause safety problem or badly affect the performance of the battery. Dendrite lithium metal will deposit on the surface of the graphite anode when overcharing, which will cause explosion or fire. And also, electrolyte will decompose when overcharging, which will destroy the performance of the battery.
Charging Voltage of Lithium-ion Polymer Battery
Nowadays, the material’s electrochemistry window of commercial lithium-ion battery is above 4.5V. That’s to say, the battery is stable when charging voltage is not exceed 4.5V. But if the charging voltage is too low (for example less than 4.15V), it will affect the charge capacity obviously. If the charge voltage is 4.13V, the charge capacity is 60~80% of the full capacity, which will restrict the performance of the cell .The advisable charge voltage is 4.20V~4.25V.
In fact, the charge voltage is related with battery configuration system, not the discharge rate.
General Handling Precautions
Do not use knife or other sharp edge to hit the cell.
Keep away from metallic objects when transportation or storage.
Discard, pitch, impact, bend, trample or knock on the cell is forbidden.
Do not use metallic objects, such as electrical wire, to short circuit the cell.
Do not short circuit the positive /negative pole with the Al layer of the package film.
Disassembly the cell is strictly forbidden on any circumstances.
Do not immerge into water or sea water, the cell can not be affected with damp.
Handling or placement the cell away from fire or heater.
Do not over-heating the cell.
Do not weld the cell directly.
Charge the cell away from fire or high temperature circumstance.
Do not put the cell into microwave oven or high pressure vessel.
Do not put or use the cell under high temperature circumstance, such as under strong sunlight, in hot cars. Otherwise, it may overheat the cell, which maybe cause fire or affect the performance of the cell, especially service life.
When skin, eyes or other parts of human body contact the leakage electrolyte, please wash with clean water immediately under this condition and go to the doctor when necessary.
Do not use damaged batteries. If the electrolyte leak out or electrolyte scent emanate, please keep the cell far away from fire, or it may cause fire or explosion.
General Handling Instructions:
Chargers should have constant current /constant voltage and parallel charge function (We advise to use DN POWER professional balance charger). 1C5A charge current is much better, and the highest charge voltage can not exceed 4.25V.
Overdischarge will deteriorate the performance of the cell or even destroy the cell. Users should keep the discharge cut-off voltage above 2.75V.
To preserve the cell for a long time, please charge the cell aperiodically to keep each cell’s voltage between 3.6V and 3.9V.
Temperature 0～40℃ is preferred when charging, and -20-60℃ when discharging, 20~30℃ for storage.
The cell should be charged to 10％~50％ of the full capacity when transportation.
Disposal Procedures:
To discard a useless cell, first to cut the Al package film a spilt, then swash clean water for one minute, then you can discard the cell without pollution. Or you can deliver the useless battery to professional organization. It is advisable to consult with local authorities as disposal regulations.
