Classification of polymer lithium batteries
1. According to the structure
Winding type: Using the same winding process as the production of liquid lithium-ion batteries, the positive electrode, negative electrode and electrolyte membrane are rolled up and packed with packaging aluminum foil.
Laminated type: Using the hot pressing process, the positive electrode, negative electrode and electrolyte membrane cut into a certain size are hot pressed together and packaged with packaging aluminum foil.
2. Classification by electrolyte
Gel polymer electrolyte lithium ion battery, which is to add additives to solid polymer electrolyte to improve ionic conductivity, so that the battery can be used at room temperature;
Solid polymer electrolyte lithium ion battery, the electrolyte is a mixture of polymer and salt, the ionic conductivity at room temperature is low, suitable for high temperature use;
Lithium ion battery with composite gel polymer cathode material, conductive polymer as cathode material, its specific energy is 3 times that of existing lithium ion battery, it is the latest generation of lithium ion battery.
Third, the advantages of polymer lithium batteries
1. High safety: due to the use of polymer materials, the battery will not catch fire or explode.
2. No leakage: The polymer battery does not contain liquid electrolyte and uses colloidal solid.
3. Thin thickness: with a capacity of 6V400mAh, its thickness can be as thin as 0.5mm.
4. Light weight: 40% lighter than steel-shell lithium batteries of the same capacity and 20% lighter than aluminum-shell batteries.
5. Large capacity: 10-15% higher capacity than steel-shell batteries of the same size, and 5-10% higher than aluminum-shell batteries.
6. Small internal resistance: The internal resistance of the polymer cell is smaller than that of the general liquid cell, which can be less than 35mΩ.
7. The shape can be customized: any shape can be customized according to the actual product application requirements.
Fourth, polymer lithium battery parameters
1. Voltage
Nominal voltage: 3.7V
Charging voltage: 4.1V~5V
Discharge voltage: 2.8~4.2V
Storage voltage: 3.7~3.8V
2. Capacity
The capacity of polymer lithium batteries depends on the thickness, width and length of the battery. In addition, it is related to the material and size of the battery.
To quickly estimate the capacity of polymer batteries, the commonly used estimation formula (for estimation only):
Capacity = thickness * width * length * K (K unit is mah/mm^3)
3. Internal resistance
Internal resistance refers to the resistance of the current flowing through the lithium battery when the lithium battery is working. It is mainly composed of electrode materials, electrolyte, diaphragm resistance and the contact resistance of various parts, and is related to the size, structure, and assembly of the battery. .
4. Discharge rate
Charging rate = charging current / rated capacity
The maximum charging rate is the safest, but not the best charging rate, and a lower charging rate can better extend the life of the battery.
5. Discharge rate
Discharge rate = discharge current / rated capacity
The discharge rate is the speed at which the battery can be safely discharged. It refers to the current value required by the battery to discharge its rated capacity within a specified time. The data value is equal to the multiple of the battery's rated capacity, usually represented by the letter C.
