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Lesson on Li-ion Batteries
1. About Li-ion Batteries
1) Full Name: Li-ion Rechargeable Battery
discharge
2) Formula: LiCoO2 +
C
charge
Li1-xCoO2 + LixC6
Notes:
1) LiCoO2 is the main material at anode and C6 is the material at cathode.
2) To charge and discharge the battery is to have the Li+ come in or come out of the
cathode, so li-ion battery is nicknamed “Rocking Chair Battery”.
2. Construction
Active materials at Anode + Active materials at Cathode + Insulator + Electrolyte + shape
1) Main material at Anode
a. LiCoO2 (most common used)
b. LiMnO4
c. LiFePO4
2) Material at Cathode – C6
3) Insulator
There are 3 layers (PP + PE + PP) in total and the thickness is 20-25um.
4) Electrolyte – conductive liquid that allows the Li+ to move freely in and out of C6.
Commonly, the PH value is around 6.2
5) Shape
a. Rectangular
b. Cylindrical
c. Button/Coin
3. Characteristics
1) Voltage
a. Voltage for storage – 3.65V-3.90V, the best condition to store Li-ion battery is at 3.8V
and charge the battery to half capacity.
b. Operating voltage – 3.6V
c Maximum voltage for charging – 4.2V
d. Minimum voltage for discharging – 2.75V
Notes:
a. For energy type battery, the maximum discharging current is 2C. Only 85% - 92% of the
voltage is available if a battery is discharged at 2C.
b. Charging battery – The battery is charged to 4.2V at a constant current and then
charged at IC at constant voltage, the whole process takes about 2.5 hours.
c. Discharging battery – the battery is discharged at constant current to 2.75V. For energy
type battery, the current is usually 0.2C, 1C or 2C, and for power type, it is usually 3C,
5C and 10C.
2) Internal Impedance
a. When a PTC is added, the internal impedance of the battery increases.
b. The impedance changes during different periods of charging.
3) Capacity
a. Formula – capacity (mAh) = Current (I) X Time (t)
b. Most Li-ion batteries can be used for about 300 cycles, after that the capacity goes
down to 80% and less of its initial and the battery is considered as “no use”.
4) Life
The number of charge/discharge cycles that the battery can be recharged to at least 80%
of the stated capacity. Normally, the life should be more than 300 cycles.
4. Production Process
Materials Mixing
Coating
Jelly Roll
Film making & cutting
Capacity Sorting
Activating
Liquid Injecting
Assembling
Capacity Sorting
Storing
Inspecting
Packaging
5. Information needed for an inquiry
1) Operating current
2) Operating voltage
3) Operating temperature
4) Working time
5) Dimensions (Space available in the device to be powered, for battery or battery pack)
E-Mail: [email protected] ● Phone: 585-265-2000 ● Fax: 585-265-2542
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