Specifications of Lithium Ion Cell

Depending on the design and chemistry of your lithium cell, you may see them sold under different nominal "voltages". For example, almost all lithium polymer batteries are 3.7V or 4.2V batteries. What this means is that the maximum voltage of the cell is 4.2v and that the "nominal" (average) voltage is 3.7V. As the battery is used, the voltage will drop lower and lower until the minimum which is around 3.0V. You should see the number 3.7V written on the battery itself somewhere.

For example, here is a profile of the voltage for a 'classic' 3.7V/4.2V battery. The voltage starts at 4.2 maximum and quickly drops down to about 3.7V for the majority of the battery life. Once you hit 3.4V the battery is dead and at 3.0V the cutoff circuitry disconnects the battery (more on that later.

• Under which situation we observe the changes in dimensions and weight of a cell.

1) The increase in external volume (also referred to as swelling) of LIBs either arising from gas generation from electrolyte decomposition or volume expansion of electrode is not desirable.

2) (i) expansion and contraction of host materials due to lithium intercalation

(ii) electrode volume increase caused by irreversible reaction deposits

(iii) dead volume and pressure changes within the cell case depending on battery structure and construction.

3) Crack, dislocation, deep scratch or leakage on either terminal of cell or on cell casing

Most primary lithium cells have a warning printed on the label that cautions against the

following conditions:

- Short-circuit

- Charging

- Forced over-discharge

- Excessive heat or incineration

- Crush, puncture, or disassembly

Not guarding against these conditions may result in a hot cell or a battery pack that could vent

or explode. With Electrochem cells, the ensuing hazards associated with a hot cell typically will

not occur the instant the cell is abused. Rather, the cell will heat up over a period of time. This

can take place in a matter of seconds or hours. Subsequently, the end result has the potential

to result in a cell vent or explosion once the critical temperature is reached.

primary cells and batteries are labeled with their maximum operating temperature, indicated in

degrees Celsius. This temperature should not be exceeded.

• List out various mechanical testing and standards.

1 Short Circuit :-The cell is to be short-circuited by connecting the positive and negative terminals of the cell directly with copper wire with a resistance of less than 0.05Ω.

2 Impact Test:- A test sample battery is to be placed on a flat surface. A 5/8 inch (15.8mm) diameter bar is to be placed across the center of the sample. A 20 pound (9.1kg) weight is to be dropped from a height of 24 ±1 inch (610±25mm) onto the sample.

3 Overcharge(3C/10V):- The cell is connected with a thermocouple and putin a fume hood. The positive and negative terminals are connected to a DC power supply set at 7.8A and 10V until the cell reaches 10V and the current drops to approximately 0A. Monitor thetemperature of cell. When the temperature of the cell is approximately 10 less than the peak value, the test is completed.

4 Thermal shock:- After standard charging, heat the cell to 130±2 at a rate of 5±2 /min and keep it at this temperature during 30 minutes.

1 High temperature performance:- The fully charged cell is put at 55±2 for 2℃ hours and then discharged to 3.0V at 1.3A

2 Low temperature performance:- The fully charged cell is placed during 16-24 hours at -20±2 and then discharge to 2.75V ℃ at 0.52A

3 Anti-vibration:- The fully charged cell is fixed on a platform and vibrated in the X , Y and Z directions for 30minutes at the speed 10ct/min Frequency: 10~30Hz, Vibration amplitude 0.38mm. Frequency: 30~55Hz, Vibration amplitude 0.19mm.

4 Drop Test:- The fully charged cell is dropped from a height of 1m onto a 15~20mm hard board in X, Y and Z directions once for all axis. Then the cell is discharged at 1.3A to 3.0V followed by 3 or more cycles with the standard charge rate and a discharge at 1.3A.

• What is the discard procedure suggested generally for used Li ion+ batteries?