What Is the Internal Pressure of Battery?
It’s the internal air pressure of the battery. And that is caused by the gas generated during the charging and discharging of the sealed battery. The main influence factors are battery materials, manufacturing processes, and battery structure. The main reason for this is that the gas generated by the decomposition of moisture and organic solution inside the battery accumulates in the battery. Generally, the internal pressure of the battery is maintained at a normal level. In the case of overcharge or overdischarge, the internal pressure of the battery may increase.
For example, overcharge, positive electrode: 4OH–4e → 2H2O + O2↑; ①
The generated oxygen reacts with the hydrogen precipitated on the negative electrode to produce water 2H2 + O2 → 2H2O ②
If the speed of reaction ② is lower than that of reaction ①, the oxygen generated will not be consumed in time, which will cause the rising of internal pressure of the battery.