How much influence does moisture have on lithium-ion batteries?

Date:Oct 11, 2019

1. The electrolyte deteriorates and the battery rivets are rusted

The electrolyte used in a lithium-ion battery cannot be used in an environment where the moisture is too high. When injecting the battery, it must be in an environment of less than 1% humidity and seal it immediately after filling to prevent the inside of the battery from coming into contact with the air. If the moisture is too high, the electrolyte reacts with the water to generate a trace amount of harmful gas, which has an adverse effect on the environment of the injection chamber; this also affects the quality of the electrolyte itself, resulting in poor battery performance; and rusting the battery rivet.

2. The internal pressure of the battery is too large

Moisture reacts with a component of the electrolyte to form a harmful gas. When the moisture is sufficiently large, the pressure inside the lithium battery becomes large, causing the battery to be deformed by force. If it is a mobile phone battery, it will be a drum shell; if it is our 26650 battery, it will be highly exceeded. If it is our 32xxx battery, the explosion-proof valve will crack and the battery will be scrapped. When the internal pressure is high, the battery is dangerous. The explosion causes the electrolyte to splash, and the battery fragments are also easy to injure.

3. Low capacity

The internal moisture of the lithium-ion battery is too high, the effective component of the electrolyte is lost, and the lithium-ion is also lost so that the lithium-ion undergoes an irreversible chemical reaction in the negative electrode of the battery. By consuming lithium ions, the energy of the battery is reduced.

4. Battery leakage

When there is a lot of water inside the lithium battery, the electrolyte inside the battery reacts with water, and the product will be gas and hydrofluoric acid. Hydrofluoric acid is a highly corrosive acid, which can make the metal parts inside the battery. Corrosion, which in turn causes the battery to eventually leak. If the battery leaks, the performance of the battery will drop rapidly, and the electrolyte will corrode the user's machine, resulting in more dangerous failure.

5. Battery charge and discharge capacity

When the water content in the lithium-ion battery is less than 0.015%, the first discharge capacity of the battery meets the national standard and the change is small; when the battery moisture is in the range of 0.015% to 0.04%, the first discharge capacity of the battery decreases as the moisture in the battery increases.

6. Battery internal resistance

For the long-term storage of lithium batteries, the internal resistance will increase with the increase of storage time, and the internal resistance will exceed a certain value, which will have a great impact on the performance of the battery. Since the moisture content has an effect on the quality of the SEI film in the lithium battery, the introduction affects the internal resistance of the battery.

Previous: What is the memory effect of the battery?

Next: Advantages of lithium iron phosphate battery as power lithium battery pack