Common Analysis Methods and Typical Failure Cases of Lithium Thionyl Chloride Batteries

Common analysis methods and evaluation methods for Lithium Thionyl Chloride Batteries

For the failure of lithium thionyl chloride batteries, comprehensive testing and analysis can be carried out through non-destructive testing analysis (such as CT/X-ray), capacity testing analysis, internal resistance testing analysis, SEM/EDS analysis, and dismantling analysis to find the cause and mechanism of battery failure, and provide direction and basis for improving battery quality.

The main commonly used analysis methods and objectives are shown as follows:

CT/X-ray

• Judge whether there are defects or abnormalities in the internal structure of the battery without destroying the structural state of the battery, and confirm the failed part of the battery;

• Detect whether there are abnormal metal particles in the battery.

Capacity testing

• Test whether the initial capacity of the battery meets the specifications;

• Determine whether the battery self-discharge is abnormal.

Resistance testing

• If the internal resistance is too small, there may be a short circuit inside;

• It can determine whether there is an open circuit inside the battery.

Dismantling analysis

• Check whether the internal structure, diaphragm and appearance of active materials are normal;

• Whether there are foreign objects.
  

SEM/EDS analysis

• Detect whether the internal material morphology (material particle size, diaphragm porosity, etc.) is normal;

• Whether there are abnormal elements.
  

Typical failure cases of Lithium Thionyl Chloride Batteries

Lithium thionyl chloride batteries are widely used in power grid meters, communication equipment, monitoring systems, etc. Among them, zero voltage of the battery is a common failure mode of lithium thionyl chloride batteries in the market.

Diaphragm damage causes internal short circuit: Due to diaphragm damage, micro-short circuits may occur inside, continuously consuming power, and ultimately causing the battery to have zero voltage. Diaphragm damage may be caused by defects in the diaphragm material or external forces during the battery manufacturing process.

Manufacturing process abnormalities cause internal short circuits: Due to the sealing nail piercing the insulating film, the positive and negative electrodes are short-circuited, and the self-discharge is abnormally increased, which shortens the battery life. This type of defect is mainly caused by abnormalities in the manufacturing process. The solution is to avoid the location of the sealing nail on the insulating film.

Although the self-discharge rate of Lithium Thionyl Chloride Batteries is low, and their storage life is long, due to design defects, poor processes, abnormal materials, or extreme environmental factors, the battery's self-discharge increases, and the battery's self-consumption is serious, ultimately causing the battery to have zero voltage.

Compared with other failure modes, the failure mode where the battery life does not meet usage requirements is more common in the market. Therefore, it is particularly important to evaluate and judge the design reliability and application reliability of lithium thionyl chloride batteries.