Quality inspection is a critical aspect of square lithium - ion battery production to ensure that the batteries meet the required performance and safety standards.

Electrical performance testing is one of the primary inspection methods. The battery's capacity is measured by subjecting it to a controlled charge - discharge cycle. The actual capacity should be close to the rated capacity specified by the manufacturer. Internal resistance testing is also important. A high internal resistance can lead to energy loss and reduced battery performance. This is typically measured using an impedance analyzer. The battery's voltage - current characteristics are also monitored during charge and discharge to ensure that they follow the expected profiles. Any deviation from the standard profiles may indicate a problem with the battery's chemistry or internal structure.

Physical inspection is another key area. Visual inspection is carried out to check for any visible defects on the battery casing, such as cracks, dents, or signs of electrolyte leakage. The electrodes and separator are also inspected for proper alignment and any signs of damage. X - ray imaging can be used to detect internal defects, such as misaligned electrode layers or foreign particles inside the battery.

Safety testing is of utmost importance. Batteries are subjected to over - charge and over - discharge tests to ensure that they can withstand abnormal charging and discharging conditions without catching fire or exploding. Thermal abuse tests are also conducted, where the battery is exposed to high temperatures to evaluate its thermal stability. In addition, mechanical abuse tests, such as dropping the battery from a certain height or subjecting it to vibration, are performed to assess its durability.

Chemical analysis is also part of the quality inspection process. The composition of the electrolyte and the electrode materials is analyzed to ensure that they meet the specified standards. For example, the concentration of lithium - salt in the electrolyte and the purity of the cathode and anode materials are carefully measured. By conducting comprehensive quality inspection, battery manufacturers can identify and eliminate defective batteries, ensuring that only high - quality square lithium - ion batteries are released into the market.