Preventing Lithium-Ion Battery Disasters: The Importance of Advanced Testing Techniques

Battery explosions and fires in lithium-ion products, including electric vehicles and power tools, often occur during charging due to the expansion of the negative electrode material (graphite or mixed silicon). This expansion can cause the positive and negative electrodes to come into closer proximity, leading to an internal short circuit. This inflated phenomenon can continue to worsen with each cycle of charging and discharging and does not resolve after a single charge. These types of accidents can happen during the manufacturing process or after the product has been sold. It's important to note that this type of internal short circuit is different from those caused by long-term lithium dendrite growth. To prevent these dangerous incidents, it's crucial to properly design and test lithium-ion batteries to ensure their safety and reliability.

To ensure the safety of lithium-ion battery cells, it's important to test the "distance between electrodes" for insulation. However, many manufacturers do not have the necessary technical knowledge to properly test for this, so they rely on measuring resistance instead. This is often insufficient, as an internal short circuit may not be present even if the insulation distance is too small. To accurately assess the insulation distance, it's necessary to apply higher voltage during testing. Without doing so, it's impossible to determine whether the distance between the electrodes is sufficient for safe operation. It's important for manufacturers to prioritize the proper testing of lithium-ion battery cells to ensure their safety and reliability.

It's not uncommon for burrs to cause intermittent, short-term insulation breakdowns during testing, even when sufficient voltage is applied. These breakdowns may appear to recover due to the shrinkage of the burrs, but in reality, the separator has been damaged and a molten hole has formed. Without the protection of the separator, the insulation layer is compromised and the burrs are exposed. Over time, the expansion of the negative electrode material can lead to a short circuit between the material and the burr, resulting in serious accidents. A standard WV/IR test may not be able to detect these abnormal products, as it only measures leakage current at a specific time. The most comprehensive methods for testing these types of issues include flashover detection during the test and leakage current determination with time measurement. It's important for manufacturers to use these more thorough testing methods to ensure the safety of their lithium-ion battery cells.

The Chroma 11210 Battery Cell Insulation Tester is a specialized tool designed to detect abnormal insulation in lithium-ion battery cells. It can detect and analyze partial discharges or flashovers in the insulator during high voltage testing, which helps to determine whether the effective insulation distance is sufficient before electrolyte injection. This helps to prevent defective products from entering the next stage of production or the market. Compared to traditional insulation testing methods, the Chroma 11210 Battery Cell Insulation Tester offers a higher level of safety for electronic and electrical products powered by lithium-ion batteries.

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