UL certification is mainly engaged in product safety certification and operating safety certification business. Its ultimate purpose is to obtain products with safety standards for the market, and to contribute to the assurance of personal health and property safety. In terms of product safety certification as an effective means to eliminate technical barriers to international trade, UL also plays an active role in promoting the development of international trade. As one of the most important performance parameters, safety is one of the core indicators of lithium-ion batteries. In the case that lithium batteries are increasingly widely used in power drives, whether they have passed UL certification has become the authoritative basis for identifying and selecting power lithium batteries.

1. UL‘s testing and inspection of power lithium batteries are concentrated in seven standards, namely shell, electrolyte, use (overcurrent protection), liquid leakage, mechanical test, charge and discharge test, and identification.

    Among them, the mechanical test and the charge-discharge test are the two core links with more content.

Mechanical test, that is, through the transformation of mechanical force and mechanical force, the power lithium battery is under pressure, and the state displayed is the result of the mechanical test.

2. Mechanical test, that is, the power lithium battery is placed under pressure through the transformation of mechanical force and mechanical force, and the state displayed is the result of the mechanical test.

  There are also seven aspects of mechanical testing: extrusion, impact, acceleration, vibration, thermal shock, thermal cycle testing and high-altitude simulation. Previously, the fire test of the GM Volt electric vehicle that attracted widespread attention occurred during the mechanical test of the LG lithium battery. The charge-discharge test is a test method for judging the performance of lithium batteries by the performance of the battery under normal and abnormal conditions.

  The charge-discharge test also includes five aspects: charge-discharge cycle, short-circuit test, abnormal charge test, forced discharge test, and overcharge.

3. Among them, the charge-discharge cycle is a normal test. It is required that at 25 °C, the battery cell is charged and discharged according to the manufacturer‘s requirements, and the cycle is terminated when the capacity is 25% of the initial nominal capacity or after 90 days of continuous cycles. A security event has occurred.

    The remaining four are abnormal tests, which are simply "three overs and one short": overcharge, overdischarge, overcurrent, and short circuit tests. Detect the overcharge, overdischarge, high current and short circuit resistance of power lithium batteries respectively. The scientific use of lithium battery charging is a factor that seriously affects the life of lithium batteries.

    Therefore, qualified power lithium batteries should meet the "three nos" after the above tests: no leakage, no fire, and no explosion are qualified battery products.