Lithium-ion batteries are generally safe, but in millions of industrial and consumer applications, failures sometimes occur. Tiny metal particles in contact with other parts of the battery caused Sony to recall. Lithium-ion battery manufacturers strive to minimize the presence of such particles; however, assembly technology makes the elimination of such dust a challenge.
There are two types of battery failures. One is a one-in-a-million accident involving manufacturing defects and mainly leading to recalls. The second is a rare random event similar to being hit by a meteor. Since the damaged battery cannot be rebuilt, it is difficult to find the cause of such failures. Possible causes are charging at temperatures below freezing, high temperatures, excessive vibration, or repeated heavy loads.
Most battery failures that lead to disintegration start with a slight electrical short circuit, but go unnoticed. The battery is operating normally and the user does not know that a failure is about to occur. This is different from a failure structure that shows stress marks before falling. Structural abnormalities are recorded in detail, and the fault threshold is known. In this regard, the lithium ion power pack is more like a black box with its own ideas. Organizations such as NRTL, ANSI, UL, IEEE, etc. began to study the application of li ion batteries for sale and mandated their correct use. Heavy-duty trucks will get durable engines instead of enhanced engines from sports cars with the same horsepower.
Battery failure is also caused by electrode deflection or abnormal solder joints. Fast charging at low temperatures will promote the formation of lithium dendrites. Therefore, lithium batteries are stored at a voltage lower than 1.5V for more than a week. These stresses may cause increased self-discharge and electrical short-circuits, thereby forming hot spots that weaken the separator.
During thermal runaway, heat from a malfunctioning battery in the lithium-ion battery pack may be transmitted to the next battery, causing thermal instability. A chain reaction may occur, where each cell breaks down according to its own schedule. Therefore, with the consumption of each battery, a lithium-ion battery pack can be destroyed in a few seconds or a few hours. The packaging should include dividers to prevent malfunctioning cells from spreading to adjacent cells.