New technology of lithium battery is announced to avoid fire caused by heat runaway to the greatest extent
Recently, foreign media reported that a study published in the Nano Letters provided a possible solution. This scheme adopts a new technology, which can quickly limit the lithium ion battery and turn it off when the battery overheats. Lithium ion batteries have been widely used in various devices, including smart watches and electric vehicles, due to their small size and high energy storage. However, the battery is prone to fire or explosion when overheating.
Basically, many batteries use the same chemicals. Through electronic devices in the circuit, electrons shuttle from one electrode of the battery to the other. However, in lithium ion batteries, the electrolyte between the electrodes will evaporate when it is overheated, and even lead to runaway short-circuit heat, that is, the process of uncontrolled self heating of the battery.
In electric vehicles, multiple lithium ion battery cells are connected together, and the phenomenon of thermal runaway may spread from one battery cell to another, resulting in a fire that is difficult to extinguish. To prevent this, many batteries are now equipped with fail safe devices, such as external vents, temperature sensors or flame retardant electrolytes. However, these facilities either react too slowly or affect performance. Therefore, researchers want to create a lithium ion battery, which can not only shut down quickly and automatically, but also work like the existing technology.
The researchers used a thermally responsive shape memory polymer coated with a conductive copper spray to create a material. This material can transmit electrons most of the time, but when it overheats, it turns into an insulator. At about 197 ° F (91.6 ° C), a programmed micro 3D pattern will appear in the polymer, which can block the copper layer and stop the flow of electrons. In this way, the electric core can be permanently stopped to prevent potential fire risk. In contrast, under the same temperature, the traditional electric core is still running. If it continues to get hot, it will face the risk of thermal runaway.
At normal operating temperatures, batteries using new polymers can maintain high conductivity, low resistivity, and similar cycle life to traditional batteries. The researchers said that this technology can improve the safety of lithium ion batteries, but does not affect the performance.
