According to foreign media reports, Oleg Levin, a professor at the Department of Electrochemistry at St. Petersburg University, said that from 2012 to 2018, there were 25,000 reports of fires caused by electronic devices in the United States, compared with only 1,013 between 1999 and 2012. This shows that as the number of batteries used increases, the risk of fire is also increasing.
Overcharging and short circuits are the main causes of fire or explosion in lithium-ion batteries. Lithium-ion batteries become overheated after overcharging and short circuiting, and the battery cells enter a state of thermal runaway, which causes chemical reactions when the temperature rises to 70 or 90°C, further increasing the temperature and causing fire or explosion. To prevent battery fires, people use adjacent devices, such as electronic microcircuits, which track all parameters of the battery and can shut down the battery in an emergency. However, most fires are caused by defects in battery manufacturing and malfunctions in electronic microcircuits.
Developing safety strategies for batteries based on chemical reactions is particularly important for blocking the flow of current inside the battery pack. The use of special polymers, whose conductivity can be adjusted according to the voltage fluctuations inside the battery. If the battery is working properly, the polymer does not prevent the flow of current; if the battery is overcharged, short-circuited, or the battery voltage drops below normal operating levels, the polymer can turn into an isolator and enter circuit breaker mode.
Scientists have conducted a lot of basic research on the physical and chemical properties of various polymers and found a class of polymers that can change resistance with voltage.
There are many types of cathodes in lithium-ion batteries, such as the positively charged electrode through which electrons enter electronic devices. They also have different operating voltages. Therefore, safe polymers need to be able to cope with different types of cathodes. Such a polymer has been found, but it only works for a specific type of battery, namely lithium iron phosphate batteries. Changing the structure of the polymer may cause its conductivity to change, so that it can be used for other types of cathodes. By adding safety components to the polymer to adapt to the changes in the temperature level of the battery, this safety strategy will become more universal and hopefully eliminate all fire hazards associated with batteries.