The photo is sourced from rscf.ru
The purpose of the study was to improve safety of lithium-ion batteries, which often pose high risk of fire due to the combination of active oxidising agents, reducing agents and organic electrolytes in their chemical composition. The “prologue” for ignition is an emergency increase in battery temperature that often occurs during overcharging (when the battery voltage exceeds the maximum allowable level) and overdischarging (when the battery’s voltage falls below the minimum). While overcharging is most often associated with defects in the charging units, then overdischarging is associated with a malfunction of the device’s electronic circuits. However, both cases can result in short circuit, which can also occur due to battery design errors.
The SPbSU scientists proposed to reduce fire risks by using a polymer [Ni(CH3 OSalen)], which is distinguished by its ability to switch between the conductive and insulating phases during overdischarge or a sharp temperature jump. When applied to batteries, this new polymer does not affect their charge and discharge under normal conditions. However, in the event of a short circuit, it provides a decrease in current due to a drop in the protective layer conductivity. It results in a discharge without heating and noticeable damage to the electrode material.
“Our short-circuit protection concept can be applied to many types of electrode materials used in a wide variety of devices, from phones to high-capacity industrial batteries. The choice of polymer is limited only by its electrical properties. The development of such materials can significantly improve short-circuit protection for elements with high-voltage materials, say, in electric vehicles”, the Russian Science Foundation quotes Oleg Levin, Doctor of Chemistry, Professor at the Department of Electrochemistry at the Institute of Chemistry, St. Petersburg State University.
