Graphene Based Composite Nanomaterial Helps Prevent Overheating of Lithium-Ion Batteries
To perform it efficiently, LIBs require operation circumstances that are within a certain range of current density, temperature and voltage. On the other hand, while they are subjected to abuse conditions, exothermic reactions do take place, leading to a quick boost in pressure and internal reactions. What does it really mean? The battery may explode!
The current Lithium-Ion batteries comprise of external sensors to prevent overpressure and overheating but, unfortunately, pressure and temperature inside the cells can basically boost it a lot quicker than they can be easily detected by the external sensors. Because of this, several different alternatives have been developed in this regard to comprise of internal components that help solve the issue. For instance, ceramic coating has proven to be extremely effective approach to shut down the after the battery shuts off, it cannot be used again. Making solid-state electrolytes can be another vital option, but the entire feat of the battery is decreased due to their low ionic conductivity.
A few years ago, researches from Stanford University came up with an extremely interesting paper where they presented the world with a new alternative: introducing a new material internally into the electrodes. Their material nanomaterial comprises of conductive graphene-coated spiky nanostructured nickel particles as the conductive filler along with a polymer matrix with a large thermal expansion coefficient. These spiky particles come with a high electrical conductivity at a very low filler fraction along with a high thermal sensitivity, whereas graphene offers high electromechanical stability that helps prevent oxidation as well as the decomposition of the electrolyte. Browse through acsmaterial for more details
The batteries that come along graphene based nanocomposite works efficiently even in a wide voltage window running at normal temperature, whereas they can shut down extremely fast while the operating conditions go off limits. Although the best part here is that such batteries can be used again right after the overheating event takes place, which is a big advantage.
Basically, the nickel nanoparticles promoted conductive percolation and, once their temperature reached a well defined point, the entire nanocomposite started to insulate due to the increase in the volume of polymer matrix, mainly interrupting the conductive pathways. However, as the temperature decreases, the matrix contracts once again, hence allowing the material to recover all of its conductivity. Moreover, it should be highlighted that the right temperature at which the material cuts the current is basically a design parameter which can be easily controlled by modifying the material composition.