Graphene Found To Prevent Fire In Lithium Batteries
Market Expertz | May 29, 2019
Researchers at the University of Illinois at Chicago College of Engineering have found that graphene may take oxygen out of lithium battery fires. Their findings have been published in the journal Advanced Functional Materials. Lithium batteries power electric vehicles, but they have been known to catch on fire occasionally; a phenomenon that scientists have called “thermal runaway.” The fires usually occur when the batteries overheat or cycle rapidly. With the increasing presence of electric vehicles on the road, there is an urgent need to reduce the occurrence of such incidents. The major causes of these fires are high temperatures in the battery and rapid cycling, i.e. charging and discharging. These conditions can cause the cathode in the battery to decompose and release oxygen. If this oxygen is exposed to other flammable products given off by decomposition of the electrolyte under sufficiently high temperature, it can trigger spontaneous combustion.
Reza Shahbazian-Yassar, the corresponding author of the paper, had initially used graphene, a super-thin layer of carbon atoms with exceptional properties, to help control lithium buildup on electrodes in lithium metal batteries. They were aware that graphene sheets are impermeable to oxygen atoms. Soroosh Sharifi-Asl, a graduate student and lead author on the paper, believed that wrapping tiny particles of the lithium cobalt oxide cathode of a lithium battery in graphene might prevent the emission of oxygen. The researchers modified the graphene to make it electrically conductive followed by wrapping the tiny particles of lithium cobalt oxide cathode electrode in the altered graphene.
When they examined the graphene-wrapped lithium cobalt oxide particles, they observed that the release of oxygen under high temperature was dramatically lower than in unwrapped particles. After this, the researchers bound the wrapped particles together with a binding agent to create a functional cathode and incorporated it in a lithium metal battery. They observed that almost no oxygen was released even at high voltages and the battery continued to give superior performance even after 200 cycles.