The flakes also form a protective layer between the cathode surface and resulting lithium peroxide discharge product, which is highly corrosive. “Sulfur interacts with the metal sites in nickel cobalt sulfide, and there’s a strong synergistic interaction between the graphene surface and nanoflakes,” explains Shanmugam. “When this happens, the electrons can move about better within the graphene and so electrical conductivity is improved,” says Shanmugam.Ĭoating the cathode surface with nickel cobalt sulfide nanoflakes provides an added boost by increasing catalytic activity. Because sulfur atoms are much larger in size compared with their carbon counterparts, sulfur-doping the cathode expands the porous carbon lattice structure, increasing its surface area. Sulfur also provides additional benefits to the battery, says physical chemist Sangaraju Shanmugam from Korea’s Daegu Gyeongbuk Institute of Science and Technology, and one of the paper’s co-authors. “The sulfur atoms provide local glue spots, anchoring points for things to stick to,” he says. Modifying the carbon cathode with sulfur makes it easier for lithium peroxide to stick to it, says Hoster. And the more lithium peroxide that accumulates on the graphite cathode, the higher the battery’s charge capacity. Because oxygen can be supplied continuously from air rather than stored in finite amounts within the cell, lithium-air batteries can theoretically provide an energy density 10 times that of their lithium-ion cousins. The cathode is supposedly where the magic happens. The resulting product is lithium peroxide (Li 2O 2). In the case of lithium-air batteries, lithium from the anode gets oxidized while oxygen molecules are reduced at the cathode. “It’s a very interesting design approach,” says Harry Hoster, director of Energy Lancaster, a U.K.-based research institute dedicated to energy technologies.īatteries usually generate electrical energy through a redox reaction. The result: an electrode that boasts both improved electrical conductivity and catalytic activity. In a study published in Applied Catalysis B: Environmental, the team from South Korea and Thailand describe how they coated nickel cobalt sulfide nanoflakes onto a graphene cathode doped with sulfur. One option is lithium-air, and a team of researchers has invented a new type of cathode that they claim can lengthen the life of such batteries. Car manufacturers, keen to bring EVs to the mass market, have for years sought alternatives that could store more charge than today’s lithium-ion batteries. To dispose of a lithium-ion battery, contact the EHS office for disposal of damaged batteries.For owners of electric vehicles, range anxiety-the fear of running out of power before the next charging station-is real.When there are no more visible flames, use water to cool down the battery to avoid reignition. If a lithium-ion battery is on fire, use a water or ABC extinguisher.metal desk, concrete) away from combustible items and stay clear until the battery cools down. If a lithium-ion battery is abnormally hot to the touch, remove any electrical connections if possible and put it on a nonconductive container or surface (e.g.If a lithium-ion battery has bulged, remove it from service.It might be internally damaged and might ignite or explode if used. If a lithium-ion battery experiences a hard crash or is otherwise subjected to extreme forces, it is safest to pull the battery from the device and remove it from service.At MIT these incidents were related to batteries left on chargers for extended times, unattended charging, incompatible chargers, cheap knock-off batteries and shorts from improperly wired or isolated connections. News reports involving devices powered by lithium-ion batteries catching fire are on the rise, and also MIT has experienced a number of fires and emergencies related to Li-ion batteries. Even when the electrolyte is not flammable, a short can still start a fire. Unfortunately, there is a downside, the electrolyte in Li-ion batteries is often highly flammable. They are often chosen by researchers for advantages that include lightweight, higher energy density, low memory effect, and longer life span. These batteries are found in consumer electronics and power tools along with many research devices requiring portable electrical power. Lithium-ion and Lithium-polymer batteries are used widely across the MIT campus.
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