Researchers from Carnegie Mellon University's Mellon School of Science and Engineering have developed a semi-liquid lithium metal anode that represents a new paradigm for battery design. Lithium batteries made using this new type of electrode can have higher capacity and are safer than typical lithium metal batteries using lithium foil as the anode. The research results have been published in Joule.
Lithium batteries are one of the most commonly used types of rechargeable batteries in modern electronic devices because they can store large amounts of energy. Traditionally, these batteries were made of a flammable liquid electrolyte and two electrodes (anode and cathode), which were separated by a membrane. After the battery is repeatedly charged and discharged, lithium dendrites grow on the electrode surface. Lithium dendrites can pierce the membrane that separates the two electrodes, making contact between the anode and the cathode, which may cause a short circuit of the battery, and in severe cases, the battery will catch fire.
"Lithium-ion batteries with metallic lithium anodes have the theoretical potential to create larger-capacity batteries than graphite anode batteries," said Krzysztof Matyjaszewski, a professor of natural sciences at JC Warner University's Carnegie Mellon University. "But the most important thing we need to do is make sure the batteries we make are safe."
One solution to the volatile liquid electrolytes used in existing batteries is to replace them with solid ceramic electrolytes. These electrolytes are highly conductive, nonflammable, and strong enough to resist dendrites. However, the researchers found that the contact between the ceramic electrolyte and the solid lithium anode was insufficient to store and provide the power required by most electronic devices.
To overcome this shortcoming, create a semi-fluid that can be used as a metal anode. New Materials.
Collaborated with Mely Institute of Technology Matyjaszewski (leader in polymer chemistry and materials science) and Jay Whitacre, professor of energy at the School of Engineering, and the well-known Carnegie Mellon Wilton E. Scott Energy Innovation Institute In the work on new technologies for power generation, a bi-conductive polymer / carbon composite matrix was created, in which lithium particles were uniformly distributed throughout the matrix. The matrix remains fluid at room temperature, which allows it to make sufficient contact with the solid electrolyte. By combining semi-liquid metal anodes with garnet-based solid ceramic electrolytes, they are able to cycle batteries at a current density 10 times higher than batteries with solid electrolytes and traditional lithium foil anodes. The lithium battery has a much longer cycle life than conventional batteries.
"This new processing route makes the lithium metal-based battery anode fluid, which has very attractive safety and performance compared to ordinary lithium metal. Implementation of such new materials may lead to phased changes in lithium-based rechargeable batteries. Extensive testing can see how it works in a variety of battery architectures. "
Researchers believe their method could have profound implications. For example, it can be used to make high-capacity batteries for electric vehicles and special batteries for wearable devices that require flexible batteries. They also believe that their method can be extended to other rechargeable battery systems other than lithium batteries, including sodium and potassium metal batteries, and can be used for grid-scale energy storage.