According to the latest issue of Nature Materials, in order to develop alternatives to lithium-based batteries and reduce dependence on rare metals, researchers at the Georgia Institute of Technology have developed a promising new cathode and electrolyte system at low cost. The replacement of metal fluorides and solid polymer electrolytes in place of expensive metals and traditional liquid electrolytes is expected to lead to safer, lighter and less expensive lithium-ion batteries.
The new cathode is made of a ferric fluoride active material and a solid polymer (a plastic) electrolyte nanocomposite. To make such a cathode, the researchers developed a method of infiltrating a solid polymer electrolyte into a preformed ferric fluoride electrode and then hot pressing the entire structure to increase density and reduce voids. The polymer-based electrolyte has two outstanding advantages. One is its ability to bend and adapt to the swelling of iron fluoride during cycling, and the other is its ability to form a very stable flexible interface with ferric fluoride, which solves the problem of using fluorine in previous battery designs. Key issues such as the expansion of iron and a large number of side reactions.
The researchers tested several variants of the new solid-state battery to analyze its performance over 300 charge and discharge cycles at 50 °C. As a result, it was found that the key to enhancing battery performance is a solid polymer electrolyte. When used with a solid polymer electrolyte, metal fluorides exhibit extraordinary stability even at high temperatures. This is expected to lead to safer, lighter and cheaper lithium-ion batteries. In addition, the lithium capacity of ferric fluoride is more than twice that of a conventional cobalt-based or nickel-based cathode. And iron is 300 times cheaper than cobalt and 150 times cheaper than nickel.
In the future, researchers will continue to improve and develop new solid electrolytes for fast charging and incorporate solid and liquid electrolytes in new designs to be fully compatible with traditional battery manufacturing techniques used in large battery plants.