Scientists Develop New Designs For Lithium Batteries, Or Reduce The Dependence On Rare Metals Such As Cobalt And Nickel

- Sep 16, 2019-

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 Georgia Tech have developed a promising new cathode and electrolyte system at low cost. Transition metal fluorides and solid polymer electrolytes replace expensive metals and traditional liquid electrolytes.

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 a very stable and flexible interface with iron fluoride, which solves the problem of fluorination used 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.