Three scientists pushing chemistry in new directions

Solid-state batteries can be lighter, store more energy, and improve safety by replacing flammable liquid electrolytes with stable solid materials. Performance depends on ion movement through a solid electrolyte, which is often slower than ion transport in liquid electrolytes. Halide compounds are investigated because their conductivity can be very high. Lithium indium chloride is a promising halide solid electrolyte candidate, but it is difficult to produce. Conventional synthesis involves grinding lithium chloride and indium chloride into powder, then rapidly heating and slowly cooling to change structure and properties. This approach is hard to scale up, motivating alternative production methods.

"Solid-state batteries offer many advantages over lithium-ion batteries: they're lighter, they can store more energy, and because they use a stable solid material instead of a flammable liquid electrolyte, they're safer. But for the technology to become more widespread, "there are many issues we need to solve", says Xiaona Li, an inorganic chemist at the Eastern Institute of Technology in Ningbo, China."

"In a battery, electrons flow from an anode to a cathode through an external circuit to deliver power, while charged ions move through the electrolyte between two electrodes to maintain charge balance. In lithium-ion batteries, ions move relatively easily through a liquid electrolyte; in solid-state designs, the ions move through a solid electrolyte, which is typically slower and can constrain performance."

"One option that Li is investigating is halides - compounds made by combining a halogen element, such as fluorine or iodine, with another element, often a metal. "The conductivity of halides can be very high," she says. One type of halide, lithium indium chloride, is a promising candidate, but it's difficult to produce."

"The process usually involves grinding lithium chloride and indium chloride - crystalline salts made of metal and chlorine atoms - into a fine powder before rapidly heating and then slowly cooling the material to alter its structure and properties. "It's a method that's hard to scale up," says Li."

Read at Nature