The current energy storage market has been dominated by Lithium-ion batteries (LiBs); however, LiBs are nearing their theoretical limit, and as a result researchers are now looking into novel methods to develop batteries that offer higher energy densities and larger capacities. LiBs require lithium and other expensive rare earth element, such as cobalt, that involve extensive extraction techniques. Furthermore, lithium is dangerous to work with and can react with air, so an inert atmosphere is necessary to assembly the batteries. One potential solution is to fabricate metal anode batteries. Metal anodes provide a much larger theoretical capacity than metal ion batteries, yet numerous problems must be addressed before they can compete with and replace LiBs in the global market. For example, an alternative to lithium is zinc. Zinc is an abundant metal that is found all around the globe – it is safe to work with, nonreactive in air, can work in aqueous conditions, and is inexpensive. However, like all other metal-anode batteries, zinc anodes are prone to the same failure mechanisms. Metal anodes in aqueous electrolytes fail from one of the following mechanisms: passivation layer formation, dendrite formation, hydrogen evolution and other undesired side reactions. Researchers have tried a variety of potential solutions to improve the plating mechanics, and they found that the cycle life of the cell can be improved through electrolyte optimization, the addition of alloys to the metal, metal coating and using a porous 3-D structure in place of the standard 2-D planar structure. Using a porous structure as the anode in place of planar metal can improve dendrite suppression by lowering the diffusion limiting current, weakening the local electric field strength, thus allowing for even plating cycles and preventing the dendritic cycle. Therefore, there is an urgent need for a method to fabricate porous zinc anodes for metal-anode batteries that can compete with LiBs.
Researchers at the University of New Mexico’s Department of Chemical and Biological Engineering have developed a binder fabrication method for the surface characterization and optimization of porous zinc anodes. The researchers used different starting zinc particle sizes to determine optimal surface area, porosity, zinc-to-zinc oxide ratio to maximize cycle stability and mitigate dendrite growth. Through this method, porous zinc electrodes are created to be candidates for metal-anode batteries in the future. The proposed technology has initiated a path to make rechargeable zinc-air batteries competitive with Lithium-ion batteries.
Name: Gregg Banninger