Zinc-Air Fuel Cells (ZAFC)

In a typical zinc/air fuel cell, there is a gas diffusion electrode (GDE), a zinc anode separated by electrolyte, and some form of mechanical separators. The GDE is a permeable membrane that allows atmospheric oxygen to pass through. After the oxygen has converted into hydroxyl ions and water, the hydroxyl ions will travel through an electrolyte, and reaches the zinc anode. Here, it reacts with the zinc, and forms zinc oxide. This process creates an electrical potential; when a set of ZAFC cells are connected, the combined electrical potential of these cells can be used as a source of electric power. This electrochemical process is very similar to that of a PEM fuel cell, but the refueling is very different and shares characteristics with batteries. ZAFCs contain a zinc "fuel tank" and a zinc refrigerator that automatically and silently regenerates the fuel. In this closed-loop system, electricity is created as zinc and oxygen are mixed in the presence of an electrolyte (like a PEMFC), creating zinc oxide. Once fuel is used up, the system is connected to the grid and the process is reversed, leaving once again pure zinc fuel pellets. The key is that this reversing process takes only about 5 minutes to complete, so the battery recharging time hang up is not an issue. The chief advantage zinc-air technology has over other battery technologies is its high specific energy, which is a key factor that determines the running duration of a battery relative to its weight. When ZAFCs are used to power EVs, they have proven to deliver longer driving distances between refuels than any other EV batteries of similar weight. Moreover, due to the abundance of zinc on earth, the material costs for ZAFCs and zinc-air batteries are low. Hence, zinc-air technology has a potential wide range of applications, ranging from EVs, consumer electronics to military. Powerzinc in southern California is currently commercializing their zinc/air technology for a number of different applications. Last Update: Friday 12 December 2008 Time: 0:0