Lifetime of the Gas Evolution Electrode of the Zn-H2 Storage System

A novel electrically chargeable galvanic system is presented that efficiently stores energy in the form of zinc and releases hydrogen and electricity upon discharge. In this concept, oxygen is released at the gas electrode during charging, and zinc oxide is reduced to metallic zinc at the counter electrode. When the cell is discharged on demand, the zinc is converted back to zinc oxide, but the water is reduced at the gas electrode to produce hydrogen. The system can therefore be used not only to store electricity - in combination with a fuel cell - but also as an on-demand hydrogen generator, for example, for industrial use. When used as an electrical storage system, the overall round-trip efficiency can approach 50%, significantly exceeding the efficiency of alternative power-to-gas technologies. There are no hydrogen storage or transportation losses. The electrochemical cell combines two breakthrough technologies: a bifunctional catalyst for hydrogen and oxygen evolution reaction that survives thousands of oxidation and reduction cycles, and a dendrite-free deposition of thick, high-capacity zinc coatings that can be cycled almost indefinitely thanks to pulsed charge current and intelligent electronic control.