A new battery fuelled by hydrogen could one day provide a cheaper and more effective alternative to lithium ion batteries, say researchers.
The concept involves integrating a metal hydride storage electrode into a reversible fuel cell, says Associate Professor John Andrews from RMIT University‘s School of Aerospace, Mechanical and Manufacturing Engineering.
“It is an experimental system that we’ve used in a preliminary way to show the basic feasibility of the concept,” says Andrews, whose research with colleague Saeed Seif Mohammadi is published in a recent issue of theInternational Journal of Hydrogen Energy.
Hydrogen power involves using electricity to split water to produce hydrogen and oxygen.
In conventional systems, the hydrogen ions (protons) initially produced during this electrolysis are converted to hydrogen gas, which is then stored in compressed form.
Getting electricity back out of the system requires a fuel cell that combines hydrogen and oxygen.
“The normal hydrogen system for storing electrical energy has got three components. It’s got the electrolyser [which splits water], the storage of gas, and a fuel cell,” says Andrews.
“We were seeking to get one integrated unit that was more like a battery but still using the basic principles of hydrogen production from water.”
Proton flow battery
Andrews and colleagues used a “proton flow battery” concept, in which protons are combined with electrons in an alloy and are stored in metal hydride form, rather than converted to hydrogen gas.
“The key innovation is to combine a reversible fuel cell with this integrated storage electrode,” says Andrews.
“The whole device becomes really much more like a battery.”
To utilise the stored energy in the battery, oxygen from the air combines with protons from the storage electrodes to generate electricity and reform water.
This design requires fewer steps than when electricity is discharged from a fuel cell.
“We’ve eliminated a whole step of going from protons to gas and we’ve got our hydrogen directly into a solid state storage,” says Andrews.
Andrews says the current low-powered experimental device would be easy to scale up and could provide a cheaper alternative to lithium ion batteries, especially if the storage electrode was made of carbon instead of metal hydride.
He says the batteries could be as efficient as lithium ion batteries but provide more energy per unit mass or volume.
Andrews says the system could one day be used in small-scale consumer electronic devices, for electricity grid storage, and even cars.
“It could be a rechargeable system for vehicles,” he says.
In the flow battery model, the charging process involves feeding in a small amount of water as a source of protons to the system.
Andrews says one advantage to this is that it is possible to store more energy than in conventional batteries where the source of ions is fixed by the volume of the battery.
“These are promising early developments but a lot more research and development is needed to take it to the point where there is a practical application,” says Andrews.
“We’re probably within 5 to 10 years of this.”
Read article at the ABC