DR NEERAJ Sharma, from UNSWs School of Chemistry, is developing next-generation rechargeable batteries that couple with solar cells, and run on seawater.
While renewable power has made leaps and bounds, it is still limited by the lack of affordable power storage solutions.
The current lithium-ion batteries which power phones and laptops are powerful. Large companies continue to make research and development breakthroughs in the technology, and some, like Tesla, are selling residential-scale lithium-ion systems for use with renewable power sources like solar.
Despite progress, many researchers consider the batteries far too expensive to be used on the scale needed to store renewable energy in the home, or on a commercial or community scale – and alternatives such as lead acid batteries are heavy and inefficient.
Dr Sharma is working to replace the lithium with sodium, which is available in salty water. By then improving the efficiency of sodium-based batteries, he hopes to develop batteries that are one-fifth the cost of lithium-ion batteries, but with the same efficiency.
Such seawater-powered batteries would be affordable enough to buy and use in bulk, unlocking the full potential of renewable energy sources.
While sodium batteries at their most basic simply consist of two electrodes in seawater, Dr Sharma is working to tweak the electrodes at the structural level, so the battery can provide eight to ten hours of constant electricity.
The main issue has to do with the size of sodium ions.
“Sodium ions are a bit bigger and harder to pull in and out than lithium, so we have to design an electrode material that has more space,” says Dr Sharma. “It’s visualising this process that’s our area of expertise. And we can use that information to build better electrodes.”
The researchers visualise the battery in action at the atomic level, by leveraging the equipment at the Australian Synchrotron and the Australian Nuclear Science and Technology Organisation (ANSTO) to bombard the material with X-rays or neutrons.
This has allowed the scientist to make significant improvements with the positive electrode, or cathode, boosting its performance to match that of modern lithium-ion batteries.
They are now proceeding apace with the negative anode.