According to project leaders Drs Manickam Minakshi and Danielle Meyrick of Murdoch’s School of Chemical and Mathematical Sciences, while the efficiency of wind and solar technologies has improved rapidly, one major problem has remained unsolved.
“The central obstacle facing sustainable energy is unreliability. Wind turbines don’t turn on a still day. Solar doesn’t work at night and can be hampered in the day by cloud, dust or snow coverage,” Dr Minakshi said.
“To provide power at non-generation times, excess energy needs to be stored in batteries, but storage technologies now being considered, such as molten salt or molten sulfur, work at high temperatures, making them expensive and impractical.”
“Our water-based sodium-ion battery has shown excellent potential for affordable, low-temperature storage.”
Dr Minakshi said he was drawn to sodium because its chemical properties were similar to lithium, the element that powers most portable electronic devices.
His challenge was to find material for cathodes and anodes capable of accommodating sodium’s ionic size – which is 2.5 times larger than that of lithium.
“Ions travel out of the cathode and into the anode to form a current. As an imperfect analogy, you can think of them as mesh filters that ions pass through. We had to find materials with larger gaps in their mesh,” Dr Minakshi said.
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