Guanjie Li, University of Adelaide's School of Chemical Engineering, with the aqueous zinc batteries and the decoupled dual-salt electrolyte.
A team of University of Adelaide researchers are exploring ways to create a safer and more sustainable battery for electric mobility and power grids.
While lithium-ion batteries are currently the favoured option by industry, the limitations associated with supply of the resource and environmental drawbacks are driving the search for more resilient alternatives.
Led by Professor Zaiping Guo, School of Chemical Engineering, the research group has been exploring the possibilities of rechargeable aqueous zinc batteries (AZB).
"An AZB will use water-based liquid, usually water with dissolved zinc salts as the electrolyte and zinc metal as the anode," says Professor Guo.
"The liquid is water-based so it is not flammable which makes it much safer than other batteries. They are also a promising alternative because of the abundance of zinc as a resource, its low environmental impact and the battery's high volumetric capacity."
However, AZBs have limited life cycles due to their narrow working temperature range, which has slowed down their practical use. The reactions between the zinc and electrolytes in AZBs are uncontrollable which can cause hydrogen gas release and corrosion within the battery.
Professor Guo's team has developed a Decoupled Dual-Salt Electrolyte (DDSE) -- a battery electrolyte the uses two different zinc salts to enhance the performance of a liquid to control the behaviour of ions.
The research was published in the journal Nature Sustainability.
"One type of salt helps the battery work well in different temperatures and improves how fast the battery can charge, while the other type helps protect the zinc metal inside the battery, so it lasts much longer, " says first author Guanjie Li from School of Chemical Engineering.
"Together, they give the battery very good performance. It can charge quickly and work for many cycles, over a wide range of temperatures, and with very little energy loss when sitting unused.
"In our DDSE, the first salt like zinc perchlorate, Zn(ClO4)2 stays mostly in the liquid and controls how the battery handles freezing and how fast ions move.
"The second salt like zinc sulfate, ZnSO4 sticks to the zinc metal surface and protects it from damage. Because each salt stays in its own area and does its own job, the battery works much better overall. We used lots of advanced tools to see this special distribution and to understand the deeper science behind how it works."
Senior Research Fellow and co-author Dr Shilin Zhang says the cells kept 93 per cent of their capacity even after 900 charge-discharge cycles, and worked from temperatures as cold as -40°C to as warm as +40 °C.
"This is the first time such a well-balanced performance has been achieved in our field," says Dr Zhang.
"Unlike conventional 'lean-water' designs by high-concentration or organic-aqueous hybrid electrolytes, our decoupling strategy results in a non-flammable, affordable, and sustainable electrolyte formula, retaining the intrinsic merits of aqueous systems.
"This approach provides a clear path toward the practical deployment of AZBs in smart grids and electric vehicles, which in turn, offers nations safer and more sustainable energy
"Our next step is to try this electrolyte in more practical battery systems. We want to fine-tune the recipe and also improve other battery parts, so we can build a real battery prototype that has a long-life, high-energy density, and low cost."
