Developed by chemists at the University of Waterloo in Canada with larger power systems in mind, the battery uses safe, non-flammable, non-toxic materials and a pH-neutral, water-based salt. It also costs half the price of current lithium-ion batteries to manufacture, researchers said.
The battery generates electricity through a reversible process called intercalation, where positively charged zinc ions are oxidized from the zinc metal negative electrode, travel through the electrolyte and are inserted between the layers of vanadium oxide nanosheets in the positive electrode, researchers explained. This drives the flow of electrons in the external circuit, creating an electrical current. The reverse process occurs on charge.
The cell represents the first demonstration of zinc-ion intercalation in a solid state material that satisfies four vital criteria, they said: 1) high reversibility, 2) rate, 3) capacity and 4) no zinc dendrite formation. It provides more than 1,000 cycles with 80% capacity retention and an estimated energy density of 450 watt-hours per liter.
Lithium-ion batteries also operate by intercalation, but they typically use expensive, flammable, organic electrolytes. The zinc battery can be produced at a lower cost because its fabrication does not require special conditions, such as ultra-low humidity or the handling of flammable materials.
While much of the research attention in this area has been on minimizing battery size and weight for the portable electronics and automotive markets, University of Waterloo researchers decided to focus on the renewable energy storage needs of grid systems.
“Worldwide demand for sustainable energy has triggered a search for a reliable, low-cost way to store it,” said Linda Nazar, a Canada Research Chair in solid state energy materials and research professor in the Department of Chemistry. “The aqueous zinc-ion battery we’ve developed is ideal for this type of application because it’s relatively inexpensive and it’s inherently safe.”