A global team of researchers and industry collaborators led by Royal Melbourne Institute of Technology (RMIT) University has invented recyclable water batteries that won’t catch fire or explode.
Lithium-ion energy storage dominates the market due to its technological maturity, but its suitability for large-scale grid energy storage is limited by safety concerns with the volatile materials inside.
Lead researcher and distinguished professor Tianyi Ma said their batteries were at the cutting edge of an emerging field of aqueous energy storage devices, with breakthroughs that significantly improve the technology’s performance and lifespan.
“What we design and manufacture are called aqueous metal-ion batteries – or we can call them water batteries,” said Ma
The team uses water to replace organic electrolytes – which enable the flow of electric current between the positive and negative terminals, meaning their batteries can’t start a fire or blow up, unlike their lithium-ion counterparts.
“Addressing end-of-life disposal challenges that consumers, industry and governments globally face with current energy storage technology, our batteries can be safely disassembled and the materials can be reused or recycled,” Ma said.
The team’s water battery is closing the gap with lithium-ion technology in terms of energy density, with the aim of using as little space per unit of power as possible.
Magnesium will likely be the material of choice for future water batteries, said Ma.
“Magnesium-ion water batteries have the potential to replace lead-acid battery in the short term – like one to three years – and to replace potentially lithium-ion battery in the long term, 5 to 10 years from now,” said Ma.
“We use materials such as magnesium and zinc that are abundant in nature, inexpensive and less toxic than alternatives used in other kinds of batteries, which helps to lower manufacturing costs and reduces risks to human health and the environment.”
In the research teams latest work, published in Advanced Materials, they’ve triumphed over a major challenge – the growth of disruptive dendrites, which are spiky metallic formations that can lead to short circuits and other serious faults.
The team coated affected battery parts with a metal called bismuth and its oxide (otherwise known as rust) as a protective layer that prevented dendrite formation.
“With impressive capacity and extended lifespan, we’ve not only advanced battery technology but also successfully integrated our design with solar panels, showcasing efficient and stable renewable energy storage,” said Ma.
Potential applications of the batteries include large-scale applications such as grid storage and renewable energy integration.
And small-scale application energy storage application such as powering homes and entertainment devices
“We recently made a magnesium-ion water battery that has an energy density of 75 watt-hours per kilogram (Wh kg-1) – up to 30 per cent that of the latest Tesla car batteries.”
The team has made a series of small-scale trial batteries for numerous peer-reviewed studies to tackle various technological challenges, including boosting energy storage capacity and the lifespan.
The technology is supported by peer-reviewed research, government funding and industry engagement.