The new "water battery" is safer and cheaper than lithium-ion batteries

RMIT has led a team of global researchers and industry partners to develop a new recyclable "water battery" expected to be significantly safer than lithium-ion batteries.

 

Lithium-ion energy storage dominates the market due to its mature technology, but its suitability for large-scale grid energy storage is limited due to safety issues with its internal volatile materials.

 

Lead researcher Ma Tianyi, a professor in the School of Science at RMIT University, said their battery is at the forefront of the emerging field of water energy storage devices, with breakthroughs that significantly improve the performance and longevity of the technology.

 

Professor Ma said: "What we designed and built is called a water metal-ion battery - or we can call it a water battery."

 

The team used water instead of an organic electrolyte - which allows electricity to flow between the positive and negative electrodes - which means their battery won't catch fire or explode like lithium-ion batteries.

 

"Current energy storage technologies solve end-of-life disposal challenges faced by consumers, industry and governments around the world, with our batteries being safely dismantled and materials reused or recycled."

 

"The simplicity of the water battery manufacturing process makes mass production possible."

 

"We use materials such as magnesium and zinc, which are abundant in nature, are cheap and less toxic than alternatives to other types of batteries, which helps lower manufacturing costs and reduces risks to human health and the environment."

 

Energy storage and life cycle potential

 

The team has produced a series of small-scale trial batteries for numerous peer-reviewed studies to address a variety of technical challenges, including improving energy storage capacity and longevity.

 

In their latest research, published in the journal Advanced Materials, they succeeded in overcoming a major challenge -- the growth of destructive dendrites, sharp metallic structures that can cause short circuits and other serious failures.

 

The team coated affected battery components with a metal called bismuth and its oxide (also known as rust) as a protective layer against dendrite formation.

 

"Our batteries now last longer and are comparable to commercial lithium-ion batteries on the market, making them ideal for high speed and intensive use in real-world applications."

 

"With impressive capacity and extended service life, we not only have advanced battery technology, but we have also successfully combined our design with solar panels to demonstrate efficient and stable renewable energy storage."

 

The team's water battery is closing the gap with lithium-ion technology in terms of energy density, with the goal of using as little space as possible per unit of power.

 

"We recently created a magnesium-ion water battery with an energy density of 75 watt hours per kilogram (Wh/kg), which is equivalent to 30% of the latest Tesla car battery."

 

The research was published in the journal Small Structures.

 

"The next step is to increase the energy density of water batteries by developing new nanomaterials as electrode materials."

 

Professor Ma said that magnesium is likely to become the material of choice for future water batteries.

 

"Magnesium-ion water batteries have the potential to replace lead-acid batteries in the short term (say one to three years) and lithium-ion batteries in the long term (five to 10 years from now)."

 

"Magnesium is lighter and has greater potential energy density than alternative metals such as zinc and nickel, which will enable batteries with faster charging times and better ability to support power-hungry devices and applications."

 

Potential Applications

 

Professor Ma said the team's battery was well suited for large-scale applications, making it ideal for grid storage and renewable energy integration - especially in terms of safety.

 

"As our technology advances, other types of small energy storage applications, such as powering people's homes and entertainment devices, may become a reality."

 

As part of the ARC linkage project, Professor Ma's team is working with industry partner GrapheneX, a Sydney-based technology innovation company, to continuously develop their water battery.

 

"We also work closely with researchers and experts from leading universities and research institutions in Australia, the United States, the United Kingdom, Japan, Singapore, China and elsewhere."

 

"These collaborations facilitate the exchange of knowledge and access to cutting-edge facilities. With the expertise of this global team in different areas, we can approach the complex challenges involved from different perspectives."