Water and electronics don't usually mix, but as it turns out, batteries could benefit from some H 2 O. By replacing the hazardous chemical electrolytes used in commercial batteries with water, scientists have developed a recyclable 'water battery' – and solved key issues with the emerging technology, which could be a safer and greener alternative.
They expend energy when electrons flow the opposite way. The fluid in the battery is there to shuttle electrons back and forth between both ends. In a water battery, the electrolytic fluid is water with a few added salts, instead of something like sulfuric acid or lithium salt.
The advent of water batteries highlights a potential new future of energy storage, particularly for electric vehicles (EVs), where safety and sustainability are paramount. With their non-flammable nature, water batteries could significantly reduce the risk of fires in EVs, enhancing vehicle safety and consumer confidence.
Ma said magnesium was likely to be the material of choice for future water batteries. “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.”
“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% that of the latest Tesla car batteries, so the next step is to increase the energy density of our water batteries by developing new nano materials as the electrode materials.”
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. Distinguished Professor Tianyi Ma (left) and Dr Lingfeng Zhu at RMIT University with the team’s water battery.