Breakthrough: Recyclable ‘water batteries’ are explosion-proof

Australian researchers have introduced a groundbreaking ‘water battery’ technology, which stands out by not using a flammable electrolyte, offering a safer and more environmentally friendly alternative to conventional lithium-ion batteries for storing renewable energy.

Professor Tianyi Ma from RMIT University, the project’s lead, explains that these are aqueous metal-ion batteries, essentially water batteries, which are constructed from three basic components: the cathode (positive electrode), the anode (negative electrode), and an electrolyte that allows ions to move between electrodes.

The innovation lies in substituting the typical electrolytes with a water solution containing simple salts, making these batteries less hazardous and more eco-friendly. They utilize metals like magnesium or zinc, which are not only more affordable but also less damaging to the environment than lithium or lead-acid counterparts.

A notable advantage of using water as an electrolyte is its potential to prevent dendrite growth—tiny metallic spikes that can lead to battery short-circuits. The team tackled this issue by coating the anode with bismuth, which forms a protective, rust-like layer upon oxidation.

This approach has led to batteries that maintain over 85% of their capacity after 500 charge-discharge cycles, outperforming many lithium-ion batteries at a similar stage of use.

“Our batteries now achieve a lifespan comparable to that of commercial lithium-ion batteries and are suitable for frequent, high-speed usage,” stated Ma. The team has successfully combined these batteries with solar panels, demonstrating their capability for efficient and stable storage of renewable energy.

The researchers have created several prototypes, ranging from small, coin-sized batteries ideal for devices like clocks, to larger cylindrical versions comparable to AA or AAA batteries found in stores.

Looking ahead, Ma and his team aim to enhance the energy density of their water batteries by exploring new nanomaterials for the electrodes, promising further advancements in this innovative battery technology.