Could this aluminium battery be safe, efficient and non-toxic?

A team of scientists from Australia and China say they’ve designed an early prototype battery that could be safe, efficient and non-toxic.

The researchers, from Australia’s Flinders University and China’s Zhejiang Sci-Tech University, reported the first step in the development of an aqueous aluminium radical battery that doesn’t harm the planet, in a paper published in the Journal of American Chemistry this week.

Lithium-ion and lead-acid batteries, by far the most common globally, can leak toxic chemicals like chromium, lead, and thallium into the ground as they corrode in landfill, if not properly recycled.

These chemicals wreak all kinds of havoc on the plants and animals they come into contact with, from causing developmental abnormalities in invertebrates to triggering cardiovascular diseases in humans.

According to an old study from 2011, the Chinese and Indian solar industries alone had the potential to release nearly 2.4 million tonnes of lead into the environment by 2022. Even today, only a handful of countries have the infrastructure to recycle lithium batteries, accounting for just 5% of the total battery waste created each year.

Professor Zhongfan Jia, from Flinders University’s College of Science and Engineering, hopes to use biodegradable materials for the development of these soft-pack batteries in the future to make the whole product safe and sustainable.

He says that multivalent metal ion batteries – batteries that use elements that are abundant in the earth’s crust, like aluminium, zinc and magnesium – are attracting attention from researchers hoping to create low-cost, sustainable batteries.

With that in mind, the researchers developed an early prototype of an aluminium radical battery which uses water-based electrolytes that are fire-retardant and air-stable, delivering a stable voltage output of 1.25V.

It is the likely the initial use will be for small appliances, but could also emerge for energy storage, although will unlikely be suitable for EVs. One of the big challenges is lowering the cost of electrolytes.

Another of the challenges in developing aluminium-ion batteries has been the slow movement of aluminium ion complexes, making existing aluminium ion batteries (AIBs) inefficient.

The solution? Stable radicals, a class of organic electroactive molecules.

Radicals make good electrode materials with high redox potential (a measure of the ease with which a molecule can accept electrons) and fast electrochemical processes. Though they’ve been used widely as cathode materials in other metal-ion batteries, this is the first time they’ve been shown to work in AIBs.

This is good news, because AIBs could in theory be cheap, easy to make and environmentally safe.

“Aluminium-ion batteries attract great attention because aluminium is the third most abundant element which makes AIBs potentially a sustainable and low-cost energy storage system,” explains Jia.

Other researchers have attempted to develop their own, non-toxic batteries, including a non-toxic, organic flow battery created by a team at Harvard University, US, in 2017, a non-toxic, saltwater battery prototypedeveloped at Imperial College London, UK, in 2019, and a room-temperature liquid metal battery from the University of Texas, US.