It might sound counterintuitive, but soon we may be able to make batteries biodegradable.
Researchers at Flinders University, with Australian and Chinese collaborators, are developing an organic polymer battery that could become a sustainable and biodegradable household alternative to traditional metal-based batteries.
The researchers say that the battery could deliver a cell voltage from 2.8V up to 3.0V – a big leap in improving the energy storage capability of previous prototypes of organic radical batteries.
“In our lab, we are aiming to create a radical polymer that is made from biodegradable plastic, just like a biodegradable plastic bag,” explains senior lecturer in chemistry Dr Zhongfan Jia, a research leader at Flinders University’s Institute for Nanoscale Science and Technology.
“There are already biodegradable batteries in the US, but their performance is very bad. But we are improving constantly. The improvements never end, even for traditional batteries.”
Dr Jia says that the batteries they are working on could be ready for commercial interest within “one to two years”. But before then, the main improvement that needs to happen is to achieve performance level on par with traditional metal batteries.
“We aim to achieve similar performance to classic lithium-ion batteries – only when we reach that stage will industry have the interest to commercialise this. Right now, the capacity is not comparable to classic lithium-ion battery performance.”
“When we achieve that performance level, we can commercialise it.”
The researchers aim for organic batteries to “replace a large amount of household batteries”.
The problem with lithium-ion batteries
Traditional metal-based lithium-ion batteries are common in household and portable devices, and even in electric vehicles. But lithium, cobalt and other minerals are resources that have led to a range of social and environmental impacts, including the safety issues with use and disposal.
And while lithium is a valuable mineral, only two per cent of Australia’s lithium-ion battery waste is recycled – despite being 95 per cent recyclable, according to the CSIRO.
Market analyst Benchmark Mineral Intelligence (BMI) predicts that from this year there may be an “acute” shortage of lithium.
“These shortages will extend out to the end of the decade,” BMI analyst George Miller told Reuters last year.
“Lithium prices are currently going through the roof. Lithium is very limited on earth,” says Dr Jia.
“What we are looking at is if other materials can be used for batteries. We want to reduce household pollution caused by metal batteries. We want to make nontoxic batteries to reduce the dependence on lithium mines.”
Organic biodegradable batteries
Ethically sourced, sustainable and organic rechargeable batteries represent a safer and more sustainable alternative to lithium.
Organic radical batteries (ORBs) are more environmentally friendly than conventional metal-based batteries, because instead of using metals they use organic radical polymers (flexible plastics) to provide electrical power.
“We already know organic redox-active materials are typical electroactive alternatives due to their inherently safe, lightweight and structure-tuneable features,” Dr Jia explains.
“Most importantly, they’re sustainable and environmentally friendly.”
According to the team’s research paper, the organic battery is based on TEMPO (2,2,6, 6-tetramethylpiperidyl-1-oxy) radical polymer cathode, poly (TEMPO methacrylate) (PTMA), and conjugated dicarboxylate anode such as silver terephthalate (Ag2TP).
Dr Jia explains: “Organic molecules store the energy in batteries. These can be made from the most simple organic resources, such as ammonia, like is used in fertiliser, and acetone.”
“The TEMPO radical is made from acetone and ammonia – a very simple resource. We convert this TEMPO radical into a polymer – a material like you have in plastic bags, tires, cups, and plates. This biodegradable plastic has advantages because you can use it to create any material, it is very flexible to make into any shape.”
Getting it to market
Dr Jia’s team is collaborating with Dr Kai Zhang from the Zhejiang Sci-Tech University in China on the organic battery, aiming for capacity above 200mAh/g through the innovative organic electrode materials and innovative structure design.
“Although the capacity needs further improvement, our work shows the promise of developing high-voltage, fully organic batteries with a judicious electrode design,” Dr Jia says.
Improving fully organic batteries cell voltage and capacity is top priority for these researchers, who are also considering durability of materials to contribute to recycling in a circular economy.
“In the future, we will be able to get industry partners and be able to consider the cost. At this stage, we are focussing purely on research.”
Dr Jia says the batteries could be ready for commercial interest within one to two years.