The Power of Polymers.

Chemistry is about what things are made of – it’s the field of science that helps us understand how the molecular structure of materials determines their properties and applications. Flinders University chemist Dr Zhongfan Jia applies his expertise in molecules known as polymers to create new energy storage solutions for small and very large batteries.

Polymers are all around us. They make up the stretchy lycra in bike pants, the non-stick lining of frying pans and the hardy rectangles of Australian banknotes. Polymers exist in nature too, found in seaweeds, silk and wool.

At the molecular level, polymers all have something in common: they’re made up of repeated individual units joined together like a string of beads. Though we can’t see it with the naked eye, it’s this structure that gives polymers their vital properties.

“Polymers are incredibly useful to us because they are strong, they can be made into different shapes, they are flexible and in general they are cheap to make,” says Dr Jia, Senior Lecturer in Chemistry.

With his Flinders research team Polymers for the Environment, Energy and Catalysis, and national and international collaborators, Dr Jia works with both synthetic and natural polymers to create new molecules that solve problems.

“I love to explore and find out what things are made of and work out how the properties of molecules can offer useful applications for humans,” he says. “It’s fascinating to use my skills to create new materials that have never existed before and that can make our lives better in so many different ways.”

Polymers could be very strong, which means they are exceedingly useful for making physical materials, such as packaging. However, polymers are incredibly versatile, offering features that can be applied for different types of product development too.

In Dr Jia’s lab, they are developing polymers that can store energy and be used in batteries.

“Traditional batteries use metals such as lithium, cobalt and others, which are increasingly difficult to source through mining, and they present a risk to the environment when they enter landfill after use,” Dr Jia says. “To provide an alternative, we are creating polymers that can replace the metals in batteries.”

Batteries are made of physically separate components, namely cathode and anode. Chemical reactions where electrons flow from the anode to the cathode create electrical power. Nowadays, most batteries are rechargeable. An example is lithium-ion batteries which store electric energy as chemical energy when charging and convert chemical energy to electric energy when discharging.

“We have developed a metal-free battery by creating polymers that can be charged and used as replacements for the metals typically used for the cathode and the anode,” Dr Jia says.  

Dr Jia’s metal-free battery is about the size of a USB stick, and it can be created in a coin shape as well. Once the metal-free battery was shown to work, Dr Jia set out to improve how much energy it could store.

“A normal lithium-ion battery has an output voltage of 3.6 to 4 Volt,” says Dr Jia. “While most non-metal batteries could only deliver 1 to 2 Volt, we’ve been able to improve that up to 2.8 Volt in more recent work.”

The polymer battery is also rechargeable, a core characteristic in demand for reusable consumer batteries.

Dr Jia’s next challenge is to further increase the battery storage capacity and to transition to natural instead of synthetic polymers.  

“Synthetic polymers are easy to work with and are useful for all sorts of applications, but they are typically made from petrochemicals,” Dr Jia says. “And so an important part of our work focuses on natural polymers, as we’d like to be able to use these to replace synthetics in a wide range of applications.”

The idea is to create a battery that is completely safe and biodegradable.

“We’re now working with polymers from materials such as seaweed, plant cellulose and starch to create a natural, non-metal battery, and for other applications as well,” says Dr Jia.  

On a much bigger scale, Dr Jia is also working on a redox flow battery. Redox flow batteries can be large, making them suitable for storing power from solar panels or other applications in green energy, industry and housing.

“Rather than being made of solid ingredients like smaller batteries, a redox flow battery is made of liquids,” Dr Jia says. “It consists of two tanks of energy storage materials dissolved in liquid solvents set up next to each other, separated by a membrane.”

Dr Jia aims to improve redox flow batteries by applying his expertise in polymer science. His first target is the size of the molecules that store energy.

“Currently, a major factor keeping the cost of redox flow batteries relatively high is the membrane separating the battery fluids, because it needs to be of very fine grade to stop the energy storage materials leaking from one side to the other,” says Dr Jia. “We’re designing polymers that can be used to store the energy and are of a large molecular size so a much cheaper membrane can be substituted for the expensive one.”

Dr Jia is also refining the solubility of the polymers.

“We’re making the polymers dissolvable in water, as this will make the battery much safer and more environmentally-friendly than using chemical solvents,” Dr Jia says.

He hopes that one day home solar units can be connected to water-based, polymer-filled rechargeable redox flow batteries as a relatively cheap and safe way to store power.

Dr Jia’s work is funded by the Australian Research Council and a range of industries interested in the potential of polymers. It’s research that requires specialist equipment and infrastructure and hands-on practical and analytical work.

“I am fortunate to have a range of different set-ups which enable us to make all polymers we are interested in,” says Dr Jia. “Then we use Flinders University’s analytical centre to assess how good we’ve been at making specific molecules, and a newly established electrochemistry lab to do all the functional testing for battery and other applications.” 

With batteries the most common form of household hazardous waste, growing by 20% per year in Australia, the annual waste they generate is predicted to exceed 100,000 tonnes by 2036 – making Dr Jia’s quest for a safe and biodegradable solution not just important, but urgent.