Lithium-sulphur batteries a sustainable option, research shows
Monash University researchers have developed a new lithium-sulphur battery design with a nanoporous polymer-coated lithium foil anode that reduces the amount of lithium required in a single battery.
PhD student Declan McNamara, Professor Matthew Hill, and Professor Mainak Majumder of Monash Engineering, with Dr Makhdokht Shaibani of RMIT University, outlined in their recent paper, “A Nanoporous Permselective Polymer Coating for Practical Low N/P Ratio Lithium Metal Batteries”, how applying the nanoporous polymer directly onto the lithium foil anode created a new battery design that used less lithium, had more energy per unit volume, lasted longer and would be half the price of lithium-ion batteries.
Lithium-sulphur (Li-S) batteries are an emerging energy storage technology that utilise metallic lithium and sulphur to deliver more energy per gram than lithium ion batteries. While Li-S batteries are highly efficient, the process of finding, extracting and transporting lithium leaves a significant environmental footprint.
Li-S batteries also have their limitations.
Typically they contain a lithium anode (negative electrode) and sulphur cathode (positive electrode) with a separating layer.
When the battery charges and discharges, large amounts of lithium and sulphur are reacted with one another, placing the lithium metal under a lot of strain.
PhD student and lead researcher Declan McNamara of Monash Engineering says the thin polymer coating on lithium significantly improves the number of times the battery can be cycled.
“The polymer contains tiny holes less than a nanometre in size – one billionth of a metre – which allow lithium ions to move freely while blocking other chemicals that would attack the lithium,” he said.
“The coating also acts as a scaffold for lithium, and helps it charge and discharge repeatedly.
“Metallic lithium is a bit of a double-edged sword.
“Lithium is packed full of energy, but in a bad battery, this energy is wasted on side reactions.
“On the other hand, if the energy is channelled correctly, it can make some incredible energy storage devices that are easier to make.
“This coating is a step towards highly efficient, easily manufactured Li-S batteries.”
The new design does not require nickel or cobalt, removing the need for minerals that have a significant environmental and social cost.
Professor Majumder says these developments are promising steps towards more widespread adoption of Li-S batteries and other lithium metal-based energy storage systems.
“Li-metal protection technologies will become crucial in our quest towards energy dense and sustainable batteries of the future,” he said.
“The study establishes a new framework to protect Li-metal from rapid decay or catastrophic failure which has been an achilles heel for Li-S batteries.”
Professor Hill says the technology can make an immediate impact.
“The market for electric vehicles, drones and electronic devices is on a steep growth pattern and this research is commercially ready for manufacturing to support that growth,” he said.
“Producing more economical and environmentally sensitive battery options in Australia would be a great use of this technology, and we look forward to working with commercial partners to develop and manufacture this technology.”
