SWEET TREAT FOR LONGER-LASTING BUS BATTERIES

By: Catherine Fitzpatrick, Photography by: courtesy Monash Energy Institute


ADDING A GLUCOSE-based additive to the positive electrode on lithium-sulfur batteries can lead to longer vehicle battery life – including bus batteries – newly released data from Monash Energy Institute research has found.

SWEET TREAT FOR LONGER-LASTING BUS BATTERIES
The new lithium-sulfur battery technology could store two to five times more energy in vehicle batteries, including bus batteries, according to the Monash Energy Institute.

Lithium-sulfur (Li-S) batteries could be a lighter, more sustainable alternative to Lithium-ion (Li-ion) batteries for use in electric vehicles, now that Li-S batteries have been stabilised, says the Institute.

Li-S batteries - theoretically - store as much as five times the energy of Li-ion batteries, say the authors of a new paper on the Institute’s research titled ‘A saccharide-based binder for efficient polysulfide regulations in Li-S batteries’, published in the journal Nature Communications. However, their efficiency was hampered by instability of the battery electrodes, which deteriorated rapidly and led to a short battery life, it explains.

The positive sulfur electrode (cathode) suffered from substantial expansion and contraction, weakening it and making it inaccessible to lithium, and the negative lithium electrode (anode) became contaminated by sulfur compounds, it adds.

Research has therefore been focused on developing a system that could address these issues directly on the anode and cathode of the battery, it says.

The Institute’s new research has found the solution: a "saccharide-based aqueous slurry" that, "…promotes the formation of a web-like electrode microstructure…" on the cathode. This stabilises the sulfur, allowing for increased expansion tolerance on the cathode, and preventing the sulfur from moving and blanketing the anode, which can cause short-circuiting.

Additionally, the sugar solution can, "…be fabricated at scale from commonly sourced materials," say the authors.

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INCREASED CAPACITY

"In less than a decade, this technology could lead to vehicles, including electric buses and trucks, that can travel from Melbourne to Sydney without recharging," said lead author Professor Mainak Majumder from the Department of Mechanical and Aerospace Engineering and associate director of the Monash Energy Institute.

"It could also enable innovation in delivery and agricultural drones where light weight is paramount," he added.

Test-cell prototypes constructed by the team have been shown to have a charge-discharge life of at least 1,000 cycles, while still holding far more capacity than equivalent Li-ion batteries.

"So each charge lasts longer, extending the battery’s life," said first author and PhD student Yingyi Huang.

"And manufacturing the batteries doesn’t require exotic, toxic and expensive materials."

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Above (L-R): The Monash Energy Institute team - Mahdokht Shaibani, Mainak Majumder, Matthew Hill, Yingyi Huang.

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TEAM EFFORT

The process was developed by the Monash team with significant contribution from Dr Matthew Hill’s research group in CSIRO Manufacturing.

The Lithium-sulfur Battery Research Program at Monash University has been supported by the Commonwealth Government through the Australian Research Council and the Department of Industry, Innovation and Science.

In addition, the work has also been supported by Cleanfuture Energy, Australia, an Australian subsidiary of the Enserv Group of Thailand. Enserv Australia hopes to develop and manufacture the batteries in Australia, the world’s largest producer of lithium, it confirms.  

"We would be looking to use the technology to enter the growing market for electric vehicles and electronic devices," said Mark Gustowski, managing director of Enserv Australia.

"We plan to make the first lithium-sulfur batteries in Australia using Australian lithium within about five years."

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NEXT STEP

According to a report released in June this year from market research company Facts and Factors, global electric bus sales are predicted to increase from 135,000 units in 2019 to 600,000 units by 2026, with a compound annual growth rate of 25 per cent from 2020 to 2026.

With the focus being on reducing the cost of electric vehicles and extending the range of a vehicle per charge, Li-S batteries could now become a viable alternative to Li-ion batteries for bus battery manufacturers.

Results published at the end of last year in the International Journal of Powertrains - by researchers from the UK’s Cranfield University and Iran’s Kermanshah University of Technology - investigated the suitability of Li-S batteries for use in electric city buses.

They concluded, compared to two commercial Li-ion batteries tested, the Li-S battery pack fulfilled the power requirements of the bus while also achieving a, "…considerable increase in the vehicle’s range". However, the limited cycling life of Li-S batteries, "…prevents this technology to be commercialised for such an application at the time being," said the authors.

Now that a sugary solution has been found that increases the life of Li-S batteries, Dr Mahdokht Shaibani, second author of the Monash Energy Institute’s paper, said: "Many of the challenges on the cathode side of the battery has been solved by our team".

Further research is now required, she added, to looking into "…protection of the lithium metal anode to enable large-scale uptake of this promising technology – innovations that may be right around the corner".

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ABOUT MEI

The Monash Energy Institute has the vision of, "bringing people together to solve global energy problems," it says; accelerating the transition towards a sustainable energy future through impactful interdisciplinary research and education programs, it adds.

The Institute has been involved in the Net Zero Initiative, the Grid Innovation Hub and the Woodside Monash Energy Partnership, connecting leading educators and researchers with industry to facilitate problem-solving, innovation and commercialisation in the energy sector, as well as help align educational goals with the current and future needs of the energy sector, it confirms.

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