Could we be on the brink of cleaner, longer-lasting batteries?

Batteries made with sulphur could be cheaper, greener and hold more energy.

Could we be on the brink of cleaner, longer-lasting batteries?

Mahdokht Shaibani, Monash University

Lithium-ion batteries have changed the world. Without the ability to store meaningful amounts of energy in a rechargeable, portable format we would have no smartphones or other personal electronic devices. The pioneers of the technology were awarded the 2019 Nobel Prize for chemistry.

But as society moves away from fossil fuels, we will need more radical new technologies for storing energy to support renewable electricity generation, electric vehicles and other needs.


Read more: Charged up: the history and development of batteries


One such technology could be lithium-sulphur batteries: they store considerably more energy than their lithium-ion cousins – in theory as much as six times the energy for a given weight. What’s more, they can be made from cheap materials that are readily available around the world.

Until now, lithium-sulphur batteries have been impractical. Their chemistry allows them to store so much energy that the battery physically breaks apart under the stress.

However, my colleagues and I have engineered a new design for these batteries, which allows them to be charged and discharged hundreds of times without breaking down. We hope to have a commercial product ready in the next two to four years.

What’s so good about sulphur?
Lithium-ion batteries require minerals such as rare earths, nickel and cobalt to produce their positive electrodes. Supply of these metals is limited, prices are rising, and their mining often has great social and environmental costs.

Industry insiders have even predicted serious shortages of these key materials in the near future, possibly as early as 2022.

In contrast, sulphur is relatively common and cheap. Sulphur is the 16th most abundant element on earth, and miners produce around 70 million tonnes of it each year. This makes it an ideal ingredient for batteries if we want them to be widely used.

What’s more, lithium-sulphur batteries rely on a different kind of chemical reaction, which means their ability to store energy (known as ‘specific capacity’) is much greater than that of lithium-ion batteries.

The prototype lithium-sulphur battery shows the technology works, but a commercial product is still years away. Mahdokht Shaibani, Author provided

Great capacity brings great stress
A person faced with a demanding job may feel stress if the demands exceed their ability to cope, resulting in a drop in productivity or performance. In much the same way, a battery electrode asked to store a lot of energy may be subjected to increased stress.

In a lithium-sulphur battery, energy is stored when positively charged lithium ions are absorbed by an electrode made of sulphur particles in a carbon matrix held together with a polymer binder. The high storage capacity means that the electrode swells up to almost double its size when fully charged.

The cycle of swelling and shrinking as the battery charges and discharges leads to a progressive loss of cohesion of particles and permanent distortion of the carbon matrix and the polymer binder.

The carbon matrix is a vital component of the battery that delivers electrons to the insulating sulphur, and the polymer glues the sulphur and carbon together. When they are distorted, the paths for electrons to move across the electrode (effectively the electrical wiring) are destroyed and the battery’s performance decays very quickly.

Giving particles some space to breathe

A CT scan of one of the sulphur electrodes shows the open structure that allows particles to expand as they charge. Mahdokht Shaibani, Author provided

The conventional way of producing batteries creates a continuous dense network of binder across the bulk of the electrode, which doesn’t leave much free space for movement.

The conventional method works for lithium-ion batteries, but for sulphur we have had to develop a new technique.

To make sure our batteries would be easy and cheap to manufacture, we used the same material as a binder but processed it a little differently. The result is a web-like network of binder that holds particles together but also leaves plenty of space for material to expand.

These expansion-tolerant electrodes can efficiently accommodate cycling stresses, allowing the sulphur particles to live up to their full energy storage capacity.


Read more: A guide to deconstructing the battery hype cycle


When will we see working sulphur batteries?
My colleagues Mainak Majumder and Matthew Hill have long histories of translating lab-scale discoveries to practical industry applications, and our multidisciplinary team contains expertise from materials synthesis and functionalisation, to design and prototyping, to device implementation in power grids and electric vehicles.

The other key ingredient in these batteries is, of course, lithium. Given that Australia is a leading global producer, we think it is a natural fit to make the batteries here.

We hope to have a commercial product ready in the next two to four years. We are working with industry partners to scale up the breakthrough, and looking toward developing a manufacturing line for commercial-level production.The Conversation

Mahdokht Shaibani, Research Fellow, Mechanical & Aerospace Engineering, Monash University

This article is republished from The Conversation under a Creative Commons licence. Read the original article.

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    COMMENTS

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    Horace Cope
    28th Jan 2020
    12:24pm
    Whilst this article is a nice positive one, I can't see anywhere the technology applies to power storage or motor vehicles bigger than the family sedan. Those people who blame climate change for every single problem that we face want us to do away with power stations and rely on renewable energy with the promise that a battery will be invented well in time for adequate storage when the baseload power is no longer there.

    As to motor vehicles, I can't get a definitive answer to a number of questions:
    When the battery is getting low, does the vehicle slow down?
    How many charging points will be available at charging centres, especially on holiday weekends, to enable a quick stop and resumption of the journey?
    Will there be electric heavy vehicles, plant & equipment?
    Will motorists be able to tow a caravan?
    Until now, there have been educated guesses and the pie-in-the-sky promise that technology will invent a battery to cover all of the points raised.

    I am a strong believer in the fact that there is climate change. I also strongly believe that it is cyclical and no more than 3% of it is caused by human intervention. I read that we have to reduce our carbon footprint but I have never had that trite phrase explained. I read that CO2 is blanketing the earth and is causing global warming yet CO2 is measured at 0.04% of the earth's atmosphere. I read that the "science is in" and that no further discussion is necessary but I have not read anything that defines exactly what will happen when all of the suggested measures are carried out.

    What I do know is that some people are getting rich by promoting a climate change/ global warming scare and asking others to make sacrifices to do what I believe is impossible. I also know that politicians are very quick to read the mood of the people and will say and do anything to get elected so their answers on climate change/global warming are merely a repeat of what people are reading and seeing from the media. The media also parrots doomsayers because good news doesn't sell newspapers. We even place a 16 year old autistic child on a pedestal for telling people what they want to hear. I know her life experience at that age cannot equip her with all of the knowledge to know all sides of the argument.
    Janus
    28th Jan 2020
    1:57pm
    Horace, Thanks for your comment. It has a level of disinformation and lack of scientific understanding that is not atypical, given that there is so much poor publicity out there by people who have similar views, promulgated as "facts".

    The first part is mainly about vehicles, but this is a red herring. It is the technology that is important, not the scale. To me, it is the high population that needs/wants high power levels that is the problem, not the fact that we need to store the energy. Like an ant's nest, we have outgrown the capacity of the planet.

    As for CO2, a quick look at paleohistory (not just a few thousand, but millions of years) will clearly show that high levels of CO2 have been present before, and are usually associated with very high temperatures, and mass extinctions. Nothing unusual there. Extreme levels are 1500 to 2000ppm. We are at ~450ppm and climbing. There are very few people of science that dispute the evidence that humans are contributing to the problem. You might also research how humans cope with really high temperatures, with associated high humidity. They die. Plants love it, and thrive.

    I am happy for you that you can't understand the science, as it won't worry you. It is dreadful for those that do understand it, but I am sorrier for the following generations that will curse us for not acting.
    Triss
    28th Jan 2020
    2:04pm
    Yes to all of those points, Horace. I accept we did need to cut our use and dumping of things like plastic but, historically, there have always been climate change/global warmings. When you think about it the changing seasons are a type of climate change and nobody has been able to change that.
    In the course of the last few million years global warming and cooling has caused temperatures and sea levels to rise and lower many times so perhaps we should prepare ourselves to live with it instead of doing a Canute and trying to turn it back
    Horace Cope
    28th Jan 2020
    2:28pm
    Oh dear, Janus, could you have been more patronising? Your response is typical of those who champion climate change, lots of words but nothing to support your argument. I will say, however, that your claim that there are too many people in the world is a new discussion point. Again, you are generalising with no specific numbers to support your claim.

    As for CO2, paleohistory shows that the last time we had levels of 0.04%, humankind didn't exist. It's OK to scare people by quoting figures that will kill humankind but surely there should be a model of when scientists predict this will happen. Remember that the dangerous level is 0.20% and the current level is nowhere near that. No science has been shown to even suggest that those levels are expected.

    It's not easy to understand the science when there are so many conflicting opinions as well as the scare tactics thrown around by those with an agenda. All I ask for is someone to produce irrefutable proof of the statements that we are asked to accept. Perhaps that is too much to ask.
    Janus
    28th Jan 2020
    3:22pm
    "irrefutable proof"? You don't want much, Horace! Some things (Evolution, various gods, afterlife, and so on) we can't "prove" but many are willing to base their life on their beliefs without any proof at all.

    I have a background in science (40+ years consulting in environmental and other sciences) and enjoy a proof, but don't often see one. I don't even trust a consensus view, because scientists don't work that way. It only needs sufficient evidence to convince a person that a theory is likely to be valid, and there is so much evidence - not just conjecture but solid science - that the likelihood of climate change being human influenced is very hard to argue rationally against.

    And: I don't mean to patronise, but if you put up an argument that is clearly erroneous, it should be challenged. However this is not the place to use a massive bibliography of research data, technical papers and so on. If you are happy in your beliefs, good for you.
    Anonymous
    28th Jan 2020
    11:46pm
    Well - as I said - climate change is an argument - and one from which all dissenting views have been driven by the Usual Suspect methods of scorn, personal vilification, name-calling, abuse personal and employment-wise, and even physical assault.

    The same kind of thing that happens when men hold a public meeting to discuss the issues that affect them in today's society - female people, feminists and their supporters, fling themselves on the stage and start screeching about how hateful they all are, even before a single word has been spoken.... let alone issues raised..... so YES - this style of 'discussion' was created by the 'feminists'...which is why they cop blame from me all the time...

    A fair hearing of all views and calculations shows that, rather than being '98% agreement on climate change man-caused" - the real figures are about 50/50....

    So please - let's speak of solid things - not the propaganda put about...
    Couldabeen
    6th Feb 2020
    11:33pm
    Hello Horace, I will try and help with some of your concerns. I've been following the allied industries for a few years and there are often blanks left in what the public are told in the enthusiasm for "great leaps forward".
    The battery revolution has been "just around the corner" for over 100 years now and we're still waiting.
    No, when the battery in an electric car goes below a critical point it will just shut off. After giving the driver warnings that same as we get in present ICE with a Low Fuel light and "Distance till empty". Typically, with the Lithium families, if they are discharged below 10% of rated capacity they are badly compromised internally and so the computer power management systems will shut it off before that happens.
    A very big problem with battery recharging is that you are not putting fresh electrons in but reversing a chemical reaction. The rapid chargers that are talked about can and do degrade the life of the battery significantly. That's why the slow overnight trickle charge is preferred. It is not anticipated that there will be sufficient reserve capacity on the Australian Grid to cope with mass over night recharging for well over a decade yet.
    Many shopping centres have promised recharge parking bays, but that comes with a compromise, that shopping centres don't really want people parking for hours on end.
    At this stage there is no EV that would qualify as a practical and viable caravan (or horse float) capable tow car. The same as with normal cars, the moment you hitch a load on the back, the fuel/energy consumption goes up.
    Australia is different to the environment that Europe and the US present for the use of heavy trucks with towns closer together. No prime mover exists beyond a few display creations that could do a full trip from say Brisbane to Melbourne towing a B double load without having to have several stops of several hours to recharge. Nothing exists that can do the Adelaide to Darwin route more or less non-stop.
    Beware that the push for electric vehicles in Australia is not based on any real need economically or environmentally but mainly from political pressure. When the suitable electric vehicles arrive, the transport industry would embrace them whole heartedly as they do promise a simpler and easier drive train from energy to wheels on the road.
    And a point on relative CO2 levels in our atmosphere, even if it doubled to 800ppm,(ie 0.08%) the percentage of Oxygen in the atmosphere available for respiration would still be at least 20%. There is no reason to believe that it would cause any distress to Oxygen breathing creatures.
    Tuesday127
    28th Jan 2020
    4:52pm
    Good on you Janus. I am a climate scientist with 35 years experience ( note how I don't have to prove this ). You have just reinforced why there are so many sceptics to the science out there.The preaching at, the i'm right and you're wrong lecturing. The lack of an absolute concensus because it's all theory but it's a believable theory??? You say "It only needs sufficient evidence to convince a person that a theory is likely to be valid" and I think that says it all.It only needs a male to think he's a female and it's likely to be valid?
    Good on you Horace, I think you are the silent majority.
    Anonymous
    28th Jan 2020
    11:47pm
    Nah - dissenters are The Silenced Majority......
    Tuesday127
    28th Jan 2020
    4:52pm
    Good on you Janus. I am a climate scientist with 35 years experience ( note how I don't have to prove this ). You have just reinforced why there are so many sceptics to the science out there.The preaching at, the i'm right and you're wrong lecturing. The lack of an absolute concensus because it's all theory but it's a believable theory??? You say "It only needs sufficient evidence to convince a person that a theory is likely to be valid" and I think that says it all.It only needs a male to think he's a female and it's likely to be valid?
    Good on you Horace, I think you are the silent majority.
    Janus
    28th Jan 2020
    6:28pm
    All so sad.
    I don't pretend to be an expert on cars, or horses, or building, or plumbing. So I get advice and mostly trust that advice, even of it is not what I want to hear, because I might not know much about it. I suppose you don't accept evolutionary theory? How about Einsteinian relativity and many other theories that have not and possibly can't be proven, but are generally accepted?


    BTW, what's this male/female thing? What a person thinks they are might work for them, even if it doesn't work for you. Basic Psychology 101, and nothing to do with this discussion.
    Anonymous
    29th Jan 2020
    1:56am
    Well - I identify as the lass in my avatar piccie... well.. not really.. but for the sake of argument....
    Triss
    29th Jan 2020
    10:08am
    That’s just Trebor, Janus, he can turn any debate into an attack on women.
    MICK
    29th Jan 2020
    8:24pm
    ?????? The routine deniers are at work again.
    Next it'll be climate change is a hoax, again.

    28th Jan 2020
    11:40pm
    I have my Polar Sanels - 6.6kw on the roof... do a great job considering I need to keep the caree cool all the time.... I would like some good reliable batteries to store a heap, rather than paying out for night time.

    Political statement:- Regardless of the rights and wrongs of the 'climate change' ARGUMENT - cutting down on excess smoke and stuff in the atmosphere has to be a good thing....
    MICK
    29th Jan 2020
    8:27pm
    Have you heard about the studies about long term health due to smoke inhalation? There are nearly always consequences for accepting bad things.
    It was interesting that NSW MP Andrew Constance was unhappy about the recent fires which almost burnt him out. Always different when reality comes a calling.
    All that you said is factual TREBOR. Hope you've had a good start to the new year.


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