Power to your Elbow: Better Batteries

Wednesday, the 2nd of April was World Autism Awareness Day so to help you get to grips with this often misunderstood condition here's your Quickfire Science with Hannah Critchlow and Kate Lamble

- Autism, was first described as a unique syndrome in 1943 by the American psychiatrist and physician Leo Kanner

- Today, Autism spectrum disorder, or ASD is recognised to affect around one in every 100 people worldwide

- Each case is different, but everyone on the spectrum shares three main areas of difficulty; social interaction, communication, and imagination or flexible thinking.

- On the flip side people with ASD may exhibit common strengths with a focused attention to detail, an excellent memory, and a tendency to logical thinking.

- Other common traits of ASD include a love of routines, sensory sensitivity in one of the five senses, and having intense special interests, topics that they enjoy talking about and engaging in over and over again.

- However it's hard to characterise a condition which ranges from the one in ten people who cannot speak to those who are high functioning and have a milder form of Autism Spectrum Disorder. 

- ASD Symptoms typically start to develop in early childhood, but some people with milder forms are not diagnosed with the condition until adulthood.

- In the past, some people believed that the vaccine for measles, mumps and rubella caused ASD. However further investigation showed that there is no link between the two, instead the age at which communication problems begin to appear in ASD patients is around the same age that the vaccine is given.

- While we don't yet know the cause of autism, it's been suggested that high levels of testosterone in the womb may affect brain development and lead to the condition. This may be why males are more likely to have autism than females, at a ratio of about 4:1

- Genetics also seems to play a role in 90% of autism cases, with an increased risk of a baby developing the disorder if relatives have it. But it's likely that many genes are involved, possibly interacting with environmental factors.  

- There is no 'cure' for ASD, but education and behavioural support can help. If you are concerned that your child may exhibit characteristics of the disorder, visit your GP who can refer you for an assessment

Kat - UK scientists have shown that fathers who started smoking before puberty producesons that are more likely to be overweight. Very confusing. Bristol researcher Marcus Pembrey led the study and he joins us now to explain more. What are you trying to find out that led to this study?

Marcus - Well, we're basically interested in the possibility that some of our inheritance might go beyond the genome and be rooted in early life parental and ancestral experience, a sort of transgenerational response system.

Kat - So, things that your parents do or your grandparents did are reflected in your own self then.

Marcus - That's true. We were able to ask some questions along these lines. In the children of the '90s study in Bristol, this is the world's most comprehensive follow up in terms of detail of 14,000 children and thir mothers who were born in '91, '92. They were ascertained in pregnancy and of course, they're now 22, 23. In all that time, we've collected an enormous amount of information, genetics, measurements, diet, everything else.

Kat - So tell me a bit about this particular link with smoking. So, who were you looking at what did you find?

Marcus - Well, what we were trying to do was to test a hypothesis that was generated by some earlier Swedish studies that showed that period before puberty, mid-childhood was an exposure sensitive period with respect to these transgeneration effects down the male line, through the father. So, what we were doing was, we got information on when the fathers and the mothers actually started smoking. Although we had about 10,000 fathers responded, half of them had smoked at some time, 3% 166 had started before the age of 11. So, those are the ones we were interested in their offspring.

Kat - So then, what did you find about the offspring of those particular dads?

Marcus - Well, we analysed the boys and girls separately and we found that the sons, by the time they were in their teenage years - from 13 to 17 - had much larger BMI than the comparison group. The comparison group were all the others, the sons of fathers who started smoking after the age of 11 and also, the sons of fathers who didn't smoke at all.

Kat - This does sound quite strange. What do you think is actually going on? Do you think that there's something else happening that's influencing this or is it some kind of effect of the chemicals in the cigarette smoke at that group of time?

Marcus - Well, there are about 2,000 chemicals in cigarette smoke, so we don't know, but we know it has a big biological effect, smoking. It seems that something is being transmitted through the reproductive system. The exposure before puberty gets under the skin in some way in endures. It affects the reproductive system, probably carried by sperm to the son, but could be - I don't know - through the seminal fluid. In humans, we don't know what the mechanism is.

Kat - Thanks very much. That's Marcus Pembrey whose research is published in the European Journal of Human Genetics this week.

Chris - What actually is a battery? How does it work?

Fiona - So, a battery is electrochemical device. So, it converts chemical energy into more useful electrical energy and it does this via oxidation and reduction reactions which involve the loss and gain of electrons respectively, which then go around the external circuit to then produce electricity. The three main components to make this happen, you need to have 2 electrodes - the cathode, the anode, and you need an electrolyte which is ionically conductive, so that the ion or the charged species can be transported.

Chris - So, when I look at a battery which I might pick up from the supermarket or take out from my alarm clock, if I were to open one up, what would I see inside?

Fiona - One of the classic examples to look at is one that's used in most laptops, phones, tablets at the moment, developed by Sony in 1990. It uses graphite as the anode, so it's got carbon.

Chris - It's a carbon like a pencil lead actually.

Fiona - Exactly, which has the sheets of carbon, which the lithium get intercalated or inserted in-between these sheets of carbon. In the cathodes, you've got a material called lithium cobalt oxide which has a similar layered structure to graphite but instead of carbon, it's cobalt dioxide. And then the lithium is in-between these sheets.

Chris - Does that make the power though?

Fiona - So then, the cobalt is in a 3 plus charge state and then it can go to the plus 4 then the lithium ion then goes across the electrolyte and it goes into the graphite while the electron goes around the external circuit then they recombine. And that's how you get your electricity.

Chris - So, once all the lithium has made that journey, that's when the energy is spent from the battery.

Fiona - That was in the discharge state. That was actually charging the battery and then to use it, the reverse process happens. So, this is a rechargeable battery. So, the lithium ions can then rock back and forth because now, the cobalt 4 plus could go to the cobalt 3 plus state then the lithium goes from the intercalated graphite sheets, goes across the electrolyte into cobalt dioxide layers, and the electron goes around the external circuit. So, it was called the rocking chair battery because the lithium rocks back and forth. You can think of it like a Victoria sponge with the two layers of cake as the sheets of cobalt oxide, the jam of lithium inside.

Chris - I love the analogy. I wouldn't like to eat a battery though. There's lots of very toxic things in it.

Fiona - Yeah, I wouldn't advice it.

Chris - Shall we build one?

Fiona - Yeah. So, what we make in the lab is called a coin cell battery or button battery which is used in a lot of watches, phones, clocks.

Chris - The little thing, they look a bit like a coin, don't they?

Fiona - Yeah, exactly. So, you've got the stainless steel base and Chris, you can have a go at making one.

Chris - It's like a little saucer, isn't it?

Fiona - Exactly. So, just to proove how easy it is and then we've got our cathode material which is a lithium cobalt oxide which we have as just a piece of paper today.

Chris - That would sit inside the base, just against the base.

Fiona - Exactly. But then you need to have this rubber gasket sat inside the base because you can't have an electrical contact between the anode and a cathode or else it would be a short circuit.

Chris - It's a short circuit inside the battery, wouldn't it? Yeah, okay.

Fiona - Exactly. And so then, we have our...

Chris - So, I've got my gasket. So, I basically got little cup like a stainless steel cup and I've got my chemical in the bottom that's the lithium cobalt oxide that's going to be one source of the charge. Now, I've put a rubber disk in there to separate it. Then what do I put in next?

Fiona - Yeah, exactly. Because the electrolyte is a liquid electrolyte, we need to have a physical barrier between the anode and cathode. It's a glass fibre that sits on top of the cathode and then you would soak it in electrolyte and then we can place our anode on top and then we need a stainless steel current collector and to ensure that we have a good electrical contact between our anode and our cathode and then...

Chris - Okay, that's now a little sort of disk that goes on on top of the sandwich.

Fiona - Exactly and then the top of our battery which is a kind of like another saucer like the base.

Chris - And just plugs inside.

Fiona - This coins cell battery, you can think of it as a AA battery or AAA by just rolling your sheets of anode, cathode and electrolyte, and then place in a cylindrical case.

Graham Verity from GP Batteries - There isn’t a difference. I mean, the USB probably doesn’t - in some circumstances - have the ability to give quite as much power to the charge, but generally speaking, the USBs you have on your computer will charge in roughly the same time.

Chris - When I was in Chicago recently, I met up with a group at Argonne National Laboratory who are spending 100 million dollars over the next 5 years to make batteries that they say should be - if they had the money, 5 times better than the present generation. George Crabtree and Jeff Chamberlain are leading the project.

George - We need new batteries for the transformation of the two of the most important energy sectors: transportation and the electricity group. Transportation is obvious. It's to electric cars, replace gasoline engines. In the case of the grid, it's to enable renewable wind and solar energy to be deployed at a high level, say, 20 or 30%. These are variable sources and you need a backup for them.

Chris - Jeff, what's wrong with the batteries we have at the moment to fulfil both of those tasks that George has outlined?

Jeff - So, the batteries we have at a moment, lithium ion are the best batteries out there for transportation and actually, for the grid. However, we need batteries that are significantly smaller, lighter, less expensive, recyclable, using Earth-abundant materials. So, we need to advance the technology, not just beyond where we are today with lithium ion, but even if you go as far as you can go with lithium ion, it won't meet the challenges that George has outlined.

Chris - Pretty high aspirations. Can you achieve this?

George - We're looking to be transformative and less than say, 5 times the performance at 1/5 the cost will not be transformative. The second answer is that it's well within what science will allow. So, if you take the back of an envelope and a pencil and ask, "What's the best I could do?" It's a factor of 10 and technology in the energy sector typically delivers half as a theoretical potential and that's true of lithium ion batteries for example.

Chris - So, what approach are you taking Jeff, to try to explore how to build these better batteries?

Jeff - It's a materials challenge, developing new active materials down to the nano or meso scale as well as the engineering challenge of how to put those materials into a chemical system that functions as a battery. So, our approach is to couple those two approaches in a highly interactive way so that while the science is occurring to discover and develop new materials, we're actually putting them in cells and connecting our cells directly with industrial partners to try to expedite that entire innovation timeline.

Chris - So George, how did you go about developing a new battery? Is it literary loads of wet chemistry you're fiddling with chemicals in the laboratory and seeing if they work together or is there a strong theoretical arm to it?

George - So, the typical way the R&D community operates now is, "I would like to have a better cathode. Give me one. I'll try it. If it works, I'll use it. If it doesn't work, I'll throw it away and try something else." But they will not ask the question, "Why did it fail?" or "Why did it work?" And that's the question that we want to ask. So, we're very different from typical battery R&D in this sense. We'd like to understand the phenomena and the materials of energy storage at the atomic and molecular level. And we feel that once we have that fundamental basic understanding, we'll be able to design rather than discover by chance. But actually, design the materials and the phenomena that we want in our next generation batteries.

Chris - It's quite interesting that you're taking that fundamental, "We want to understand" approach and then asking, how do we use that to inform the development rather than just going hell for leather saying, "I need a better battery. Let's just try lots of things."

George - Well, the typical community today actually does everything by serendipity. "I found something. It works. I'm finished." We want to take that to the next level and our feeling is that as we were saying earlier, that beyond lithium ion space is rich with opportunities. So, once you understand why phenomena work and how the materials operate, you can then design more than one solution to the battery challenge. There may be two or three solutions that are equally, let's say, appealing but for various different applications.

Chris - We're returning to the question which was how are you actually going about it, to what extent is it theoretical and driven on the computer and to what extent are you actually getting your hands dirty with different mixtures of chemicals?

George - So, on the very basic side of the spectrum of research that's performed in the centre, we do combine computation and experiment. We've created, actually launched in a beta test format inside the centre, something we call 'the electrolyte genome'. The idea is to take a somewhat genomic approach to developing a new chapter in the book of knowledge if you want to think of it that way, and how electrolytes function. We do that using supercomputers that launch Brooklyn National Lab and here at Argonne National Laboratory. So, in a sense, we can explore with our deep understanding of the quantum chemistry. We're going to explore new molecules computationally. We couple that with experiments done all the way from vacuum phase, truly looking at individual molecules and a single crystal of metal, all the way to putting it inside of cells and monitoring its performance and testing, real time, the degradation or the function of those materials as we build them. So, the idea here is again, to combine the deep science with the engineering, but coupling that in a very hard way with a new way to compute and look for in a database, new discovery of new materials rather than a more hunt and peck method of developing materials in the lab.

Chris - That must save an enormous amount of effort because you can try things in the computer which if they're going to draw a blank there saves you than having to go and discover that by making the system in a real world.

George - That's the whole idea that will save an enormous amount of effort by using the computer to look at thousands or tens of thousands of things that might take decades to do experimentally.

Chris - George Crabtree and Jeff Chamberlain. They're both from Argonne National Laboratory.

Clare Grey at the University of Cambridge is investigating how we can make those sorts of batteries even better...

Clare - We're looking at the diversity of different approaches of which one of them is lithium and I think the reason why it's lithium is that lithium is the lightest element. It's one of the most reactive elements and so that, in principle gives you the highest voltage from the material. There's also a massive industry associated with lithium and so, it's quite important to actually work on the technology we have and improve what we have got. Why am I doing it? So, if you take the material that's in your laptop, most of the laptops contain this material lithium cobalt oxide. It turns out that you can only pull out 50% of the lithium out of lithium cobalt oxide before 2 things happen. First of all, if you put all of the lithiums out, you get structural rearrangements. And so, what happens is the layers slip over each other and then it becomes very difficult to put those lithium back in again. And so, that means that you actually have to keep some of the lithium in those structure. You can't pull them all out. And so, we're carrying around 50% of dead weight in this lithium cobalt oxide that we can't use. And so, if we can figure out how we can make other layered materials cycle. So charge and discharge, pulling out all of the lithium, we would have a battery that would almost be twice as effective. So, that's reason number one. Reason number two is that lithium cobalt oxide, when you pull all the lithiums out, forms all cobalt 4 plus. Cobalt 4 plus is not a very stable oxidation state and it tends to lose oxygen. And so, it's this loss of oxygen, very rapidly associated also with heating and self-discharging that results in the safety instance and the fires that you may have seen on the web. And so, for safety reasons again, we only pull out 50% of the lithium. So, you've got this idea of the fact that you've got a fact of two just sitting in the materials we used today. If we could get that to work, that's the difference between a car which has a range of 100 kilometres going twice as far.

Kate - If you're sticking with lithium because that's what we got. That's the business model that we got laid out, what other aspects of a battery could you possibly change to improve its performance?

Clare - Well, just going back to this idea of approving the electrodes themselves and we talked about lithium cobalt oxide. So there are materials out there where people replace the cobalt with nickel and manganese. And those, instead of having 140 milliampers per gram of charge, so that's just how many electrons can you get per unit of weight, they can allow you to cycle up to 200 and 220 milliampers per gram. So, that's a significant improvement. Then on the anode side, a few could find materials that stored more lithium and the anode that would help. One of the materials for example that we're looking at is silicon. So, silicon allows you to store 10 times more lithium per amount of weight. And so, that's very exciting. At the same time going back to the cathode, you can increase the capacity, but you can also go up in voltage to increase the overall energy density. Now, the trade off with that is safety, The higher voltage, the more oxidising things become and increased risks there. But people are looking at trying to coat electromaterials and protect them in the same way that you might - you think about metal in the environment. You have a passivating coating on the copper on a church. And similar things, we're trying to coat the materials to protect them from these very harsh oxidising environments.

Kate - You've just mentioned a lot of different options. How do you go about testing the effectiveness of all the different options? Do you have to build this battery and how do you decide which materials to test out first?

Clare - So, there's been a lot of work using theoretical methodologies. You can take a structure now at this point and you can use first principle methods to actually calculate the voltage of the material. The challenge is actually to calculate the difficulty of pulling the lithiums out of the structure because the lithium has got to move through different holes. As they jump from site to site, there might be large activation barriers associated with that. in other words, you've got to supply additional energy to get it out. And we would supply that additional energy in a battery in the form of what's known as an over potential. So, a little bit of extra voltage to kick it out and that's inefficient fuel battery. So, those are some of the challenges associated using computations. So, what we would do as chemists, there are people who'd go into the lab and make new materials. So, one of the things that we're going for was instead of just taking cobalt 3 plus to 4 plus, we want to try and find elements where we can change the oxidisation state by more than one. So, we could nickel 2 plus to nickel 4 plus. At the same time, we need to be able to pull the lithiums out. So simply, if we're going to do a 2 plus to 4 plus, we need 2 lithiums. So, we can go in to the lab with those sort of design criteria and try and make materials that might fit that.

Kate - What are the limits on how much you're able to improve these batteries?

Clare - So, I think one thing that's important to remember is that if you have a material that's made up of atoms and ions, and there are only certain number of electrons that you can pull out per ion that you have in your material. So, if you have nickel, the chances are, you're only going to be able to oxidise between 2 plus and 4 plus. And so, the point is, for a unit mass of material, there were only so many numbers of electrons and that puts a fundamental limit in where we're going to go. And so, we can play games and we can find lighter materials, we can use a wider range of oxidation state, but there's a fundamental limit to what we're going to be able to do and I think people do need to recognise that in terms of how we move forward in terms of developing strategies for electrification or for designing of new devices.

Kat - Kate Lamble talking to Clare Grey from the University of Cambridge about her work.