Skip to 0 minutes and 4 seconds Maria, we’ve talked in this course about the need for better energy storage batteries. Cheap, rechargeable batteries, like the lead-acid batteries in our cars, have been around for over 150 years. Why do we need better batteries? - The lead-acid battery is a great device, certainly. And we have had it around more than 150 years. However, it’s got limitations. It’s a very heavy battery, metal is, obviously. Is it’s not really useful for lightweight applications, like electric vehicle applications. There’s a cost of– there’s the electrolyte, which is acid, which is corrosive. And there are limitations, for example, how many times you can charge and recharge it. So it doesn’t last very long. A typical car battery lasts for three years.
Skip to 0 minutes and 51 seconds It’s still a very valuable battery. It’s used throughout uninterrupted power supplies. But again, limitations in terms of lifetime, in terms of how you charge it, in terms of lead being a poisonous element, basically. So we need better batteries. Lithium-ion obviously has become very popular. Everyone owns some device which has a lithium-ion battery, be it a phone, be it a smart device, like a Fitbit, be it laptop computers. And more and more, we’re seeing lithium-ion now going into applications like electric vehicles. And also, of course, energy storage, to backup for renewable energy. Now, that’s all well and good. Lithium-ion batteries are certainly better than the lead-acid batteries for many of the applications. But they still have problems.
Skip to 1 minute and 36 seconds So the job’s not done yet, in terms of getting better batteries. Lithium-ion, at the moment, the chemistry with lithium-ion, it can be variable. You have batteries, the original batteries that Sony put out the 1990s, were based on lithium cobalt oxide. Now, cobalt is not an element that is very available worldwide. It’s available in only one or two particular countries, including Australia. Mining of it is not particularly ethical. And it’s a critical element. Other elements in lithium-ion are also critical elements. Even the graphite that goes into lithium-ion batteries is a critical component of the battery. The electrolyte that goes into a battery at the moment is an organic solvent with a lithium salt, like LiPF6.
Skip to 2 minutes and 18 seconds These are not particularly friendly, when you think about safety. You think about a fire– well, imagine if a battery catches fire, you’ve got organic volatile solvents in there. You’ve got PF6 that forms fluorine gas, Hf. The PVDF in the binder is a problem, in terms of the toxic fumes that would come off. So there are issues with the existing batteries. Now, of course, companies put a lot of effort into trying to minimise those risks. Both in the engineering of the battery, but also in terms of the chemicals themselves, adding fire retardants, for example, into the electrolyte. Nevertheless, there are a lot of problems with the lithium-ion.
Skip to 3 minutes and 0 seconds In the lithium-ion chemistry, the cathode can be quite different, can be anything from the lithium cobalt oxide, the original layered oxide system. The LFP, the lithium-ion phosphate, which is cheaper and safer than the lithium cobalt oxide. However, lithium ion phosphate doesn’t have as much energy density. What that means is, you couldn’t really drive a car on a lithium-ion phosphate battery. Because the energy density of lithium-ion phosphate and how many electrons you can store in the battery, how far you can drive your car, is going to be limited by the fact that that cathode doesn’t have as much energy density. So now people are looking at making nickel and NMCs, nickel-manganese-cobalt-type systems.
Skip to 3 minutes and 40 seconds And they do this by making nanostructured materials, putting coating on them. They’re very reactive. By very reactive, it means we get more energy from them. But it also means that we have issues with safety and stability. There’s a lot of work going onto how we can actually make those electrode materials more stable, so the battery lasts more than just 100 cycles. Which is fine if you have a phone battery. It might even be fine if you have a car battery, in terms of 100 cycles. Because that means your battery lasts maybe 100 days. It’s maybe not so good. So we want to try to make the batteries last longer.
Skip to 4 minutes and 15 seconds And if you’re going to try and put a battery system to back up your solar and wind farm, well, 100 cycles is not– even 1,000 cycles is not really enough. So there’s a lot of work going towards, how can we improve stability, safety, energy density? All that’s still really important.
Current battery research
By now you have learned the basics of how a battery works, some of the materials that are used in the batteries and the types of battery.
You have also heard that there is no perfect battery yet and that the materials in a battery can be polluting, their availability could be scarce, and there are even worries about how ethical materials like cobalt are obtained, with potential fears of child labour in the countries that have cobalt mines.
For all these reasons researchers continue to look for better materials to use in batteries so that they can become more efficient, charge faster, hold more energy, have a lower environmental impact and reduce the ethical problems.
Most of us know that there are many different types of batteries. At present, most research takes place into:
- solid state batteries
- lithium-ion batteries
- sodium ion batteries
Critique on batteries
Above and one the following pages, we see excerpts of an interview between David Officer and Maria Forsyth from Deakin University. Maria is an expert on the topic of batteries and what is happening in current research in this field. In this excerpt, she talked about some of the issues today’s batteries have.
We are now at a stage that lithium-ion battery demand has the potential to grow faster than the supply of lithium can meet. So, we need to be on the lookout for other battery materials. We also need other storage options such as hydrogen fuel technology, which we will look at in week 4.
What is the critique on batteries that stands out most to you? Why?
© University of Wollongong, 2019