Hot new battery technologies need a cooling off period
IBM boffins want to run your car on air - and lithium
IBM is already making claims that lithium-air technology could allow vehicles to travel up to 500 miles on a single charge. Big Blue's plan would see ‘Lithium Metal’ at the bottom of a composite structure below ‘Electrolyte 2’, a ‘Lithium-ion Transport Membrane’, ‘Electrolyte 1’ and a carbon structure on top. The membrane is there to stop the air from going through and attacking the lithium-metal - possibly solving the problem of lithium-dendrites - but there remain many outstanding issues with the very flammable and reactive Lithium Metal that are yet to be properly identified.
Professor Grey explains:
“Firstly, any membrane must entirely remove all water and carbon dioxide so that only completely dry air enters the battery system. Then there are problems of reversible cycling and reducing over-potential, or the difference in voltage between charge and discharge. Next a stable electrolyte needs to be identified that allows cycles over many years in an application such as a car battery. And that’s on top of any problems with the anode. So for me the technology is still a long way away.”
One intrinsic problem is that any material has weight, and with most materials it is only practically possible to get one, or in some cases two, electrons out of each atom. So there are fundamental limits as to how good a battery can be. In theory, because lithium is so light and oxygen arrives with common air, lithium-air technology proposes the lightest combination available. So if IBM or another team can react lithium and oxygen (or even sodium and oxygen which is a similar concept) then that almost represents the end of the game.
Air technology is already proving useful in other applications. Zinc-air batteries, for example, have had success in hearing aid technology, despite not being rechargeable. But can lithium-air really power a car over anything like a 500-mile range? A Nissan Leaf can currently travel an absolute maximum of 100 miles on an expensive battery. If it could go 100 miles on a cheap battery, that would also be game changing, in a different way. So perhaps getting costs down, using inherently more recyclable materials and managing expectations, is a more realistic approach right now?
Although it might not sound like such an exciting goal, taking a proven technology and achieving just a little higher energy density and making it a little bit cheaper is more attractive to manufacturers that survive on real-world commercial success. Firms like Nissan and Toyota are relatively happy investing in small progressive changes in systems that work, even if they are too expensive and the batteries don’t live as long as desirable. Major brands understandably need to plan their car roadmaps around technologies that already exist.
IBM of course is not a car company, and portable electronics will also be a driver. Batteries are not going to go away and we will only get more reliant on them. Our world will increasingly be controlled by things that need batteries. This progress will hopefully be coupled with more efficient electronics. But more efficient batteries that last ever longer will always be required. And then there’s also a push for more batteries on the electric grid. More renewables will require more efficient methods for short-term storage, and we will need more and better batteries, all of which will also drive research. And maybe somewhere in that mix is where Lithium Air will play its first role.
So perhaps what we really have is a more basic quandary affecting battery technology innovation. Should you over-hype projects that are nearer to concept than commercial reality in order to create as much interest and funding as possible? Or should you be realistic and not over-predict anything that may backfire further down the road?
We’re at a tipping point, explains Professor Grey:
“Lithium-air and lithium-sulphur are both fields that we should definitely be seeing more work in, because they are technologies that offer huge potential. But they also present some familiar challenges of battery and fuel cell development. How can you buy-in to a timeline when there are still a number of obvious technological showstoppers? How do you put a timeline on discovery? Certainly you accelerate the probability of discovery if you dedicate more clever people to working on the problems and combine academia with industry, but in most new systems there is generally a 15-year traditional timeframe until inventions become products.”
If battery project teams stop putting a positive spin on cutting-edge research, then they will never attract the levels of VC interest and funding that they so badly need to make vital breakthroughs. But on the other hand, we don’t want to see technologies pushed too enthusiastically down the road to becoming marketable products before sufficient tests and demonstrations of safety and reliability.
In the meantime, we will have to pick our way though the research hype while putting up with singed laps, grounded flights and electric cars whose performance is generally rather sub-par. ®