The best Electric Vehicles (EVs) on the road have a range of around 300 miles between charges. You then have to charge them relatively slowly as they could explode if exposed to too much energy. A new technology has come about that could have EVs with a 600-900 mile range on the road, and that can be charged in just minutes with no risk of explosion in the next 3-5 years. This piece will look at the technology in batteries and just what makes ‘solid state batteries’ the next major breakthrough in battery technology.
How Lithium ion batteries work
Lithium is one of the most reactive alkali metals of all. Look on Google to see how it responds when it hits water – pretty bloody dramatically! It reacts by releasing ions and in water, decomposes into Lithium Oxide while releasing massive amounts of energy which is why you see the explosion.
Lithium has the highest electrochemical potential of all metals. Scientists spent around 40 years trying to work out just how to control the energy release as if controlled, Lithium based batteries would be the way to replace lead acid batteries. The idea was to have a plate of lithium as a cathode (the positive plate) and another of carbon (the negative plate). Ions would pass through an electrolyte from the cathode to the anode.
The problem is that metal strings (‘dendrites’) would form that linked the cathode to the anode. Energy would rush between the two plates and the battery would heat up and explode due to the short circuit. In the early 1990’s a mobile phone battery exploded in someone’s face in Japan and scientists went back to the drawing board.
John Goodenough breakthrough
In the late 1980’s, battery researcher, John Goodenough was working in his University of Texas labs on a lithium oxide cathode and a dense electrolyte gel between the anode and cathode. A Japanese researcher worked with him and then went back to Japan. He was clearly given a top job at Sony since they ‘mysteriously’ patented the new lithium ion battery we all use today. Lawsuits rapidly followed but Sony held onto the patent. Goodenough got no money from it even though by rights he’d be a billionaire today for it. The fact that people credit him for his work has to be, well, good enough for now…
Goodenough’s use of lithium oxide cathodes sacrificed energy density for safety. The issue therefore was in working out how to increase energy density and charging times? Tweaks have been made to the chemistry of the batteries, with the addition of graphite anodes (that one day may be replaced with graphene, a one atom thick cathode that could considerably increase energy density) and tweaking the chemistry of the anode to make it more reactive. In the case of tweaking the anode, you always hit a safety issue of overheating and explosions. You can only tweak lithium ion batteries so much…
The solid state idea
If you got rid of the liquid electrolyte, so in theory you could kill off the risk of dendrites forming between the anode and cathode and getting rid of the risk of explosion. You could whack in massive amounts of energy to charge it, and use a very reactive metal that has a much higher energy density. Two universities are racing to commercialise their inventions that do just that today…
Ilika Technologies is a firm that works with the University of Southampton in the UK. In part sponsored by the automotive giant Toyota the firm has developed two forms of solid state batteries, one for EVs and the other for smaller gadgets – perhaps a mobile phone that you may never have to charge.
Ilika’s battery uses silicon anodes. According to the Battery University, “It takes six carbon (graphite) atoms to bind to a single lithium ion; a single silicon atom can bind to four lithium ions. This means that the silicon anode could theoretically store over 10 times the energy of graphite…” Ilika and Toyota’s batteries are claimed to have twice the energy density of lithium ion batteries.
Ilika and Toyota have done a deal where Toyota funded the research for ten years and then co-owned the patents for EV batteries, while Ilika took the patents for gadget batteries – a pretty good one. Toyota can now start planning long range EVs while Ilika can start hitting up the multibillion dollar mobile phone and tablet industry to sell game changing new gadgets. Licenses have already been sold and it is believed that the first EVs and gadgets could hit the market as soon as 2020.
900 miles per charge Goodenough?
It seems however that while the Ilika / Toyota technologies are being rushed out to market, 94 year old Goodenough may be about to patent something even better. An article on the University of Texas website claims, “The researchers demonstrated that their new battery cells have at least three times as much energy density as today’s lithium-ion batteries.” This could mean we would see EVs going 900 miles per charge. That simply kicks diesel’s arse and would make ICE vehicles the ones with ‘range anxiety’.
There’s another cool thing about the solid state battery – you can put huge amounts of current into it without worrying about dendrites. You could charge an EV in 15 minutes and then drive from London to Milan on a single charge!
The best thing of all for us earth loving geeks is that Goodenough’s batteries can be made from planet loving metals such as sodium that can be taken from sea water. “The glass electrolytes allow for the substitution of low-cost sodium for lithium. Sodium is extracted from seawater that is widely available,” Goodenough’s fellow researcher, Maria Helena Braga told the website. Now that’s what you call a good battery – earth loving, dirt cheap and so energy dense it would make petrol and diesel look like a bit of a joke. Don’t know about you, but I can live with that!
By Richard Shrubb