Thanks to Dr Crittenden from OXIS Energy for clarifying some points with an earlier version of this article. Appropriate edits have been made below.
As followers of electric car technology will no doubt be aware, every few weeks another company announces that it has cracked the magic code that will make current battery technology obsolete. But as you delve into these announcements, they are either far from mass production, or are in a state where further research results in world changing promises becoming small incremental improvements in technology. Not only that, but these developments often take many years from announcement to market.
The first example of a battery technology we excitedly read about that ended up being a little further from production than we hoped was Lithium Sulfur. Back in 2013 the UK company OXIS Energy signed an agreement with GP Batteries which, it was hoped, would lead to the mass market production of Lithium Sulfur batteries. Whilst GP Batteries have begun production, they’re certainly not as common as we might think given their potential advantages.
In Li-S batteries, rather than an intercalated lithium compound as one electrode, and lithium metal as the other (as in lithium ion batteries),
the chemically complex intercalated lithium electrode is replaced with one made from lithium sulfide. the anode remains Lithium, but the cathode is a Sulfur/Carbon mixture with a polymer binder. Through a process of passivation the Lithium anode develops a protective layer of Lithium Sulfur — and this relatively simple sounding change produces battery cells that are more stable, and potentially vastly more energy dense. Back in 2013, the predicted theoretical maximum energy density for such a chemistry was an astonishing 2.7kWh/kg (which vastly outpaces the current 150Wh/kg-180Wh/kg available from current Lithium-Ion cells used in most electric cars today). But lifespan was a substantial issue – just 500 cycles took you to only 70% of original capacity.
However, as we approach the summer of 2016, we’re still waiting and watching. OXIS Energy has hit an energy density now of 325Wh/kg – still a massive improvement on Li-Ion, and despite evidence it has resolved the lingering lifespan challenge (1500 cycles now only drops the batteries to 80% of original capacity), Li-S batteries aren’t yet in EVs.
Why? Well, back in 2013 our colleagues at Foro Choches Electricos suggested that OXIS Energy had not overcome the inability to rapid-charge this chemistry.
Unless rapid charging becomes a reality, Li-S is effectively out of the running for the mainstream EV market. However, excitingly, as part of a European Commission funded project — Advanced Lithium Sulfur Batteries for EVs — a Lithium Sulfur module is being developed and installed in a SEAT Leon which achieves the current norm of 80% charge in 30 minutes. Lithium Sulfur, therefore, remains one to watch.
But Li-S is by no means the only new exotic battery chemistry, or technological advancement that would transform EV motoring that’s trundled through the news cycle.
So when, in June last year, we covered the preliminary steps of another such development, we did so with substantial caution. A team of scientists in South Korea, led by Dr. Lu Wu of Gwangju Institute of Science and Technology, indicated that they had developed a method for the mass production of graphene supercapactitors. Supercapacitors have long held the dual promise of enabling EVs that charge in minutes, rather than hours, and of overcoming many of the concerns of battery degradation – some of which have been seen in cars such as the early model Nissan LEAF, particularly in challenging climate conditions.
Then in October last year, a small Spanish company – Grabat – made the kinds of self-aggrandizing promises that many have dismissed as being the faith of a snake-oil salesman. But given its technology partners, it is a possibility that this snake-oil may have some promise.
It started small – an announcement on its Facebook page that it was working towards obtaining certification and completing manufacturing tests for graphene based batteries, but little other information was forthcoming.
But as time has progressed, the claims have switched from small to seemingly outlandish. A production cost that would be 77% cheaper than equivalent lithium ion batteries; vastly higher energy density – reportedly as much as 1kWh/kg – apparently already achieved; and 80% capacity at 8000 charge cycles. All of this was wrapped up in a remarkably well produced video (in Spanish).
Then came the fall – with the Spanish newspaper El Confidencial suggesting that Grabat had deliberately mislead people by posting the first page of a TüV report on this new battery technology and suggesting instead that it was a certification.
The claims of having completed certification were later retracted by Martin Martinez, CEO and founder of Graphenano, who claimed that the high expense of obtaining certification had prevented the company from obtaining final certificates, and suggested that certification institutes lack the standards required to test their batteries, but reiterated that the tests indicated that 1kWh/kg is the energy density of Grabat’s graphene cells.
It may seem outlandish that it will be able to meet its claim of producing 80 million cells per year at their factory by October this year. Certainly the balance of these claims means that they should be considered with the hefty pinch of salt that one would take any alleged similarly dramatic enhancements in battery technology. However with several automakers apparently in talks, or actively working with Grabat, the Chinese transmission and distribution giant Chint paying 18 million euro for a 10% share in Grabat, and public statements of working with Airbus, perhaps it pays not to dismiss these seemingly outlandishh claims out of hand.
Grabat themselves stated to El Mundo that they are working with automotive manufacturers who are assisting with the homologation process for their batteries with the intention of introducing them in 2017 model lines, which if true, would be a truly remarkable rate of transition both for Grabat and for the EV market. But as yet, the enigmatic company have not responded to our queries about their production schedule or technical specifications.
If Grabat’s new Graphene cells manage to fulfil even one half of its claims, then it will certainly be a fascinating company to watch, and truly transformative for the EV market. But we at Transport Evolved won’t be holding our breath for Graphene battery’d EVs just yet.
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