My read on Recapping is the simple one: what they are trying to do is not easy. :-) It's amusing to me that they have embarked on what is best described as an EEStor-like project, something many of them have spoken on negatively in the past. (I put it that way to see if I can invoke correction emails behind the scenes if you must know).
In the meantime, Vinod Khosla is not waiting around to see if Recapping can recreate EEStor technology. Instead, he has placed yet another bet in yet another similarly described energy storage startup. As avid readers of this blog know, ARPA provided funding to multiple energy storage startups last year. Two of the projects sounded similar to me: Recapping and a project from Stanford lead by researcher Fritz Prinz. I learned this week from another cleantech blog that Khosla is also invested in a company which intends to license the All Electron Battery Prinz and team are working on. That company is called Quantumscape, a name chosen perhaps to signal arrival at that "Netscape moment" in energy spoken about by several VC's like John Doerr at Kleiner Perkins over the years. Khosla's latest slide deck describing his philosophy of energy and interests in it include reference to Quantumscape.
So what about this other battery project at Stanford? To find out, I contacted Fritz Prinz who told me that it is "premature to make any statements at this point" about his progress. I pointed out to him that referencing statement making is rarely done when things are going poorly to which he replied cautiously:
In my long history of science I learned that it take sometimes much longer than one thinks to get things done. Premature statements can lead to loss of credibility. I want to keep my credibility with you and rest of the community high by remaining neutral at this point and not making any statements until we are ready to publish. Our results are not ready for peer review.
Of course, the proper retort was to point out that patent disclosures for his project have included claims of energy density around 250wh/kg which he acknowledged was true. He told me that the patents are still under review and that some of the earliest identified structures are now out of date....which was intriguing. We closed out the conversation by agreeing that I would be the first person to interview him once he has news, an honor I won by simply requesting it...in contrast to everyone else who had simply requested an interview irrespective of order. ;-)
Ok, time to drive this article closer to completion. Why is Khosla so vocal about lithium ion and other legacy energy storage technologies? Is it because he knows Recapping & Quantumscape have the goods? You tell me. If they do or they don't, there is, as it turns out, yet another opportunity to hedge one's bets.
ARPA awarded some funding to Gerhard Welsh of Case Western Reserve University for yet another capacitor based energy storage technology. In previous disclosures, Welsh has been modest in describing his prospects by saying his technology could be best geared for power electronics applications more so than battery replacement. He mentioned that he is working with Rutile (TiO2) or titanate based dielectrics (remember Rolf's Quantum battery?). I asked Dr Welsh about disclosures in his patent application which suggest that 2000J/cc is possible in a capacitor based storage system. Was this something he has achieved? His reply:
a) 2000 J/cc in a capacitor dielectric is theoretically possible. However, we have not achieved it yet, and it is uncertain whether is can be practically achieved. The highest we have achieve so far is near 400 J/cc in a self-repairing (Ti-oxide based) dielectric. The self-discharge times (CV-time constants) of such capacitors need improvement. The ARPA-e grant allows us to work on developing dielectrics with higher energy density than the best commercial capacitors and to address their reliability .
b) the quoted energy densities are for dielectrics operating at a high fraction of their theoretical field strength. Such high fields (500 to 1000 Volt/micrometer) can only be sustained in an electrolytic capacitor. As the volume fraction of dielectric in an electrolytic capacitor is usually less than 20%, the energy density of the capacitor is less than 0.2 times the energy density of the dielectric. This is still much better than what can be achieved in a ceramic capacitor. With geometric optimization this factor can be improved. We are also working on achieving a high geometrical efficiency (form factor). In part this enable utilization of a high volume fraction of dielectric. It is also necessary for power, i.e., low series resistance in a capacitor enables rapid charging and discharging of a capacitor. A power capacitor needs both an energy-dense dielectric and a geometry that allows a low series resistance.
So, there you have it. Measured results of 400J/cc with prospects for going higher. I think these projects prove that it isn't so crazy to suggest capacitors will one day replace batteries, as some of us have been saying for years (in my case, upon learning about EEStor). Congratulations to you if like me, you made such statements when it was deemed crazy talk. ;-)
Now for an obligatory discussion question. What do you make of Khosla's money following ARPA's money? Clearly, he is hedging his bets but isn't it correct to point out that he could shoulder all of these risky projects entirely on his own dime? This situation caused me to have the following idea. It seems like it would be a good idea if the US Federal Govt or DOE maintained some level of equity in projects it funds. This would allow things that become a hit to help pay for further research. I hope someone in DOE already had that idea and implemented it. I'd hate to see taxpayers shoulder a majority of risk allowing billionaires like Khosla to reap a majority of the value. That's not cool if that is what is going on....unless you are Vinod Khosla.