Sunday, December 6, 2015

Waiting for a breakthrough… to solve the breakthrough culture in batteries.

After my post on the hype in batteries, I had promised my seven readers that there would be a follow-on post with solutions.  But, I got to say, this has been a bit of a problem.  I have been toying with this question over the Thanksgiving break and don’t have anything profound to say… yet.    

I was toying with writing another blog post lampooning the hype culture! But I kind of regret the last post already (one does not make fun on one's own, and all that sentimental stuff) so that did not seem like a good idea. 

On top of that I’m off on vacation the coming week to India and will be gone till the end of the month.  So postings will have to wait till the New Year (although I may post something about batteries in the Indian context.  Let us see). 

But, TWiB will continue in my absence.  I have a guest blogger whose post will come up in the next 2 days.  I have couple of others who are also looking at guest blogging.  So you may actually learn something useful for a change! 

In the meantime, as I sit on the plane for 24 or 36 or whatever god-awful number of hours I have to sit on a plane, I shall be contemplating how we can get all the battery folks to tell us what is really going on.  I typically have one profound thought in a year, and have not had one yet.  So there is still hope. 


1 comment:

  1. Hi Venkat, I hope you're having a great holiday in India. Regarding the battery hype problem: what are your thoughts on establishing a standardised framework to objectively compare emerging battery technologies. The idea is the same as NREL's solar efficiency chart: Someone reputable like LBNL could establish a similar comparison chart for batteries. I know we have the Ragone chart but I'm talking about a chart with year on the x-axis, that would be very useful to assess and compare developing technologies.

    The challenge is obviously that solar only has a couple of major metrics: efficiency and cost per watt. Batteries however have many metrics: energy density, specific energy, cycle life, calendar life, safety etc. Batteries also have many input variables that influence these metrics such as temperature, C-rate, depth of discharge, charging profile, etc. Nevertheless, establishing some universal metrics for emerging battery technologies would be really helpful to assess new ideas at a glance.

    Here's some potential charts:

    - Average coulombic efficiency (to 0.1% accuracy). With the following variables constant: 100 cycles, 25°C, 1C, 80% DOD. This would be useful to compare technologies like Li-S, Li-O2, Si-anode, Li-anode, solid state electrolyte. Note: I'm talking about comparing any changes so for example within the umbrella of Li-S alone there's at least 20 data points with different cathode, electrolyte and anode configurations, i.e. multiwall carbon nanotube sulfur cathode, yolk shell sulfur cathode, electrolyte with LiNO3, etc.

    - Current density (mAh/g). With the following variables constant: 100 cycles, 25°C, 1C, 80% DOD. This would be useful for technologies like Li-S, Li-O2, Si-anode, Li-anode, solid state electrolyte.

    - Ionic conductivity. With temperature fixed at 25°C. For solid state electrolytes.

    I know journal articles publish a lot of this data already but its nearly impossible to compare results because their variables are not the same (i.e. different number of cycles, different charging rates) and it would be trusted a lot more if measured by an independent third party.

    Eager to hear your thoughts on why this wouldn't work or wouldn't be a valuable service.

    Ryan Z