Transport Phenomena is over for the year at NYU. Here’s me with some of the class on the last day.
Author Archives: joshuagallaway
Tesla Gigafactory
The current Tesla plant in California. (photo credit)
The Gigafactory is a giant battery production facility planned by Tesla, to be built in one of the following states: Nevada, Arizona, New Mexico, Texas, or California. It’s a powerful effort to force down lithium-ion battery costs by bringing together all the members of the supply chain and consolidating the process in one location. Tesla can do this because it buys a lot of batteries, but also because it has star power.
Tesla is the most exciting thing in batteries at the moment. Lithium-ion battery cost is about $500/kWh, and Tesla wants to bring that down significantly to make electric vehicles a reality for everyone (not just people who can afford expensive cars). Some analysts believe that lithium-ion batteries, as they are currently constructed, have an inherent limitation between $200-300/kWh. This is due to the production costs and the materials (active material, electrolyte, etc). The target cost for electric vehicle batteries is lower than that, under $200/kWh, but it seems like Tesla’s effort will go a long way to making it work. Other battery applications, like utility-scale stationary batteries, will need to be even cheaper though. So it’s clear other battery chemistries will need to fill that space.
Yes
Why post mortem battery analysis is hard
I was looking though some research photos and I found this nice example of why post mortem battery analysis is better done by some X-ray technique. Once you start opening things up, you mix the materials around, you oxidize them, etc, unless you have a very good method, which is probably tedious.
Leveling zinc with bismuth
Just published a paper called “An in situ synchrotron study of zinc anode planarization by a bismuth additive.” It’s a mechanistic study to explain a result we discovered in the early days of the CUNY Energy Institute. I was looking for an additive to kill dendrite formation in zinc, working with Dan Steingart and Abhinav Gaikwad, who was a graduate student at the time. Turns out a little bit of bismuth can keep zinc layers quite flat when electroplated from a flowing electrolyte. The middle image below shows it clearly:
The percentages are % of the bismuth saturation limit, which is very low. 10% is 3 ppm, an almost undetectable amount, and it has an enormous impact. This result could be used to increase the energy density of zinc batteries, by keeping the zinc layer compact. When naming the paper I called it “planarization” instead of “leveling” because the mechanism is different than that of a leveler in traditional electroplating.