Episode 6 - Aqueous Electrolytes and Electrolyte Restrictions

Alternate episode title: Wat(t)ery Battery

Sorry about the wait for this episode! Our editor Hope was busy dropping out of grad school and then spending time with family over the holidays. But oh those long weeks ago, Hope and Ana convened to discuss electrochemical stability windows, solid electrolyte interphases (SEIs), and the pros and cons of aqueous electrolytes (as well as some proposed fixes for those cons). Cameos by Hope's sister Dana with a story about water and lithium, and by Hope's brother Alex with a note about water and lead.

Spoiler warning for The Music Man (the musical), if anyone has concerns about that

Sources:

Flame tests of metal salts: https://www.youtube.com/watch?v=nS77SPywI9w (this has nothing to do with batteries but it's pretty)

Water-in-salt electrolytes: "“Water-in-salt” electrolyte enables high-voltage aqueous lithium-ion chemistries" by Suo et al http://science.sciencemag.org/content/350/6263/938

Coating which turns into an SEI in an aqueous electrolyte: "4.0 V Aqueous Li-Ion Batteries" by Yang et al http://www.cell.com/joule/abstract/S2542-4351(17)30034-X 

Summary of "4.0 V Aqueous Li-Ion Batteries": https://www.sciencedaily.com/releases/2017/09/170906135613.htm 

Supplemental information of "4.0 V Aqueous Li-Ion Batteries" including video (Movie S3): http://www.sciencedirect.com/science/article/pii/S254243511730034X?via%3Dihub#mmc4  "Surprisingly, as the multimeter in the video shows, the cell managed to maintain its open circuit voltage (OCV) at 4.03 V, which gradually decayed to ca. 0.031 V overnight" - quote from the full paper (not the supplemental info) also here's another source for the video in case you can't access the supplemental info https://phys.org/news/2017-09-water-based-lithium-ion-batteries-explosive-reality.html 

passivation layers on lead (or galvanized) pipes (these are a similar concept to an SEI layer in a battery!): http://michiganradio.org/post/heres-what-drinking-water-pipes-look-and-without-corrosion-control