Good evening my fellow scientists it is Sunday July 15th 2018 and I want to give you the weekly update on the all iron battery. This week we have been refining our results on the battery separator. For those of you who are new here the way in all iron batteries going to work is we're going to have an iron anode, an iron salt cathode. In between this got to be some sort of separator membrane that keeps everything from mixing up and discharging. A better membrane would keep the two chemistry separate while allowing ions to flow so that the battery will function. To build a good battery membrane we need something that is a polymer that is going to restrict diffusion through the membrane something like a gel. We also need something with a chemistry that will allow some ions to flow and other ions to not and that usually takes the form of an acidic group such as a sulfuric acid in the case of naphion or an acrylic acid in the case of sodium polyacrylate that will restrict that motion of negative ions. You can see here a control poor membrane that blocks fluid access completely except through very narrow pores can also serve the same function. So far has been very clear that the naphion is by far the superior membrane type that should be surprising even our ad hoc membrane made of paper soaked in a naphion solution is definitely our best home brew separator. We're going to compare that this week to a commercial naphion that I purchased from the fuel cell story can see that here. We're going to see how the naphion in paper works whether it's as good or how much worse it is as compared to the solid naphion membrane. In the meantime we have been working with sodium acrylate that's the sodium salt of polyacrylate acid. So you can think of that as a long chain of acidic molecules all bonded together with sodium along every acidic group to neutralize the charge. And that is commonly marketed as a highly absorptive gel sometimes on endipers and you can see how it works here. So here's some sodium acrylate powder and it's just a solid like salt and if you add some food coloring and water to it and switch around for a minute it will eventually soak up all of that water and become this sort of viscous gel that doesn't obey gravity anymore doesn't slosh. And it does that for an amazing amount of water. So if we add a bunch more water you know 100 times the volume of the original solid polymer it will absorb all of that. And if I switch it around for another minute that all incorporates into the structure and generates this semi solid material that doesn't slosh. And we've been trying to figure out how to get this material into paper to make a membrane. That turns out to be a little more challenging than it might be. We need to dissolve it but of course it makes this viscous gel. Now we need to push it into paper we tried doing that while it was still solid that didn't work. And Niko tried dissolving it in ethanol and I suproponol alcohol that kind of worked and that's how we got these results. But I'm interested to see if we might be able to dilute it until it is liquid enough to flow into the paper and then dry it out and repeat that to concentrate that polyacrylic acid into the paper matrix and make it better membrane. So we'll call these results preliminary but as you can see so far Nafion is still winning. We've got our polyacrylate gel that we made in house in the paper as a as a distance second and this commercial absorbative polymer impregnated into the paper that is a third place. But definitely the easiest to get the safest to work with and something that I think I will recommend in the final paper depending on how good we can get it as a sort of safe budget alternative to purchasing the Nafion solution and making a membrane out of that. So if you like that kind of thing please do tune in every week. We update on progress on the all iron battery. Thank you very much to our crowd funders who have made this summer research possible and thank you very much to Nico for his hard work making all the actual experiments. Until next week this has been Peter Allen in the Allen Lab.