Good evening fellow scientists. It is Sunday June 17th 2018 and I would like to update you on the all iron battery All iron battery has an iron anode and an iron salt cathode you can check out a previous video to find out about that the Current problem is how do we construct a separator so a separator membrane is what is allowing the charge on the anode and cathode to balance I'll still preventing electrons from flowing through the cell and rather forcing them to flow through the load Obviously it's a pretty important role to play in the battery last week Except so to talk a little bit about how that allows the battery to function What kind of chemistry is good for a separator? One of the better membranes that I have available to me is naffion naffion is a sulfonated poly tetrafluorethylene So what does that all mean? Let's start with polyethylene polyethylene is the common milk carton type of plastic has a chemical structure of CH2 groups all lined up Seems a lot like wax in terms of its chemical reactivity, but is crosslinked to make it stronger will melt Poly tetrafluorethylene is just like polyethylene except it has four fluorines on it that those fluorines make it far more chemically inert really dislikes waters a lot of the super hydrophobic surfaces are based on tetrafluor groups and if you want to take this which is essentially tefflon and Convert it to a naffion substance you add these sulfonate groups which I've drawn with a little red there to show that negative charge That negative charge carries a hydrogen so it is able to react or carry an H plus Ion through its structure, but it completely prevents water from entering the structure That means it's a pretty good barrier to just aqueous conductive ions Doesn't allow electrolytes to enter its structure, but it does allow for H plus to pass through itself thereby balancing the charge on two sides of a cell To examine the process of leakage through that separator that is to say self discharge or the way in which the cell is just going to ruin itself for time We rigged up this system with just two carbon electrodes and then two different concentrations of that same iron two to iron three chemistry On either side so on one side it starts at all iron two and then other side it starts on all iron three and eventually those are going to reach equilibrium where all The iron two and iron three concentrations of the same on both sides and as iron diffuses through there We're going to see the cell potential drop off which is exactly what happens With the naffion membrane between there you see that the cell comes to steady state Chemistry arranges itself around that membrane and then slowly falls at about point two volts per day Versus an open cell potential of point two five volts. So we expect to see it fully discharge over the course of 24 hours of air about A-Gar cell one seems to have a much lower voltage. That's probably because it's actually Discharging essentially immediately as it penetrates through the A-Gar upon setting up the steady state And then it loses point eight volts over the course of two or three hours that will lose all of its Potential so we need something a little better naffion is definitely better than a-Gar but we can examine polyacrylamide coacrylic acid Which has some of those same properties of naffion that Negative charge hopefully will help allow some ions but not charges Speak is another option sulfonated poly ether ether ketone which we will try to get a hold of if we can So tuning every week for our updates on Battery separators and battery construction We will continue to try to find a DIY friendly alternative membrane for this particular kind of battery It's kind of looking like we may have to go to a Commercial source or a commercial chemistry, but I'll try to find a nice cheap option in any case Thank you very much to Nico for his hard work this week and we deeply appreciate the support of our crowd funders Who make this summer research possible Stay tuned every week we update on the all iron battery and I will see you then