2014 “Plastic Metals”

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With our 2013 vehicle “The Deyhdrated Water Mobile,” one of our members has started a tradition of naming our cars with oxymorons (we did however both split and recombine water molecules on our car). Following this newly founded tradition, this year’s name is “Plastic Metals” (arising from the metal that we use in our batteries and the large amounts of 3D printed plastic parts we used). The car placed 1st in the region at the PWNR Comepition at Washington State University. The win secured a spot as one of the 31 out of 144 teams across North America to qualify for the National Competition. At the 2014 AIChE National Chem-E-Car Competition, the car tied for 8th out of 36 teams from around the world at Georgia Tech.

Zinc-Air Batteries:

overall reaction: 2Zn  + O2  ->   2ZnO

We went through three complete iterations of zinc-air batteries. Our first tests were conducted with zinc powder, paper towel, steel wool and an alkaline solution (max power ~0.032 mW/250 g cell). Our next iteration consisted of a prototype PLA casing (tested in alkaline solution prior to ensure compatibility), copper current collectors,  zinc dust, alkaline solution, paper towel, home-made manganese dioxide catalysts on a carbon felt electrode (max power ~0.4 W/80 g cell), which was 10x better than our first iteration. Our final design consists of an ABS casing with USB ports as power connections, copper current collectors, filter paper as a separator, zinc dust, alkaline solution and a high performance commercial cathode catalysts  (max power >2 W/~30 g cell, later measured to be >4 W). Of course, there were more unrealized iterations that saw revision before the final three iterations. Moreover, there are many improvements that are planned for the year.

Battery casings for our zinc-air batteries.

Ruben carefully preparing an iodine clock.

 

Iodine clock: 

clear solution + time + magic -> black solution

The clock this year underwent a few improvements from last year:
1. All edges in clock are smooth to promote good mixing
2. Passive stirring accomplished by a simple bevel gear and magnetic stir beans. A well mixed solution ensures consisted kinetics from trial to trial thus improving the timing of the chemical clock.
3. Superhydrophobic surfaces ensure that the residual from one trial to the next is minimized – it also speeds up the cleaning process.
4. Laser and photosensor are perfectly aligned and never removed from the device under normal operations giving us consistent measurement conditions from one trial to the next.

 

Kirsten setting up the clock.

Our safe, yet haphazard looking, electro-chem-mechanical set up during prototyping & testing.