Gourmet Cells: When Electrochemistry Comes with Extras

I just came back from Mexico, and I want to ask you a question:

Do you know what a Mexican torta and a lithium-ion battery have in common?

Let's think about a classic torta. It has two slices of bread. Inside, we have the ham, the cheese, some lettuce and tomatoes, the dressings like fried beans or mustard and, of course, some spicy sauce. Well, the battery also has two “caps”: positive and negative, inside there is a cathode like LiNiO₂, the separator, an anode as graphite, current collectors (Cu and Al) and the electrolyte. In both cases, the important thing is that they store energy that will be consumed later. So, let’s talk about some tortas.

Not all tortas are the same: there are chicken, vegan, beef, tuna, and cheese. There is not a unique recipe; we need diversity depending on the application.

In my case, what I’m doing with my ‘torta’ is simple: I’m looking for a ham that is yummier and cheaper. To do that, it happens that we also can add extras (or toppings) to make the ham taste better and deliver more energy, for example: we can add avocado, bacon, onions, basically we can make a new hams... In batteries, the toppings are call dopants, such as Al, Co or Mn. In my study, I’m trying to get the tastier torta using the ham with the best topping.

To find out if these extras really improve the recipe, we need specialized critics, right? At SLAC, I shared these tortas to test which beam scientist last longer (and enjoy) during beamtimes. Of course, we use multiple critics to find what is the best torta and which ham is the best from the smallest detail to a big picture. We taste the new ham individually, we taste the whole torta, we taste tortas with different toppings, freshly-made tortas and some that have been aged a little. Yes, I was talking about the cathode in Li-ion batteries, where we used X-rays to see what happens from the atomic level to a group of particles.

The result? We discovered that, just as a ham is improved with avocado, this particular ham in this torta is a LiNiO₂ cathode with some aluminum. With just 5% of avocado, the torta showed the best taste, the most energy, and it lasts longer.

So, returning to the initial question: yes, a Mexican torta and a lithium-ion battery have a lot in common. So, what you say? Would you like to try this torta?

Do you know what a Mexican torta and Li-ion battery have in common?