PA: Could you please talk a little about your very interesting paper “High‐nickel NMA: A cobalt‐free alternative to NMC and NCA cathodes for lithium‐ion batteries”? Are there any updates on that project that you could share with us?
AM: I love oxides. My PhD was on oxides, and later I worked on oxide cathodes, crystal chemistry, how the atoms arrange and the structure. During my PhD, I didn’t learn much physics. Because I worked with Goodenough who is a physicist, I was exposed to physics and chemistry together, e.g. band structure, redox energy levels, etc.
By combining good crystal chemistry, structural knowledge, and the positions of redox energies of different ions, we have a good understanding of which metal ion will do what in the layered oxide. That’s how we were able to design some cathode compositions. Synthesis condition is very critical. When you increase the nickel content, the synthesis temperature must be lower because Ni3+ is not very stable at high temperature. Cobalt oxide can be heated at 800 to 850 °C with no problem. When you keep on putting nickel, the temperature will go down. For the NMA, good crystal chemistry knowledge, good knowledge of the redox energies of different ions, plus good control of the tank reactor synthesis were helpful. All these together we were able to achieve NMA.
The paper you mentioned has been published, since then we have opened the cells, we have been analyzing those four or five materials to see what the differences are. It’s almost completed and is a subject of another pending paper.
PA: What sparked this study and what is the end goal?
AM: Cobalt is expensive and the overall cost of EVs will go up if we use a lot of batteries with cobalt. Add to that supply chain issues. Cobalt is mined in the Democratic Republic of Congo, there are other issues there, child labor, children getting exposed; all these were concerns to me. All these issues, as well as the cost and supply chain issues for US and Canada, prompted us to first reduce the Co amount and then finally eliminate it completely. We were working with a composition that contained 94% Ni and 6% Co before. We were working on that for three years and have at least five or six published papers on that subject. Slowly, from 94% Ni and 6% Co, we went to Co-free composition. For a very long time, the general belief was that you really need Co and if you remove Co, you cannot get the desired performance. Our group demonstrated that this is not necessarily true, and we can make materials work without Co.