Not only did the gigantic NI62 nickel particle prove out to be pure but also the large silicon oxide ash particles were essentially pure
Axil, that oxide particle cannot be silicon oxide (much more likely to be silicon dioxide in any case). There is not enough silicon detected.
It is far more likely to be a lithium oxide of some sort. Maybe even lithium hydroxide. Lithium and hydrogen cannot be seen with EDS, so the only oxygen shows up. There is not enough atoms of elements heavier than Li to make other heavier oxides and have that much oxygen detected without them. (Obviously it was not an oxygen particle).
Pure Ni particles and almost pure LiO (or even worse LiOH particles) suggest a mix of particles that were never heated at high temperature together. That is far more likely than highly heated ingredients that miraculously separated into pure, or nearly pure, substances. Especially these particular ingredients