Thanks. Came across this article and it offers a good...

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    Thanks. Came across this article and it offers a good explanation - if it's accurate. So my takeaway is, assuming purity is equal, " jumbo" flake is more expensive to micronise than large flake.... How much more I have no idea but lower costs are always better obviously.

    "starting purity levels tend to decrease with flake size, so flake material with an average diameter of 150 μm (+150 mesh) or greater is typically used. This is, of course, a double-edged sword, since the larger the flakes used, the more energy will be required to reduce the average size of the flakes to the desired 10-30 μm. Smaller particles are preferred, as this makes it easier for the lithium ions in the electrolyte to diffuse between graphite particles.

    It should be noted that it is the tendency for purity levels to increase with flake size that is the real reason for the common 'mantra' that for battery-grade materials, the bigger the flake size, the better. In fact, the ideal precursor material would have small flake size if it had sufficient purity levels for the subsequent processing to be cost-effective.

    http://www.techmetalsresearch.com/2014/03/going-natural-the-solution-to-teslas-graphite-problem/
 
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