Readers here is some more information to consider on the subject of flake size for specifically EV battery market to potentially identify which graphite brownfield explorer -come-producer has the better product for Battery market.
Its possible we have been sold on flake size from a number of sources, but we need to consider whats best for the EV battery sector which will be " first cab-off-the rank usage" for graphite as a near term mass market product!!
Also DDZX can I ask that you tone down your aggressive tone in your responses down as they come across as a personal attack which is also not needed
DDZX i welcome your thoughts relating to the info below in a more constructive manner - play the ball not the man ok?
I think this current conversation also teaches us to look beyond the flake size argument which has been commented on my many including myself and for ALL of us and to further increase our knowledge banks and be objective to gain a better understanding -
In the information below you can see that during the Spheroidizing the graphite flakes also reduces their size, a process known as micronization. ......... read on.......... Cheers G101
Battery-grade graphite requires very high purity levels, typically >99.9% carbon-as-graphite (Cg). This material also needs to be spheroidized using careful processes that convert the flat graphite flakes into potato-like shapes, which pack much more efficiently into a given space. The high purity levels and the enhanced "tapping" density (to >0.9 kg/m3) are important for producing the high electrical conductivity that is required during anode operation.
Spheroidizing the graphite flakes also reduces their size, a process known as micronization. Standard battery-grade materials require an average diameter of approximately 10-30 μm, so in theory, feedstock materials with flake sizes greater than 30 μm (+400 mesh) could be used. However, 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.
One other important factor in the production of battery-grade materials is that of wastage. The standard spheroidizing and micronizing processes used in China waste up to 60-70% of the mass of total graphite flakes present during processing. Therefore, for every one tonne of spheroidal graphite produced in China, approximately three tonnes of feedstock materials might be required (though the waste materials can be used for other purposes).
The graphite may be purified before or after spheroidizing and micronizing, depending on the manufacturer. As mentioned earlier, the low-cost approach typically used in China is to leach the impurities from the graphite with acid, with the associated environmental concerns that that brings. Alternatively (and far more acceptable in Western jurisdictions), a thermal process can be applied. This typically involves the use of halogen gases to cause chemical reactions at high temperatures with the impurities, which covert the resulting compounds into gases too and eliminate them from the bulk graphite material.
The higher the starting purity levels of the graphite after initial concentration at the mine site, the lower the cost will be for purification, and this can make a substantial difference when comparing concentrate feedstocks with different starting purity levels. TMR estimates that the cost difference in purifying a 95% Cg concentrate to >99.9% Cg, versus taking a 98% Cg concentrate to >99.9% Cg could be as much as $2-3,000/t of concentrate, using thermal processes.
The final step for preparing spheroidal graphite for anode production is the application of a coating to the particles to reduce their specific surface area. This is important, as reducing the specific surface area will increase the long-term capacity of the battery cell. Intercalation of the electrolyte solvent into the graphite and its reaction with it causes expansion of the graphite, with the potential for delamination and a lowering of the life expectancy.
During the first charge of the battery cell, an initial, irreversible chemical reaction occurs between the electrolyte and the graphite in the anode, resulting in the formation of a so-called surface electrolyte interphase (SEI) layer. Once formed, this layer reduces further decomposition of the electrolyte and actually protects the graphite anode from exfoliating.
With too large a specific surface area, the formation of the SEI layer can reduce the graphite's ability to subsequently hold and to release the lithium ions in the electrolyte, thus reducing lifetime capacity for the battery. Coating the graphite prior to anode production reduces this effect and helps to maintain the maximum capacity possible for the battery. The coating can also reduce the chances of a runaway chemical reaction in the battery.
http://www.techmetalsresearch.com/2014/03/going-natural-the-solution-to-teslas-graphite-problem/
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