@Prime1
You do raise some interesting points.
Prime1
“High-grade? If the stuff is to be used as a refractory, for furnace lining, yes. If it is intended for battery use, then, emphatically, no. Battery-grade spheroidal graphite is required to be 99.9% graphite, 99% just does not cut it. 1.0% impurity is ten times as high as 0.1%, a fact which does not appear to be clearly understood”
Hazer Announcement wording:
“Hazer is pleased to announce that it has produced graphite at 99% tgc(total graphite content), through initial methane decomposition and a single stage chemical purification. Importantly, the chemical purification can be undertaken without the use of hydrofluoric acid (HF). Prior to chemical purification, the graphite product harvested directly from the Hazer reactor under non-optimised conditions has tgcpurity of 86%.”
Hazer’s Chief Technology Officer, Dr Andrew Cornejo,
“It is promising that even under non-optimized conditions the characteristics of the graphite produced by the Hazer Process correlates well with commercially available premium graphite. These initial results show that Hazer’s graphite is highly crystalline with few defects, key requirements for high-end graphite markets such as battery applications.”
If we first deal with the point regarding purity. The raw “Ore” from the process was reported as 86% therefore a fairly high grade ore when compared to any miners. The 99% purity has been achieved by non-optimised single stage chemical purification. Graphite purification processes are well known and there is nothing to suggest that 99.9% will not be achieved under optimised conditions such as an increased exposure period or second chemical purification stage. With the first stage acid consumption stated by yourself to be 90kg/T of graphite the upgrade from 86-99% would cost around $18/T. With Hazer able to profitably produce graphite at <$500/T it is very unlikely that the purification to 99.9% will pose an economic barrier to competing in the battery market. Also worth looking into is the nature of impurity, keep in mind that Hazer graphite is structurally unique and the Fe that is left behind by non-optimised chemical purification would not necessarily negatively impact the electrochemical properties as ions unavailable for acid digestion are likely both chemically and electrochemically inert.
Prime1
”In Li-ion batteries, very small spheroids do provide high power, because of their large surface area per kg. The trouble is that they also rapidly build up an impermeable layer on the surface, which stops them working after a few charge-discharge cycles. So the battery makers use spherical graphite with a spheroid diameter of between 15 and 25 microns, as a compromise, depending on the application. If a device will only be charged ten or twenty times in its lifetime, then they use the smaller sizes. If the batteries are for cars, it's a different story. Tesla would be very unhappy if their vehicles littered the sides of the freeway, due to failed batteries, when they were only a month out of the showroom. So electric vehicles use spherical graphite with about 23 micron diameter spheroids.”
2012 Research paper
“However, synthetic graphite is still the dominant one available on the market because of the electrochemical properties of other kinds of anode materials are not viable for practical applications. Nature graphite (NG) has been paid much attention for its low cost compared to synthetic graphite [1]. NG is endowed with inartificial graphitic structure during the natural evolution instead of heat-treatment at high temperature (2800oC). Unfortunately, NG anodes cannot be applied for commercial lithium-ion batteries for its large irreversible capacity loss and poor cycling [2-4], which are mainly caused by the high anisotropy of the graphite surface [5], imperfect structures such as sp3-hybridized carbon atoms, carbon chains and edge carbon atoms [6] and some impurities [7]. These structural characteristics result in profound difference in chemical and electrochemical reactivity, interaction with the solid electrolyte interphase (SEI), kinetics for lithium intercalation and de-intercalation of the basal plane and the edge plane of the graphite [8], leading to the decomposition of electrolyte molecules to produce large irreversible capacity and cycling performance deterioration”
As I’m sure you as a SYR holder (NG) would agree battery technology is rapidly changing and it is now possible to utilise NG in battery applications as a “cheaper” substitute to for synthetic. This interchangeability has come about largely due to an increased understanding of SEI layers. The SEI layer plays an essential role within a battery, without it the electrolyte would erode the graphite. The SEI layer is formed in the initial charge cycle and passivates the graphite particle, one of the primary reasons that spherical graphite is needed is to allow surfaces the required clean contact area to build this protective layer, without a complete SEI layer on the first pass the layer can build up inconsistently and too thick, restricting the lithium intercalation rates. To overcome the adverse effects of thick SEI layers historically you are correct in that larger particles were needed.
More recently the SEI layer understanding has improved leading to advances in chemistry and additives such as vinylene carbonate are used in the electrolyte to prevent graphite exfoliation of the carbon during cycling. Spherical graphite coatings are another enabler of technology improvements. This understanding has allowed battery chemists to utilise smaller particles with increased surface areas to improve charge densities without reducing cycle life.
In summary the same technological advances in electrochemistry that allow SYR to compete in the battery grade graphite space allow HZR to excel.
