@Scarpa as you know I always respect your contributions.The...

@Scarpa as you know I always respect your contributions.
The obvious positive of SSBs is that both the cathode and anode will require forms of lithium.
There is some debate as to whether a high Nickel Hydroxide based cathode (ie NMC811) will be the way to proceed, LiFePo4 (Carbonate) or even Li Sulfur variants.
On the anode front Li metal will be required which is produced from Lithium Chloride (LiCl)
There are several pathways to produce LiCl. As seen with Hydroxide production, spodumene has a comparative cost advantage over brine due to fewer steps. Thus it follows logically that the most economic solution will be a process that can achieve the desired level of purity with minimal steps.
LiCl is commonly described as being produced from Li2CO3 (Carbonate) using Hydrochloric Acid. LiOH.H2O (Hydroxide) can similarly be reacted with HCl to produce LiCl.
Many would know that Lithium Chloride is found in brines along with other various salts. Briners produce Li2CO3 from LiCl. It should be noted that while it is possible to directly produce LiCl suitable for conversion to Li metal, the carbonation step removes substantial impurities that may otherwise render the LiCl unsuitable for use in Li metal applications (boron is one such impurity of critical importance to remove).
That being said there are various techniques that have long been commercially available to purify the LiCl without undergoing the transition to Li2CO3.
What I consider to be one of the leading lithium extraction engineering firms Veolia discusses the process for suitable production of high purity Lithium Chloride from brine here:
http://www.veoliawatertech.com/news-resources/case-studies/hpd-lithium-chloride-argentina.htm
My understanding is that for Li metal production from hardrock the most cost effective method is to initially produce Lithium Carbonate, whereas from brine there are two options, either LiCl into Carbonate (for impurity removal) then back to LiCl or a dedicated process for the initial LiCl when Li metal is the intended final product.
There is certainly a point to be considered regarding the purity of LiCl and in some cases (depending on the source) high purity Lithium Hydroxide has been considered necessary to convert to Li Chloride and onto Li metal.
It is also relevant that Li2CO3 converted from spodumene concentrate tends to have fewer of the highly detrimental impurities for Li metal production.
I would note that some of the information regarding this requirement is dated as advancements have been made.
Here is an effective method of brine LiCl purification for Li metal usage patented in 1989
https://patents.google.com/patent/US4980136A/en
So in summary there is an argument as to whether brine or hardrock will be the preferred raw source for Li metal in SSBs.
To my mind both are similarly economically competitive to produce the required purity.
However the cathode component of the battery will also be of great importance.
Either way, the introduction of solid state batteries will be beneficial to all upstream producers due to the substantial percentage increase of Li in batteries.
Whatever the case may be, I will leave you with a screenshot from a fairly recent Benchmark Intelligence presentation demonstrating that it will take many years for facilities to be decommissioned once built (Capex spent) despite more advanced technological breakthroughs becoming mainstream or more desirable.