RE: Silicon battery?18 Jul 2019 09:28
somtam - if you compare this with the complexity of this idea with scaling energy storage in a vanadium flow battery (take V2O5, dissolve in Sulphuric acid, pour into tank) you will see just what a nonsense their thing is. Cripes it doesn't even scale into the second dimension well as wafers can be made only so big - at the recent intersolar exhibition I was interested to see a 4m long 300mm diameter boule of silicon that is used to make PV panels. Out of this they get about 4000 wafers of c. 0.7mm thick (i.e. 30% already lost). I was told that the boule costs around $1M - so around $250 per wafer from this estimate.
How does this compare with other published data ? - Well https://semiengineering.com/mixed-outlook-for-silicon-wafer-biz/ shows 2018 production of 12,700 Million square inches at a cost of 11 Billion dollars - So roughly 12e9 Square inches for 12e9 dollars - or a dollar per square inch. A 12 inch wafer is about 110 square inches so $110 dollars - so we're looking at 100-250 dollars per single wafer.
How many wafers might they require for, say a car, even if they could get 4 times the energy density. Well the battery pack on a tesla weighs 540Kg, so if you only had, say 125Kg of silicon wafers, how many would this be ? Well a standard 300mm wafer is 125g ( https://en.wikipedia.org/wiki/Wafer_(electronics) ) so this brings us precisely to the 1000 wafer mark. That's already $100,000 before you have even though about etching them or adding anything else to them.
These claims are about as credible as wishing for a unicorn.