Don't lithium-ion batteries degrade extremely quickly, though? Won't these all be down to half capacity or so within a decade?
Is it really worth investing in gargantuan quantities of energy storage if they need to be replaced every few years? I'd be eyeing EDLC technologies or something like molten salts over giant stationary phone/laptop/car/etc batteries.
Li-ion batteries have the second slowest self-discharge of any battery and the longest cycle life/easiest upkeep.
An li-ion battery will do about 500 discharge cycles from 0-100. They'll do several thousand from 20-80, and tens of thousands cycles from 30-70%. If you have a few days of storage, the battery as a whole will last an incredibly long time even when cycled every day.
As for why: When the battery is kept at a high or low voltage, it puts an overpotential on one side or the other of the battery. There's more or less lithium on one side of the battery and it tries to diffuse across the battery very slowly. It never makes it to the other side and reacts with the electrolyte and is lost, reducing capacity.
The closer it is to 50%, the less lithium is pulled/pushed out into the electrolyte.
They degrade extremely quickly in the usage pattern of a typical consumer device (alternating between full charge and full discharge). They last fairly long if you keep them between 30% and 80% charge.
It's not the most long-lasting technology, but we replace most infrastructure every 20-years already. A 10 year lifetime wouldn't be that bad.
> They last fairly long if you keep them between 30% and 80% charge
wait. does that mean that, effectively, for a careful Tesla owner seeking to maximize battery life, most of the time her practical range will be roughly 70% of the stated value?
Is it really worth investing in gargantuan quantities of energy storage if they need to be replaced every few years? I'd be eyeing EDLC technologies or something like molten salts over giant stationary phone/laptop/car/etc batteries.