Why wouldn't recycling be an option? Chances are that, if large batteries become commonplace, it will be cheaper to mine lithium from used batteries than to do so from the earth because they will have very high lithium content.
Also, covering 1/3 of daily use seems low to me. It wouldn't get one through a few windless winter days with dense cloud cover, for example.
Is it possible that perfect is the enemy of good here? You could choose a lower ratio of battery storage to average use and just use non-carbon neutral peaker plants for the few days in winter where there's a shortfall of renewable energy. Still a huge boost to renewable energy, still a huge reduction in carbon emissions.
Extraction of lithium from old batteries is five times more expensive as mining lithium. At some point it may become profitable.
On the other hand, there is lots of lithium. If the environmental impact of lithium mining going off the roof is not a problem, there is no reason to reuse.
>Extraction of lithium from old batteries is five times more expensive as mining lithium.
Even as an upper bound that's still a silly thing to say. It means comparing a lab-scale extraction with massive multinational, highly-automated mining operations. At scale lithium recycling would certainly be much cheaper than five times more expensive.
Also, covering 1/3 of daily use seems low to me. It wouldn't get one through a few windless winter days with dense cloud cover, for example.