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Gel and lithium-ion tech could enable 1000-mile EV range on one charge
(interestingengineering.com)
This is a most excellent place for technology news and articles.
When you work out how to do this in practice, it doesn't actually matter. You really should be stopping for ~20 minutes every few hours, anyway. Put in better charging infrastructure and there isn't much point to vehicles over 400 miles of range. Even 250mi is probably enough. Use further advancements to reduce weight, not push range further.
And before someone shows up who thinks nobody else has heard that batteries have shorter range in cold weather, yes, I'm accounting for that.