>IANAchemist, but this makes me wonder if there's some other chemistry out there, either undiscovered or deemed uneconomic, that offers even better performance than lithium.
There are, but of course there's tradeoffs. Lithium is the best all around cathode choice for economical reasons, but Sodium and Potassium are being explored as well. The real gains can be found in new electrolyte chemistries, though. My money is that we will be using lithium for the foreseeable future, and that advances in electrolyte chemistry will get us to the $100/kWh point.
I wonder what the problems with sodium and potassium are. Sodium, for one, is an extremely common element on Earth's surface, which I can't say for Lithium. Potassium is also very common. You can get all the sodium you could possibly want just by drying out seawater. By contrast, lithium supply seems to be limited to a few places such as Bolivia.
There are, but of course there's tradeoffs. Lithium is the best all around cathode choice for economical reasons, but Sodium and Potassium are being explored as well. The real gains can be found in new electrolyte chemistries, though. My money is that we will be using lithium for the foreseeable future, and that advances in electrolyte chemistry will get us to the $100/kWh point.