Sounds like the Tesla wall batteries might be using Na in two or three generations.
Don't bet on any technology unless you're a gambler! There's no magic bullets, and the choice of battery in the Tesla Powerwall is driven by Tesla's needs in automotive applications, rather than the optimal tech for static batteries. Considerations of duty cycling, maximum power, operating conditions, mass and density, charge rate all differ.
Re-use of automotive batteries is worthy of consideration because static batteries have a charmed life compared to the brutal demands of traction use, so a cell that is no longer suitable for vehicle use may still have decades of life in a static array. The consideration is cost of alternative disposal options for the end of life traction batteries. I've seen well argued articles conclude that the incremental cost of disassembly, test and repurposing of traction batteries will be too costly to justify the effort as and when high volume cell recycling is available, and I think that's probably right - but we're not there yet.
Biting the hand that feeds IT
