I assume you're using "performance" to mean "kwh/kg", which is a bit of a narrow view. Even if they had have the gravimetric energy density, grid storage doesn'

I assume you're using "performance" to mean "kwh/kg", which is a bit of a narrow view. Even if they had have the gravimetric energy density, grid storage doesn't care about that. With an annual growth rate of 60~80% in the CAISO grid there's plenty of places to put lower density but safer batteries.