Lithium Shortage
may help pave the way for VRFBs in utility-scale applications.
"Benchmark forecasts that lithium chemical supply will be in a deficit of over 300,000 tonnes [equivalent to 2019 global production] by 2030"
https://www.mining.com/carmakers-will-need-to-become-miners-benchmark/
Lithium is essential for mobile applications whereas its favourable capacity/mass ratio is not much of a factor in stationary applications.