Actually CATL the largest EV Battery manufacturer in the World...

Actually CATL the largest EV Battery manufacturer in the World is already using it,
And even with the high price of Rubidium,
Sodium-Ion Batteries are still Cheaper than Lithium.
Cherry and BYD will also be using them.

Not sure people are understanding the Size of CATL,
BYD or Cherry.
The Chinese EV Market is Huge,
And CATL also supplies Tesla.

From an article:
"The energy density of CATL’s sodium-ion battery cell can achieve up to 160Wh/kg, and the battery can charge in 15 minutes to 80% SOC at room temperature. Moreover, in a low-temperature environment of -20°C, the sodium-ion battery has a capacity retention rate of more than 90%, and its system integration efficiency can reach more than 80%. The sodium-ion batteries’ thermal stability exceeds the national safety requirements for traction batteries. The first generation of sodium-ion batteries can be used in various transportation electrification scenarios, especially in regions with extremely low temperatures, where its outstanding advantages become obvious. Also, it can be flexibly adapted to the application needs of all scenarios in the energy storage field. "

It's not just EV Batteries,
But Grid Storage and Smoothing,
For use with Solar,
And other forms of Green Energy Etc.

Another source states that sodium-ion batteries could cost around USD$40-77/kWh, whereas lithium-ion sits currently at around USD$138/kWh (AUD$205/kWh).

Anyhow with CATL starting mainstream use,
In EV's this year,
With brands that have huge amounts of sales,
Demand for Rubidium will increase.

Many sources have suggested that both Sodium-Ion and Lithium,
Will be required for the transition to green energy.