Sineng Electric's 50 MW/100 MWh sodium-ion battery energy storage system (BESS) project in China's Hubei province is the first phase of a larger plan that will eventually reach 100 MW/200 MWh. The initial capacity has already been connected to the grid and can power around 12,000 households for an entire day.
According to a paper published in 2020 here, the specific energy and energy density are in line with what you are saying. But according to the article that Wikipedia cited here, sodium batteries show the opposite.
You’re probably right but it looks like there’s conflicting info about this currently.
I talked to an energy engineer about it, and I’m pretty sure it’s what he said. Would also make sense when China use it like this.