We don’t need magic battery tech. Current PV + Batteries can already 24/7 power cheaper than nuclear. It’s only vs fossil fuels where batteries have trouble.

China is building nuclear because they are building everything, but they are effectively building 3x as much solar and 7x as much wind because nuclear just costs more than any other option.

From 2020-2022 China increased generation power by:

   51,600 GWh/year Nuclear
  156,600 GWh/year Solar 
  357,500 GWh/year Wind

Currently they get as much power from solar as nuclear and twice as much from wind. In total they are 34% renewable vs 5% from nuclear. It’s the US that’s heavily invested in Nuclear not China.