Static battery technology is still very primitive and hence we see people using expensive portable batteries as a stand in for now. Using old EV batteries rather than mining them for lithium isn’t really going to be a solution for a long time.
People are looking into all sorts of technologies, even supercapacitor bricks.
Larger scale the electricity generators have been looking at flow batteries.
As Ian says, none of these technologies currently make financial sense when compared to charging the car from the Grid on a cheap overnight tariff. Worth noting that during the recent heat & low winds the gas generators became less efficient and a coal fired power station needed to be fired up.