Plastic batteries, $62/kW/h (Lithium battery $130/kWh), full loading 5 minutes, no toxic, no inflamable, 95% to recycle, higher energy potential,.
Lightweight, but 2-5 times bigger (yet), because of this in the moment no usefull for cars or smartphones, but for energy storage in buildings with solar cells or similar use.
See also
I add the independence of third countries, such as China, for the Lithium