But, as the article explains: “They have a weakness, however, in the relatively low quantity of energy that they can store, a property known as their energy density.”
The energy density disparity is huge for standard capacitors compared to physical batteries. You expect a battery to supply power for a matter of hours. Capacitors, on the other hand take on chores like taking the voltage ripple out of power supplies by charging and discharging over 100 times a second.
Even though these guys are improving the energy density, it is going to be a far cry from being able to supplant batteries for long haul operations.