To further demonstrate the potential for practical application,
we assembled two supercapacitors in series to light a red lightemitting
diode (LED). As shown in Fig. 6c, two asymmetric supercapacitors
after charging for only 15 s to 3.2 V are capable of power
a red LED. Even after 5 min the red LED still remained bright,
indicating their high energy storage (Fig. 6d).