Porous NiCo2O4 as an anode material for 4.5 V hybrid Li-ion capacitors

A novel hybrid Li-ion capacitor has been constructed with a porous NiCo2O4 anode and an activated carbon cathode. The capacitor exhibits an ultrahigh working voltage of 4.5 V, good Ragone performance (39.4 W h Kg−1, 554 W Kg−1) and excellent cycling behavior (no energy loss after 2000 cycles).