Quinolinediol Molecule Electrode and MXene for Asymmetric Supercapacitors with Efficient Energy Storage
Long Jiao, Fuquan Ma, Xiaotong Wang, Zhimin Li, Zhongai Hu, Qing Yin
Abstract
Asymmetric supercapacitors (ASCs) need positive and negative electrodes to produce a larger redox peak position difference to achieve a higher energy density. Here, 2,8-quinolinediol (QD) is adopted to modify reduced graphene oxide (rGO) and prepare an organic molecule electrode (OME), in which the Faraday reaction occurs in a more positive potential range. The electrochemical tests show that the optimized OME (QD/rGO-0.75) releases a high special capacitance (371 F g–1 at 5 mV s–1) and exhibits an excellent rate capability (86.8% of the initial value at a scanning rate multiple of nearly 20 times). Meanwhile, an MXene (Ti3C2Tx) with a relatively negative potential is prepared. QD/rGO-0.75 and Ti3C2Tx are, respectively, used as positive and negative electrodes to assemble an ASC. The measurements indicate that the assembled ASC is able to store charge within a wide voltage window of 1.6 V in the 1 M H2SO4 electrolyte and exhibit better energy storage performance. Furthermore, the device delivers an excellent cycling stability (83.5%, over 10,000 cycles). The two series-connected devices can light 37 red light-emitting diodes, indicating their potential application.