(603g) Cof Used As Cathode for High Performance Asymmetric Supercapacitors

Asymmetric supercapacitors (ASC) with high specific capacitance of electrodes, which operates at high voltage, can solve the low energy density (E) problems which exist in the symmetric supercapacitors. Asymmetric supercapacitors employing two different electrode materials with a large redox peak position difference as negative and positive electrodes, can effectively overcome the thermodynamic limitation of solvent molecules in electrolytes. Carbon-based electrode materials, especially covalent organic framework (COF) connecting with redox-active carbonyl-containing organic molecules (carboxylate, quinone and ketone) have attracted much attention in ASCs for the features of relatively low-cost, chemical and structural diversity, rich oxidation/reduction conversion sites and fast reaction kinetics. We synthesized a series of COFs mixed with graphene (GN), which increase the conductivity to around 1000-fold, as well as show a high specific capacitance at ~ 1000 F/g in three electrodes system. In addition, MXene nanosheets was synthesized through etching MAX with HF, and was used as the anode, which demonstrates a stable performance of 600 F/g in wide CV scanning ranges. The ASCs device was assembled by applying COFs mixed with GN as positive electrode and MXene as negative electrode, which was able to increase the window voltage to around 0-2 V, and demonstrated higher energy density and power density than classic symmetric supercapacitors using carbon electrodes.