A high over-potential binder-free electrode constructed of Prussian blue and MnO2 for high performance aqueous supercapacitors

摘要

Extending the potential window of aqueous supercapacitors (SCs) up to 2.0 V is still a great challenge.Based on their good dynamic structural reversibility and open framework structure,the coordination superamolecular networks (CSNs) exhibit rapid charge/discharge ability and excellent cycle stability.As a typical coordination superamolecular network (CSN),Prussian blue (denoted as CSN-PB),which self-assembled by the CN-ligand and iron ions is firstly in-situ grown on carbon cloth,followed by electro-deposition of MnO2 to form CSN-PB/MnO2 composite electrode.Benefiting from synergistic effect of the constituent components,as well as the open framework structure of CSN-PB,this composite electrode reaches a high potential window of 1.4 V (vs.Ag/AgCl) and delivers a good specific capacitance of 315.3 F·g-1 in aqueous electrolyte.An aqueous asymmetric device,constructed with CSN-PB/MnO2 composite as cathode and activated carbon as anode,can work in a stable potential window of 2.4 V,exhibits a high energy density of 46.13 Wh·kg-1 and excellent cycling stability with 85.5％ capacitance retention after 20,000 cycles.This work provides a new concept of high dynamic structural reversibility from CSNs to increase the cell voltage of asymmetric SCs for further boosting energy density.