InSitu Growth of Zeolitic Imidazolate Framework-67-derived Nanoporous Carbon@K0.5Mn2O4 for High-Performance 2.4V Aqueous Asymmetric Supercapacitors

Aqueous asymmetric supercapacitors (ASCs) with a wide voltage window can effectively improve energy storage capacity of energy storage devices. Zeolitic imidazolate framework-67 (ZIF-67) was used as a precursor to prepare nanoporous carbon (NC), and K0.5Mn2O4 nanosheets were subsequently grown on the NC surface through a facile insitu redox process (denoted as NCMO). The electrode potential window of NCMO was extended to 1.2V in a three-electrode system and the value of the potential window was higher than that of most reported manganese oxides. To assemble the asymmetric supercapacitor with a high voltage range, the as-prepared NCMO and NC (with a potential window of -1.2-0V) were used as the positive and negative electrode, respectively. A 2.4V NCMO//NC aqueous ASC was constructed and displayed a large energy density of 60Whkg(-1) at a power density of 1200Wkg(-1) and excellent rate performance (41Whkg(-1) even at a specific power density of 12.3kWkg(-1)) as well as good cycling stability (92.6% capacitance retention over 10000cycles at 10Ag(-1)). This work provides new opportunities for the development of high voltage ASCs with a high energy density for further practical application.