NxCyMz metal hydroxide with Br− intercalation for high-performance structural supercapacitors

Abstract

The rational design of advanced structural electrodes with superior electrochemical capacitive properties is one of the crucial hindrances be overcome for high energy density all-solid-state structural supercapacitors (ASSC). Herein, a simple synthesis of flower-like NxCyMz-layered metal hydroxides with high performance on nickel foam (NF) was proposed. Br− was inlaid to NxCyMz as a modified anion for the first time (denoted as B-N3C1M0.5-6U-1Br−). Compared with N3C1M0.5, the electrochemical performance of B-N3C1M0.5-6U-1Br− has been significantly enhanced. It reaches a maximum areal capacitance of 16.2 F/cm2 at 10 mA/cm2 and maintains a high capacitance retention of 11.6 F/cm2 even at a current density of 50 mA/cm2. Furthermore, the assembled asymmetric ASSC with B-N3C1M0.5-6U-1Br− as the positive electrode achieves a high areal energy density of 135.47 μWh/cm2 at a power density of 2250 μW/cm2. More importantly, six fully charged ASSCs with a total volume of 3 cm3 connected in series can power a temperature and humidity indicator successfully for approximately 18 min. These results demonstrate the good application potential of our B-N3C1M0.5-6U-1Br− electrode in buildings.