Electroactivated Modulation of Highly Aligned Manganese-Doped Cobalt Sulfide Nanoplate Arrays for High-Performance Hybrid Supercapacitors

Abstract

Transition-metal sulfides have been identified as one of the promising cathode materials of battery type for hybrid supercapacitors (HSCs). However, there are still huge obstacles to their practical applications due to the major problems of poor structural stability and limited redox active sites. In this work, a high-performance cathode material based on three-dimensional porous Mn-doped Co 9 S 8 nanoplate arrays (Mn-Co 9 S 8 NPAs) on Ni foam has been synthesized via a facile electroactivation-modified metal−organic framework selftemplating sulfurization strategy. It has been found that the introduction of Mn 2+ ions can guarantee the structural integrity of the nanoplate arrays and effectively reduce the electron density near Co sites. By the synergistic modulation of the geometric and electronic structures, the Mn-Co 9 S 8 NPAs electrode delivers an ultrahigh capacity of 569.4 mAh g −1 (4099.7 F g −1 ) at 1 A g −1 with superior cycling stability. An HSC assembled with the electrode materials exhibits a high energy density of 73.1 Wh kg −1 at a power density of 737.5 W kg −1 and yields a 98.2% capacitance retention after 5000 cycles, indicating robust cycling stability as well. This work demonstrates a doping engineering strategy to regulate the physicochemical properties of metal sulfides for efficient energy-storage and conversion applications.

M2+-Doped Nickel Selenide Nanoflowers (M = Co, Cu, and Zn) for Supercapacitors

“…As shown in Figure S7b, the diffusion-controlled contribution of the Co x Ni 1– x Se electrode is 85.7, 81.1, 75.5, 71.4, and 67.7% at 10, 20, 40, 60, and 80 mV s –1 , respectively. These results can further verify that the Co x Ni 1– x Se electrode exhibits a greater diffusion-controlled battery-type behavior than the capacitive behavior …”

“…Accordingly, the fitted cathodic b values for NiSe and Co x Ni 1– x Se are about 0.56 and 0.54, respectively, which confirm the battery-type diffusion-controlled behavior . The ratio of diffusion-controlled and capacitive contribution can be quantitatively calculated according to Power’s law . As shown in Figure S7b, the diffusion-controlled contribution of the Co x Ni 1– x Se electrode is 85.7, 81.1, 75.5, 71.4, and 67.7% at 10, 20, 40, 60, and 80 mV s –1 , respectively.…”

“…With the scan rates increasing, the anodic and cathodic peak current densities of Co x Ni 1– x Se quickly rise and drop, respectively, indicating a reversible and fast redox reaction with a relatively low resistance . The current ( I , mA) and scan rate ( v , mV s –1 ) usually follow a power-law relationship , : i = a v b in which a and b are adjusting constants. Based on the CV curves and eq , the fitting lines of log ( v ) versus log ( i ) curves are depicted and shown in Figure S7a.…”

NiCo-OH Nanosheets Coated with NiCoS Nanosheets for Supercapacitors and Alkaline Zinc Batteries

“…Among them, the synthesized electrode material NiCoS/NiCo-OH shows the lowest R ct value, which indicates that its reverse bias interface connection facilitates the charge transfer between the surface of the electrode material and the electrolyte. The Nyquist plot of NiCoS/NiCo-OH shows a nearly vertical straight line in the low-frequency region, implying that it has a low Weber impedance (a smaller ion diffusion resistance) …”