Structure-Designed Synthesis of CoP Microcubes from Metal–Organic Frameworks with Enhanced Supercapacitor Properties

Abstract

Metal-organic framework-based supercapacitors have been widely recognized as the best energy storage devices for future portable electronic equipment. Herein, CoP- T ( T = 300, 350, and 400 °C) microcubes with a solid and hollow microstructure were successfully synthesized by low-temperature phosphorization of [CHNH][Co(HCOO)] precursor at desired temperatures. The morphology, structure, and composition of the prepared CoP-350 °C samples were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Hollow CoP-350 °C microcube has a larger specific surface area (25.9 m g) than that of solid ones (16.1 m g). When the two samples were used as electrode raw materials for supercapacitors, the hollow CoP-350 °C electrode exhibits better electrochemical performance (560 F g) than that of the solid one (427.6 F g) at a current density of 1 A g. The enhanced supercapacitor properties may be attributed to the large surface area and the unique hollow structure. Further, an asymmetric supercapacitor was prepared by employing the hollow CoP-350 °C microcubes as anode and N-doped graphene as cathode. It has a high rate capability (capacitance retention of 69% from 0.5 to 8 A g), a high energy density (21.4 W h kg at a power density of 373 W kg), and outstanding cycling stability (remained 81.2% after 6000 cycles).

Nanoporous CuCo2S4 Microspheres: A Novel Positive Electrode for High-Performance Hybrid Energy Storage Devices

“…EIS was further used to study the electrochemical behavior of the electrodes , and the Nyquist plots of the CCS and CCO electrodes are shown in Figure f. Generally, both CCS and CCO electrodes exhibit semicircle behavior at the high-frequency region followed by a straight line at low-frequencies that are related to the charge transfer resistance ( R ct ) and mass transfer resistances controlled by a diffusion process, respectively . The impedance plot of the CCS modified electrode exhibited a smaller semicircle with a real axis intercept ( R ct = 0.27 Ω) compared to that of CCO ( R ct = 0.46 Ω), verifying its lower internal resistance.…”

Porosity Engineering of MOF‐Based Materials for Electrochemical Energy Storage

“…Another study also suggests the advantage of the hollow structure. [ 194 ] Compared to solid CoP microcubes, the hollow structure allows for reduced charge‐transfer resistance due to facile ion transfer as well as abundant active sites, thus giving rise to excellent rate performance (560–324 F g −1 at 1–20 A g −1 ) and stability (91.2% capacity retention after 10 000 cycles).…”

High-rate transition metal-based cathode materials for battery-supercapacitor hybrid devices

“…Common battery-type transition metal compounds used as cathode materials, such as nickel oxide, 93 cobalt oxide, 25,94 nickel sulfide, 95,96 and cobalt phosphide, 97 usually behave poor electrical conductivity, slow ion diffusion, and bad cycling stability, thus inducing low rate performance. Such transition metal compounds with low rate performance are not able to meet the needs and greatly limit practical applications.…”