Metal
sulfides are regarded as the most promising candidates for
sodium-ion battery (SIB) anodes because of their merits of high theoretical
capacity, stable redox reactions, and low-cost raw materials. However,
low electronic conductivity, sluggish ionic diffusion, and unstable
reaction interfaces have largely limited their practical applications.
To tackle these problems, a special pomegranate structure, composed
of many nitrogen-doped carbon-coated bimetallic sulfide nanoparticles
(FeS/NiS@NCS), is deliberated designed. When used as the anode of
SIBs, FeS/NiS@NCS has exhibited a high reversible capacity (668.7
mA h g–1 at 0.1 A g–1), a superior
cycling stability (414.6 mA h g–1 with 86.7% capacity
retention after 500 cycles at 1 A g–1), and a high
rate capability (251 mA h g–1 at 5 A g–1). Moreover, when paired with the cathode material of carbon-coated
Na3V2(PO4)2F3 (C-NVPF), the full cell delivers good cycle performances (65.07
mA h g–1 with 75.8% capacity retention after 100
cycles at 1 A g–1). Besides, the in situ X-ray diffraction
technique was performed to analyze its structural evolution, confirming
that the FeS/NiS@NCS anode undergoes a two-step reaction mechanism
(first Na+ insertion process and then phase conversion
reaction during the discharging process, conversion reaction, and
ionic extraction during the charging process).
Modified activated carbon/carbon nanotubes (AC*/CNT*) composite electrode was used as the electrode in a capacitive deionization (CDI) process for desalination in this study. The morphology and electrochemical characteristics of the modified electrode were discussed, and the results showed that after modification, the specific surface area of AC* reached 672.48 m2/g, increased by 29.43%; while the specific surface area of CNT* was 117.39 m2/g, reduced by 9.94% due to the strong oxidation of the mixed acid, the pore volume of CNT* increased by 48.28%. The electrode regeneration test proved that the electrode had good cycling stability. The pseudo-first-order kinetic model could better describe the adsorption rate of the electrodes for ions and the desalination ratio of the AC*/CNT* electrode reached 7.11 mg/g; the Langmuir model could well describe the adsorption mechanism of capacitive deionization, and indicated that the adsorption process of CDI was near to single ion layer adsorption; the change trend of electric mobility with migration time could be well fitted by exponential equations. This study explored a novel composite electrode coating, and initially explored the behavioral characteristics and trends of CDI technology.
Metal-organic coordination compounds (MCCs) have received a lot of attention as anodes for lithium-ion batteries (LIBs) due to their abundant structural configuration, tunable morphology, high surface area, and low cost, but the lithium storage mechanism of MCCs is still a mystery. Herein, we synthesized a kind of nickel-based coordination compound (marked as Ni-PP-x, x = 1, 2, or 3) with tunable morphologies and different solvent ratios via a microwave irradiation solvothermal method and then applied them as anodes for LIBs. Among them, the Ni-PP-2 electrode, with a hollow and urchin-like structure, showed the longest lifespan and maintained a high capacity of 713 mAh g−1 at 2.0 A g−1 after 800 cycles. Measured by ex situ X-ray photoelectron spectroscopy (XPS) and ex situ Fourier transform infrared spectroscopy (FT-IR), the Ni-PP-2 electrode was confirmed by a redox reaction mechanism of Li+ cations with a benzene ring and O-Ni2+/O-Ni0 coordination bonds, and the cyclic voltammetry curves have exhibited a capacitive dominated lithium storage behavior. This work provides a new type of Ni-based coordination compound and an in-depth understanding of their lithium storage mechanism, paving the way for the application of MCC compounds in the future.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.