Nickel-manganese structured and multiphase composites as electrodes for hybrid supercapacitors
| Autor: | Antonia Stoyanova, M. Kalapsazova, L. Soserov, Radostina Stoyanova, T. Boyadzhieva, Violeta Koleva |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Supercapacitor
Materials science General Chemical Engineering Oxide chemistry.chemical_element 02 engineering and technology Electrolyte 010402 general chemistry 021001 nanoscience & nanotechnology Electrochemistry 01 natural sciences 0104 chemical sciences Electrochemical cell chemistry.chemical_compound Nickel Adsorption chemistry Hydroxide Composite material 0210 nano-technology |
| Zdroj: | Electrochimica Acta. 283:1063-1071 |
| ISSN: | 0013-4686 |
| DOI: | 10.1016/j.electacta.2018.06.191 |
| Popis: | Hybrid supercapacitors with the composite electrode materials display high energy density at the expense of the reduced cycle stability. Herein, we provide new data on the electrochemical performance of hybrid electrodes based on mixed nickel hydroxides/manganese oxides in the form of structured and multiphase composites. As structured composites, two types of less known structure modifications are examined: interstratified modification of Ni(OH)2 (i.e. α/βIS-Ni(OH)2) and e-modification of MnO2. The multiphase hydroxide/oxide composites are prepared by the conventional grinding of α/βIS-Ni(OH)2 and e-MnO2 and by the in-situ formation after the reaction of layered Na0.5Ni0.5Mn0.5O2 with mixed LiOH-KOH electrolyte. The structure, morphology and porous texture properties of composites are analyzed by means of powder X-ray diffraction, scanning electron microscopy (SEM) and low-temperature nitrogen adsorption, respectively. The electrochemical performance of composites electrodes is determined by galvanostatic experiments in concentrated individual KOH and mixed LiOH-KOH electrolytes. The ex-situ X-ray diffraction is used to monitor the changes in composite electrodes during electrochemical cell function. It has been found that α/βIS-Ni(OH)2 participates in electrochemical reaction concomitantly with H2O and Li+ intercalation, while the electrochemical performance of e-MnO2 is determined by surface adsorption of electrolyte alkaline ions. The best electrochemical performance (in terms of discharge capacity, rate capability and cycling stability) is achieved for α/βIS-Ni(OH)2 especially when it works in mixed LiOH-KOH electrolyte. In alkaline electrolyte solution, layered Na0.5Ni0.5Mn0.5O2 is transformed into a phase mixture between slightly sodium deficient oxide Na0.5-xNi0.5Mn0.5O2 and α-type nickel hydroxide. Thus generated multiphase composite demonstrates the highest areal capacitance and a rate capability comparable with that for α/βIS-Ni(OH)2. |
| Databáze: | OpenAIRE |
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