Evaluating the mechanism and the capacitive properties of nickel boride electrodes for supercapacitor applications

Mehtap Arslan-Kaba, Servet Timur, Guldem Kartal Sireli*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

This study investigates the electrochemical properties of nickel boride electrodes produced via a novel molten salt boron diffusion method; known as cathodic reduction and thermal diffusion-based boriding (CRTD-Bor). Pure nickel substrates with two different geometries (i.e. flat and foam) were borided in the borax-based electrolyte. The presence of nickel borides, composed of NiB, Ni4B3 and Ni2B with the order locations from the surface towards the matrix, was confirmed by X-ray diffractometry (XRD) and scanning electron microscopy (SEM) attached with electron probe microanalyzer (EPMA). The electrochemical behaviors of the produced electrodes were inspected through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), as well as impedance spectroscopy (EIS). The areal capacitances of the electrodes were calculated as 478 and 1385 mF/cm2 for flat and foam samples, respectively after the 2000th cycle of CV at 10 mV/s scan rate. The reaction kinetic followed the mixed-controlled model according to the Trasatti approach. The capacitive contribution (Co) measured in flat samples was 71 %; whereas, it was found as 40.6 % in the foam-shaped electrodes. Additionally, the mechanism behind the faradaic reactions was explored through X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) which were conducted both before and after the CV experiments. The obtained results showed that the possible mechanism was related to the formation of Ni[sbnd]O bonds due to the oxygen saturation in the defective regions of the surfaces during electrochemical testing. Moreover, the importance of the electrode geometry on the performance was determined by the fact that the porous structure leads to more energy storage and favors a fast charge-discharge trend.

Original languageEnglish
Article number113299
JournalJournal of Energy Storage
Volume99
DOIs
Publication statusPublished - 1 Oct 2024

Bibliographical note

Publisher Copyright:
© 2024 Elsevier Ltd

Keywords

  • CRTD-Bor boriding
  • Electrochemical characterization techniques
  • Nickel boride electrode
  • Supercapacitors
  • Trasatti method

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