Self-templated hollow nanospheres of B-site engineered non-stoichiometric perovskite for supercapacitive energy storage via anion-intercalation mechanism

• Published in: Journal of colloid and interface science Vol. 600; pp. 729 - 739
• Main Authors: Iqbal, Sarmad, Mady, Amr Hussein, Kim, Young-Il, Javed, Umer, Shafi, P. Muhammed, Nguyen, Van Quang, Hussain, Iftikhar, Tuma, Dirk, Shim, Jae-Jin
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.10.2021
• Subjects: Anion-intercalation; Hollow nanospheres; Non-stoichiometric perovskite; Ostwald ripening; Peroxide pathway; Supercapacitor; Anion-intercalation; Peroxide pathway; Supercapacitor; Non-stoichiometric perovskite; Ostwald ripening; Hollow nanospheres
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2021.03.147

[Display omitted] •Hollow spheres of non-stoichiometric perovskite KNi1-xCoxF3-δ K (x = 0.2; δ = 0.33) were synthesized via Ostwald ripening during solvothermal treatment.•The as-synthesized perovskite yielded a specific capacity/capacitance of 714.8 C g−1 (1435 F g−1) at 1 A g−1 based on anion-intercalation mechanism.•The as-prepared asymmetric supercapacitor delivered an energy density of 40 Wh kg−1 with an excellent cyclic stability of 98% for 10,000 cycles. The continual increase in energy demand and inconsistent supply have attracted attention towards sustainable energy storage/conversion devices, such as electrochemical capacitors with high energy densities and power densities. Perovskite oxides have received significant attention as anion-intercalation electrode materials for electrochemical capacitors. In this study, hollow nanospheres of non-stoichiometric cubic perovskite fluorides, KNi1−xCoxF3−δ (x = 0.2; δ = 0.33) (KNCF-0.2) have been synthesized using a localized Ostwald ripening. The electrochemical performance of the non-stoichiometric perovskite has been studied in an aqueous 3 M KOH electrolyte to categorically investigate the fluorine-vacancy-mediated charge storage capabilities. High capacities up to 198.55 mA h g−1 or 714.8 C g−1 (equivalent to 1435 F g−1) have been obtained through oxygen anion-intercalation mechanism (peroxide pathway, O-). The results have been validated using ICP (inductively coupled plasma mass spectrometry) analysis and cyclic voltammetry. An asymmetric supercapacitor device has been fabricated by coupling KNCF-0.2 with activated carbon to deliver a high energy density of 40 W h kg−1 as well as excellent cycling stability of 98% for 10,000 cycles. The special attributes of hollow-spherical, non-stoichiometric perovskite (KNCF-0.2) have exhibited immense promise for their usability as anion-intercalation type electrodes in supercapacitors.