Anion-Based Pseudocapacitance of the Perovskite Library La 1- x Sr x BO 3-δ (B = Fe, Mn, Co)

Caleb T. Alexander, J. Tyler Mefford, Jennette Saunders, Robin P. Forslund, Keith P. Johnston, Keith J. Stevenson

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    37 Citations (Scopus)

    Abstract

    We have synthesized a library of perovskite oxides with the composition La 1-x Sr x BO 3-δ (x = 0-1; B = Fe, Mn, Co) to systematically study anion-based pseudocapacitance. The electrochemical capacitance of these materials was evaluated by cyclic voltammetry and galvanostatic charging/discharging in 1 M KOH. We find that greater oxygen vacancy content (δ) upon systematic incorporation of Sr 2+ linearly increases the surface-normalized capacity with a slope controlled by the B-site element. La 0.2 Sr 0.8 MnO 2.7 exhibited the highest specific capacitance of 492 F g -1 at 5 mV s -1 relative to the Fe and Co oxides. In addition, the first all-perovskite asymmetric pseudocapacitor has been successfully constructed and characterized in neutral and alkaline aqueous electrolytes. We demonstrate that the asymmetric pseudocapacitor cell voltage can be increased by widening the difference between the B-site transition metal redox potentials in each electrode resulting in a maximum voltage window of 2.0 V in 1 M KOH. Among the three pairs of asymmetric pseudocapacitors constructed from SrCoO 2.7 , La 0.2 Sr 0.8 MnO 2.7 , and brownmillerite (BM)-Sr 2 Fe 2 O 5 , the BM-Sr 2 Fe 2 O 5 //SrCoO 2.7 combination performed the best with a high energy density of 31 Wh kg -1 at 450 W kg -1 and power density of 10 000 W kg -1 at 28 Wh kg -1 .

    Original languageEnglish
    Pages (from-to)5084-5094
    Number of pages11
    JournalACS Applied Materials and Interfaces
    Volume11
    Issue number5
    DOIs
    Publication statusPublished - 6 Feb 2019

    Keywords

    • asymmetric
    • intercalation
    • La Sr CoO
    • La Sr FeO
    • La Sr MnO
    • perovskite
    • pseudocapacitor

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