Anion-Based Pseudocapacitance of the Perovskite Library La_1–xSr_xBO_3−δ (B = Fe, Mn, Co)

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 allperovskite 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 .

A Systematic Study to Improve the Performance of SrCoO3 as anAnion-Intercalation-Type Electrode for Supercapacitors Through Interface, Oxygen Vacancies, and Doping

“…Other theoretical studies have also predicted that strontium cobaltite has the highest OER ability among all perovskites through DFT calculations 21 . This makes SrCoO 3 a good candidate for supercapacitors because oxygen vacancies increase conductivity, especially in anion-intercalation supercapacitors 26 .…”

Performance of asymmetric supercapacitor fabricated with perovskite‐type Sr 2+ ‐incorporated LaMnO 3 (La 0. 7 Sr 0 . 3 MnO 3 ) n

“…In both alkaline and neutral electrolytes, intercalation of ions with active sites plays the main role in charge storage. The redox reaction occurs in the present case can be expressed as 19 :…”

“…ABO 3 -type perovskites also possess the ability of rapid faradaic redox reaction at their surface, which enables them to be potential candidates for supercapacitor electrodes. 18,19 Moreover, ABO 3 -type perovskites with lanthanide or alkaline-earth elements as A and transition metals as B atom have intrinsic oxygen vacancies, which enable them to act as electrode material for supercapacitors via faradic redox reaction. Pseudocapacitive charge storage mechanism involves mainly three processes: (a) adsorption of electrolyte ions to form a monolayer over metal or metal oxide surface, known as underpotential deposition, (b) fast reversible redox reaction at the electrode surface, and (c) fast intercalation/deintercalation of electrolyte ions into bulk electrode.…”

Selective Effect of Gel Polymer Electrolytes on Suppressing Decomposition and Evaporation of Electrolyte in Acetonitrile‐Based Supercapacitors at Elevated Temperature

“…With the soaring demand for electrical energy storage in mobile devices, supercapacitors (SCs), which are driven by non‐faradaic charge‐discharge cycling, have been studied extensively for use in electric devices due to their high power density and long span life, despite having a lower energy density than lithium ion batteries (LIBs) . Many groups have struggled to develop superior SCs with extremely high rate performance by modifying the electrodes, enhancing the capacitance using novel redox active materials, or widening the cell voltage with improved electrolytes . In addition, considerable efforts have been made to produce stable cell performance under ambient conditions, such as freezing or hot circumstances, to satisfy myriad demands …”