Solution combustion synthesis and electrospinning of La0.7Sr0.3Co0.5Mn0.5O3: Impact of morphology on electrochemical energy storage performance

초록

This study investigates the influence of solvent and morphology of perovskite on the electrochemical properties of La0.7Sr0.3Co0.5Mn0.5O3 (LSCoMn), a promising perovskite material for supercapacitor (SC) electrodes. LSCoMn powders were synthesized via the solution combustion method using dimethylformamide (DMF) and deionized (DI) water as solvents. Additionally, LSCoMn nanofibers (NFs) were fabricated via electrospinning, utilizing polyvinylpyrrolidone (PVP) as a polymer precursor. All samples were calcined at 800 degrees C for 3 h to achieve the desired perovskite crystalline phase. The effect of solvent on the structure and morphology was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray absorption near edge spectroscopy <bold>(</bold>XANES) analysis. Electrodes were prepared by coating the LSCoMn powders and by the direct deposition of NFs on Ni substrate during electrospinning and the impact of morphology on energy storage performance was studied in detail. XRD analysis confirmed the formation of a perovskite phase. SEM analysis of LSCoMn powders revealed an irregularly shaped morphology, whereas NFs exhibited a highly entangled fiber network, with an average diameter of similar to 130 nm and lengths extending several microns, obtained under an applied potential of 18 kV, a flow rate of 0.6 mLh(-1), and a chamber temperature of 25 degrees C. TEM analysis confirmed the similar morphology and high resolution (HR)-TEM validated the XRD analysis results. Electrochemical performance was assessed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) in 1 M KOH electrolyte. The LSCoMn (NFs) electrode exhibited a maximum specific capacitance (C-sp) of 542 Fg(-1) at 1 Ag-1, with an energy density of 27.07 Whkg(-1) and a power density of 0.30 kWkg(-1), significantly outperforming LSCoMn powders (412 Fg(-1) for LSCoMn synthesized in DI water). Furthermore, the NF-based electrode demonstrated excellent cyclic stability, retaining 91.6% of its initial capacitance after 5000 charge-discharge cycles. EIS measurements confirmed a low charge transfer resistance, indicative of efficient charge storage kinetics. LSCoMn (NFs) sample, when tested as an anode in asymmetric supercapacitor device, possessed energy density of 63.20 Whkg(-1) and power density of 2.40 kWkg(-1) at current density of 3 Ag-1. These findings establish LSCoMn (NFs) as a high-performance electrode material, exhibiting superior charge storage capability, high energy and power density, and excellent long-term stability, making it a promising candidate for next-generation SC applications.

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