Effect of strontium doping on the electrochemical pseudocapacitance of Y1−xSrxMnO3−δ perovskites

• Published in: Physical chemistry chemical physics : PCCP 2022-12, Vol.25 (1), p.326-340
• Main Authors: Abhay Narayan Singh, Nigam, Krishna Gopal, Mondal, Rakesh, Kushwaha, Vishal, Gupta, Asha, Rath, Chandana, Singh, Preetam
• Format: Article
• Language: English
• Subjects: Activated carbon; Aqueous electrolytes; Aqueous solutions; Discharge; Doping; Electrochemical analysis; Electrodes; Electrolytes; Energy storage; Energy technology; Hopping conduction; Impedance method; Perovskites; Redox reactions
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d2cp03310k

Grid-scale bulk energy storage solutions are needed to utilize the full potential of renewable energy technologies. Pseudocapacitive electrochemical energy storage can play a vital role in developing efficient energy storage solutions. The use of perovskites as anion intercalation-type pseudocapacitor electrodes has received significant attention in recent years. In this study, Sr-doped YMnO3i.e. Y1−xSrxMnO3−δ perovskite was prepared by the solid-state ceramic route and studied for electrochemical pseudocapacitance in aqueous KOH electrolyte. Microstructures, morphologies, and electrochemical properties of these materials were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance method. The formation of the mostly cubic phase, with 50% strontium doped YMnO3 (YSMO-50) provides an equivalent three-dimensional network and superior conductivity due to Mn3+–O2−–Mn4+ hopping conduction. YSMO-50 exhibited low intrinsic resistance, 1.45 Ω cm−2, and the highest specific capacity, 259.83 F g−1 at a current density of 1 A g−1 in 2 M KOH aqueous electrolyte. Redox-mediated interconversion of oxide to hydroxide (M2+O2− + H2O + e− ↔ M+OH− + OH−) in aqueous media is shown to be the reason behind the high capacitance of YSMO-50. The excellent electrochemical performance of YSMOs was attributed to the reversible interconversion of oxide-ion into hydroxide ion coupled with surface redox reaction of Mn2+/Mn3+ and Mn3+/Mn4+ occurring during the charge–discharge process. The maximum energy density of 65.13 W h kg−1 was achieved at a power density of 0.45 kW kg−1 for an asymmetric mode, in which YSMO serves as a negative electrode and Activated carbon (AC) as a positive electrode in the PVA–KOH gel electrolyte. Our study reveals that the doping of low valence atom (Sr) at the A-site in perovskite manganites (YMnO3) may be an effective tool to enhance the pseudocapacitive performance of perovskite-based electrodes.