Enhancement in the Electrochemical Performance of Strontium (Sr)-Doped LaMnO3 as Supercapacitor Materials

Abstract

In this study, Strontium (Sr)-doped perovskite lanthanum manganite (La1−xSrxMnO3) nanoparticles were prepared by the sol–gel method and used as electrode materials of supercapacitors. Microstructures, morphologies, and electrochemical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), a transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET) surface area measurements, cyclic voltammetry (CV), and galvanostatic charge/discharge (GCD) cycling. Investigations demonstrated that the La0.85Sr0.15MnO3 nanoparticles had a maximum specific capacitance of 185.5 F/g at a current density of 0.5 A/g and a low charge transfer resistance (0.38 Ω) in 3 M KOH aqueous electrolyte solutions. La0.85Sr0.15MnO3 electrode yields the highest capacitance behavior because of the larger specific surface area, lower charge transfer resistance, and higher concentration of oxygen vacancy. This result demonstrates that Sr doping significantly improved the electrochemical properties of the LaMnO3 system. The anion-intercalation mechanism was examined by a charge–discharge process. This provides a promising electrode material for supercapacitors.

Enhanced Electrochemical Performance of LaMnO3 Nanoparticles by Ca/Sr Doping

“…Doping causes a reduction in the average ionic radius at point A due to the larger ionic radius of La 3+ (1.06 Å) compared to Ca 2+ (0.99 Å). The presence of alternating long and short A-site cation radii can lead to a significant mismatch in the MnO 6 octahedra and a pronounced bending of the Mn-O-Mn bond angles [21,22,29]. This mismatch exerts a considerable influence on the orthorhombic structure, causing elongation along the c-axis due to the Jahn-Teller effect and amplifying the lattice distortion of the compounds [21,22,29].…”

“…The presence of alternating long and short A-site cation radii can lead to a significant mismatch in the MnO 6 octahedra and a pronounced bending of the Mn-O-Mn bond angles [21,22,29]. This mismatch exerts a considerable influence on the orthorhombic structure, causing elongation along the c-axis due to the Jahn-Teller effect and amplifying the lattice distortion of the compounds [21,22,29]. It is clear that replacing La 3+ with a smaller Ca 2+ reduces the lattice volume and thus increases the diffraction angle.…”

“…Pseudocapacitance relies on oxygen vacancies within perovskite as locations for storing charges [18]. The oxygen vacancies can be determined using neutron powder diffraction and X-ray photoelectron spectrometry [19][20][21][22]. According to the findings, it is primarily the pseudocapacitance resulting from the intercalation of oxygen anion that contributes significantly to the high specific capacitance of perovskite materials [1].…”

Establishing the correlation of negative permittivity and AC conductivity of La2−xSrxNiO4 (x = 0, 0.1, 0.3, 1.0) for microwave shielding applications

“…It is reported that La 2 NiO 4 is a p-type conductor. 27 If charge compensation occurs according to eqn (6), doping of Sr will generate more charge carriers, and hence conductivity will increase. On the other hand, a decrease in the activation energy with increasing Sr content is possible due to an increase in the number of hopping sites.…”

“…To address these limitations, researchers have shifted their focus toward exploring negative permittivity in homogeneous or single-phase materials. Negative permittivity has been reported in various single-phase materials: Sr-doped LaMnO 3 , [6][7][8] Mn-doped Sr 2 SnO 4 , 9 Nbdoped Sr 2 MnO 4 , 10 Sb-doped SnO 2 , 11 and Sn-doped In 2 O 3 . 12 We have put continuous efforts into exploring single-phase materials to achieve negative permittivity at room temperature in pristine (undoped) compounds.…”