Influence Of Calcium Doping On Performance Of LaMnO₃ Supercapacitors

Among energy storage systems,supercapacitors have attracted great attention in recent years due to their fast charge–discharge characteristics,high power density,and excellent cycle stability.Electrode materials,which are one of the key factors affecting the electrochemical performance of supercapacitors,have become the subject of intensive study.Electrode materials mainly can be divided into carbon materials,excessive metal oxide materials,conductive polymer materials.Transition metal oxide electrode materials have a higher energy density than carbon materials and have better electrochemical stability than conductive polymers.Among many transition metal oxides,perovskite structure electrode materials are confirmed for the electronic and ionic conductivity requirements of supercapacitor electrodes due to their high specific capacitance and large potential window.In this paper,the series Ca-doped lanthanum manganite perovskite(La_1-xCa_x MnO₃,LCM)as electrode materials for supercapacitor were prepared via an improved sol-gel method.The microstructure,morphology and electrochemical properties of the samples were systematically studied through X-ray diffraction（XRD）,scanning electron microscopy（SEM）,Brunauer-Emmett-Teller（BET）surface area measurements and CHI660E workstation,respectively.The effect of Ca²⁺doping on the electrochemical properties of lanthanum manganite perovskite was explored.Among all component materials,the LCM050 has the lowest intrinsic resistance of 2.13?·cm² and the largest specific surface area of 23.0 m²·g^-1.The maximum specific capacitance delivers to 170F·g^-1 at a current density of 1 A·g^-1 in 1M KOH.However,all the Ca-doped lanthanum manganite perovskite as electrode materials showed bad cycle stability.To clarify this phenomenon,the charge storage mechanism of LCMs and the leaching of elements in alkali solution were further discussed.This charge storage mechanism further extended the anion charge storage of oxygen intercalation and adsorption in low valence elements doped perovskites.The surface redox reaction of Mn²⁺/Mn³⁺and Mn³⁺/Mn⁴⁺that occured in the electroactive material wad further promoted by the introduction of the low-valent cation of A site.Finally,LCM050 was assembled into symmetrical device,the maximum energy density of 7.6 Wh·kg^-1 was achieved with a power density of 160W·kg^-1.