Effect of Pd doping on the structural properties and supercapacitor performance of La0.8Sr0.2Cu0.7Mn0.3O3 and La0.8Sr0.2Cu0.4Mn0.6O3 as electrode materials

•LSCM0.3, LSCM0.6, LSCMP0.3 and LSCMP0.6 were prepared for investigation as supercapacitor electrodes.•The presence of a larger amount of Mnn+ cation with high oxidation states in the B site led to an increase in surface active points and an improvement in the electrochemical performance of LSCM0.6 compared to LSCM0.3.•Obtained high capacitance of 113 F.g−1 for LSCMP0.6 at a discharge current density of 1 A g−1.•LSCMP0.6 // LSCMP0.6 as a symmetric supercapacitor achieves high energy density of 63.28 W.h.kg−1 at 1000 W.kg−1.