Synthesis, structure and electrochemical properties of lanthanum manganese nanofibers doped with Sr and Cu

La x Sr 1 − x Cu 0.1 Mn 0.9 O 3 − δ (LNF- x ) (0.1   ⩽   x   ⩽   1) nanofibers are prepared by electrospun method. The structure of LNF- x and the electrochemical properties of LNF- x in 1   M Na 2 SO 4 aqueous electrolyte are investigated. As a result, LNF- x nanofibers present a perovskite structure, and the LNF-0.5 sample exhibits the highest specific capacitance value of 464.5   F   g − 1 at a current density of 2   A   g − 1 . The maximum energy density of 64.5   W   h   kg − 1 are achieved at a power density of 2   kW   kg − 1 for the symmetric supercapacitor prepared by La 0.5 Sr 0.5 Cu 0.1 Mn 0.9 O 3 − δ nanofibers. More importantly, this symmetric supercapacitor also shows an excellent cycling life after 2000 charging and discharging cycles. Those results offer a suitable design of electrode materials for high-performance supercapacitors.