Sr-doped Lanthanum Nickelate Nanofibers for High Energy Density Supercapacitors

The series La x Sr 1−x NiO 3−δ (0.3≤x≤1) nanofibers (LNF-x) samples are prepared by using electrospun method. We investigate the structure and the electrochemical properties of LNF-x in detail. As a result, LNF-x nanofibers present a perovskite structure, and the LNF-0.7 sample with high specific surface area display remarkable performance as an electrode material for supercapacitors. The maximum specific capacitance value of 719   F·g −1 at a current density of 2   A·g −1 , which retains 505   F·g −1 at a high current density of 20   A·g −1 , is obtained for LNF-0.7 electrode in 1   M Na 2 SO 4 aqueous electrolyte. Moreover, the LNF-0.7//LNF-0.7 symmetric supercapacitor device using 1   M Na 2 SO 4 aqueous solution is successfully demonstrated. The capacitor device can operate at a cell voltage as high as 2   V, and it exhibits an energy density of 30.5   Wh·kg −1 at a high power density of 10   kW·kg −1 and a high energy density of 81.4   Wh·kg −1 at a low power density of 500   W·kg −1 . More importantly, this symmetric supercapacitor also shows an excellent cycling performance with 90% specific capacitance retention after 2000 charging and discharging cycles. Those results offer a suitable design of electrode materials for high-performance supercapacitors.