Hollow sphere formation by the self aggregation of perovskite fluoride NaNiF3 nanocrystals and the application of these spheres as an electrode in an ultrahigh performance asymmetric supercapacitor

Abstract

Herein, we proposed a simple and cost-effective approach to synthesize perovskite fluoride (NaNiF₃) hollow spheres as well as the detailed formation mechanism of these hollow spheres. As an electrode for supercapacitors, the perovskite fluoride (NaNiF₃) hollow spheres exhibited a high specific capacitance (1342 F g⁻¹ at 5 A g⁻¹), excellent rate performance and a long cycle stability (more than 90% capacity retention after 8000 cycles). The NaNiF₃//AC asymmetric device displayed a wide voltage window (1.65 V) and delivered a maximum energy density (51.78 Wh kg^-1 at the power density of 1.65 kW kg⁻¹) with an excellent cyclic stability (100% capacity retention from 1400 to 10 000 cycles). The LED lighting further confirmed the high energy and power density of the ASC device.