Open 3D structure of Ni2−xSnxP/C microflowers electrodes assisted by ion-exchange in metal-organic skeleton for battery-supercapacitor hybrids

Abstract

Transition metal phosphides are promising electrode materials for battery-type supercapacitors. Herein, the Ni2−xSnxP/C microflowers electrode materials are synthesized through ion-exchange of metal-organic frameworks and subsequent calcination processes. The introduction of Sn species significantly alters the microstructure of Ni2−xSnx-MOF and Ni2−xSnxP/C. The optimum Ni1.6Sn0.4P/C exhibits 3D (3-dimensional) open flower-like microstructures, which are composed of large quantities of nanorods. As battery-supercapacitor hybrid electrode materials, the as-prepared Ni1.6Sn0.4P/C exhibits an excellent specific capacity of 839.6 C g−1 at the current density of 1 A g−1 and superior capacity retention in a three-electrode system. Moreover, the assembled Ni1.6Sn0.4P/C//AC asymmetric supercapacitor demonstrates a high energy density of 59.3 Wh kg−1 at the power density of 750 W kg−1, and good cycling stability with 92% capacity retention after 5000 cycles at current densities of 10 A g−1. Therefore, the Ni1.6Sn0.4P/C with flower-like microstructures are expected to be an ideal battery-type electrode material for high-performance energy storage devices in the future.