NiCo-MOF directed NiCoP and coconut shell derived porous carbon as high-performance supercapacitor electrodes

Abstract

Bimetallic mickel/cobalt metal-organic frameworks(MOFs) have showed important applications as supercapacitor electrode materials due to their rich redox active sites, regular pore structure and huge specific surface area. But their specific energy and capacitance are limited. In this paper, a MOFs phosphorization strategy was proposed for preparing high-performance NiCo bimetallic phosphide nanosheets (NiCoP) by simple OH− ion etching and phosphorization. The formed nanosheet structure possesses a huge specific surface area, which is beneficial for the Faraday reaction. The as-prepared Ni1Co1-10P nanosheets present significant synergy among transition metal ions, which contributes to enhanced electrochemical performance. Because of structural and composition advantages, the optimized Ni1Co1-10P nanosheets show a superior specific capacitance (1188.4 F g−1 at 1 A g−1) than corresponding hydroxide (Ni1Co1-OH) and Ni1Co1-MOF precursors. The as-assembled asymmetric supercapacitor (ASC) using Ni1Co1-10P nanomaterial as the positive electrode and coconut shell derived porous carbon (EC) with huge surface area and electric double layer capacitor (EDLC) property as negative electrode delivers a high specific capacitance of 135.5 F g−1 at 1 A g−1 and a maximum energy density of 55.01 Wh kg−1 at 849.94 W kg−1 as well as excellent capacitance retention (86.12 % after 10,000 cycles). Therefore, the prepared Ni1Co1-10P electrode materials have a broad application in high-performance supercapacitors.