Hierarchical honeycomb-like networks of CuCo–P@Ni(OH)2 nanosheet arrays enabling high-performance hybrid supercapacitors

Abstract

Abstract Transition metal phosphides (TMPs) are conceived as an emerging class of battery-type materials promising for hybrid supercapacitors (HSCs) because of their intrinsically excellent electrical conductivity as well as high theoretical capacity. However, their practical use has been largely restricted due to their interior rate capability and relatively poor cycling stability. In this work, we demonstrate that by introducing a suitable amount of Cu metal ions into the Co–P matrix and depositing Ni(OH)2 shell layers, the integrated honeycomb-like nanosheet arrays of Cu0.5Co0.5-P@Ni(OH)2 supported on carbon textiles with delicately designed composition and structure can achieve an extraordinary specific capacity of 230.6 mAh/g at a current density of 2 mA/cm2. The HSC device assembled by employing Cu0.5Co0.5-P@Ni(OH)2 as the cathode and activated carbon as the anode exhibits a high energy density of 40.0 Wh/kg at 319.6 W/kg and demonstrates good capacity retention up to 6000 cycles. These results present an efficient and feasible strategy for developing new battery-type electrodes based on TMPs for energy storage and conversion systems.