Construction of CuO/Cu-nanoflowers loaded on chitosan-derived porous carbon for high energy density supercapacitors.

Abstract

Copper oxide (CuO) and copper (Cu) have been viewed as the prospective pseudocapacitive electrode materials for supercapacitors. Nevertheless, the poor electron transfer capacity, loading amount, and cycling stability limit their wide applications, which can be addressed by developing the CuO based heterojunction on conductive carbons. Here, a CuO/Cu@C comprising CuO/Cu nanoflowers and chitosan-derived N-doped porous carbon was compounded by simple mechanical mixing, freeze-drying, and carbonization. The composite heated at 700°C exhibited a high specific capacitance of 2479F/g at 0.5 A/g and excellent cycling stability with capacitance retention of 82.43% after 10 000 charge-discharge cycles. In addition, the asymmetric supercapacitor (ASC), i.e., CuO/Cu@C-700//AC assembled by CuO/Cu@C (as a positive electrode) and activated carbon (AC, as a negative electrode) displayed a great energy density of 76.87Whkg-1 at 374.5Wkg-1 and kept as high as 25.83Whkg-1 even at 14998Wkg-1. Our work provides a new pathway to preparing transition metal oxide-based electrode materials with distinguished electrochemical performances.