Construction of 3D interconnected NiCo2S4/bio-carbon coated Ni foam as binder-free electrode for high-performance supercapacitor

Abstract

Although transition metal hydroxides/sulfides are considered as promising potential electrode materials for supercapacitors due to their excellent electrochemical activity, the low electrical conductivity , easy agglomeration of nanomaterials and poor rate performance seriously hinder their practical applications. Herein, we construct 3D interconnected binder-free electrode NiCo 2 S 4 /bio-carbon coated nickel foam (NiCo 2 S 4 /GRCNF) by growing NiCo 2 S 4 nanosheets on the surface of low-cost and highly conductive GRCNF substrate via a simple hydrothermal reaction followed with subsequent sulfidation. As suggested by systematic characterizations, the advantages of obtained NiCo 2 S 4 /GRCNF include that the ultrathin 3D interconnected network of NiCo 2 S 4 can furnish massive electrochemically active sites for faradic reaction, and the highly conductive GRCNF substrate promotes electron transfer and meanwhile prevents the aggregation of NiCo 2 S 4 nanosheets . With a high specific capacitance of 7.71 F cm −2 at 3 mA cm −2 , NiCo 2 S 4 /GRCNF has a huge application advantage over the contrast samples Ni-Co LDH/NF (3.29 F cm −2 ) and Ni-Co LDH/GRCNF (5.97 F cm −2 ). In addition, NiCo 2 S 4 /GRCNF shows a much higher rate performance (82.1%) than Ni-Co LDH/NF (44.5%) and Ni-Co LDH/GRCNF (66.4%). Furthermore, hybrid supercapacitor NiCo 2 S 4 /GRCNF//GNPC which is assembled with NiCo 2 S 4 /GRCNF as the anode possesses an impressive energy density of 0.429 mWh cm −2 at a power density of 7.023 mW cm −2 and good cycling stability (82.3% over 5000 cycles). The outstanding electrochemical performance of NiCo 2 S 4 /GRCNF suggests that the reported strategy provides new inspiration for the design and preparation of new binder-free composite electrodes for electrochemical energy storage.

Topics & Concepts