Polyethyleneimine-assisted growth of NiCo2S4/Co2C on carbon matrix towards a high-performance supercapacitor electrode

Abstract

Due to the development and production of new materials in the field of supercapacitors (SCs), which have a considerable capacity to store energy, they have become a pressing and indispensable matter in daily life. In this work, the nickel cobalt sulfide/cobalt carbide (NCS/CC) composite is uniformly distributed on the surface of carbon-derived polyethyleneimine (PEI), acting as a template, forming NCS/CC on a carbon matrix (C-NCS/CC). C-NCS/CC was synthesized using a solvothermal approach with PEI as a carbon source, followed by calcination at 400 °C for two hours in the air, and finally by a hydrothermal technique with Na2S as a sulfur source. C-NCS/CC has unique electrochemical energy storage property due to its good conductivity and specialized surface area that facilitates ion transportation. The prepared electrode material, C-NCS/CC, was utilized for SCs, and demonstrated an excellent capacitance of 970 F g−1 (427.5 C g−1) at 1 A g−1. For practical application, a C-NCS/CC//activated carbon (AC) asymmetric device was fabricated using a C-NCS/CC as a positive electrode and commercial AC as a negative electrode. The device displayed a remarkable specific energy of 28 Wh kg−1 at a specific power of 1105 W kg−1 and a current density of 1 A g−1, satisfying capacity retention of 87 % after 5000 cycles, and achieving a coulombic efficiency of 100 %.