Abstract:

Mesoporous α-NiS, Co₃S₄ and CoNi₂S₄ electrode materials were synthesized by a simple one-step hydrothermal method, and their electrochemical properties were investigated. X-ray diffraction and electron microscopy results show that as-obtained mesoporous sulfide electrode materials are assembled by single-phase sulfide nanoparticles and the CoNi₂S₄ electrode materials have the unique structure of ruffle-like microspheres consisting of 2D nanoplates. The binary CoNi₂S₄ electrode exhibits much higher specific capacitance of 1678.3 F/g than that of either Co₃S₄(1532.7 F/g) or α-NiS(787.4 F/g) in 6 mol/L KOH at a scan rate of 5 mV/s, and shows excellent capability retention of 45.8% from 5 mV/s to 100 mV/s, which is ~15% higher than that of α-NiS and Co₃S₄. The excellent cycling stability of binary CoNi₂S₄ electrode is achieved with 96.3% of the initial capacitance over 900 consecutive cycles at 15 A/g. Moreover, the columbic efficiency consistently remains above 94.3% within 900 cycles. The fine specific capacitance and good cycling stability demonstrate that the mesoporous CoNi₂S₄ electrode has potential applications in supercapacitors.

Key words: nickel and cobalt metal sulfide, supercapacitor, rufflelike microsphere, hydrothermal, mesoporous electrode material