Approaching high-performance electrode materials of ZnCo2S4 nanoparticle wrapped carbon nanotubes for supercapacitors

In this work, CNTs-wrapped ZnCo2S4 nanoparticle composites were constructed by a simple hydrothermal process. This process allows to wrap ZnCo2S4 nanoparticle in an interconnected CNT matrix that combines excellent electronic conductivity with good mechanical stability. The CNTs wrapping suppresses the aggregation of ZnCo2S4 nanoparticle, and assures an effective contact between electrolyte and ZnCo2S4 particles, then promotes rapid ion transportation. Specifically, ZnCo2S4@CNTs (5 wt%) composite shows the highest specific surface area, lowest polarization and the highest reversibility during cycling among all samples. ZnCo2S4@CNTs (0, 2.5, 5 and 10 wt%) electrodes deliver specific capacitances of 360.4, 1012.8, 1190.4 and 1015.6 F g−1 with capacitance retentions of 32.9%, 81.3%, 84.2% and 79.3% at 10 A g−1 after 10,000 cycles. Even at higher current density of 30 A g−1, ZnCo2S4@CNTs (5 wt%) composite also delivers a specific capacitance of about 880 F g−1 with a capacitance retention of 93% after 30,000 cycles, revealing outstanding cycling stability. The above results exhibit that ZnCo2S4@CNTs composites can be promising candidates as electrode materials for pseudocapacitors with excellent electrochemical property in future applications.