Confined growth of uniformly dispersed NiCo₂S₄ nanoparticles on nitrogen-doped carbon nanofibers for high-performance asymmetric supercapacitors

Confined growth of uniformly dispersed NiCo₂S₄ nanoparticles on nitrogen-doped carbon nanofibers for high-performance asymmetric supercapacitors. Xueliang Ning, Fei Li, Yu Zhou, Yue-E Miao*, Chun Wei, Tianxi Liu*. Chemical Engineering Journal 2018, 328, 599-608.

To pursue high-performance energy storage devices with both high energy density and power density, nitrogen-doped carbon nanofibers (CBC-N) derived from bacterial cellulose are used both as a threedimensional template for space-confined hydrothermal growth of NiCo₂S₄, and as the highly conductive negative electrode material for asymmetric supercapacitor assembly. Notably, uniformly dispersed NiCo₂S₄ nanoparticles with only 3–5 nm are successfully immobilized on the surface of CBC-N fibers to form the CBC-N@NiNiCo₂S₄ composite, which effectively prevents the severe aggregation of NiCo₂S₄ nanoparticles and fully utilizes the outstanding electrochemical activity and capacity of NiNiCo2S4as the pseudocapacitive electrode material. Benefiting from the conductive CBC-N fiber template with hierarchical architectures and its coupling with uniformly dispersed NiCo₂S₄ nanoparticles, the CBCN@NiCo₂S₄ composite exhibits high capacitance of 1078 F g^-1 at 1 A g^-1 and excellent capacity retention of 94.6% (918.5 F g^-1 at 5 A g^-1). Furthermore, the asymmetric supercapacitor demonstrates high energy density of 42.6 Wh kg^-1 at power density of 1500 W kg1, and long-term cycling stability of 96.8% retention after 5000 cycles. Therefore, this work provides a new strategy to develop biomass-derived highperformance electrode materials for potential applications in supercapacitors.