A self-supporting nanoflower-like film of 3D walnut shell derived carbon/NiCo2S4 for supercapacitors and zinc-ion batteries with high energy density

Abstract

Nanocomposites with special structures can generally provide more efficient electron and ion transfer kinetics during electrochemical charge storage, resulting in satisfactory energy densities. Herein, we adopted a simple hydrothermal method to prepare a nanoflower-like NiCo2S4 growing on hierarchical porous N, O co-doped walnut shell-derived carbon (10-WSC-N/O@NiCo2S4). Metal ions (Ni2+, Co2+) enhanced the active site to obtain better electrochemical activity, as well as the porous carbon framework helped achieve better ion transport and electron conduction. Importantly, 10-WSC-N/O@NiCo2S4 exhibits 1176 F g−1 at 0.5 A g−1, the prepared 10-WSC-N/O@NiCo2S4//WSC-N/O displays a remarkable energy density of 68.6 Wh kg−1 at 375 W kg−1 and only decreases a 12 % in capacitance after 8000 cycles at 3.0 A g−1. Additionally, the 10-N/O@NiCo2S4//Zn device achieves a high energy density of 88.54 Wh kg−1 at 750 W kg−1. Overall, this work provides an efficient strategy for fabricating high-performance electrode materials.