NiCo2S4 on yeast-templated porous hollow carbon spheres for supercapacitors
Xueying Yang, Cuili Xiang, Yongjin Zou, Fen Xu, Xiaoqi Mao, Xuebu Hu, Jian Zhang, Lixian Sun
Abstract
Biological templates have unique structures, which are promising as a carbon source for electrode materials in energy storage devices. Yeast, a type of single-celled fungus widely available in nature possesses a unique elliptical structure and could be an ideal candidate for excellent performance supercapacitor electrode materials. In this work, we used a self-template technique to synthesize hollow carbon spheres using yeast cells as the carbon source (YC). NiCo2S4 nanosheets were further grown on the YC surface by hydrothermal synthesis. The functional groups on the YC facilitate the adsorption of the metal ions, which enables strong anchoring of the NiCo2S4 nanosheets. The YC/NiCo2S4 composite exhibits great electrochemical performance, showing a specific capacitance of 747 F g−1 at 1 A g−1. Furthermore, a device composed of an YC/NiCo2S4 positive electrode and an activated carbon negative electrode shows a maximum energy density of 43.7 Wh kg−1 at 400 W kg−1. Considering the low environmental impact of preparing the yeast-derived material and the outstanding performance of YC/NiCo2S4, the composite is a promising candidate for use in energy storage devices.