Synthesis of single-phase CuCo2-xNixS4 for high-performance supercapacitors

S Q Gao; P P Zhang; S H Guo; W Q Chen; M Li; F Liu; J P Cheng

doi:10.1016/j.jcis.2019.07.091

Synthesis of single-phase CuCo_2-xNi_xS₄ for high-performance supercapacitors

J Colloid Interface Sci. 2019 Nov 1:555:284-293. doi: 10.1016/j.jcis.2019.07.091. Epub 2019 Jul 30.

Authors

S Q Gao¹, P P Zhang², S H Guo³, W Q Chen¹, M Li⁴, F Liu¹, J P Cheng⁵

Affiliations

¹ State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Zhejiang University, Hangzhou 310027, PR China.
² Ocean College, Zhejiang University, Zhoushan 316021, PR China.
³ State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Zhejiang University, Hangzhou 310027, PR China; Center for High Pressure Science and Technology Advanced Research (HPSTAR), 1690 Cailun Road, Shanghai 201203, PR China.
⁴ Research Institute of Narada Power Source Co., Ltd, Hangzhou 311305, PR China.
⁵ State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Zhejiang University, Hangzhou 310027, PR China. Electronic address: chengjp@zju.edu.cn.

PMID: 31394315
DOI: 10.1016/j.jcis.2019.07.091

Abstract

Developing safe, efficient and environment-friendly energy storage systems continues to inspire researchers to synthesize new electrode materials. Doping or substituting host material by some guest elements has been regarded as an effective way to improve the performance of supercapacitors. In this work, single-phase CuCo_2-xNi_xS₄ materials were synthesized by a facile two-step hydrothermal method, where Co in CuCo₂S₄ was substituted by Ni. Cobalt could be easily substituted with Ni in a rational range to keep its constant phase. But, a high content of Ni resulted in a multi-phase composite. Among a series of CuCo_2-xNi_xS₄ materials with different Ni/Co mole ratios, CuCo_1.25Ni_0.75S₄ material presented a significantly high specific capacitance (647 F g^-1 or 272 C g^-1 at 1 A g^-1) and the best cycling stability (∼98% specific capacitance retention after 10,000 charge-discharge cycles), which was mainly due to the modified composition, specific single phase, higher electroconductivity, more electroactive sites and the synergistic effect between Ni and Co. Moreover, the assembled asymmetric capacitor using CuCo_1.25Ni_0.75S₄ as a positive electrode and activated carbon as a negative electrode delivered a high energy density of 31.8 Wh kg^-1 at the power density of 412.5 W kg^-1. These results demonstrated that ternary metal sulfides of CuCo_2-xNi_xS₄ are promising electrode materials for high-performance supercapacitors.

Keywords: Ni/Co mole ratios; Single phase; Supercapacitor; Synergistic effect; Ternary metal sulfides.