Rational design of cobalt-nickel double hydroxides for flexible asymmetric supercapacitor with improved electrochemical performance

Yatao Wu; Hao Chen; Yingzhuo Lu; Jin Yang; Xinqiang Zhu; Yu Zheng; Gaobo Lou; Yitian Wu; Qiang Wu; Zhehong Shen; Zhenghui Pan

doi:10.1016/j.jcis.2020.08.013

Rational design of cobalt-nickel double hydroxides for flexible asymmetric supercapacitor with improved electrochemical performance

J Colloid Interface Sci. 2021 Jan 1;581(Pt B):455-464. doi: 10.1016/j.jcis.2020.08.013. Epub 2020 Aug 6.

Authors

Yatao Wu¹, Hao Chen², Yingzhuo Lu¹, Jin Yang¹, Xinqiang Zhu¹, Yu Zheng¹, Gaobo Lou¹, Yitian Wu¹, Qiang Wu¹, Zhehong Shen³, Zhenghui Pan⁴

Affiliations

¹ School of Engineering, Zhejiang A&F University, Hangzhou 311300, PR China.
² School of Engineering, Zhejiang A&F University, Hangzhou 311300, PR China; School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, PR China. Electronic address: haochen@zafu.edu.cn.
³ School of Engineering, Zhejiang A&F University, Hangzhou 311300, PR China. Electronic address: zhehongshen@zafu.edu.cn.
⁴ Department of Materials Science and Engineering, National University of Singapore, 117574 Singapore, Singapore. Electronic address: msepz@nus.edu.sg.

PMID: 32805666
DOI: 10.1016/j.jcis.2020.08.013

Abstract

Rational design of micro-nano morphology and suitable crystalline structure are highly desired for metal hydroxides to achieve overall high-performance in the advanced electrodes for flexible supercapacitors. Herein, a novel wisteria flower-like microstructure of cobalt-nickel double hydroxide (CoNi-DH) is successfully constructed on carbon cloth (CC) using an in-situ hydrolysis-induced exchange process between hydroxide ions and organic ligands of the Co-MOF in four different kinds of solutions containing Ni²⁺. The as-prepared wisteria flower-like microstructure grown on CC shows vertically aligned arrays with high specific area and abundant active sites, which not only guarantee the CoNi-DH active materials to be thoroughly exposed in the electrolyte, resulting in highly effective pseudocapacitive energy storage, but also are beneficial to rapid and reversible redox kinetics and thus give rise to high-rate capability. In addition, compared to Ni(NO₃)₂, NiCl₂, and Ni(CH₃COO)₂ solutions, the Ni₂SO₄ solution is found to facilitate the formation of the most regular morphology and the largest interlayer spacing on (003) plane of the layered nickel hydroxide phase in the resultant CoNi-DH. As a result, the optimal CoNi-DH-S@CC (CoNi-DH prepared in Ni₂SO₄) serves as an advanced electrode to show high-rate capability (only 13% C_s decay after a 15-fold current elevation) and a superior specific capacity (C_s) of 929.4 C g^-1, which remarkably exceeds those of CoNi-DH-N (823.1 C g^-1, in Ni(NO₃)₂), CoNi-DH-Cl (798.4 C g^-1, in NiCl₂), CoNi-DH-C (803.8 C g^-1, in Ni(CH₃COO)₂), and other similar metal hydroxides. Moreover, with this CoNi-DH-S electrode as the positive electrode, the as-prepared asymmetric supercapacitor (ASC) delivers an impressive capacity of 204.8 C g^-1, a superior energy density of 42.5 Wh kg^-1, and satisfactory cycle life (81.5% reservation after 7500 cycles). As a proof-of-concept application, a quasi-solid-state ASC is further successfully fabricated based on the CoNi-DH-S electrode to exhibit encouraging application potential.

Keywords: Cobalt–nickel double hydroxide; Flexible electrode; High-rate capability; Supercapacitor; Wisteria flower-like.