Enhancing Capacitance of Nickel Cobalt Chalcogenide via Interface Structural Design

Fei Lu; Min Zhou; Kun Su; Tao Ye; Yijun Yang; Tran Dai Lam; Yoshio Bando; Xi Wang

doi:10.1021/acsami.8b19035

Enhancing Capacitance of Nickel Cobalt Chalcogenide via Interface Structural Design

ACS Appl Mater Interfaces. 2019 Jan 16;11(2):2082-2092. doi: 10.1021/acsami.8b19035. Epub 2019 Jan 7.

Authors

Fei Lu¹, Min Zhou², Kun Su³, Tao Ye¹, Yijun Yang¹, Tran Dai Lam⁴, Yoshio Bando^{5

6}, Xi Wang^{1

5}

Affiliations

¹ Key Laboratory of Luminescence and Optical Information, Ministry of Education, Department of Physics, School of Science , Beijing Jiaotong University , Beijing 100044 , P. R. China.
² College of Physical Science and Technology, Institute of Optoelectronic Technology , Yangzhou University , Yangzhou 225002 , P. R. China.
³ Baotou Medical College , Inner Mongolia 014000 , P. R. China.
⁴ Institute of Tropical Technology , Graduate University of Science and Technology, Vietnam Academy of of Science and Technology , 18 Hoang Quoc Viet Road , Hanoi , Viet Nam.
⁵ Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Chemical Engineering and Technology , Tianjin University and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Tianjin 300072 , P. R. China.
⁶ International Center for Young Scientists (ICYS) & International Center for Materials Nanoarchitectonics (MANA) , National Institute for Materials Science (NIMS) , Namiki 1-1 , Tsukuba , Ibaraki 305-0044 , Japan.

PMID: 30571918
DOI: 10.1021/acsami.8b19035

Abstract

Spinel NiCo₂X₄ (X = O or S), comprising two geometrical cobalt ions, Co²⁺ in the tetrahedral site (Co²⁺_Td) and Co³⁺ in the octahedral site (Co³⁺_Oh), has been widely evaluated as a promising pseudocapacitor electrode material. Previous literature mainly demonstrated that much higher specific capacitance of NiCo₂S₄ than that of NiCo₂O₄ was ascribed to the higher electronic conductivity. However, we argue that only a small amount of capacitance can be induced by the electronic conductivity, while the significance of electrochemical active species in these system has long been ignored. Here, we propose that geometrical-site-dependent pseudocapacitive activity will generate enhanced specific capacitance through the interface structural design. It reveals that specific capacitance of NiCo₂S₄ (1862 F g^-1 at 4 A g^-1) is 50% higher than that of NiCo₂O₄ (1230 F g^-1 at 4 A g^-1), which is derived from the designed increase of Co²⁺_Td ions (cobalt ions in the tetrahedral site) in NiCo₂S₄. These results have significant implications for the design and optimization of the electrochemical properties of transition-metal-based pseudocapacitors.

Keywords: all-solid-state asymmetric supercapacitor; geometrical-site dependence; interface structural design; nickel cobalt chalcogenide; pseudocapacitance.