Phosphorous-containing oxygen-deficient cobalt molybdate as an advanced electrode material for supercapacitors

Shude Liu, Ying Yin, Dixing Ni, Kwan San Hui, Kwun Nam Hui, Chu-Ying Ouyang, Seong Chan Jun

Research output: Contribution to journalArticlepeer-review

70 Citations (Scopus)
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Abstract

The intrinsically poor electrical conductivity and insufficient number of electrochemically active sites of transition-metal oxides hamper their wide application in high-performance supercapacitors. Herein, we demonstrate an effective strategy of creating phosphorus-containing cobalt molybdate (CoMoO4) with oxygen vacancies (P-CoMoO4-x) on nickel foam for use as a supercapacitor electrode. Experimental analyses and theoretical calculations reveal that the electronic structure of P-CoMoO4-x can be efficiently modulated by incorporating P heteroatoms and O vacancies, thereby simultaneously reducing the energy band gap and increasing electrical conductivity. Moreover, incorporating P into P-CoMoO4-x weakens the Co-O bond energy and induces the low oxidation states of molybdenum species, facilitating surface redox chemistry and improving electrochemical performance. Accordingly, the optimized P-CoMoO4-x electrode exhibits a high specific capacity of 1368 C g−1 at a current density of 2 A g−1, and it retains 95.3% of the initial capacity after 5000 cycles at a high current density of 10 A g−1. An asymmetric supercapacitor assembled with the optimized P-CoMoO4-x as positive electrode and activated carbon as negative electrode delivers a high energy density of 58 W h kg−1 at a power density of 850 W kg−1 as well as achieves excellent cycling lifespan.
Original languageEnglish
Pages (from-to)186-196
Number of pages11
JournalEnergy Storage Materials
Volume19
Early online date30 Oct 2018
DOIs
Publication statusPublished - May 2019

Keywords

  • CoMoO4
  • phosphorus incorporation
  • oxygen vacancy
  • electrochemical performance
  • supercapacitors

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