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 language | English |
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Pages (from-to) | 186-196 |
Number of pages | 11 |
Journal | Energy Storage Materials |
Volume | 19 |
Early online date | 30 Oct 2018 |
DOIs | |
Publication status | Published - May 2019 |
Keywords
- CoMoO4
- phosphorus incorporation
- oxygen vacancy
- electrochemical performance
- supercapacitors
Profiles
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Oscar Hui
- School of Engineering - Reader in Energy Storage & Conversion
- Emerging Technologies for Electric Vehicles (EV) - Member
- Energy Materials Laboratory - Member
Person: Research Group Member, Academic, Teaching & Research