Easy-Controlled Vacancy Concentration and Effect on Electrochemical Performance of Co3o4
Alghough it is widely reported that crystal defects are able to enhance catalytic activity in catalysis field, the studies about the influence of defects on electrochemical performance of a electrode material are far fewer than those in catalysis field, and the defect-related electrochemical mechanisms are not fully understood. In this work, the oxygen vacancy concentration is controlled simply by calcining different precursors. The as-obtained Co3O4 samples by cobalt-thiourea coordination compound and cobalt nitrate precursors are named as S1 and S2, respectively. It is found that cobalt-thiourea coordination compound can provide an oxygen-rich skeleton, thus reducing oxygen vacancy of S1. Furthermore, the specific capacitance of S1 (79.5 F g-1) is 12.5 times higher than that of S2 (5.9 F g-1) at 0.2 A g-1. The remarkable higher capacitance is mainly attributed to the appropriate amount of oxygen vacancy of S1. Theory calculations confirm that an appropriate concentration of oxygen vacancy favors the desorption of K+ and the adsorption of OH-, thus accelerating intercalation/de-intercalation of K+ and the kinetics of surface redox reaction. However, excessive oxygen vacancies are disadvantageous to the electrochemical process. Additionally, the S1-based asymmetric supercapacitor (ASC) displays a high energy density of 176 μWh/cm3, a high power density of 218 mW/cm3, and a long cycling life (72.6% capacitance retention after 2500 charge/discharge cycles). The ASC is so flexible that it can be easily assembled in series to drive a light-emitting diode to work. Hence, this study provides a simple, low-cost method for producing high-quality electrode materials on a large scale
Year of publication: |
[2022]
|
---|---|
Authors: | Hao, Weiyi ; Yuan, Chen ; Ruan, Wansheng ; Ma, Ben ; Teng, Fei |
Publisher: |
[S.l.] : SSRN |
Saved in:
freely available
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