A carregar...
Publicação
Nickel - 3 Yttria Stabilized Zirconia - Graphite Electrical Energy Storage Device
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 1.17 MB | Adobe PDF |
Orientador(es)
Resumo(s)
A Nickel-3 Yttria Stabilized Zirconia-Graphite Electrical Energy Storage (EES) device was fabricated using porous 3% mol Yttria-Stabilized Zirconia (3YSZ) as the separator and potassium hydroxide (KOH) as the electrolyte. The porous separator was fabricated through uniaxial pressing of 3YSZ nanopowder mixed with solid particles of Poly-vinylidene fluoride (PVDF) with a ratio of 2:1.5, respectively, to obtain maximum open porosity (59%). The resulting pellet was sintered using 2 ºC/min heating ramp (from 25 ºC to 1100 ºC) with a two-hour platform at this same temperature. Chemical exfoliation of graphite powder into graphene was performed mixing graphite powder in 25% water and 75% acetone solution (particle concentration of 3 mg/ml), that undergone a four-hour ultrasonication bath. The liquid phase of this solution was then evaporated at room temperature (RT). In order to determine qualitatively the amount of graphene present in the exfoliated graphite powder obtained, peak intensity ratios of its Raman spectrum were determined (I2D/IG=0.90, ID/IG=0.85), revealing the presence of multilayer graphene. To fabricate the exfoliated graphite electrode, the powder was mixed with a binder consisting of PVDF dissolved in N,N-Dimethylfomammide (DMF) in a proportion of 1:10 w/v, respectively. A ratio of 1:5 exfoliated graphite to binder was used to attain a maximum conductivity of (1.17 ± 0.18) x 103 S/m, a concentration of majority carriers of -5.22 x 1017 cm-2 and a mobility of 1.98 cm2/V∙s, all for a percentage of active material of only 27.93%. The nickel electrode was obtained from a commercial source, being that both electrodes were deposited on opposing sides of the separator by drop casting, and left to dry at RT. The performance of the device was measured by Cyclic Voltammetry (CV), galvanostatic Constant Current Cyclic Charge Discharge (CCCD), Constant Current Discharge (CCD) and Electrochemical Impedance Spectroscopy (EIS), from which it was possible to design an Electrical Equivalent Circuit (EEC) based on the Randles Cell and to determine the Equivalent Series Resistance (ESR), 63.55 Ω ± 8.62 Ω. The analysis of the data allowed to attest the high non-linearity of the device, that demonstrated to have a high capacitance (0.99 Fg-1) and a calculated energy and power densities of 0.31 Wh∙kg-1 and 10.29 μWh cm-2.
Descrição
Palavras-chave
Electrical Energy Storage Supercapacitors Porous 3% mol Yttria-Stabilized Zirconia (3YSZ) Chemical exfoliation of graphite Nickel electrode