Figure 3 - uploaded by Shi Yixiang
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Performance characteristic of liquid Sb anode fuel cell in the battery mode (a) polarization curves; (b) EIS curve.
Source publication
A liquid Sb anode direct carbon fuel cell (DCFC) was fabricated on a smooth single crystal YSZ electrolyte (Ra=0.67nm) substrate with porous Pt cathode to reveal the intrinsic reaction kinetics of electrochemical oxidation of liquid Sb in battery mode and the reduction characteristic of Sb2O3 in carbon fuel mode using Taixi de-ash coal. The reducti...
Contexts in source publication
Context 1
... Figure 3(a), the anode, cathode and ohmic polarizations of the cell are also estimated. The polarization of the Pt cathode used in this study was characterized separately using a symmetrical cell experimental set up. It can be seen that the cathode polarization can almost be neglected compared with anode and ohmic polarizations. It is also noteworthy that the cell performance in Figure 3 was achieved by using a thick single crystal electrolyte-supported button cell. If the electrolyte thickness is further reduced by using cathode supported cell or by using novel materials, the electrolyte polarization will be greatly reduced. It seems that the major portion of the polarization resistance in the impedance of the liquid Sb anode SOFC is due to the liquid anode polarization. And it can be deduced that the ohmic polarization and the cathode polarization were the same in both the forward and backward scanning IV curves, and the anode polarization of the backward IV testing was only about half of the forward anode polarization. The anode polarization reduction after discharging process may be ascribed to the production of liquid Sb 2 O 3 at the liquid Sb/electrolyte interface, which can enhance the oxygen ions transport to liquid Sb, and effectively extend the electrochemical reaction area by forming liquid Sb and Sb 2 O 3 ...
Context 2
... Figure 3(a), the anode, cathode and ohmic polarizations of the cell are also estimated. The polarization of the Pt cathode used in this study was characterized separately using a symmetrical cell experimental set up. It can be seen that the cathode polarization can almost be neglected compared with anode and ohmic polarizations. It is also noteworthy that the cell performance in Figure 3 was achieved by using a thick single crystal electrolyte-supported button cell. If the electrolyte thickness is further reduced by using cathode supported cell or by using novel materials, the electrolyte polarization will be greatly reduced. It seems that the major portion of the polarization resistance in the impedance of the liquid Sb anode SOFC is due to the liquid anode polarization. And it can be deduced that the ohmic polarization and the cathode polarization were the same in both the forward and backward scanning IV curves, and the anode polarization of the backward IV testing was only about half of the forward anode polarization. The anode polarization reduction after discharging process may be ascribed to the production of liquid Sb 2 O 3 at the liquid Sb/electrolyte interface, which can enhance the oxygen ions transport to liquid Sb, and effectively extend the electrochemical reaction area by forming liquid Sb and Sb 2 O 3 ...
Context 3
... Sb Anode Performance in the Battery Mode Figure 3 shows the IV curves and EIS spectra of liquid Sb anode fuel cell in the battery mode. The open circuit voltage (OCV) of liquid Sb anode was 0.750V, compared to a theoretical OCV of 0.738V (assuming that the activities of liquid Sb and Sb 2 O 3 are both equal to 1) at 1073K. The current density was measured by decreasing the cell operating voltage from OCV at the rate of 10mV s -1 , which was called the forward IV curve in this study. When the cell potential reached zero, the potential was ramped up at the rate of 10mV s -1 to OCV, which was called backward IV curve in this study. The IV curve showed that when the cell working voltage was lower than 0.68V, the forward scanning current density was lower than that of the backward scanning current density at the same working voltage. The maximum voltage difference between the forward and backward current density was around 91A m -2 at 0.4V. When the cell voltage was lower than 0.4V, the forward IV curve appeared to be linear with a slope of 20 cm 2 , which demonstrates that the area specific resistance (ASR) of the cell was independent of current density in this region. On the other hand, for the backward IV curve, when the working voltage was higher than 0.4V, the backward IV curve appeared to be linear with a slope of 14 cm 2 , which demonstrates that the cell performance turns better in the cell discharging processes. It should be noted that the OCV decreases to 0.70V from 0.75V for the backward scanning IV curve, which is probably due to the accumulation of reacting product Sb 2 O 3 at the interface of liquid anode and ...
Citations
... 11 Ability to operate using solid fuel directly, improved anode tolerance to impurities and fuel flexibility are important advantages compared with conventional SOFCs. [12][13][14] The robustness of liquid metal anode SOFCs is inherently enhanced by the fact that the anode is able to act as an additional energy source (electrochemical oxidation of the anode itself), the so-called "battery" effect, which can be beneficial in case of interruption of fuel supply. 15,16 Technological developments of these SOFC systems operating with various anode metals have been reviewed recently. ...
Liquid metal anode (LMA) solid oxide fuel cells (SOFCs) are a promising type of high temperature fuel cell suitable for the direct oxidation of gaseous or solid fuel. Depending upon the operating conditions they can be run in four different modes. In this first of a series of studies concerning the mechanism of reaction and species transport in LMA SOFCs, the oxidation of hydrogen fuel in a liquid tin anode has been investigated. An electrochemical model is developed based upon fast dissolution of hydrogen in a molten tin anode, slow, rate-determining homogeneous reaction of hydrogen with oxygen dissolved in the liquid tin, followed by anodic oxygen injection under diffusion control to replace the oxygen removed by reaction (so-called Chemical-Electrochemical mode or CE mode). Experimentally-generated data are used to validate the model. The model has introduced a new key parameter, z¯ which takes a value between zero and unity; its value is determined by geometric and convective factors in the cell as well as the partial pressure of the supplied hydrogen fuel. Current output of the cell is proportional to the value of z
... Taixi de-ash coal which has a particle size of 50-100 lm and ash 133 takes 2.56 wt% [10], will serve as the solid carbon fuel in the exper- During this period, the metallic Sb is oxidized to Sb 2 O 3 : ...
A methane-fuelled solid oxide fuel cell (SOFC) with molten tin anode (Sn(l)-SOFC) is designed, fabricated, demonstrated and characterized. This SOFC design incorporates molten tin contained in an alumina crucible as anode for the solution of oxygen atoms transported to an anode | Yttria stabilized Zirconia (YSZ) electrolyte interface and provides bubble | molten tin interfaces for the reaction of methane with oxygen atoms during cell operation. A peak power density of ca. 100 W m⁻² at a current density of 222 A m⁻² and potential difference of 0.45 V is obtained for this methane-fuelled Sn(l)-SOFC at 850 °C. The ohmic and non-ohmic impedance are ca. 16.72 and 3.36 Ω cm², respectively. Ohmic potential losses control the reactor performance, with about ca. 59% of those arising from the inherent difficulty in achieving a low resistance contact at the silver wire (silver wool) current collector | Lanthanum strontium manganite cathode interface. Improved performance is achievable by eliminating contact resistance, utilising a molten metal/alloy with greater activity for methane oxidation and operating the cell at higher temperatures. The reaction of methane at bubble | molten tin interface involves its coupling in addition to oxidation, to produce steam, carbon dioxide, hydrogen, ethane and ethylene.
A direct carbon fuel cell unit is assembled based on an electrolyte supported tubular SOFC (Solid Oxide Fuel Cell). The system adopts liquid Antimony (Sb) as anode and is operated at 800°C to evaluate the electrochemical performance of the direct carbon fuel cell. Fluidization gas is introduced into the fuel cell and the liquid Sb anode works under two types of working conditions: (1) fixed bed operation and (2) fluidized bed operation. The effects of fluidization state on fuel cell performance are investigated. De-ash coal is introduced into the liquid anode chamber in both of these two operating modes. The experimental results indicates that the fuel cell performance can be promoted by coal addition and the fuel supplied by fluidized bed exhibits better performance than that by fixed bed. The experimental result approves the potential of continuous operation of the direct carbon fuel cell unit.
A bench scale direct carbon fuel cell unit was assembled based on an electrolyte supported tubular SOFC. The system adopted liquid Sb as anode and was operated at 800°C to evaluate the electrochemical performance of the direct carbon fuel cell. Fluidization gas was introduced into the fuel cell and the liquid Sb anode worked under two working conditions: fixed bed and fluidized bed, and the effects of fluidization on fuel cell performance were investigated. De-ash coal was also introduced into anode chamber in both of these two ways, the fuel cell performance was promoted by coal addition and fuel supplied by fluidized bed exhibited better performance. The experimental results also showed the potential of continuous operation of the direct carbon fuel cell system.
