科研之友
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摘要
Zinc-air battery is a high-power electrochemical system. Experimental data indicate that material usage decreases significantly with increasing applied current density. A one-dimensional mathematical model was established to simulate the discharge process of a high-power zinc electrode working under high current density conditions. Variable distributions within the electrode such as ionic concentrations, transfer current density, electrode porosity, and volume fraction of solid zinc oxide were predicted based on numerical solutions. The results demonstrate that the limitation of the mass transfer process by precipitation of solid zinc oxide is the main factor causing electrode failure. The precipitation time of solid zinc oxide and its concentrated distribution area have significant impacts on the electrode performance. The limitation of the mass transfer process is greatly aggravated if the volume fraction of zinc oxide exceeds specific values within a small range, approximately 30% - 35%. The optimal designs of zinc electrodes were discussed. The numerical results indicate that high-power electrodes with higher ionic conductivities and porosities behave better. However, the most important requirement is to maintain a relatively high concentration of hydroxyl ions. For enclosed electrodes, infusion is an effective method, whereas an ideal design would consist of an open system with a circulating electrolyte, such as fluidized bed electrolyte.
- 出版日期2013-9
- 单位中国科学技术大学
