Numerical Simulation For Quinone-Bromide Flow Cell In The Non-Isothermal And Unsteady Process

In recent years, due to the growing energy crisis and the development of modern science, there has been an increasing trend to substituted renewable energy resources for non-renewable resources. However, the use of renewable energy technologies suffers from a major challenge due to their unreliability and the unsteadiness of the renewable energy resource may contribute to serious security risks. Large-scale energy storage technologies can enable load leveling and peak shaving to balance the generation and consumption of power, which can improve the security of the power grid. Consequently, an emphasis has been placed on the development of large-scale energy storage batteries. The limited metallic reserves of conventional inorganic flow batteries prevent it from being relied upon for long-term widespread use.A new type of organic quinone-bromide flow battery was investigated in this work. The flow battery does not rely on metal and unlimited by the metallic reserves. In addition, the organics as electrolyte materials can be improve and modify based on desired performance. In this paper, the model was set up by coupling the three fundamental conservation laws and electrode reaction kinetics through Comsol Multiphysics software. Furthermore, the comparison between computational results and the experimental data proves the validity of this model and the analyses are in the following.The results show that the structure of channel can greatly affect the distribution of the current density as well as the transmission of the electrolyte. Thus, it has a notable effect on the battery performance during the charging or discharging process. Because of the existence of the flow channel structure, the current density is unevenly distributed in the porous electrode. Meanwhile, with the influence of the electrolyte transmission, it will cause the low concentration of reactants, product accumulation and the increment of overpotential. The polarization degree and the corresponding energy loss will advance.Based on the change of process parameters, the model predictions show that using a small current density can decrease the polarization degree and the ohmic potential loss, so it is beneficial to improve the battery performance. However, it will take more time to complete a charge and discharge cycle under the small current density. The flow rate has a small effect on the battery performance at a low applied current density. Increasing the porosity can accelerate the electrochemical reaction as well as can enhance the polarization degree. In a certain temperature range, a higher temperature leads to a better cell performance of the battery, but after reaching a certain temperature, a further increase does not affect cell performance. The internal energy change of the battery is closely related to the current density. Thus, it is critical for large-scale energy storage to incorporate a temperature control system to maximize the economic benefits, depending on the season and current during the charge and discharge processes.The corresponding simulation was set up after the study on our team’s bromine ion crossover experiment for quinone-bromide flow battery. The results show that when the bromine crossover through the three modes of species transport in the membrane, the diffusion is the main way. To reduce the excessive electrolyte solution concentration of the positive electrode side can decrease the bromine crossover amounts and improve the coulombic efficiency. Meanwhile, to increase the flow rate of negative electrolyte solution can also decrease the bromine crossover amounts and improve the coulombic efficiency.