氢溴储能电池结构的优化和运行条件对电池性能的影响

研究了氢溴电池的电池结构、正极氢溴酸和溴电解质浓度、负极的氢气压力、质子交换膜厚度对氢溴电池的性能和电池效率的影响。对氢溴电池结构进行改进，单电池实现了200 mA·cm^-2电流密度恒流充放电，电池库伦效率100%。溴电极电化学反应受浓差极化控制，提高氢溴酸浓度，电池充电性能提高，同时，溴在氢溴酸的溶解度增大，电池放电性能也提高，氢溴酸浓度由0.5 mol·L^-1提高至1 mol·L^-1，电流密度200 mA·cm^-2，电池的能量效率和电压效率提高27.9%。氢溴电池充电过程，降低电池负极氢出压力，有利于提高充电性能，但膜透酸严重，放电过程中最佳的氢出压力是维持氢在碳纸憎水催化层的单层吸附，充放电过程氢出压力均为40.0 kPa，电池的能量效率80.2%。膜厚度与膜电阻极化和膜透酸密切相关，充电过程，膜由50.0 μm降至15.0 μm，膜透酸严重，负极电化学活性比表面积下降，电池充电性能降低。膜厚度对放电性能的影响还与电流密度有关，电流密度较低时，膜透酸造成负极电化学比表面积下降居主导地位，50.0 μm Nafion膜放电性能更高；电流密度超过200 mA·cm^-2时，膜电阻极化居主导电位，15.0 μm Nafion膜性能更高。采用20.0 μm质子交换膜，在200 mA·cm^-2电流密度循环充放电五次，电池的能量效率和电压效率达到85.3%，库伦效率100%。

Hydrogen Bromine Battery Structure Optimization and the Operation Condition Effects on Battery Performance

This paper studies how particular factors affect hydrogen bromine batteries, including the cell structure, the hydrobromic acid and bromine concentrations, the hydrogen pressure and the proton exchange membrane thickness. After the Pt/C hydrophobic catalyst layer was loaded onto the carbon paper, the hydrogen bromine battery worked at 200 mA·cm^-2 current density and the battery Coulombic efficiency was 100%. The bromine electrode electrochemical reaction was controlled by the concentration polarization. The battery performance improved when the hydrobromic acid concentration increased. The bromine solubility also increased at the higher hydrobromic acid concentration and the battery discharge performance improved. When the hydrobromic acid concentration was increased from 0.5 mol·L^-1 to 1 mol·L^-1, the energy efficiency and the voltage efficiency increased by 27.9% at the current density of 200 mA·cm^-2. In the charge process, as the hydrogen pressure was reduced, the battery charging performance improved, but severe membrane acid permeability was observed. In the discharge process, the optimal hydrogen pressure was able to maintain the monolayer hydrogen adsorption on the hydrophobic catalyst layer on the carbon paper. The energy efficiency was 80.2% at 40.0 kPa hydrogen pressure in the charge and discharge processes. In the charge process, the membrane thickness was closely related to the membrane resistance polarization and the membrane acid permeability. After the membrane thickness was reduced from 50.0 to 15.0 μm, acid permeability through the membrane was more severe. This reduced the electrochemical active surface area and a reduction in the battery performance was observed. In the discharge process, the membrane acid permeability was the leading factor at the lower current density; the battery with the 50.0 μm Nafion membrane had a higher discharge performance. As the current density was >200 mA·cm^-2, the membrane polarization resistance was the dominated factor; the battery with the 15.0 μm Nafion membrane had a higher discharge performance. With the 20.0 μm proton exchange membrane, the energy efficiency and voltage efficiency of the hydrogen bromine battery were 85.3% and the Coulombic efficiency was 100% at the current density of 200 mA·cm^-2 with five cycles.