电解液流速对锌镍单液流电池性能的影响

Effects of Electrolyte Flow Speed on the Performance of Zn-Ni Single Flow Batteries

通过电化学测试、扫描电子显微镜观察和X射线衍射分析研究了电解液流速、电流密度和锌沉积面容量三者关系及对锌镍单液流电池充放电性能和负极锌沉积形貌的影响.结果表明,锌沉积面容量是影响锌镍单液流电池充放电效率和负极锌沉积形貌的最主要因素,电解液流速不宜过高或过低.随着锌沉积面容量的增大,电池的充放电效率和循环稳定性对电流密度的变化更为敏感,适宜的电解液流速范围变窄.锌沉积面容量在25 mA·h/cm2以上,锌沉积皆呈海绵状.在较低锌沉积面容量下,电解液流速也较低时,海绵锌沉积较为均匀致密.而在高的锌沉积面容量下,海绵状锌沉积的团簇和颗粒变大,不均匀性加重,仅在适中的电解液流速(7.1 L/min)下,锌沉积部分致密规整,电池具有较好的充放电性能.

The effects of current density, zinc deposition area capacity and electrolyte flow speed on the per- formance of Zn-Ni single flow batteries and zinc deposition morphology were investigated by electrochemical measurements combined with SEM observation and XRD analysis. The results show that the zinc deposition area capacity is the most important factor which influences the charge-discharge performance of Zn-Ni single flow batteries and zinc deposition morphology. The electrolyte flow speed should be neither high nor low. With the zinc deposition area capacity increasing, the charge-discharge efficiency and the cycling stability of test cells are more sensitive to the change of current density. Meanwhile, the preferable electrolyte flow speed range becomes narrow. The spongy zinc deposition is exhibited at zinc deposition area capacity beyond 25 mA · h/em2. But, at low zinc deposition area capacity and low electrolyte flow speed, the spongy zinc deposition is relatively uniform and compact. While, at higher zinc deposition area capacity, clusters and par- ticles turn into larger and their irregularity is more serious. Only at the moderate electrolyte flow speed of 7. 1 L/min, the zinc deposition is partly compact and regular and the preferable charge-discharge performance of the cell is exhibited.