Study On Improving The Property Of Iron Negative Electrode For Rechargeable Fe-Ni Battery

With the rapid development of the modern industry, there is a crisis of energy shortage of non-renewable resources such as coal, petroleum, and natural gas. In order to alleviate the current crisis, many countries are looking for new pollution-free green energy; Iron-nickel storage battery which was made in 1901 has become a research area in the field of new energy. The lead-acid battery and cadmium nickel battery own the largest share in the battery market; although the materials are poisonous, heavy metal, radioactive substance, i.e. it lead a serious pollution problems to our environment. For iron-nickel electrodes battery, the constituent materials are extensive, nonpolluting, nontoxic and high discharge specific capacity. Therefore, the Iron-nickel battery will replace the lead-acid and cadmium nickel batteries.At present, the iron-nickel battery research work focuses on improving the performance of the negative iron electrode. The research method is to introduce additives in the iron electrode materials and electrolyte for increasing the discharge capacity. In this thesis, the iron negative electrode of the iron-nickel battery is regarded as our study subject. By aiming on the complex production methods of the iron electrode, poor rate discharge performance, and vulnerable performance brought by impurity ions, the study work focuses on improving the discharge capacity of negative electrode of the iron-nickel battery. Firstly, the traditional bag production process of iron negative electrode has been changed to pressure process. Therefore, a complex problem on preparation of the traditional cathode iron is solved. Secondly, to improve the different discharge performances, the iron electrodes are prepared by four kinds of materials such as nickel plated foam nets, steel belt with nickel plated round holes, mesh with compressed nickel plated holes and mesh with expanded holes, respectively. The result shows that the current collector prepared with nickel plated foam nets appears good property in specific capacity and low-rate discharge, and the current collector composed with compressed nickel plated holes behaves well property in high-rate discharge. Thirdly, the premise that discharge capacity is guaranteed, choosing appropriate electrolyte concentration to avoid expanding of iron electrode, three electrolyte types are prepared, experimental results demonstrate that the electrolyte concentration 1.15g/cm³ is better for reducing the iron electrode plate expander. Fourth, choosing new bond and the bond for a long time in the comparative experiment, experimental results demonstrate that measurement with new bond is better than that bond for a long time, and the latter will damage the structure of iron electrode. Lastly, for the possibly damage of impurity ions, CO₃^-2, NO₃^-1, Cl^-1, SO₄^-2 were added into the electrolytes, the effects on the performances of pressed iron electrodes were investigated. The results showed that the impurity ions could decrease the capacities of the pressed iron electrodes and discharge plateau, shorten the cycle life and result high self-discharge rate.