The Influence Of Electrode And Electrolytic Additives On Performance Of Anode In Nickel-iron Battery

In recent years, the development of electric vehicles has raised higher requirements on power battery which seems as an energy source of electric vehicles.because of its advantages of high theoretical energy, long cycle life, environment friendly, high safety factor and so on, iron-nickel battery attracts attention again. However, so far the iron electrode of iron-nickel battery still remains several problems such as passivating easily and gassing seriously that need to be resolved. Therefore, this paper will explore from three aspects including the preparation of Fe3O4, electrode additives, electrolyte additive, and aim at solving several problems iron electrode faced with.Iron elcectrode material nano-Fe3O4was synthesized successfully by sedimentation-oxygenation method. It obtained a size of80~100nm and good crystallinity, large electrochemical active surface area and could slow down passivation. The initial discharge capacity of electrode made from this material at0.1C was260mAh/g.A conclusion that NiS exhibited excellent doping performance whatever simply mechanical mixing or making compounds with Fe3O4was obtained by doping metal oxide, metal sulfide and hydrogen absorbing alloy powder in a total of11kinds of additives into iron electrode. Further exploration found that the iron electrode exhibited the best performance when the doping amount of NiS was10%, whose discharge capacity at0.1C was480mAh/g and maintained between450~525mAh/g during50cycles. Moreover doping NiS also improved low temperature performance of b electrode, whose discharge capacity of5℃at0.1C was380mAh/g, whereas which of the controlled electrode was only130mAh/g under the same condition, and the improved percentage was192%compared with the improved percentage. Self-discharge tests showed that doping NiS would not accelerate self-discharge rate of the battery, whose terminal voltage was up to1.35V after six days’ rest. The results of doping with hydrogen storage alloy powder showed that LaNi5could absorb H2generated in charging process, formed LaNi5H6, and involved in the charge-discharge reaction, but played limited role. So LaNi5was not suitable for use in iron-nickel battery as hydrogen absorbing powder.Another conclusion that doping0.03mol/L Na2S into electrolyte could improve high-rate discharge performance of the battery by adding organic and inorganic in total of six kinds of additives to the electrolyte, whose discharge capacity at0.1C was580mAh/g and420mAh/g at1C. In addition, temperature performance of battery was also improved by doping with Na2S, whose discharge capacity of5℃at0.1C was550mAh/g, and650mAh/g at40℃. Self-discharge tests showed that doping Na2S into electrolyte did not cause the self-discharge of battery, the terminal voltage of which was still up to1.33V at the end of six days’ rest. So Na2S was an ideal electrolyte additive.