Study On Anode And Electrolyte Additives For Nickel-iron Batteries

With the development of electric energy vehicles,the requirements for secondary batteries are gradually increasing.Nickel-iron batteries have received extensive attention based on their advantages such as high theoretical specific capacity,long cycle life,good overcharge resistance and environmental protection.Many scholars have conducted in depth research on electrodes and electrolytes for a long time.In this paper,we select ferric oxide as iron anode material,which is low-cost and easily prepared.To improve some problems of electrode passivation and hydrogen evolution.the prepare method of ferric oxide,the electrolyte concentration and formulation,the electrode additive?metal sulfide?and the electrolyte additive?thioalcohol?were studiedFerric oxide prepared by sol-gel method,roasting method,and post-processing of industrial materials were characterized by scanning electron microscope,energy spectroscopy system,and X-ray diffraction analyzer.The results show that the structure of ferric oxide prepared by different methods and at different temperatures is corresponding to the same?crystal form.Fe₂O₃ prepared by sol-gel method at 800?or calcination method at 850?and 900?,they all have good discharge performance,and superior to the discharge performance of calcined industrial Fe₂O₃.Meanwhile,the better the discharge performance,the thinner the structure is.In this paper,LiOH and Na₂S are added to the electrolyte to increase the discharge specific capacity,and the LAND battery test system was used to test the electrochemical performance of single cell.The results show that electrolyte with Li?S has the best discharge performance,electrolyte with Li is better than the last.Electrolyte with LiOH and Na₂S its specific capacity can reach to 490 mAh/g and can be stable for a long time at 480 mAh/g.In this paper,metal sulfides are added to the electrodes to increase the discharge specific capacity,and the LAND battery test system was used to test the electrochemical performance of single cell.The results show that several kinds of sulfides,such as NiS,FeS,Bi₂S₃ and FeS₂ can improve the specific capacity.NiS is the best of them all,and it can reach high capacity at a small amount,which can save the cost.Bi₂S₃ and FeS can reach better discharge performance when the amount is large.Considering of mix the additives,we found that the increase of battery discharge is most obvious when compound with 10%NiS+10%FeS,it can reach to 340 mAh/g and stable at 300mAh/g.The compound addition of 5%NiS+15%FeS is the next.In this paper,different kinds of thioalcohol are added to the electrolyte to decrease the self-discharge of the battery,and the LAND battery test system was used to test the electrochemical performance of single cell.The results show that in low concentration LiOH,all thioalcohol can improve the specific capacity and decrease self-discharge,and the decrease performances are similar.However,in high concentration LiOH,only1-Dodecanethiol can increase the specific capacity,but it will promote self-discharge,the less the better.1-Octanethiol and 3,6-Dioxa-1,8-Octanedithiol can both inhibit self-discharge,but 3,6-Dioxa-1,8-Octanedithiol will decrease the capacity,so it's not appropriate to high concentration LiOH.The dosage should be controlled as needed during use.