Study On Synthesis And Properties Of A New Type Of Iron Anode Material For Alkaline Secondary Battery

Nowadays,with the increasing of energy exhaustion and environment pollution,green secondary batteries as a new and efficient energy device has gained increasing attention.Because of its excellent cycle performance,low manufacturing cost and friendly environment,the iron nickel secondly battery is considered as a more competitive chemical power source in the future.But it has many disadvantages,such as low charge efficiency,easy passivation,serious gas evolution,self discharge,high rate performance and so on.Therefore,the large-scale commercial production is restricted to a certain extent.Aiming at the shortcomings of the iron nickel battery,this paper mainly carried out the following work:?1?FeS anchored reduced graphene oxide nanosheets as advanced anode material with superior high-rate performance for alkaline secondary batteries:A new nanocomposite formulation of the iron-based anode for alkaline secondary batteries is proposed.For the first time,FeS nanoparticles anchored on reduced graphene oxide?RGO?nanosheets are synthesized via a facile,environmentally friendly direct-precipitation approach.In this nanocomposite,FeS nanoparticles are anchored uniformly and tightly on the surface of RGO nanosheets.As an alkaline battery anode,the FeS@RGO electrode delivers a superior high-rate charge/discharge capability and outstanding cycling stability,even at a condition without any conductive additives and a high electrode loading of ⁴0 mg cm-2.At high charge/discharge rates of 5C,10 C and 20C?6000 mA g-1?,the FeS@RGO electrode presents a specific capacity of ²88,258 and 220 mAh g-1,respectively.Moreover,the FeS@RGO electrode exhibits an admirable long cycling stability with a superior capacity retention of 87.6% for 300 cycles at a charge/discharge rate of 2C.The excellent electrochemical properties of the FeS@RGO electrode can be stemmed from the high specific surface area,peculiar electric conductivity and robust sheet-anchored structure of the FeS@RGO nanocomposite.By virtue of its superior fast charge/discharge properties,the FeS@RGO nanocomposite is suitable as an advanced anode material for high-performance alkaline secondary batteries.?2?Synthesis of novel spherical Fe₃O₄@Ni₃S₂ composite as improved anode material for rechargeable nickel-iron batteries:Fe₃O₄@Ni₃S₂ microspheres proposed as a novel alkaline anode material have been successfully fabricated through a facile three-step process for the first time.In this composite,Ni₃S₂ nanoparticles are coated tightly on the surface of Fe₃O₄ microspheres.Compared with the pure Fe₃O₄ and Fe₃O₄@NiO microspheres,the proposed Fe₃O₄@Ni₃S₂ delivers a significantly improved high-rate performance and enhanced cycling stability.At a high discharge rate of 1200 mA g-1,the specific capacity of the Fe₃O₄@Ni₃S₂ is ⁴81.2 mAh g-1 in comparison with ⁸3.7 mAh g-1 for the pure Fe₃O₄.After 100 cycles at 120 mA g-1,the Fe₃O₄@Ni₃S₂ can achieve a capacity retention of 95.1%,while the value for the pure Fe₃O₄ electrode is only 52.5%.The favorable electrochemical performance of the Fe₃O₄@Ni₃S₂ is mainly attributed to the beneficial impact of Ni₃S₂.The Ni₃S₂ layer as a useful additive is significantly conducive to lessening the formation of Fe?OH?2 passivation layer,enhancing the electronic conductivity,improving the reaction reversibility and suppressing the hydrogen evolution reaction of the alkaline iron anode.Owing to its outstanding electrochemical properties,we believe that the novel Fe₃O₄@Ni₃S₂ composite is potentially a promising candidate for anode material of alkaline iron-based batteries.?3?Synthesis of the NiS as the additive with influence on the nickel-iron batteries:Firstly,the NiS was synthesized by L-cysteine assisted method,and NiS was used as the additive in the anode material of iron-nickel secondary battery.Compared with the Fe₃O₄ electrode,add NiS electrode delivers a excellent high-rate performance and enhanced cycling stability,especially the addition of 10% NiS.At a high discharge rate of 6000 mA g-1,the specific capacity of the addition of 10% NiS is ³52.1 mAh g-1,After 100 cycles at 600 mA g-1,the capacity still remains406.2 mAh g-1,showing an attractive capacity retention of 80.3%.The results show that the introduction of S2-can inhibit the occurrence of the hydrogen evolution reaction and successful suppression of the formation of insulating Fe?OH?2 layer.So as to improve the high rate performance of iron anode.