Design And Modification Of A New Alkaline Rechargeable Ni/Fe Battery And Their Electrochemical Performances

With the rapid development of global economy,the depletion of fossil fuels and the increasing environmental pollution problems making human urgently need efficient,clean and sustainable energy sources and technologies related to energy conversion and storage.Electric power becomes to be the most important secondary energy,and energy consumption of main play.Electricity from burning coal,solar energy,hydropower,wind power and other energy conversion,and has penetrated into every aspect of human life.With the rapid development of modern industrial and sustained growth of the global population,human demand for energy has increased dramatically,energy storage become more and more important.Therefore,development of low-cost,high efficiency,safety,environment friendly energy storage system is particularly important.The core subject of building high performance energy storage device in water system is high performance electrode materials research and development.Based on the alkaline nickel iron battery as a starting point,the traditional anode materials of iron and nickel anode materials are optimized respectively,and studied their electrochemical properties in alkaline electrolyte,concrete research content is as follows:（1）To address the passivation issue,we put forward a dual modification of Fe₂O₃ nanorod array with an in situ sulfide treatment and a carbon coating.Firstly,in situ sulfide modification avoids any additives,ensuring the sufficiently utilizing of the active materials,and guarantees uniform dispersion of S element on the surface of Fe₂O₃which could enhance the depassivation effect by in situ production of sulfide ions on the Fe₂O₃surface.Secondly,the carbon coating enhance the electric conductivity of the electrode,and what’more,forms a protection shell for the sulfide ions,thus slows the process of the sulfide ions being oxidized at the counter electrode to sulfate.Beneficial from the unique structural design,the obtained Fe₂O₃-S@C electrode shows significant improvements in discharge capacity rate capability as well as cycling stability.（2）In this work,we reported a controllable preparation of nanoporous Ni₃S₂ films by a simple solvothermal-assisted sulfuration of nickel foam.The pore size can be easily adjusted by controlling the sulfuration time.Electrochemical tests show that the specific capacitance and the cycling performance of the Ni₃S₂films were sensitive to their pore size.The Ni₃S₂films with optimal pore size demonstrate a high specific capacitance and excellent cycling stability.An asymmetric supercapacitor by using the optimal Ni₃S₂film as the positive electrode and activated carbon coated on Ni foam as the negative electrode was also successfully assembled.（3）NiCo₂S₄ is generally studied as cathode material for supercapacitors owing to its electrochemical activity in positive voltage region.Here,we demonstrate it can be used as supercapacitor anodes in potential window of-1～0 V in 1 M KOH..Symmetric supercapacitors（SSCs）which are configurated by both Ni Co₂S₄NRAs cathode and anode distinctly extend the working potential window（1.6 V）and deliver high energy density of 55.1 Wh kg^-1and power density of 3200 W kg^-1,respectively.