Research On High-performance Electrode Materials For Nickel-iron Batteries

Nickel-iron batteries,which use nickel-based and iron-based materials as cathode and anode materials and alkaline aqueous solutions as electrolytes,have outstanding advantages of low cost and high safety,and have huge potential for large-scale energy storage applications.However,nickel-iron batteries still face problems such as low capacity,low charging efficiency,and poor cycling stability,which hinder their large-scale application.The main reason for these issues is the characteristics of the electrode materials.Therefore,solving the problems of the electrode materials is of great significance for improving the performance of alkaline batteries and promoting their large-scale application.This thesis aims to address the problems of electrode materials in nickel-iron batteries.Precursors with high yield and easy preparation were chosen,and strategies such as nanocomposite,material modification,and electrode structure optimization were applied to prepare high-performance electrode materials.Applications of these materials in alkaline batteries were also studied.The specific research content and related results are outlined below:（1）Preparation and performance study of high-performance FeS/C nanorod iron anode material based on Fe-MOF material MIL-88A.A large amount of MIL-88A nanorod precursor was synthesized at first.Subsequently,large amount of FeS/C iron anode material was obtained through a polymer wrapping and high-temperature sulfurization process.The preparation process could well maintain the rod-shaped structure of MIL-88A,and carbon-encapsulated FeS nanoparticles loaded onto a porous rod-shaped carbon skeleton doped with N and S was obtained.The high reactivity of FeS and carbon encapsulation can improve its cycling stability,and the unique electrode structure is favorable for the electron and ion transfer in the electrode.Based on the total mass of the composite material,the capacity of the prepared iron anode can reach 208.9m Ah g^-1 at a current density of 1 A g^-1.Moreover,it exhibits excellent Coulomb efficiency,rate performance,and cycle performance,making it an outstanding anode material for alkaline battery.（2）Preparation and application of Ni_0.95Zn_0.05Se cathode material in Nickel-iron batteries.The performance of nickel cathode was improved by preparing Zn-doped selenium compounds.A large amount of Ni_0.95Zn_0.05（OH）₂ nanosheet precursor was prepared using a co-precipitation method,and Ni_0.95Zn_0.05Se layered electrode materials were obtained through a selenization process.Appropriate Zn doping can increase the carrier concentration,promote electron and proton transport,increase crystal defects,improve stability.The lamellar structure of the selenide can enhance the ion and electron transport and improve the electrode kinetics.The specific capacity of the prepared Ni_0.95Zn_0.05Se can reach 270.8 m Ah g^-1(1 A g^-1)with excellent rate performance and can stably cycled for more than 1000 cycles with Coulomb efficiency close to 100%.Furthermore,a high-performance nickel-iron full battery was constructed by matching it with the FeS/C anode material prepared in the previous work.（3）Preparation of integrated Co₂VO₄/NiSe heterojunction cathode material and its application in alkaline batteries.A Co-based carbonate nanorod array was firstly constructed on a nickel foam substrate,which was then transformed into Co₂VO₄/NiSe heterojunction composite material through a one-step hydrothermal reaction.The in-situ growth of the active material on the current collector can accelerate the electron transfer.The dual-metal heterojunction material not only enables multi-component synergistic energy storage but also exhibits faster electrode kinetics and better stability.As a direct electrode,the prepared material has a capacity of 315 m Ah g^-1(1 A g^-1)and exhibits high Coulomb efficiency,rate performance,and cycling stability.Furthermore,a high-performance alkaline full battery was constructed by matching it with FeS/C anode materials.